Originally Posted by gmeyers1944

Christopher C. Horner has it right. In his book "The Politically Correct Guide to Global Warming and Environmentalism" he has this list of "Top ten 'Global Warming' Myths".

Go to "Elections and Candidates". Find my thread called "Why Al Gore is not running for President"

Originally Posted by baloney_detector

The lag between temperature and CO2. (Gore’s got it right.)

When I give talks about climate change, the question that comes up most frequently is this: “Doesn’t the relationship between CO2 and temperature in the ice core record show that temperature drives CO2, not the other way round?"





On the face of it, it sounds like a reasonable question. It is no surprise that it comes up because it is one of the most popular claims made by the global warming deniers. It got a particularly high profile airing a couple of weeks ago, when congressman Joe Barton brought it up to try to discredit Al Gore’s congressional testimony. Barton said:

• In your movie, you display a timeline of temperature and compared to CO2 levels over a 600,000-year period as reconstructed from ice core samples. You indicate that this is conclusive proof of the link of increased CO2 emissions and global warming. A closer examination of these facts reveals something entirely different. I have an article from Science magazine which I will put into the record at the appropriate time that explains that historically, a rise in CO2 concentrations did not precede a rise in temperatures, but actually lagged temperature by 200 to 1,000 years. CO2 levels went up after the temperature rose. The temperature appears to drive CO2, not vice versa. On this point, Mr. Vice President, you’re not just off a little. You’re totally wrong.

Of course, those who've been paying attention will recognize that Gore is not wrong at all. This subject has been very well addressed in numerous places. Indeed, guest contributor Jeff Severinghaus addressed this in one of our very first RealClimate posts, way back in 2004. Still, the question does keep coming up, and Jeff recently received a letter asking about this. His exchange with the letter writer is reproduced in full at the end of this post. Below is my own take on the subject.

First of all, saying "historically" is misleading, because Barton is actually talking about CO2 changes on very long (glacial-interglacial) timescales. On historical timescales, CO2 has definitely led, not lagged, temperature. But in any case, it doesn't really matter for the problem at hand (global warming). We know why CO2 is increasing now, and the direct radiative effects of CO2 on climate have been known for more than 100 years. In the absence of human intervention CO2 does rise and fall over time, due to exchanges of carbon among the biosphere, atmosphere, and ocean and, on the very longest timescales, the lithosphere (i.e. rocks, oil reservoirs, coal, carbonate rocks). The rates of those exchanges are now being completely overwhelmed by the rate at which we are extracting carbon from the latter set of reservoirs and converting it to atmospheric CO2. No discovery made with ice cores is going to change those basic facts.





Second, the idea that there might be a lag of CO2 concentrations behind temperature change (during glacial-interglacial climate changes) is hardly new to the climate science community. Indeed, Claude Lorius, Jim Hansen and others essentially predicted this finding fully 17 years ago, in a landmark paper that addressed the cause of temperature change observed in Antarctic ice core records, well before the data showed that CO2 might lag temperature. In that paper (Lorius et al., 1990), they say that:

• changes in the CO2 and CH4 content have played a significant part in the glacial-interglacial climate changes by amplifying, together with the growth and decay of the Northern Hemisphere ice sheets, the relatively weak orbital forcing

What is being talked about here is influence of the seasonal radiative forcing change from the earth's wobble around the sun (the well established Milankovitch theory of ice ages), combined with the positive feedback of ice sheet albedo (less ice = less reflection of sunlight = warmer temperatures) and greenhouse gas concentrations (higher temperatures lead to more CO2 leads to warmer temperatures). Thus, both CO2 and ice volume should lag temperature somewhat, depending on the characteristic response times of these different components of the climate system. Ice volume should lag temperature by about 10,000 years, due to the relatively long time period required to grow or shrink ice sheets. CO2 might well be expected to lag temperature by about 1000 years, which is the timescale we expect from changes in ocean circulation and the strength of the "carbon pump" (i.e. marine biological photosynthesis) that transfers carbon from the atmosphere to the deep ocean.

