Author Topic: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers  (Read 1284 times)

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Online Pdb88

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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #15 on: April 01, 2017, 04:10:02 AM »
In response to 2397 (whose response I find problematic as an example of the conflation of AGW with other widespread environmental and societal issues across the globe)

What other scenarios are there regarding refugees and climate change?
https://en.wikipedia.org/wiki/Representative_Concentration_Pathways
There are a number of scenarios as released by the IPCC - each without any probabilities attached as the IPCC has never published this information (to my knowledge), the most extreme scenario, known as RCP8.5 is the one most discussed (is that a 1/10 chance, 1/100 chance or 1/1,000,000 chance?) - these are important issues and should be discussed in conjunction with the negative effects.


This is a quote from the executive summary of the 5th IPCC report:
"Improve methods to quantify uncertainties of climate projections and scenarios, including development and exploration of long-term ensemble simulations using complex models. The climate system is a coupled non-linear chaotic system, and therefore the long-term prediction of future climate states is not possible. Rather the focus must be upon the prediction of the probability distribution of the system's future possible states by the generation of ensembles of model solutions. Addressing adequately the statistical nature of climate is computationally intensive and requires the application of new methods of model diagnosis, but such statistical information is essential."
https://www.ipcc.ch/ipccreports/tar/wg1/501.htm

So the IPCC state that long term climate states are unknowable and that only knowledge of the probability distribution of scenarios possible (but not yet achieved) yet I often hear in the news media and in popular culture the meme that we somehow have a quantified understanding of the risk distribution (like some stochastic distribution used to analyse Actuarlal risk for human disease over a large population where there can be an estimate of the chance of heart disease or colon cancer for a given age, gender and ethnicity - unfortunately we only have one Earth so it seems like building such a model would be difficult unless it could be created from some first principles - have they solved the Navier-Stokes model yet??).

Conditions are pretty poor in parts of the world, and the populations are under significant strain. I'm not seeing what kind of changes climate change can cause that are going to be improve their conditions, especially since the areas where most of the vulnerable populations live are in the center 50% of the planet around the equator, which is already plenty warm. Are you expecting Russia to be capable of supporting billions of people?
There are a number of issues around the world (primarily due to corruption and religious or tribal tensions); for example Singapore has little of the issues you mention although it has a high average temperature); I'm sure global warming will be beneficial to Russia as a whole (which is 1/8th of the land of the Earth).

In countries like Brazil and Indonesia, there are major problems with people burning down forests to clear more land for farms. We're already using all the land we can, and we rely on significant technological advances to keep up with growing needs. If existing farms get damaged from changes in temperature, where are we going to move all that production to, and what will that mean for the remaining natural environment of the planet? Do we expect it to swap to where we used to have farms? How much time will that take?
These are all difficult questions to answer - deforestation is an issue entirely distinct from AGW but luckily if global greening continues it will counteract the land clearing (although, obviously, will not help with biodiversity or local issues). I suppose in general that is an issue with overpopulation (another assumption in the IPCC scenarios) that is another problematic issue but the hope is as urbanisation occurs the family size will drop and the rate of growth of world population with it.
« Last Edit: April 01, 2017, 07:53:35 AM by Pdb88 »
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Offline murraybiscuit

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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #16 on: April 01, 2017, 12:02:03 PM »
Those posts are too long for me to read. I don't follow AGW much because of these kind of time sinks. My lay thoughts on things:

1. I don't think it's controversial that the planet will get greener. Interpreting greener as beneficial is problematic. We are part of a broader ecosystem. I prefer my ecosystems as they are. It took milennia to get there after all.

2. The short term gain of greenness doesn't really address the other long-term detrimental effects. If you're hoping that vegetation becomes a natural response to the carbon imbalance, I'd have to ask whether that response will be proportionate and sufficient. That's a big gamble in my books. In this wager, there's a lot to lose.
« Last Edit: April 01, 2017, 12:04:09 PM by murraybiscuit »

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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #17 on: April 01, 2017, 05:57:42 PM »
As the IPCC states "[t]he climate system is a coupled non-linear chaotic system" meaning prediction is difficult even without the uncertainty of future technology and human actions. My main concern is the public discussion seems to assume a far greater certainty than the IPCC (or any other expert I"m aware of) is claiming.

The precautionary principle is laudable, however, risk must at the very least look at both severity and likelihood. There are all sorts of risks that are real and severe yet are so unlikely we mostly ignore or spend very few resources mitigating.

One of the more obvious confusions is that a larger value in prediction will have a larger variance in its distribution (the same reason why high inflation is so damaging - it's the uncertainty about the future rather than the inflation itself): if we look at a distribution of models:



It appears that the red (RCP8.5) is much more likely because it has a larger variation in outcomes - when it could be all outcomes are equally likely or even (as I believe the case to be) RCP8.5 is the least likely scenario (not to mention the inherent difficulty in modelling climate centuries in advance - how well would we have modelled the climate from 1700 to 200?).

If there were a rational appraisal of our limited resources and competing interests it may not be clear that money spent on carbon abatement is the most useful.

http://data.myworld2015.org/

In fact the UN survey placed Climate Change action as the least important of the 16 priorities listed.

If the effects of AGW are unclear (as the IPCC states they are) and that there are inbuilt negative feedback systems in the world (global greening as well as greater bioavailability of Iron in the Oceans due to acidification http://www.biogeosciences.net/7/1065/2010/bg-7-1065-2010.pdf leading to greater Carbon sinks in the Ocean - which is already the greatest source) should we prioritise global action on AGW above action on deforestation, education, clean drinking water, recyclyable materials etc.

Much of my concern about an overestimation of our ability to know the effects of AGW is that it demonises dissident voices and is using political pressure to focus our limited resources as a globe to effect change at the expense of other pressing concerns - for example the current clean energy bill legislation was predicted to  cost ~$214,000,0000,0000 and reduce global temperature by 0.02*C - is that the most efficient use of our limited resources? If RCP8.5 was the most likely scenario then perhaps AGW is the most pressing concern, if RCP2.6 is the most likely it would then be less obvious that the current costs (which are real) are worthwhile to lower the chance of future negative impact.
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Offline werecow

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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #18 on: April 02, 2017, 09:10:16 AM »
There's a lot of speculation in this thread, but I'll stick to Ridley and global greening for now. First, Ridley; I've been out of this debate for a few years now, but I remember my deep disappointment (I too loved The Red Queen) in reading Ridley's uncritical support of a large number of denier talking points. Apparently he now remembers himself as deeply concerned and moving away from it. Unfortunately that's not the reality of the matter, and I would not trust him on this topic at all.

As for greening, that is a long time trope in the climate contrarian arsenal. It became famous in 2009:



That increasing CO2 alone can have a fertilizing effect is not controversial. However you cannot take this fact in isolation and just assume that increased CO2 means increased plant growth. For one thing, plants require more than just CO2 to grow including many nutrients (e.g.: nitrogen, molybdenum, phosphorus) and water. If these nutrients are not abundant, then they will limit the fertilization effect of CO2.
Second of all, the CO2 has effects on the climate and weather systems that also influence plant growth. Increased temperatures are a net negative for plant growth, on average. They also mean increased evaporation (from both the plants and their surroundings), which in turn means decreased soil moisture. Climate change also comes with more erratic weather, particularly in precipitation patterns. Stable, balanced rainfall tends to be reduced, to be replaced by extremes of weather with long droughts followed by massive downpour. And then there are some other effects, such as an increased risk of wildfires, heatwaves and floods that also come with climate change.

