You both seem to be saying that even if the worst-case scenarios of global warming are unlikely, they would be so disastrous for someone--possibly the people of Bangladesh--that it is not acceptable to take no action. A true measure of risk is not simply likelihood, but the scale of admittedly unlikely dire consequences. Unless we can be a bit more specific, this sounds to me like Dick Cheney on the subject of national security: there are bad people somewhere who may blow us up, or may make an alliance with rogue states, or may lure our young people into committing treason, or whatever, so we should all accept limitations both on our freedoms and on government oversight. Sometimes this is expressed as the "precautionary principle"--prepare for the worst case, even if it is unlikely. But no sane person ever lives that way. If parents did, they would keep their children in sealed, padded rooms. Survivalists who store food for six months are a tiny minority; those who are truly prepared to go off the electricity grid are even fewer, and so on. If our friends started acting that way, we would probably say they had gone crazy. Yet we are asked to support government programs that work that way. I say it is crazy in Cheney's case, and also crazy in Gore's case until I am shown otherwise.
This might seem to you another case, like evolution vs. creation, or even civil rights vs. Jim Crow laws, where science, enlightenment, education and sophistication are all on one side, and on the other side is a kind of primitive dull resistance to a new way of thinking, linked to selfish vested interests including oil companies.
The more I read, the less I think this is what is happening.
As I understand it, there is no large geographic area, and no long period of time, for which it is true that there is a solid correlation between elevated CO2 and other greenhouse gases, on the one hand, and temperature increase on the other. In the initial excitement of developing the IPCC model and getting it out in the world, it seemed that the 20th century, in much of the world including the U.S., was exactly the example that was needed--with a correlation between an increase in man-made CO2 (which no one denies) and increased temperature; but the more data is forthcoming, and the more it is scrutinized, the less this seems true.
Statements about surface temperature in the 20th century depend heavily on weather monitoring stations in the U.S. No other country has so many stations, going back so long. (Other countries have been poorer, have been bombed or caught up in wars, etc.). The weather monitoring stations have lots of problems, which advocates of the IPCC model have tended not to acknowledge much less investigate in a scientific spirit. Many stations were poorly sited to begin with (temperature affected by buildings, etc.); for the vast majority, important factors about the site have changed over the years (most have changed from a rural to an urban setting, which tends to be warmer); in some cases, a big change occurred such as the cutting down of trees which formerly provided shade, or the installation of a vent blowing hot air at the thermometer. It sounds ridiculous, but it's true. A few decades ago, the process of installing new high-tech electronic thermometers began--in a gradual, phased-in fashion. When advocates of these stations are honest, they will say that all readings from before the electronic era are questionable. What they are less likely to admit is that the electronic thermometers required cables to connect them to a power source, probably in a building. There was a tendency to build a new building, or move the monitoring stations closer to a building--in both cases, affecting the trend of temperature readings.
This is not small, picky stuff. It is elementary, but it makes the whole model questionable. Anthony Watts deserves credit for continuing with this line of investigation. There is not another pool of temperature data available that is comparable to the 20th century U.S. data. For other periods, and other geographic areas, it is necessary to resort to "proxies" for temperature readings, all more or less questionable. Much of the surface of the earth is water, and there are those who are trying to focus on the heat of the oceans, measured not in temperature but in joules. There is no trend to increasing heat.
Looking beyond the 20th century, there have been periods of temperatures higher than the official 20th century ones, presumably unrelated to human activity. There have been periods of higher CO2 concentrations--generally coming before, not after, temperature increases. Many (but not all) the world's glaciers have been retreating for decades--but this began in 1850 or 1880, long before the dramatic increase in CO2 in the 20th century. Not only that, the rate of retreat in the retreating glaciers slowed, rather than increasing, during the time of CO2 increase. Again, no correlation--or the initial appearance of a correlation turns out to be deceptive. Northern hemisphere glaciers appear to be on a quite different timeline than southern hemisphere glaciers.
Antarctic ice, mostly on land, shows no signs of shrinking, and only one small part of the Antarctic--the peninsula--shows a warming trend. Arctic ice shrank dramatically in 2007, but has built back up since. It is mostly on water, and has been much more changeable than Antarctic ice--from season to season, and year to year--for as long as anyone has made records. Greenland shows no signs of becoming ice-free.
Advocates of the IPCC model include some real scientists. Their excitement at having a computer model that can do the work of forecasting--and bear direct relevance to debates about energy and the environment--is very understandable. But it seems clear that they built on a very shaky foundation of data to begin with, and newer and better data is not supporting the model. There was a debate about the "hockey stick," partly because the authors who developed it were very hesitant even to share all the underlying data. It turned out to depend on one type of pine tree in California, which got bigger in the 20th century. This might indicate temperature increase, and it would at least be worth exploring whether man-made CO2, in turn, contributed to the temperature increase. But there could be other reasons why that type of tree got bigger; it is a very questionable "proxy" for temperature increase.
