Wednesday, November 28, 2007

Atmospheric CO2 Levels Follow Temperature, Data Clearly Shows....

Craig James is a Michigan meteorologist and here he explains his reasoning as to why atmospheric carbon dioxide does not drive, or control global warming.

Meteorologist Craig James explains the real CO2 sequence
In response to the many comments I have received recently questioning my position on global warming, I'd like to offer this summary:There are several possible causes for warming and cooling of the atmosphere on a global scale. Periodic astronomical cycles, such as the Milankovitch Cycles, solar variations, volcanic activity, the shift in phase of the Pacific Decadal Oscillation (PDO), the Atlantic Multidecadal Oscillation (AMO), the Arctic Oscillation (AO), plus many others certainly all play a huge role. I have written about the natural oscillation of the oceans and their affects on temperatures in several posts on this site.

Of course the mainstream emphasis today is on increasing atmospheric CO2 concentrations. If I conducted a survey asking people whether the temperature rises first and then CO2 levels increase, or vice-versa, I'm sure we could all guess the prevailing opinion is that CO2 levels increase first. I think it is very important for everyone to understand, this is not the case.

I am not doubting that humans have been responsible for an increase in the atmospheric concentration of CO2 and that this CO2 increase may have contributed to some of the warming we have experienced by a process known as positive feedback. But it does seem as if the climate models overstate this positive feedback and several others such as those for water vapor. A close inspection of the temperature and CO2 records shows that the warming we see now should be much greater if CO2 was the dominant factor. To illustrate this, let me repost one of my previous articles called "Does the Earth Have a Temperature Regulator".

It seems to me as if there hasn't really been much attention given to the fact that CO2 increases occur AFTER the temperature begins rising and therefore cannot be the initial cause of global warming. Even the most vocal proponents of anthropogenic global warming (AGW) acknowledge this fact. The web site Real Climate states:

From studying all the available data (not just ice cores), the probable sequence
of events at a termination goes something like this. Some (currently unknown)
process causes Antarctica and the surrounding ocean to warm. This process also
causes CO2 to start rising, about 800 years later. Then CO2 further warms the
whole planet, because of its heat-trapping properties. This leads to even
further CO2 release.
They are well aware that CO2 does not cause the initial warming but they say it does amplify the warming once underway. The interesting thing to me though is what causes the warming to stop, even though CO2 is still RISING?

Take a look at this chart (above) from the Vostok ice core record over the last 460,000 years.

The second chart is a close up of the last 18,000 years (since the last glacial maximum).

The third chart is of the last 200 years, encompassing the industrial revolution. The charts were all taken from this web page.

Notice on all three charts the recent rapid rise in CO2 on the right hand side of the chart WITHOUT an equivalent rise in the temperature. There was a rise in temperature but you would expect it to be more if the response was linear. This seems to be good evidence that the temperature response to rising CO2 levels is logarithmic, not linear. A subsequent doubling of CO2 concentrations in the atmosphere will not produce the amount of temperature increase the first doubling did.

But what is even more interesting to me can be seen on the first chart going back 460,000 years. There are five warm periods, or interglacials, on the chart. The current one has lasted the longest. Every time the temperature has warmed to more than 2 degrees Celcius above the mid 20th century benchmark (the 0 degree line) for a significant time, cooling followed. It appears that if the +2C threshold is exceeded for some period of time, a new glacial, or cooling, phase follows.

According to the authors of the web site where I got the chart:A linear trend line fitted to the temperature data would indicate that the critical +2C level would be reached in about 40 years. But we don't know that the trend is linear.I think it is logarithmic, not linear or exponential as the authors suggest, meaning it will take much longer than 40 years to reach the +2C threshold. But once it reaches that threshold, what makes the temperature start to fall again, especially if CO2 levels are still rising? Does the earth have a built in temperature regulator? Does melting of the Arctic ice slow down the thermohaline circulation enough to initiate a new ice age? Or is the "iris effect" real as described in this article?

Whatever it is, there certainly seems to evidence from the Vostok ice core, which the AGW people accept, that the Earth will again regulate itself to prevent any runaway global warming."Will the increasing levels of CO2 override the historical pattern of a +2C threshold? I can't find an answer to that anywhere. Also, if you look again at the long term chart above, you will see that the ice ages do not begin every 100,000 years as the Milankovitch Cycles would predict. Wikepedia states:

The Milankovitch theory of climate change is not perfectly worked out; in
particular, the largest observed response is at the 100,000 year timescale, but
the forcing is apparently small at this scale, in regard to the ice ages.
Various feedbacks (from carbon dioxide, or from ice sheet dynamics) are invoked
to explain this discrepancy.
Another issue I want to emphasize has come about because of all of the concern regarding the low Arctic sea ice extent measured this fall. I can't state this strongly enough. THERE IS NO CORRELATION BETWEEN ARCTIC AIR TEMPERATURES AND ARCTIC SEA ICE!