The dependence of plant CO2 uptake on abundance is not linear but drops with increasing CO2, flattening out above 1000 ppm CO2. So fertilization is subject to diminishing returns. This has to do with the trade-of between increased evaporation and increased CO2 uptake from having a higher number of stomata, as well as the factors mentioned above like other limiting nutrients.

Of course, climate change also implies changes in the distribution of plant species. So while it may be good news for some plant species, it's probably not so great for others that are adapted to colder climates. This is why models tend to show strong greening in the tropics, but less greening at mid to higher latitudes.

Andrew says we see CO2 fertilization today, and he seems to imply that, by contrast, we don't see these other effects today, but this is obvious bullshit to anyone who has been paying attention over the past few decades. We've seen many of these effects already, and the greening fingerprint of anthropogenic forcing only became discernible rather recently (most of the evidence has come from field experiments, not large scale observations of the biosphere). Incidentally, this fingerprint is identified by comparing models that either include or do not include CO2 fertilization, so anyone skeptical of models that are used this way to show a human impact on temperatures should be skeptical of this evidence if they want to be consistent (of course, they rarely show such consistency).

More to the point, the IPCC, believe it or not, is aware of this argument and has considered the effects of CO2 fertilization. This is why models include that effect as a factor, although at the time of the AR5 this process was not well constrained. It is thus a part of the large uncertainty estimates surrounding the different scenarios. People citing global greening as evidence that warming isn't so bad typically take a very optimistic estimate of greening and compare that to the most optimistic estimates of the other impacts of climate change to arrive at their conclusions. I'm not that much of an optimist.

EDIT:

I think this discusses the Ridley post your OP is talking about or at least a very similar one; it references greening and Nemani.

EDIT 2:

Also, this is worth a read.
« Last Edit: April 02, 2017, 09:35:13 AM by werecow »
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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #19 on: April 02, 2017, 09:41:09 PM »
Almost all environmental effects, and all effects in general, show diminishing returns (including an increase in CO2) which is why most of these graphs are logarithmic rather than linear over larger ranges. One of the consequences of global increase in CO2 levels is that even if only a small proportion of plants have CO2 (or water) as the limiting factor to growth the majority of these plants will have more growth due to the global nature of the CO2 increase. One of my concerns when I hear the idea of a "tipping point" or runaway growth without discussing the mitigating effects is that an overly pessimistic approach is adopted - again my question comes back to what sort of probability distribution data has been published of any of these scenarios - because without any probabilities a lot of these publications become "see what you want to see" which disrupts sensible conversations about AGW.


If the greening effects of increased CO2 are counteracting the increase in CO2 until 1000ppm it seems unlikely we will ever reach 1000ppm.




The IPCC reports seem to indicate that these scenarios are difficult to predict (because they include human behaviour) as well as the effects of these scenarios. I tried finding if there is any estimate of the different scenarios and the closest I could find was in http://www.ipcc.ch/pdf/supporting-material/expert-meeting-report-scenarios.pdf -

"Several publications can put the RCPs in perspective. These include the scenario overview in Chapter 3 of the IPCC WGIII AR4 (Fisher et al., 2007), the comparison of selected scenarios by van Vuuren et al. (submitted), and the publication by the US Climate Change Science Program (Clarke et al., 2007). Figures III.2 through III.6 provide an illustrative overview of how the RCP candidates and the identified RCPs represent the literature. In the figures, the range of the scenarios in the underlying postSRES literature is indicated by dashed lines showing the maximum and minimum and by shaded areas showing the 10th to 90th percentile. These percentiles reflect the frequency distribution of existing scenarios and should not be considered probabilities. The range of the baseline scenarios is shown in gray, and the range for the stabilization scenarios is shown in light blue. Cross-hatched areas indicate
the overlap between baseline and stabilization scenarios."


RCP8.5 seems to make some rather odd assumptions https://link.springer.com/article/10.1007%2Fs10584-011-0149-y -

"The scenario’s storyline describes a heterogeneous world with continuously increasing global population, resulting in a global population of 12 billion by 2100. Per capita income growth is slow and both internationally as well as regionally there is only little convergence between high and low income countries. Global GDP reaches around 250 trillion US2005$ in 2100. The slow economic development also implies little progress in terms of efficiency. Combined with the high population growth, this leads to high energy demands."

Considering that world GDP increased from around 1 trillion USD at 1900 and finished at 40 trillion in the year 2000 and already close to 80 trillion now - (so 40 times increase in a century with 2 world wars and the 21st century gets only a 6 times increase with "little progress in terms of efficiency" - an odd prediction for the end of the 21st century) http://databank.worldbank.org/data/download/GDP.pdf

Looking at the choice of RCP8.5 from the possible distribution of the inputs to the model seem to suggest that is quite unlikely (apart from the GDP where even 0 GDP is considered a possibility given complete economic collapse perhaps 400 to 600 trillion is more reasonable?) :


The Myneni article detected a 14% increase in greening which would also indicate a large amount of CO2 being taken out of the atmosphere - I assume that there are these effects in the models chosen by the IPCC but as a lay person reading the reports it is not clear how much these are taken into account. There was an article linked by the IPCC behind a paywall that seems to indicate that some mitigation processes are not incorporated into the models (obviously leading to overestimation of the danger) - is there a description of how these processes affect the sensitivity of the environment to adapt to increases in CO2?
http://www.nature.com/nature/journal/v463/n7282/full/nature08823.html -
"Extensive uncertainties exist in future forcings of and responses to climate change, necessitating the use of scenarios of the future to explore the potential consequences of different response options. To date, such scenarios have not adequately examined crucial possibilities, such as climate change mitigation and adaptation, and have relied on research processes that slowed the exchange of information among physical, biological and social scientists."
« Last Edit: April 03, 2017, 01:23:26 AM by Pdb88 »
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Offline werecow

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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #20 on: April 03, 2017, 08:47:39 AM »
You're throwing too much out there to answer all at once (unless I want to spend days looking up the exact information; like I said, I'm a bit rusty, and some of my information may be somewhat dated), so I'll try to answer what seems to be your general concern, that the IPCC is overestimating future impacts:

The IPCC uses a range of predictions for a reason; its job is to quantify the range of possible impacts so that the people who run our world can take action (or not) based on whether they find those risks acceptable or not. It's really hard to predict global development over the next century, but such an assessment should include some extreme scenarios in either direction. This also goes for the economic impact assessments of both climate change and mitigation policies, and as a result, we have a broad range of those as well. People like Lomborg and Ridley take the upper edge cases for economic impacts of prevention and compare them to the lowest projections of climate impacts, and then arrive at the (for them) politically convenient conclusion that we shouldn't do anything. But the uncertainty runs both ways, and imho it does not favor lukewarmers (at all).

I don't know the exact details of RCP8.5 off the top of my head, and I'm too lazy to look it up right now (the book weighs a ton man, when I sit and read it, it cuts off all the blood flowing to my legs - and that's just WG1), but speaking generally there are bound to be more and less realistic scenarios among the ones they choose. But that does not mean the IPCC is overestimating the future impacts. In fact, from what I've seen, I think the opposite is probably true.