Several recent papers have indeed established that there is lag of CO2 behind temperature. We don't really know the magnitude of that lag as well as Barton implies we do, because it is very challenging to put CO2 records from ice cores on the same timescale as temperature records from those same ice cores, due to the time delay in trapping the atmosphere as the snow is compressed into ice (the ice at any time will always be (older) than the gas bubbles it encloses, and the age difference is inherently uncertain). Still, the best published calculations do show values similar to those quoted by Barton (presumably, taken from this paper by Monnin et al. (2001), or this one by Caillon et al. (2003)). But the calculations can only be done well when the temperature change is large, notably at glacial terminations (the gradual change from cold glacial climate to warm interglacial climate). Importantly, it takes more than 5000 years for this change to occur, of which the lag is only a small fraction (indeed, one recently submitted paper I'm aware of suggests that the lag is even less than 200 years). So it is not as if the temperature increase has already ended when CO2 starts to rise. Rather, they go very much hand in hand, with the temperature continuing to rise as the the CO2 goes up. In other words, CO2 acts as an amplifier, just as Lorius, Hansen and colleagues suggested.

Now, it there is a minor criticism one might level at Gore for his treatment of this subject in the film (as we previously pointed out in our review). As it turns out though, correcting this would actually further strengthen Gore's case, rather than weakening it. Here's why:

The record of temperature shown in the ice core is not a global record. It is a record of local Antarctic temperature change. The rest of the globe does indeed parallel the polar changes closely, but the global mean temperature changes are smaller. While we don't know precisely why the CO2 changes occur on long timescales, (the mechanisms are well understood; the details are not), we do know that explaining the magnitude of global temperature change requires including CO2. This is a critical point. We cannot explain the temperature observations without CO2. But CO2 does not explain all of the change, and the relationship between temperature and CO2 is therefore by no means linear. That is, a given amount of CO2 increase as measured in the ice cores need not necessarily correspond with a certain amount of temperature increase. Gore shows the strong parallel relationship between the temperature and CO2 data from the ice cores, and then illustrates where the CO2 is now (384 ppm), leaving the viewer's eye to extrapolate the temperature curve upwards in parallel with the rising CO2. Gore doesn't actually make the mistake of drawing the temperature curve, but the implication is obvious: temperatures are going to go up a lot. But as illustrated in the figure below, simply extrapolating this correlation forward in time puts the Antarctic temperature in the near future somewhere upwards of 10 degrees Celsius warmer than present — rather at the extreme end of the vast majority of projections (as we have discussed here).



Global average temperature is lower during glacial periods for two primary reasons:
1) there was only about 190 ppm CO2 in the atmosphere, and other major greenhouse gases (CH4 and N2O) were also lower
2) the earth surface was more reflective, due to the presence of lots of ice and snow on land, and lots more sea ice than today (that is, the albedo was higher).
As very nicely discussed by Jim Hansen in his recent Scientific American article, the second of these two influences is the larger, accounting for about 2/3 of the total radiative forcing. CO2 and other greenhouse gases account for the other 1/3. Again, this was all pretty well known in 1990, at the time of the Lorius et al. paper cited above.

What Gore should have done is extrapolated the temperature curve according this the appropriate scaling — with CO2 accounting for about 1/3 of the total change — instead of letting the audience do it by eye. Had he done so, he would have drawn a line that went up only 1/3 of the distance implied by the simple correlation with CO2 shown by the ice core record. This would have left the impression that equilibrium warming of Antarctica due to doubled CO2 concentrations should be about 3 °C, in very good agreement with what is predicted by the state-of-the-art climate models. (It is to be noted that the same models predict a significant delay until equilibrium is reached, due to the large heat capacity of the Southern ocean. This is in very good agreement with the data, which show very modest warming over Antarctica in the last 100 years). Then, if you scale the Antarctic temperature change to a global temperature change, then the global climate sensitivity to a doubling of CO2 becomes 2-3 degrees C, perfectly in line with the climate sensitivity given by IPCC (and known from Arrhenius's calculations more than 100 years ago).

