I have a geologist friend that presented me with the argument that the problem with the man causes climate change hypothesis is that it only looks at a small period , and that most of the change today can be explained by something called milankovitch cycles and presented me this article http://www.paulmacrae.com/?p=62
Is there any response to this sort of argument ?? If so where can I find articles that talk about this matter ? Most of the people against the idea of global warming have been cranks, but this friend is a serious geologist not just random guy on the internet. Thanks in advance =)
So, it took me the entire day, and this may the last time I ever do this, but I went over this denialist wordvomit line by line:
Climate change: Learning to think like a geologist
Wrong! Any geologist who thinks like this is only a geologist in his own fantasy universe. Kinda like this guy:
Paul MacRae, June 24, 2008
I think this is the only thing he gets right in the entire article...
Most geologists aren’t part of Al Gore’s
Who cares about Gore. Stop obsessing about Al Gore. More knowledgeable people have produced massive volumes of work on climate change and you're babbling about a politician.
“100 per cent consensus” of scientists that humans are the principal cause of global warming and that we have to take drastic steps to deal with it.
Again, who cares? Geologists are not trained to understand the climate system. You wouldn't ask a neurologist about your dental health.
For example, in March 2008, a poll of Alberta’s 51,000 geologists found that only 26 per cent believe humans are the main cause of global warming. Forty-five per cent believe both humans and nature are causing climate change, and 68 per cent don’t think the debate is “over,” as Gore would like the public to believe.1
. Only 2% of those surveyed responded. 160 of those were professional geoscientists. A lot of those are likely to be engineers and geologists working in the oil industry. And even then "71% accepted at least some degree of a human role by selecting either “primarily human” (25.7%) or “both human and natural” as causing global warming"
Among geologists, denial of anthropogenic climate change is highest among economic geologists
. Among climate scientists, numerous scientific surveys (with a response rate above 2%) and literature studies have come up with percentages between 97-100
that humans are warming the climate.
The position of the American Association of Petroleum Geologists is quite clear:
The earth’s climate is constantly changing owing to natural variability in earth processes. Natural climate variability over recent geological time is greater than reasonable estimates of potential human-induced greenhouse gas changes. Because no tool is available to test the supposition of human-induced climate change and the range of natural variability is so great, there is no discernible human influence on global climate at this time.2
Note that the AAPG was one of the last (if not the
last) major scientific bodies
to maintain a wishy-washy position on anthropogenic climate change. Gee, I wonder why? Note that this article was written in 2008. Here
is the AAPG's stance on it today:
In the last century, growth in human population has increased energy use. This has contributed additional carbon dioxide (CO2) and other gases to the atmosphere. Although the AAPG membership is divided on the degree of influence that anthropogenic CO2 has on recent and potential global temperature increases, AAPG believes that expansion of scientific climate research into the basic controls on climate is important.
Why do geologists tend to be skeptics? Is it because they are, as Gore and the “consensus” charge, in the pay of the oil industry? Perhaps, but there may be other, more scientific reasons. As Peter Sciaky, a retired geologist, writes:
A geologist has a much longer perspective. There are several salient points about our earth that the greenhouse theorists overlook (or are not aware of). The first of these is that the planet has never been this cool. There is abundant fossil evidence to support this — from plants of the monocot order (such as palm trees) in the rocks of Cretaceous Age in Greenland and warm water fossils in sedimentary rocks of the far north. This is hardly the first warming period in the earth’s history. The present global warming is hardly unique. It is arriving pretty much “on schedule.”
This is an outright distortion. First of all, the planet went through several "snowball" earth phases of near complete glaciation in the proterozoic. Second, it was about 8o
C colder than it is today only about 20,000 years ago, as the graphs later on in this same blog post show. Third, while the implication is that we shouldn't worry about climate change because the climate has changed in the past, this completely ignores the fact that we are adapted to today's climate and shorelines. Cretaceous sea levels were approximately 250+m above current day.
Here's projected sea level rise in the context of the last 2500 years:
Considering a substantial portion of the earth's largest cities are on or near the shore, that might be something of a problem.
Major climatic changes, especially rapid ones, are also associated
with several mass extinctions.