At least on the climate science side, the IPCC is actually pretty conservative. Unless things have changed dramatically since I was last active in this debate (about 5 years ago), there are many important unknowns that will likely be a source of underestimates in the AR5 impacts. For example, CO2 emissions have been tracking or exceeding the worst case projections for a while now.

EDIT: found a slightly more up-to-date version of this graph:


The same is true for arctic sea ice extent:



and sea level rise:



Ice sheet dynamics, which are thought to potentially greatly accelerate the melting of the Greenland ice sheet, were not incorporated into the AR5 because their workings were not well known at the time. That's why the estimates for sea level rise have more than doubled since the report came out.

Likewise, while I think some people make a bit too much of the potential for sudden melting of large methane deposits in the permafrost (we had a good discussion about that the other month, but I can't seem to find it anymore... I guess maybe it fell off the edge of the boards? }|:o/), we do know that they are now starting to show signs of releasing methane, and this positive feedback is likely to make things worse, not better than the IPCC's estimates.

One of my concerns when I hear the idea of a "tipping point" or runaway growth without discussing the mitigating effects is that an overly pessimistic approach is adopted - again my question comes back to what sort of probability distribution data has been published of any of these scenarios - because without any probabilities a lot of these publications become "see what you want to see" which disrupts sensible conversations about AGW.

Well, I think that (for example) panicky reports by some people speculating wildly that a tipping point will turn earth into Venus over the next hundred years are not helping anyone, and I generally shy away from using tipping points as an argument for why we should make a strong effort to halt this problem because of the uncertainty in predicting them. You don't really need them anyway. The projections are bad enough even for the middle of the road scenarios without tipping points.

However I think the problem with the IPCC is more the reverse. When you do a risk-benefit analysis, in a system with a fat tail distribution of extreme events like the climate, you can't just exclude extreme cases like "humanity goes extinct" or "civilization ends" from your analysis that is supposed to inform you on how to proceed, because, rare as they might be, they actually do have a significant chance of occurring.
The climate is a nonlinear dynamic (i.e.: chaotic) system that can flip suddenly (in geologic terms) from one equilibrium to the other. We can see this in palaeoclimate data, but we usually don't know the exact circumstances that lead to such runaway effects. Because tipping points are by definition points of nonlinearity they are extremely hard to predict with accuracy, but that same nonlinearity also means they can be extremely dangerous.
Because they are hard to predict, the IPCC does not incorporate them in their estimates and only deals with them tangentially. But if we actually did stumble upon a real tipping point, we would almost certainly be completely fucked. As an example of a known tipping point, palaeoclimate records show several "meltwater pulses" at the end of the last ice age in which sea level jumped 16-25m over about 400-500 years:



These are probably unlikely to occur today, but how can we really know that if we aren't sure what led to them in the first place. And if something even remotely like that were to occur, that could be a civilization ending event. Do we want to take that risk, small as it is? Well, that's a judgment call. But ignoring that side of the equation completely seems at the very least unwise.

EDIT: Actually, let me move this to a separate post so that it does not get overlooked.
« Last Edit: April 03, 2017, 09:34:01 AM by werecow »
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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #21 on: April 03, 2017, 09:34:31 AM »
As for Myneni and Ridley, well:

Quote
Myneni told DeSmog the presentation Lord Ridley had cited had not been peer reviewed and was “work in progress” but hoped it would appear as two scientific articles, one of which was in review at the journal Nature Climate Change.

He said his analysis of satellite data covering the last 30 years did show a 13 to 14 per cent increase in vegetation growth. He said some of this could be attributed to increased levels of carbon dioxide, but changes in the way land was management was also a factor.

Myneni, in Norway for a meeting of ecologists to discuss vegetation changes in remote regions, said “in the context of being good versus bad” he was “worried about how this work is being interpreted”.

He said Ridley’s story “suffers from selective presentation of facts” and would “not survive peer-review”.

Quote
If one were to interpret the greening of the Earth as a good or a positive development then one must also accept that the accompanying climate changes (global warming, for example) and its physical (sea level rise) and biotic impacts (polar bears) as bad or negative developments.

Again, in my opinion, this benefit of greening is not worth price of all the negative changes.

Humans are one amongst many species on Earth and we have no right conducting such experiments that affect all forms of life - it is simply indecent, deeply vulgar and inhuman (you can choose any adjective).
(Emphasis mine.)

Edit:

And here:

Quote
Much of this is based on my (+colleagues) unpublished studies - the satellite data of the past 30+ years do show a “greener” vegetation over about 30% of the global vegetated land area and this translates to about 11-13% increase in gross carbon fixation by vegetation. Our analyses showed that about 42% of this greening can be attributed to climatic changes in temperature, precipitation and solar radiation and the rest to anthropogenic factors (CO2 fertilization, Nitrogen deposition, land use management history, etc.). This, Lord Ridley, does not mention, although they are contained in the same sources from which he falsely claims that CO2 fertilisation is responsible for the greening of the Earth

and

Quote
This is an inaccurate statement. Nearly all the CO2 enrichment experiments show enhanced plant growth only in the first few years after which the plants acclimatise. The fertilisation effect disappears because other factors (mainly nutrients) become limiting.
« Last Edit: April 03, 2017, 10:55:58 AM by werecow »
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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #22 on: April 03, 2017, 07:26:31 PM »
The response by Myneni is interesting and he is obviously distancing himself from Ridley's position; after seeing the negative reactions that Ridley receives that is not completely unexpected. Given that the response to this data seems to fall down political lines and academics are predominantly of the left it is possible that politics is influencing much of this discussion - that's why I appreciate probabilities or at least some sort of estimates with assumptions stated so that public discussion takes place across political stripes.

Quote
Our analyses showed that about 42% of this greening can be attributed to climatic changes in temperature, precipitation and solar radiation and the rest to anthropogenic factors (CO2 fertilization, Nitrogen deposition, land use management history, etc.).

This indicates, at the very least, 42% increase is accounted for by climate change while I can't see putting CO2 in another category is that useful when it is the cause of the climate change, so in a broader discussion perhaps most of the greening is caused by human related factors - use of synthetic fertilisers (Haber process) and farming management systems would have caused greening in the first half of the 20th century whereas this is talking about greening since the 1980s, where synthetic fertilisers have been limited due to concerns over eutrophication and algal blooms. 

Quote
This is an inaccurate statement. Nearly all the CO2 enrichment experiments show enhanced plant growth only in the first few years after which the plants acclimatise. The fertilisation effect disappears because other factors (mainly nutrients) become limiting.

CO2 increases have been occurring since the Industrial Revolution and the research timeframe was from the 1980s so the first few year of acclimatisation appears to be much greater in the world at large than in the CO2 enrichment experiments - research posted earlier in this thread showed some plants respond to increases in CO2 up to almost 1000 ppm.

Placing the doomsday scenarios as a possibility does lead to difficult reconciliation between viewpoints - in some ways this discussion is a mirror image of the abortion debate - those that are religious view the act of abortion as being unacceptable while those that have great concern for the environment (and a strong preference for the current climate) view carbon emissions and inaction on mitigation as unacceptable.