So then advocates of the IPCC model said they would not rest their argument on the hockey stick to any significant extent. Yet it keeps appearing. Temperature and greenhouse gases both low before the 20th century (which is extremely misleading, taking no account of the Medieval Warming and other changes); then a sudden increase in both in the 20th century (misleading). Then even more dramatically, the rate of temperature increase goes up dramatically, right about now, when urgent action is supposedly needed, because of positive reinforcement. There seems to be no known, specific case that anyone can point to, where clouds have exaggerated the normal "greenhouse effect" by trapping heat at the surface, so that what starts as a small temperature increase goes up dramatically. On the other hand, there is a well known phenomenon of a "negative reinforcement," releasing heat. In the rain forest, heat builds up during the day, usually culminating in a thunderstorm. Thunderstorm clouds gather together huge volumes of warm air at the surface of the earth, and send them roaring into space. The rain forest cools for evening. The Air France plane that recently went down was caught in a severe thunderstorm showing huge movements of warm air upward. This may be an important "thermostat" effect around the world.
Even including ice ages and the opposite ages, which are never entirely ice-free, the total temperature swing on earth has never been more than 3 degrees. Focussing on non-ice ages, it has never been more than a degree and a half or so. Some combination of factors keeps surface temperature extremely constant.
If there is no correlation between greenhouse gases and temperature, then even an apparent correlation in the 20th century is probably misleading. But the apparent correlation in the 20th century is not working out either. Without a correlation, there is obviously no basis to investigate cause and effect. The model is vapor when it comes to any alleged dangers of producing greenhouse gases. The possible dire consequences are not only unlikely: they are possible, but in a way that is presumably unrelated to man-made greenhouse gases.
See the report by an EPA staffer who is urging further research before CO2 is identified as a dangerous substance (it is actually good for plants and people, and has a tendency to make the world literally greener).
See the fullest report I know of on "climate change reconsidered." 31,478 scientists have signed the following statement:
We urge the United States government to reject the global warming agreement that was written in Kyoto, Japan in December, 1997, and any other similar proposals. The proposed limits on greenhouse gases would harm the environment, hinder the advance of science and technology, and damage the health and welfare of mankind. There is no convincing scientific evidence that human release of carbon dioxide, methane, or other greenhouse gases is causing or will, in the foreseeable future, cause catastrophic heating of the Earth’s atmosphere and disruption of the Earth’s climate. Moreover, there is substantial scientific evidence that increases in atmospheric carbon dioxide produce many beneficial effects upon the natural plant and animal environments of the Earth.
UPDATE June 29:
Here is a study of U.S. temperature data--raw or uncorrected, and then corrected in various ways. (UHI is Urban Heat Island). The National Oceanic and Atmospheric Administration NOAA, clearly committed to the IPCC model, has literally applied exactly the corrections it needs to temperature data to make it first, show a trend in the twentieth century, then a warming trend, and then, amazingly, a warming trend that closely matches the trend to increasing CO2 in the twentieth century.
Some weather stations have moved from urban areas to less urban ones--usually airports. NOAA carefully makes an adjustment for the newer temps--upward, to match the earlier urban temps. As Michael Hammer says, on this specific point it would make more sense to correct the earlier, urban temps downward. But generally there is little or no downward correction as stations in general become more urban, technology may require a heated site, etc. In past years there was one downward correction for Urban Heat Island, but it was very modest in comparison to actual readings of how temps spike upward as a site changes from rural to urban. Now even the one modest UHI correction is apparently not being included.
The raw data shows no clear trend, and some of the warmest years of the twentieth century before 1950. It takes some twisting and torquing-like Doug Feith working over intelligence reports on Iraq in 2003--to come up with the neat Al Gore trend line.
It would appear that the temperature rise profile claimed by the adjusted data is largely if not entirely an artefact arising from the adjustments applied (as shown in Figure 3), not from the experimental data record. In fact, the raw data does not in any way support the AGW theory.
Based on this data, the US temperature data does not correlate with carbon dioxide levels. The warming over the last 3 decades is completely unremarkable and if present at all is significantly less than occurred in the 1930’s. It is questionable whether any long term temperature rise over the 20th century can be inferred from the data but if there is any it is far less than claimed by the AGW proponents.
The corrected data from NOAA has been used as evidence of anthropogenic global warming yet it would appear that the rising trend over the 20th century is largely if not entirely an artefact arising from the “corrections” applied to the experimental data, at least in the US, and is not visible in the uncorrected experimental data record.
Thanks to Anthony Watts.