One thing, for sure, is that the environmental community has always spurned any input from geologists (many of whom are employed by the petroleum industry). No environmental conference, such as Kyoto, has ever invited a geologist, a paleontologist, a paleo-climatologist. It would seem beneficial for any scientific investigatory to include such scientific disciplines.
This is just absolute nonsense asserted without basis. Is he suggesting that someone has gone over every environmental conference and has checked the list of attendees to each of them? Preposterous. Kyoto, as it happens, was a conference where policy makers met to sign a treaty on climate change, which had been negotiated on for years (based on expert guidance by a huge variety of geo- and environmental scientists, in the guise of, among others, the IPCC), so I don't know why you'd even want a paleontologist there.
Among all my liberal and leftist friends (and I am certainly one of those), I know not a one who does not accept that global warming is an event caused by mankind. I do not know one geologist who believes that global warming is not taking place. I do not know a single geologist who believes that it is a man-made phenomenon.3 Finally, a retired scientist who emailed me after reading one of my climate columns in the Times Colonist observed: “Most of my geology friends are skeptics — but it has become politically incorrect to voice such views.”
Anecdotal, and irrelevant unless they are experts on climate-related matters. And simply untrue. As pointed out, every major scientific body of international standing now accepts the reality of anthropogenic climate change, including the ones dedicated to geology
. Consensus rises with greater expertise on matters related more closely to the issue of climate change.
Current climate conditions are not unusual
Geologists tend to question the anthropogenic theory because their education tells them that current climate conditions are not unusually warm, based on either the past few thousand years, or the past few hundred thousand years, or the past tens of millions of years, or even the past hundreds of millions of years.
Missing the point. The current warming is one of the fastest changes in the geologic record, occurring at 10 times the speed
of any recorded change in the last 65 million years, which includes the extraordinary PETM temperature spike. Here's the current rise in GHG concentration in the context of the past ice ages:
It's at a record high compared to at least
the past half a million years
(with humans having been around for maybe 150,000 of those).
Figure 1. Temperatures since 1860. Source: R.M. Carter
Temperatures since 1860. Source: R.M. Carter.
It’s possible to look at a graph of the past century and conclude: “Oh, my God, the planet is burning up!” After all, the temperature has been rising, more or less, since the 1850’s, with a dip from the 1940’s to the mid-1970’s. The chart to the right shows temperature and carbon dioxide levels from 1860 to now.4
Bit of an outdated graph. Here's temperature for several of the most important data sets up to 2013:
, temperature, and solar activity (sun spots):
But what if we take a longer view?
OK! Longer range temp+CO2
That presents quite a different picture. Only 400 years ago, the planet was quite cold, a period known as the Little Ice Age (roughly 1300-1850). Before that, though, during the Medieval Warm Period (roughly 1000-1300), the planet was a degree or two Celsius warmer than today, to the point where Greenland was warm enough for settlement by the Vikings. The Medieval Warm Period and Little Ice Age were clearly a natural occurrences since industrial carbon emissions weren’t yet a factor. Figure 1 is a graph of the last thousand years based on work by climatologist H.H. Lamb.
Temperatures over the last 1,000 years: H.H. Lamb
Figure 1. Lamb graph of temperature over the past 1,000 years
Lamb's graph is from 1982, plots 50 year averages, and ends in about 1950
. Here's the graph with continued trend up until 2007:
Needless to say, temperature reconstructions have advanced since 1982.
Curiously, the temperature graph preferred by the Intergovernmental Panel on Climate Change, the famous “hockey stick,” smooths out the Medieval Warm Period and Little Ice Age to create an impression that twentieth-century warming is “the warmest in 1,000 years” (Figure 2). Faced with the flaws in this graph, the IPCC has since dropped it and now claims the climate is the warmest in 400 years, which isn’t that impressive given that we’re coming out of the Little Ice Age.
IPCC hockey stick graph
Figure 2. IPCC hockey stick graph of the past 1,000 years
Yes, the IPCC preferred to use a state-of-the-art reconstruction instead of a dated one from 1982. Here's what a large number of more recent reconstructions look like after they "dropped" the hockey stick:
It's a hockey team!