There are large uncertainties in all of these predictions and unless they can be quantified there can't be an assessment of how much world GDP should be sacrificed now for a lower chance of future climatic impacts; even with probabilities this still remains a very subjective decision - my main concern is the apparent disregard of the degree of impact on GDP vs the environment. Often responses are along the lines of "any sacrifice made by the current generation is worth the lowering of the risk of a disastrous outcome for future generations" and while this seems plausible to avoid some of the more extreme predictions being made, I have a large number of concerns:

1) The lowering of GDP growth may stifle future innovation that could mitigate the effects of global warming
2) Often there are unintended consequences (e.g. in Australia there was a push to replace incandescent light bulbs with halogens and fluorescents (increasing landfill and replacing relatively benign materials with those containing Mercury) and to subsidise housing insulation (a program which led to deaths and corruption) - another example is the encouragement of diesels over petrol engines and the production of NOx and smog or hybrids with large waste associated with battery production and disposal not to mention the deaths caused by food price increases over ethanol production (as the poorest communities in the world are most sensitive to price increases in grains).
3) There is a move of funds and attention away from other concerns - e.g. landfills, air quality, water quality, food standards, manufacturing safety
4) Currently carbon based fuel is the cheapest energy source available - putting up barriers to its use will affect the poorest communities the most:
http://news.stanford.edu/news/2014/february/kolstad-carbon-tax-022814.html
5) The talk of a 2*C window and tipping points feels like sales tactics and these claims have been repeated for decades and it is unclear how close or far we are away from this theoretical "point of no return"
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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #23 on: April 03, 2017, 11:42:04 PM »
In general I'm challenging the chain from:
A) AGW is real - temperature changes will be greater than 1*C etc.
B) This will likely cause large and negative circumstances for the majority of life on the planet
C) We should place controls on individuals and industries to mitigate this

A to B depends on probability distributions which seem impossible to estimate and B to C depends on competency of governmental agencies...

I also challenge the 2012 graph posted by werecow as being advocacy as it is stopped at the worst possible position - may I ask where that image was found because that is the sort of representation that leads to overestimation of the current situation.


Here is the interactive graph:
http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/
« Last Edit: April 04, 2017, 01:08:53 AM by Pdb88 »
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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #24 on: April 04, 2017, 09:10:10 AM »
The response by Myneni is interesting and he is obviously distancing himself from Ridley's position; after seeing the negative reactions that Ridley receives that is not completely unexpected. Given that the response to this data seems to fall down political lines and academics are predominantly of the left it is possible that politics is influencing much of this discussion - that's why I appreciate probabilities or at least some sort of estimates with assumptions stated so that public discussion takes place across political stripes.

I don't think you can provide robust probability estimate for each of the IPCC's scenarios; The scenarios include the actions of the governments that the IPCC advises, and those actions should in turn be based on the report. Providing probabilities for each scenario would change the probability for each scenario.
I assume that the economists that participate in the IPCC have had a say in coming up with those scenarios, though (I haven't read much about this so I can't say for certain). You might be able to give probabilities for the economic forecast part of each scenario (basically, low, medium or high growth), but I'm not very well versed in economics, so I don't know if economic long term forecast models are reliable enough to really provide you with something useful there. If not, you'd just be getting a false sense of security. And, note also that the economic growth is dependent to some (possibly quite considerable) extent on how bad the impacts of climate change will be, and thus by extension on the policy choices again.
I do remember seeing a lecture by an IPCC economist on climate change a few years ago, and he noted his amazement at the intricacies and predictive accuracy of the AOGCMs and ESMs, relative to economic models. I'm not sure what that implies, though.

Quote
Our analyses showed that about 42% of this greening can be attributed to climatic changes in temperature, precipitation and solar radiation and the rest to anthropogenic factors (CO2 fertilization, Nitrogen deposition, land use management history, etc.).

This indicates, at the very least, 42% increase is accounted for by climate change while I can't see putting CO2 in another category is that useful when it is the cause of the climate change,

The CO2 increase is not driven by climate change (except for positive feedbacks that involve releasing more of it), it is the driver. We have some say over it. Once the CO2 is in the atmosphere, it influences the climate system in ways that are not up to us. I think that's the main difference.

Note also that they say attributable to climate change, but that isn't necessarily just anthropogenic, there is also internal climate variability to consider. Still, over 30 years most of the natural variability should average out, so the dominant trend should be man-made.

This part of their conclusions is worth quoting:
Quote
An accurate quantification of the responses to individual human and natural drivers, however, needs more research efforts, owing to uncertainties associated with the ESMs, weaknesses of the CMIP5 experimental design, and limitations in the observations. Relative to the observations, the simulations with ALL and GHG forcings illustrated relatively weaker interannual variability of vegetation growth (Fig. 2 and Supplementary Figs 2 and 3). This discrepancy may arise from structural errors of the land component in the ESMs (for example, weak or no representation of vegetation mortality, disturbance and successional dynamics). Because spatial and temporal patterns of vegetation growth are tightly coupled with precipitation variability the underestimation could also arise from the reported underestimation of interannual precipitation variability in CMIP models over Northern Hemisphere land.

So the observations are showing more interannual variability than the models, which is worth keeping in mind when considering the interaction between future climate change (which is likely to cause less consistent weather patterns) and greening.

Quote
This is an inaccurate statement. Nearly all the CO2 enrichment experiments show enhanced plant growth only in the first few years after which the plants acclimatise. The fertilisation effect disappears because other factors (mainly nutrients) become limiting.

CO2 increases have been occurring since the Industrial Revolution and the research timeframe was from the 1980s so the first few year of acclimatisation appears to be much greater in the world at large than in the CO2 enrichment experiments - research posted earlier in this thread showed some plants respond to increases in CO2 up to almost 1000 ppm.

Yes, but not linearly, and under controlled conditions. From the link I provided earlier:
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Notice how the net assimilation vs. ambient CO2 concentration curve trails off towards a flat response above about 500 ppm. The shape of the curve is very similar between the leaves, while one assimilates more efficiently than the other. I included two lines to represent the approximate slope of the curve in the region 300-600 ppm ambient CO2. Both lines show a much lower than double increase of assimilation for the prescribed doubling of CO2 (note that current CO2 levels are nearing 400 ppm, while preindustrial levels were just below 300 ppm), and the higher CO2 becomes, the lower that slope.

This means that even if all plants on earth showed this particular response, it is not efficient in removing the extra atmospheric CO2 provided, and becoming less and less efficient the more CO2 is offered, facts conveniently omitted by people who want to mislead.

[Editor’s note: But wait, you might say, CO2’s effect on climate is logarithmic, so the plant response doesn’t have to keep up.  Nice try, but the plants’ uptake decays faster than logarithmic, so that it plateaus at 500-1500 ppm while CO2’s radiative effect is still continuing to increase. – John N-G]

[...]

Only in situations, where there are little to now other limitations on growth, such as in modern industrial agriculture providing irrigation and fertilization, does increased ambient CO2 unfold its full potential to spurt plant growth.

Roughly as a result of the above, the IPCC concluded, cited by John, that plant yields will increase somewhere between 0-25% (10-25% for C3 plants) when doubling CO2. There will be large geographical and species-related differences, with well-nurtured woody plants representing the high end number.