In summary, the ice core data in no way contradict our understanding of the relationship between CO2 and temperature, and there is nothing fundamentally wrong with what Gore says in the film. Indeed, Gore could have used the ice core data to make an additional and stronger point, which is that these data provide a nice independent test of climate sensitivity, which gives a result in excellent agreement with results from models.

A final point. In Barton's criticism of Gore he also points out that CO2 has sometimes been much higher than it is at present. That is true. CO2 may have reached levels of 1000 parts per million (ppm) — perhaps much higher — at times in the distant geological past (e.g. the Eocene, about 55 million years ago). What Barton doesn't bother to mention is that the earth was much much warmer at such times. In any case, more relevant is that CO2 has not gone above about 290 ppm any time in the last 650,000 years (at least), until the most recent increase, which is unequivocally due to human activities.

RealClimate

Originally Posted by intangible child

The fact is it's not right-wing sympathetic posters or anyone else, it's that the media is screwing everyone! Be a ......... FREE THINKER! Get with the "fair & balanced crowd"
http://clips.mediamatters.org/static...e-20050428.jpg

Originally Posted by knot_e_lady

A lawyer who works for Exxon knows sooooo much more about global climate change then the scientists.

Only a sheeple would use that logic.

Originally Posted by Varuna

This chart shows the relationship between CO2 and temperature. The less CO2 there is, the more difference it'll make on the climate of the planet. Fluxuation in CO2 is related to fluxation in temperature. It has been fluxuating for quite some time, and we are in a warm front on the chart (but not the hottest). Its not a pefect relationship, but it is obvious. There has been a massive rise in temperature since the end of the ice age (20, 000 Ky). The chart time period is large, so its impossible tot ell what is happening with the temperature at this very moment. However, there is an obvious spike in CO2 laying right on top of the very last line (line 0). That combined with the previously obvious relationship would suggest that humans are a part of the current global heat trend. The spike at the very end in CO2 levels, is far steeper than that of any other time period. There is no chance at all, that this spike was caused by something natural. And since this data also proves relationship between CO2 and temperaturee, this graph is indesputable proof that human active has or at least will lead to global temperature changes with in the future.

This graph gives me a clear position on this issue. Those evil "left wing" scientists take this stance based on research, while political pundits convince the dopes of America not to believe them. Its quite rediculous how Americans (especially the youth) trust political pundits over scientists on this issue. The reason that the human endused global warming has not been believed in the US, is because the truth would go against their political philosophy. People who deny global warming, do so on political grounds.

Although it is true that there are many 'scientists' that disagree with the consensus that global warming is related to human activity, there is a major problem when it comes to their viewpoint being a valid point of view. This scientists are POLITICAL SCIENTISTS. Political scientists, are scientists enformed about politics, NOT the issue about global warming, which is a meteoroligical issue, not a political one. A scientist educated in politics does not qualify for making a valid arguement against the informed "left's" view of global warming. This is not a political issue, this is a scientific issue. Those who are educated about politics are not qualified to make a stance on global warming, since they are not informed in climatic process.

As for those meteoroligists that say that there is a hype involving global warming... They were all state ran meteoroligists, meaning that they are also POLITICAL SCIENTISTS, and since they recieved an education in such, they are far less knowledgable in the issue of global warming, as they also put an effort to learning about politics. Thus, half their knowledge is political while the other half is scientific, meaning they are only half as qualified as those who examined these antartic ice cores, confirming man made global warming. In fact, that graph proves that human activity at least will have an effect on global climate, and right now it seems like it already has.