Here (above) is a graph of Arctic air temperatures since 1880.The second chart is a graph of Arctic Sea Ice extent since 1900. The air temperatures in the Arctic were warmer in 1940 than now. The sea ice extent began to diminish in 1950 as air temperatures were going DOWN. If there is no correlation, there can be no causation.

Also, never once mentioned in the mainstream media is the fact that the southern hemisphere sea ice extent was at a record MAXIMUM this year. It seems to me the argument that the current rise in CO2 is solely responsible for the changes we have seen over the past several decades ignores much of the historical record and places an unwarranted confidence in computer model forecasts, which those of us who forecast weather know all to well, are NOT reality. I do think I am open to being convinced otherwise, but as of yet, I haven't seen the smoking gun that would do so.


Anonymous said...

This was really useful. Thanks for your help!! :)

SteveMDFP said...

A few thoughts

1. The long-term charts show dramatic oscillations in temperature and CO2. Some use this to suggest the current changes are merely part of a long-term pattern. What's staring us in the face with these charts, however, is that the current changes in CO2 are unpredented in magnitude and rapidity.

2. The observation that natural temperature increases precede CO2 increases is interesting. I think it's too optimistic an analysis to think simply that CO2 increases can't or don't raise temperatures. I think the more likely interpretation is that elevations in CO2 and temperature in natural cycles reinforce each other (at least until these maximums in temp happen). If so, then an artificial rise in CO2 would be a trigger to increases in global temperatures, and a hyper-rapid rise, as we're seeing now, would be expected to create a hyper-rapid rise in temperature.

That is, admittedly, just hypothesis. What's clearly evident from the data, though, is that over the very long term, natural cycles of temp and CO2 suggest that mutual positive feedback mechanisms likely exist to create swings both upward and then downwards.

Offhand, I can only think of one kind of mechanism that could explain why rising temperatures would raise CO2--an alteration in ocean waters. Warmer waters are less soluble to gases, including CO2 and methane (methane released into the atmosphere eventually reacts to form H2O and CO2). Increases in ocean acidity would also favor release of CO2 from water to air by simple chemical equilibrium. Warmer, more acidic surface waters could create a net release of CO2.

If these warmer, more acidic waters become less hospitable to phytoplankton, then less CO2 absorption would also happen.

Note that the phrase "less hospitable to phytoplankton" is potentially a euphemism for mass oceanic ecosystem devastation. Such events are known to have happened in association with warmer periods in the geological past.

Note that at warmer temperatures, with absent polar icecaps, ocean mixing between surface and deep waters may essentially cease. With minimal mixing of deep and surface waters, it then becomes possible for surface acidity and temp to increase more dramatically than would happen otherwise--creating a strong positive feedback effect.

Systems dominated by positive feedback mechanisms show oscillations (any kind of system). Most systems which show oscillations do so by virtue of positive feedback mechanisms.

Systems dominated by positive feedback mechanisms are intrinsically unstable--an explosion is a chemical positive feedback mechanism, for example.

The metaphor may sound alarmist, but a very reasonable interpretation of these data suggests that human-created increases CO2 already constitute the activation of a detonation cord in an unstable climate system.

If so, then the challenge facing us as a species is to ADAPT to now inevitable dramatic changes, not try to extinguish an ignition already triggered.

Steve Coulter, MD
SteveMDFP -at- gmail -dot- com

Peter said...

Thanks for your thoughtful comments, however your tone and language reveal you to be an ideological alarmist, a true believer, blind to common sense and reason.

I hope you do not practice medicine with the same irrational form of thinking expressed by your fear of man-caused global warming, or if you prefer, climate change.

Unknown said...

I would have to concur with Steve on the point that the rapid rise of human caused CO2 creates a different scenario than we've seen in the past. Yes, CO2 does usually follow a rise in temperatures, and then through a positive-feedback process may reinforce that rise. But we've seen a nearly instant (geologically speaking) rise in CO2, and we are indeed entering unknown territory. We are conducted a great experiment on the natural cycles...the results of which no one can predict at this point...