But then there also are another two important caveats in that IPCC statement: The first is the word unstressed. We have seen first-hand a very important stress factor on terrestrial plants, drought. Increased plant, particularly tree mortality during drought can nullify years to decades of increased growth in a single year. The “death toll” of the current drought is not yet firmly established, but the numbers coming out are staggering. All the carbon that is now in standing dead and decaying biomass as a result of the drought will eventually return to the atmosphere.

The second caveat is the IPCC statement over the short to medium term. To understand what is meant, one has to know that the last IPCC report did not yet include several newer findings from (mostly) modeling studies that considered climate change in global dynamic vegetation models. As the current changes in atmospheric CO2 pushed the biosphere-atmosphere carbon balance way out of equilibrium, the expected, and observed, uptake into the terrestrial biosphere is very complex, and considered to be transient.

Why is that? Once carbon enters into living plants, say trees, it is distributed into several compartments, such leaves and wood. As time goes by, leaves drop, branches are shed, and eventually the tree dies and its carbon enters different compartments of the soil. The so-called residence times in these terrestrial biosphere compartments (aside from changing now that it gets warmer) vary strongly geographically and as a function of compartment. At some point in the future, depending on factors including the absolute amount and rate of warming, as well as the plant growth response itself (aka how much extra carbon has come in), the terrestrial biosphere as a whole will become a net source to the atmosphere again.
(Emphasis mine)

Placing the doomsday scenarios as a possibility does lead to difficult reconciliation between viewpoints - in some ways this discussion is a mirror image of the abortion debate - those that are religious view the act of abortion as being unacceptable while those that have great concern for the environment (and a strong preference for the current climate) view carbon emissions and inaction on mitigation as unacceptable.

I get your apprehension, but one could say the same about overly pessimistic economic assessments of the costs of combating climate change on the one hand, and overly rosy views of the economic costs of its impacts on the other. And, while I think we shouldn't emphasize the really extreme edge cases, I think it's irresponsible to leave them out if they are part of a(n asymmetric) fat tail (that is, the distribution is not exponential, and extreme events still have a high chance of occurring relative to our Gaussian-like intuitions).
And, in any case, the IPCC only discusses these qualitatively, and does not include them in even its most dire model runs.

There are large uncertainties in all of these predictions and unless they can be quantified there can't be an assessment of how much world GDP should be sacrificed now for a lower chance of future climatic impacts;

To be blunt, it sounds like your position is we should gamble with the one biosphere we have in spite of potentially dire predictions, because we don't want to gamble with our money. That may be your value judgment, but my view differs.

even with probabilities this still remains a very subjective decision - my main concern is the apparent disregard of the degree of impact on GDP vs the environment.

This is why we have WG2 and WG3, which try to estimate the (costs of the) impacts and of the possible solutions. I haven't read much about that, so I can only comment in terms of generalities, but I can say that lukewarmers take an extremely pessimistic view of the economic impact of combatting climate change, and an absurdly rosy view of the impacts. Bjorn Lomborg is especially notorious for this.

I also challenge the 2012 graph posted by werecow as being advocacy as it is stopped at the worst possible position - may I ask where that image was found because that is the sort of representation that leads to overestimation of the current situation.


Here is the interactive graph:
http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/

Fair enough. You'll notice that this is a graph of variability throughout the year, whereas the graph I posted is one showing a multi-year trend. You'll further notice that the years 2015 and 2016 are well below the 1961-2010 average.

Here is the multi-year trend with the data through September 2016:



in case you fear that "September" is a cherry picked month, here it is through January 2017:



and a longer term view (up to 2015), which shows that this is not likely to be a linear trend:



And, just for fun, a very long term one based on palaeo data (up to 2011):



I used the 2012 one because that showed the comparison to model estimates. It was compiled in 2012 because Arctic sea ice was in the news that year a lot, for obvious reasons. It was also around when I was last highly active in this debate, which is why I remembered it. I'm pretty sure I first saw it (or some version of it) either on realclimate.org or skepticalscience.com. Unfortunately I don't think a newer version exists (or at least, I haven't found one), so I guess you'll have to eyeball it (if it helps, 2016 seems to be at about the 2011 level), but I think it's a safe bet that the observations still fall short of the IPCC model estimates (or at best, maybe track the lower bound predictions for arctic sea ice extent), which was the important part of the point I was making.

Also, just to be petty:


I should point out that this is just extent. Volume:



EDIT:

Your primary concern seems to be the risk of spending more than we ought to on this issue. Of course, that is why the IPCC has been trying to place bounds on the risks and benefits of climate change and enumerate the possibilities for mitigation and adaptation, so that they may be used in a cost-benefit analysis. The consensus appears to be that the benefits of mitigation outweigh the costs by a wide margin, and that mitigation is probably cheaper than adaptation. Of course, the longer we wait, the bigger the changes we have to make, and the greater the economic cost becomes.

EDIT 2:

Also worth considering (although surveys like this one should always be taken with a grain of salt in a heavily politicized debate like this), from the 2015 Expert Consensus on the Economics of Climate Change:

Quote
Experts on the economics of climate change expressed higher levels of concern about climate change impacts than the general public, when asked identical survey questions.
• Economic experts believe that climate change will begin to have a net negative impact on the global economy very  soon  –  the  median  estimate  was  “by  2025,”  with  41%  saying  that  climate  change  is  already  negatively  affecting the economy.
• Respondents believe that numerous sectors of the U.S. economy will be harmed by climate change. A majority predicted negative impacts on agriculture (94%), fishing (78%), utilities (electricity, water, sanitation – 74%), forestry (73%), tourism/outdoor recreation (72%), insurance (66%), and health services (54%).
More than three-quarters of respondents believe that climate change will have a long-term, negative impact on the growth rate of the global economy.
• More than 80% of experts believe that the United States may be able to strategically induce other nations to reduce their greenhouse gas emissions by first adopting policies to reduce U.S. emissions.
• Respondents  overwhelmingly  support  unilateral  emissions  reduction commitments  by  the  United  States,  regardless of the actions other nations have taken (77% chose this option over alternatives such as committing only if multilateral agreements are reached).
• The  vast  majority  (75%)  of  respondents  believe  that  the  most  economically  efficient  way  for  states  to  comply  with  the  U.S.  Environmental  Protection  Agency’s  “Clean  Power  Plan”  carbon  regulations  is through “market-based mechanisms coordinated at a regional or national level (such as a regional/national trading program or carbon tax).”
• The discounting approach that the U.S. government currently uses to analyze climate regulations and other  policies  –  a  constant  discount  rate  calibrated  to  market  rates  –  was  identified  by  experts  as  the  least desirable approach for setting discount rates in the context of climate policies. Nearly half (46%) of respondents favored an approach that featured declining discount rates, while 44% favored using rates calibrated with ethical parameters.
On  average,  economic  experts  predicted  far  higher  economic  impacts  from  climate  change  than  the  estimates  found  in  older  surveys  of  economists  and  other  climate  experts.  Respondents  predicted  a global GDP loss of roughly 10% if global mean temperature increases by 3°C relative to the pre-industrial era by 2090 (this increase approximates a “business as usual” emissions scenario).
Experts believe that there is greater than a 20% likelihood that this same climate scenario would lead to a “catastrophic” economic impact (defined as a global GDP loss of 25% or more).
• Our findings revealed a strong consensus (69%) that the “social cost of carbon” should be greater than or equal to the figure currently used by the U.S. government (only 8% believe the value should be lower).
(Emphasis mine.)
« Last Edit: April 04, 2017, 01:57:56 PM by werecow »
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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #25 on: April 05, 2017, 12:58:26 AM »
The strongest pieces of evidence suggesting that AGW will affect humanity are the sea levels and amount of ice at the poles. However, I would bring back a focus on both severity and likelihood - these are likely events that appear to not be very severe (after seeing their response to the elevated CO2 levels) and the flow-on effects to the biosphere.