For those of you who say I'm just a leftist moron, read this. I am a University major in EARTH SCIENCES. Global Warming is an Earth Science. I am more knowledgable about this issue than all those right-wing political propagandists on the Corporate Media. The guy who hosts that could not out debate me on this issue, since I am clearly more knowledgable on it. I am not knowledgable on Kyoto per say, but to deny global warming is in fact, as rediculous as denying the holocaust. Sorry its true. I'm not saying they are morally equivical, but they are intellectually equivical.

I would actually like to now continue on to why it is essential to control carbon emissions.



For those of you who do not know what this is, this is the carbon cycle. Carbon (CO2 when in atmosphere) does not stay in one place. When CO2 is injected into the atmosphere, it will eventially be deposited, either by photosynthesis, or with in the oceans. This carbon process brings up a new issue involving the dangers of CO2....

When CO2 deposits as carbon, it is a pollutant. Due to land usage, the amount of CO2 absorbed by photosynthesis is decreased, meaning that more will be deposited into the oceans. Since we are dumping more CO2 into the atmosphere, we are causing a rise in the carbon content in our oceans. Here is the terrible truth, this is in fact even WORSE than global temperature rises. When CO2 mixes with water, it forms a toxic dissolving chemical called Carbonic Acid.

Carbonic acid - Wikipedia, the free encyclopedia

There has been recently been a loss of life with in our oceans. Do to the increased acidity in our water, sea life is dying. Sea life (fishing) is essential for the world economy, especially for island countries such as Japan which are reliant on the sea for food supply.

When more CO2 is dumped into the atmosphere, it eventually falls into the ocean, raising its acidity. When PH drops, it'll damage ocean environments, which would eventually cause global catastraphy. Afterall, the oceans drive both our weather, and our biota. If our oceans, if our water contains a venomously high acidic content, it would be a catastrophy.

Oh, as for weather.... Moisture content that falls from rain, forming our fresh water rivers and lakes, is often obsorbed from the oceans by the sun. If the oceans are acidic, the rain will also be acidic, making our rivers and lakes acidic as well. Just think what would happen to the biota of this planet, if the water is too acidic for plants and animals. The mass death would completely devestate the world, that including the human race.

PS: It can't be because of volcanoes, since there were bigger eruptions with in the past 400,000 years (one during human history). Also, these environmental processes also have a cooling effect by blocking out the sun.

Originally Posted by gmeyers1944

I suppose that you believe that there is "consensus" about Global Warming. A lot of scientists disagree. Consensus is not science, it is politics.

Originally Posted by knot_e_lady

Yes, there is a consensus.

"

Policy-makers and the media, particularly in the United States, frequently assert that climate science is highly uncertain. Some have used this as an argument against adopting strong measures to reduce greenhouse gas emissions. For example, while discussing a major U.S. Environmental Protection Agency report on the risks of climate change, then-EPA administrator Christine Whitman argued, "As [the report] went through review, there was less consensus on the science and conclusions on climate change" (1). Some corporations whose revenues might be adversely affected by controls on carbon dioxide emissions have also alleged major uncertainties in the science (2). Such statements suggest that there might be substantive disagreement in the scientific community about the reality of anthropogenic climate change. This is not the case. The scientific consensus is clearly expressed in the reports of the Intergovernmental Panel on Climate Change (IPCC). Created in 1988 by the World Meteorological Organization and the United Nations Environmental Programme, IPCC's purpose is to evaluate the state of climate science as a basis for informed policy action, primarily on the basis of peer-reviewed and published scientific literature (3). In its most recent assessment, IPCC states unequivocally that the consensus of scientific opinion is that Earth's climate is being affected by human activities: "Human activities ... are modifying the concentration of atmospheric constituents ... that absorb or scatter radiant energy. ... [M]ost of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations" [p. 21 in (4)]."

BEYOND THE IVORY TOWER: The Scientific Consensus on Climate Change -- Oreskes 306 (5702): 1686 -- Science

Tell me, do you people ever think for yourselves, or do you just repeat the same old tired arguments put forth by Rush, Ann and Bill?