Most reconstructions are limited to the northern hemisphere because that is where most of the land mass is, and thus the most coverage; this leaves them somewhat open to internal climate variability. The medieval warm period and little ice age were very likely more pronounced in the northern hemisphere. Also, it's not the little ice age
, since the drivers that account for that phenomenon (increased volcanism and reduced solar output) cannot account for the current warming (see below).
Over the past 4,000 years, the planet has also experienced warm and cool periods, again quite naturally. In fact, warm times seem to recur on a cycle of about 1,000-1,500 years, as Figure 3 shows.5 The 20th century’s warming appeared pretty much in line with this millennial cycle.
Warming every 1,000 years
Figure 3. Warming every 1,000 years or so. Source: R.M. Carter
Going back 8,000 years or so, we encounter the Holocene Optimum, which was 2-3 degrees Celsius warmer than today’s temperatures — naturally.
Misleading graph which leaves out the warmest years of the instrumental record (and projections). Here's the projected warming for low, medium and high climate sensitivity in the context of the past 10000 years, smoothed (so, basically, all of human history):
Let’s expand our view once again, to the past 450,000 years (Figure 4). What do we see? A roller-coaster ride of glacials (cold times) and interglacials (warm times), on a cycle of about 100,000 years.
A glacial cycle every 100,000 years
Figure 4. A glacial cycle every 100,000 years
Here are the high end IPCC projections in the context of the past 800,000 years (which thus includes all of human prehistory):
EDIT: Better graph from here.
If someone has one for middle-of-the-range projections, let me know.
(Note that the instrumental record plus projections would appear to shoot straight up if the scale on the x-axis were the same.) This is the worst case scenario, though, so keep that in mind.
To back this up, compare measured CO2
Nothing to see here, move along!
By the way, this is the chart, based on ice core readings taken in Antarctica, that Gore uses in his film An Inconvenient Truth. Gore doesn’t try to explain why this roller coaster has occurred,
Who cares what Gore says? He's not a climate scientist. And why would he have to explain past climate change if that was not his focus?
since if changes in carbon dioxide levels were causing the cycle of glaciations and interglaciations, as Gore implies, then the logical question is what caused the changes in carbon dioxide levels?
Wait... Didn't he basically already admit that we are releasing large quantities of CO2
when he posted the Carter graph? But for the explanation, see below.
Gore doesn’t say, because to do so would destroy his case, but here’s what science says: temperature changes precede carbon dioxide level changes by several hundred years, and temperature changes are caused by changes in solar intensity called the Milankovitch Cycles, not carbon dioxide. The Milankovitch Cycles, based on the earth’s changing position in relation to the sun, appear to be the ultimate drivers of climate over the past few million years.
Yes, they were, however what this jackass doesn't tell you is that based on non-human drivers of climate change alone, we should actually expect a cooling trend:
The Milankovitch cycles are due to changes in the earth's eccentricity and obliquity, shown at the top of the graph above.
During the past glacial/interglacial cycles, CO2
was a feedback mechanism; as ocean temperatures rise, they release more CO2
into the atmosphere. In addition, changes in ice sheet cover and vegetation patterns caused changes in CO2
levels. The extra CO2
then caused more warming to occur, and so on, until a new equilibrium was reached. This is why, in the past, CO2 lagged temperature changes
, whereas today it's the other way around. The CO2
feedback is necessary to explain the shifts between glacials and interglacials, as the Milankovitch cycles alone are not strong enough to do so.
The four previous interglacials were warmer than today’s
Another interesting observation that Gore doesn’t make because it would destroy his case: the four previous interglacials shown on his chart are all warmer than today’s interglacial (the green line in Figure 4 shows how today’s average temperature compares with that of the three previous interglacials).
As shown above, worst case projected warming is well above the temperatures in the last 800,000 years. Also, compare current temperatures with the uncertainty envelope for the past interglacial period(s) in the 800,000 year graph above.
Also, note that the interglacial peaks are very steep. Before an interglacial becomes a glacial, warming occurs relatively rapidly (if the warming was slow, the curve would be more rounded), and cooling also occurs rapidly.
Again, most rapid warming in 65 million years by an order of magnitude
. Also, where does he think the heat trapped by the CO2
we've released is going?
(To be continued in the next post...)