When talking about an unknown distribution it is not appropriate to just assume that it has fat tails because we can imagine extreme circumstances - the fat tails are from the models collated by the IPCC rather than the underlying probability distribution (which they are at pains to emphasise yet is often not focussed on in other discussions); perhaps these have been published elsewhere?

My main objection to the graph showing September 2012 was that this was the lowest Arctic ice extent recorded so I thought it was advocacy - your response that it was chosen because it was topical that year (being such an unexpected anomaly from the previous years and models) seems fair enough. I would view the following years as a return to trend and somewhat of a validation of the IPCC models in the short term related to ice extent. The largest change (September) would by the large variability be more of a significant overshoot (or undershoot) of the model.

The weakest evidence for the dangers of AGW is, strangely enough, the low increase in temperature (0.8*C in the last 200 years after adding so much CO2)
http://www.nsstc.uah.edu/data/msu/t2lt/uahncdc.lt Again, I find it odd to see all of these logarithmic effects (or even less with the effect of stomata response to more CO2) and yet the only linear (or more sensitive) effect will be temperature change from CO2.

Fossil fuels have allowed modernisation to occur and our current lifestyle would not be possible without the large amounts of CO2 in the atmosphere - due to other effects (particulate matter, SOx and NOx etc.) the demand for more coal power plants will drop in the developed world - as will demand for oil (as is becoming apparent by the current financial state of Saudi Arabia).

If one were to think larger than the last 1450 years the current sea levels are much lower (100m) than the very long term trend so movement back to trend would be expected:



A loss of Arctic and Antarctic ice is not a desirable outcome yet it is not obvious to me that even the worst scenario would impact human life in an extreme manner, it has also yet to impact on wildlife in these extreme conditions, e.g. polar bear population has increased since the 1980s (admittedly from a very low starting point due to hunting in the early 20th century):



From the example of the polar bear it is clear that the greater concerns to the world are humans expanding into natural habitats and hunting - none of which has to do with global warming and perhaps much of the action and political capital used for action on AGW mitigation could be expended in those other more fruitful areas. One stark example of this (mentioned by Matt Ridley) was the demand by Haiti for charcoal which has led to mass deforestation compared to the Dominican Republic's reliance on fossil fuels (even including propane subsidies!), the result is stark in the following image and Haiti would have benefited much more from a focus on movement away from charcoal than any AGW concern:


The sea level rise has only been 8cm since 1980 after such large scale (and shocking loss of ice), of course sea ice should have no connection on sea level:
http://www.yaleclimateconnections.org/2014/11/loss-of-land-ice-not-sea-ice-more-sea-level-rise/   
It is suggested that a loss of sea ice may lead to an acceleration of the warming (although again this has not been observed even after such a loss of ice) which, to me, lessens the chance of AGW being the greatest threat to humanity (as it is often portrayed).

In the end (without probability distributions - which are fiendishly difficult to create about such a complex system) it does come down to assumptions being made and subjective value of GDP and the unknown danger to the environment.   
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global GDP loss roughly 10% if global mean temperature increases by 3°C relative to the pre-industrial era by 2090
   
The above statement appears to associate other events with the increase in temperature to arrive at the 10% figure which again are of an unknown nature so arriving at estimates of GDP loss which are 2 degrees removed from the temperature change (and 3 degrees removed from the CO2 increase) seem much more like guesses than anything else - a peer moderated guess aka peer pressure.
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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #26 on: April 05, 2017, 08:15:14 AM »
Again, you're going on something of a Gish gallop, and you're echoing a lot of different climate contrarian talking points that were debunked or answered years ago. Each of these requires careful scrutiny, so it would take me a whole day to respond to a post like this. So while I enjoy these discussions, I'd prefer to limit our discussion to one major theme (of your choosing) at a time.

In the meantime, I suggest you have a look at this list. While I normally wouldn't recommend relying on blogs for this topic, skepticalscience.com is kind of the talkorigins.org of climate change denial, and it generally has reliable information (at least on the climate science front; it's hard for me to comment on the economics front since I am less well versed in that topic) that is in line with the IPCC (or more recent findings) and sourced in the peer reviewed literature. You can often select whether you want the basics, intermediate, or advanced versions of the argument at the top of the page (the latter having more detail).

For example, these all seem at least somewhat relevant to the arguments you posted:
Melting sea ice is not warming the Arctic.
Polar bear numbers are increasing.
IPCC overestimate temperature rise.
Climate sensitivity is low (also here).
It's not bad.
CO2 response is logarithmic but projected temperature increase is linear.
It's a natural cycle / the climate has changed before (also here and here).
Humans have survived past climate change.
CO2 limits will harm the economy (also, here, here and here).
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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #27 on: April 05, 2017, 09:40:02 AM »
Thanks Werecow, I'll read through some of those blog posts. I was looking at a similar website with a contrarian flavour https://wattsupwiththat.com/ (which is not as well formatted as skepticalscience but has a variety of articles from the "other side").

My main point was that the distribution is unknown so talk about fat tails is unhelpful in describing the possibilities (of course we are much more captivated by extreme scenarios of by novel results); the current evidence does not point to any major catastrophe even events are often conflated with AGW  (even Obama who mentioned his daugter's asthma as being somehow AGW related http://www.chicagotribune.com/news/nationworld/chi-obama-climate-change-20150407-story.html ) and the consequence for our Earth.

The sea levels have been rising by 3.5mm per year and models show increases of 20cm to 2.0m by the end of the 21st century and yet coastal real estate is increasing around the world so the investors must have a low sensitivity to climate change or feel that future adaptation and/or mitigation will be sufficient. Such a slow change in sea levels could easily be adapted to - I fail to understand how such a slow increase in sea levels is such a pressing concern and, to my understanding, that is one of the most feared outcomes.
https://sealevel.nasa.gov/understanding-sea-level/key-indicators/global-mean-sea-level


If the worst case scenario is significant ice loss and some increase in sea levels (with the IPCC scenarios, apart from RCP8.5 which from the assumptions appears to be extremely unlikely, having less than 2.5*C by 2100 and 3*C by 2300 - an absurdly long time scale to predict) what are the impacts on the Earth as a whole and humanity in particular?
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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #28 on: April 05, 2017, 03:29:48 PM »
Thanks Werecow, I'll read through some of those blog posts. I was looking at a similar website with a contrarian flavour https://wattsupwiththat.com/ (which is not as well formatted as skepticalscience but has a variety of articles from the "other side").

Yeah, wattsupwiththat is one of the most well known climate science misinformation blogs out there (though there are a lot of others like climateaudit and junkscience), and Anthony Watts is notorious for cherry picking and other such shenanigans.

Unfortunately, during a particularly depressing episode in the climate change denial revival years during the Bush era the blog once got one of those "best science blogs" awards, for his cynical project of having non-experts go out to inspect temperature sensors and document anything that might be used to cast doubt on temperature records, and play up the urban heat island mythos (which is kind of like giving the discovery institute a "science institute of the year" award because it produced work that challenges evolution). This did not work out because climate scientists had of course long been aware of this issue and had already tested for this effect and found that their records looked nearly identical even if you didn't include any urban areas. This was mostly put to rest when then skeptical physicist Richard Muller did his own temperature reconstruction (with the arrogant acronym "BEST") and came to the exact same conclusions for the exact same reasons.

This guy (and skepticalscience) used to do frequent takedowns of Watts, e.g.:



or



My main point was that the distribution is unknown so talk about fat tails is unhelpful in describing the possibilities (of course we are much more captivated by extreme scenarios of by novel results);

There's a lot of unknowns here, but we're not entirely in the dark; we have palaeoclimate data that tells us that, for example, meltwater pulses and rapid temperature swings can occur. Ignore that data at your peril.

the current evidence does not point to any major catastrophe even events are often conflated with AGW  (even Obama who mentioned his daugter's asthma as being somehow AGW related http://www.chicagotribune.com/news/nationworld/chi-obama-climate-change-20150407-story.html ) and the consequence for our Earth.

Well, I guess that depends on your definition of "catastrophe". Certainly the high end predictions sound pretty disastrous to me. But re: Obama, I feel the same way about him as I do about Al Gore (or anyone, really); I care about their opinion on climate change only to the extent that they can demonstrate their knowledge of the subject (I've actually managed to avoid watching An Inconvenient Truth to this day).

The sea levels have been rising by 3.5mm per year and models show increases of 20cm to 2.0m by the end of the 21st century and yet coastal real estate is increasing around the world so the investors must have a low sensitivity to climate change or feel that future adaptation and/or mitigation will be sufficient.
Well, re-insurers are certainly concerned (because of this, for example). As is the U.S. military (more here).

There are certain advantages to living in a coastal area; there's a lot of opportunity for industry and trade, and the climate is generally milder because the ocean is a big heat store. In the U.S. "coastal and ocean activities, such as marine transportation of goods, offshore energy drilling, resource extraction, fish cultivation, recreation, and tourism are integral to the nation's economy, generating 58% of the national gross domestic product (GDP)". Population densities in coastal areas are about three times higher than the global average. In the U.S., approximately 25 million people live in an area vulnerable to coastal flooding. And of course there are more and more people, with more and more money to spend worldwide. So I am not surprised that there would be an increase in coastal development. And I doubt that most wealthy investors are young enough that they are highly concerned about events that will start becoming important decades from now.
In the short run, beach front property (for example) is probably not such a bad investment. People like the beach, and that's unlikely to change any time soon, especially as the climate is getting warmer. In the long run, you might end up with wet feet, but there's plenty of time to sell between now and then.

Such a slow change in sea levels could easily be adapted to - I fail to understand how such a slow increase in sea levels is such a pressing concern and, to my understanding, that is one of the most feared outcomes.
https://sealevel.nasa.gov/understanding-sea-level/key-indicators/global-mean-sea-level
You may feel that way, but many experts disagree. I live in the Netherlands, where 2m of sea level rise is a really big deal. We might be able to adapt to one or two meters, because we are relatively rich, but probably not to the next 5 meters that will come from the likely melting of the Greenland ice sheet and parts of Antarctica over the subsequent centuries. The rise in sea level doesn't just stop after a hundred years. At some point, raising your dikes a bit more just doesn't do the trick anymore.
And what about the 200 million people who are predicted to be displaced in Bangladesh, a region of the world that is already overcrowded, with two nuclearized countries that have consistently been on the edge of war for years now? When I was last active in this debate, this was named by top U.S. military officials as one of the biggest threats to long term global stability.
And of course, we've all heard about the "sinking" island nations in the pacific that stand to lose their entire country. Also, keep in mind that the oceans are not flat, and as a result sea level rise can be more dramatic in one place than another.
And it's not just that the sea will encroach on our coasts; rising sea levels can seep into and contaminate freshwater aquifers that contain most of the worlds drinkable water, making them saltier. It'll change soil chemistry.

And sea level rise is not the only danger imposed by meltwater; the inpour of fresh water from the ice shelves (and smaller glaciers, and even the melting of sea ice) will make the Arctic surface water less saline, which will likely weaken the AMOC (which is driven in part by differences between deep ocean and surface salinity, and in part by temperature differences) and disrupt one of earth's major processes of heat redistribution (which is largely responsible for Europe's mild climate), which can have unpredictable effects (a similar disruption of the AMOC is implicated in Dansgaard-Oeschger events, rapid climate swings at the end of the last glacial period - though these are not thought to be likely to repeat themselves).

If the worst case scenario is significant ice loss and some increase in sea levels (with the IPCC scenarios, apart from RCP8.5 which from the assumptions appears to be extremely unlikely, having less than 2.5*C by 2100 and 3*C by 2300 - an absurdly long time scale to predict) what are the impacts on the Earth as a whole and humanity in particular?

First of all, bear in mind that the temperature change is not uniformly distributed across the earth's surface, so a 3oC warming can mean 1oC in one spot and 5oC in another (or even 1oC cooling in one place and 7oC warming elsewhere). So the local impacts can be more severe than you'd expect from just the 3oC number alone.

Second, the IPCC's WG2 report is dedicated to enumerating the impacts, and it is nearly 2000 pages long (it's even more huge than that WG1 report that cuts off my bloodflow), so any short summary will fail to do it justice, but the skepticalscience post on "it's not bad" gives some highlights (though it's based on the AR4, so there have undoubtedly been some developments since then). If you want more detailed information, I recommend checking out the summary for policy makers or even the technical summary (which is more detailed).

The severity of the impacts depends on whether we make an effort to curtail the effects. The predictions for the higher end scenarios (which are not unrealistic under a business as usual scenario) paint a very unpleasant picture for the biosphere, of which we are a part, and many of these begin to play a role above 2oC of warming, which is why that tends to be the target for many policy makers.
A big problem is that global warming puts various additional strains on ecosystems that are already under stress. For example, we know that our ocean ecosystems are in trouble, largely because of overfishing. CO2 comes along and causes coral bleaching through global warming, and ocean acidification. And there are reasons to believe that climate change will adversely affect the bottom of the ocean food chain.
More erratic weather patterns will put stress on plants (including many food crops). Animals that have little room left for adaptation (like those living on mountains or in lakes that can't easily migrate) may go extinct. Many animal species are at risk of extinction. The IPCC AR4 notes that "There is medium confidence that ~20–30% of known plant and animal species are likely to be at increased risk of extinction if increases in global average temperature exceed 1.5 °C to 2.5 °C over 1980–1999". Of course, ecological systems have similar chaotic aspects as the climate itself does, so who knows what the downstream effects of that could be.
Risks of extreme weather events, droughts, floods, and wildfires will increase, and with it the costs of the damage they cause (that's what worries re-insurers like Munich Re). Infectious disease territories may spread. Heat waves have in recent years been responsible for more deaths among the elderly. And so on. And it's worth pointing out that the people most at risk tend to be those who have benefited the least from the industrialization that has caused the problem (in large part because they don't have the means of adapting to climate change and because they already live in ecologically and economically stressed areas).
It's true that a lot of the impacts are highly uncertain, but the uncertainty goes both ways; that is, it could be much better, but it could also be much, much worse than we've anticipated. Unfortunately, the probability distribution for climate sensitivity is asymmetric, in such a way that there is a higher risk of it turning out higher than we think than there is of it turning out lower than we think (i.e., a fatter tail towards higher sensitivity than towards lower sensitivity).
In short, it's a huge gamble to take, considering that the costs of mitigation are currently really not that draconian (yet).
« Last Edit: April 05, 2017, 09:18:28 PM by werecow »
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Re: Matt Ridley, Global Greening & Ranga Myneni: lukewarmers
« Reply #29 on: April 07, 2017, 10:27:42 AM »
I watched the two videos and it did show that Watts Up With That predicted the change in Arctic ice incorrectly, as it has dropped over time - however, I don't think Watts Up With That is alone in making poor predictions - as the Watts Up With That website is essentially commentary on articles and climate related ideas that they feel to be incorrect. To be fair we would have to compile a list of articles and see which ones turn out to be obviously false - the problem then becomes one of who is the objective arbiter as both sides accuse each other of cherry picking the data, for instance in 2014 the ice in Antarctica reached a maximum which was not likely predicted by many sites that view AGW as singularly grave danger.
https://www.nasa.gov/content/goddard/antarctic-sea-ice-reaches-new-record-maximum


I also had a look at the NASA blog post about phytoplankton, again I am much more hopeful and some of the ideas of Iron being made bioavailable in acidic conditions would apparently fertilise the ocean. The science behind the phytoplankton bloom seems solid and would be another mechanism to slow down CO2 build up (I'm not sure how this has been incorporated into the models):
http://search.proquest.com/openview/07bad47cdd5e0d811600841713524b91/1?pq-origsite=gscholar&cbl=40569
http://www.nature.com/nature/journal/v446/n7139/abs/nature05700.html
https://link.springer.com/article/10.1007%2Fs10584-010-9799-4?LI=true


Quote
More erratic weather patterns will put stress on plants (including many food crops). Animals that have little room left for adaptation (like those living on mountains or in lakes that can't easily migrate) may go extinct. Many animal species are at risk of extinction. The IPCC AR4 notes that "There is medium confidence that ~20–30% of known plant and animal species are likely to be at increased risk of extinction if increases in global average temperature exceed 1.5 °C to 2.5 °C over 1980–1999". Of course, ecological systems have similar chaotic aspects as the climate itself does, so who knows what the downstream effects of that could be.

In AR5 there is no scenario (other than the wildly unrealistic RCP8.5) that exceeds 2.5*C under any circumstance until 2100 so the chance of exceeding the 2.5*C average appears to be small (again as there is no probability of the outcomes mentioned anywhere in the report that is all supposition).

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Risks of extreme weather events, droughts, floods, and wildfires will increase, and with it the costs of the damage they cause (that's what worries re-insurers like Munich Re). Infectious disease territories may spread. Heat waves have in recent years been responsible for more deaths among the elderly. And so on. And it's worth pointing out that the people most at risk tend to be those who have benefited the least from the industrialization that has caused the problem (in large part because they don't have the means of adapting to climate change and because they already live in ecologically and economically stressed areas).

I'm sure re-insurers would be conservative in their approach to any event regardless of how unlikely because by their nature want to limit that tail end risk; has there been any increase in extreme weather events in the last decade or any discernible trend over the 20th century and into the 21st century? This would be fairly clear evidence that the dangers of climate change are to be believed; I'm aware that the death toll has risen due to greater population and movement of people yet am unsure if the number of extreme weather events has increased.

Looking at the Reuters article werecow linked:
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"Definitely we expect political courage to move in a direction that shows responsibility towards future generations and a certain interest in defending the sustainability of this planet," Swiss Re's Chief Executive, Michel Lies, told a news conference.

Swiss Re data shows natural disasters caused an average $180 billion in economic damage per year over the last decade, of which 70 percent was uninsured.

Credit rating agency Standard & Poor's said big natural catastrophes can also lead to cuts in sovereign credit ratings - making it more expensive for governments to borrow money - with Latin America and the Caribbean most at risk.

To Swiss Re there is no upside risk to AGW (there is no prediction that extreme weather events will decrease) and some non-zero probability of a greater risk so of course they would encourage governments to use taxpayers money to mitigate that risk - I wonder how much Swiss Re is personally contributing to any process to minimise AGW?

The UN poll that I linked to earlier showed that it is the most developed countries that prioritise climate change and it is the least developed that have other priorities (education, clean water, lack of corruption) - if the developed world used the resources currently used in climate change abatement related activities to effect some political change (as much as can be done externally) perhaps there would be a net benefit for the developing world; although there appears to be a tradition of the developed world using benign reasoning to continue to broaden the gap between the global rich and poor. The west has used cheap carbon rich fuels to reach the current level of development and is now finger wagging at the countries who would greatly benefit from cheap fuel.

Shipping creates more sulfur and nitrogen oxides than all the cars and yet this is not being focused on because all of the environmental air is taken up be a focus on carbon. These are actions with clear negative outcomes and should have more political will to clean up.
http://www.industrytap.com/worlds-15-biggest-ships-create-more-pollution-than-all-the-cars-in-the-world/8182
https://usatoday30.usatoday.com/news/nation/2004-08-30-ship-pollution_x.htm


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It's true that a lot of the impacts are highly uncertain, but the uncertainty goes both ways; that is, it could be much better, but it could also be much, much worse than we've anticipated. Unfortunately, the probability distribution for climate sensitivity is asymmetric, in such a way that there is a higher risk of it turning out higher than we think than there is of it turning out lower than we think (i.e., a fatter tail towards higher sensitivity than towards lower sensitivity).
In short, it's a huge gamble to take, considering that the costs of mitigation are currently really not that draconian (yet).

When these probabilities are unknown I don't know how the distribution could be known to be asymettric or having fat tails - there are a number of scenarios that would lower climate change sensitivity (such as the stomata reduction due to CO2 and the acidic induced iron fertilisation of the oceans - as well as many other known or unknown processes). It is possible that the probability distribution is in fact asymmetric favouring the climate being less sensitive.  The OECD in the "economics of climate change" predicts: "Depending on the underlying assumptions enumerated above, by 2050 the assumed emissions cuts would entail costs ranging from 0.6 to 1.7 per cent of GDP in OECD countries and from 1.2 to 2.3 per cent in non-OECD countries. Overall, the level of world GDP
would be lower by 0.9 to 1.8 per cent in 2050.
" https://www.oecd.org/eco/outlook/29173911.pdf   World GDP is now roughly 80 trillion US dollars and will likely be closer to 200 trillion by 2050 - I would consider a cost of close to 2% of that figure to be draconian. Again, this comes down to the belief in how quickly societies will move away from carbon based fuels as technologies increase and this significant cost (in the trillions of dollars) may limit the total welfare of humanity (for instance there will be a number of people, either in the thousands or more, that will have a much shorter or lower quality of life due to the resources sacrificed for the mitigation of the risk of future climate change) so we should be cautious in how much of a current day and future sacrifice we are willing to make to lower the future unknown risk.
« Last Edit: April 07, 2017, 10:31:30 AM by Pdb88 »
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