I too recall the dire warnings in the 1960s-1970s of an incipient ice age. And it is true that we really don't understand enough about the feedback mechanisms that moderate the Earth's temperature. (A quick overview of many of the issues in climate change science is in [link|http://www.geo.cornell.edu/eas/education/course/descr/EAS201/Site/Lecture%20Notes_files/Chapter%2016-20.2006.JPM.pdf|these] lecture notes from Cornell - 18 page .pdf.) Remember that 2006 was predicted to be a terrible year for hurricanes....

Ice ages seem to be correlated with long-period changes in the Earth's eccentric orbit. The rise of the Himalayas and the western continental US have apparently changed the climate. There have been vast changes in climate and CO2 levels that occurred millions of years before humans arrived.

A worrying aspect of the CO2 record in ice cores, etc., is that there are strong indications that the Earth's temperature has changed very quickly several times in the past. I don't know the details of the measurements and extrapolations to know whether they're doing something wrong, and back of the envelope calculations indicate there would have to be a tremendous change in albedo or heat input to cause such a change (the atmosphere and Earth's surface have a big mass and reasonably large heat capacity, so big changes in reflectivity or heat imput are required for a big change in temperature), but there you are.

According to the link:

Table 1: Carbon in the Atmosphere (Oceanus, 1986/6, v. 29 #4). BMT stands for billion metric tones.\n\nChanges in Atmospheric Carbon\n   1980   346 ppmv CO2 740 BMT C\n   1860   280 ppmv     600 BMT\n   Change  66 ppmv     140 BMT\n\nAdditions of C to the Atmosphere\n   Deforestation        150 BMT\n   Burning Fossil Fuels 150 BMT\n   Total                300 BMT\n\nPresent Rate of Addition of C to the Atmosphere\n   Deforestation        ~1 BMT/yr\n   Burning Fossil Fuels  5 BMT/yr\n   Total                 6 BMT/yr\n\n   Atmospheric C increase 2.5 BMT/yr\n   Ocean C increase       2.5 BMT/yr

Note that that table is based on numbers from 1980 - they're much higher now. Yes, these numbers are a small change in the total numbers for atmospheric carbon, but they're happening over decades while it took millions of years for the fossil carbon to be locked away. It's not at all clear that the Earth's buffering actions can work on such short time scales. We should be concerned about it and should work on gaining better understanding of the science. And we should also work to reduce CO2 emissions even if future results tell us that anthrogenic CO2 is only a small perturbation.

The Kyoto Protocol has had big problems from the beginning. Though Clinton signed it, he didn't submit it to the Senate for ratification because he knew it would be rejected. It was controversial even back then (e.g. [link|http://epw.senate.gov/107th/Hagel_072402.htm|Hagel comments on the history]). Having India and China and several other large countries outside the [link|http://en.wikipedia.org/wiki/United_Nations_Framework_Convention_on_Climate_Change#Annex_I_and_Annex_II_Countries.2C_and_Developing_Countries|Annex I] group (and lack of ratification by the US) means that only about [link|http://en.wikipedia.org/wiki/Kyoto_Protocol|55% of global greenhouse gas emissions are covered]. It is unreasonable to expect that the Annex II countries would be willing to spend billions of dollars to help reduce emissions in their countries and in developing countries without more of a domestic political consensus.

There are very good reasons for reducing carbon emissions, and for me worries about anthrogenic climate change are low on the list. The US economy is paying a very high price for "cheap" oil and gas. Having the market price of oil and gas reflect the true cost of our military, the cost of pollution controls, the cost of lack of diverse supplies, etc., seems reasonable to me. The UK is in a different situation with its high [link|https://www.cia.gov/cia/publications/factbook/geos/uk.html#Econ|exports] of oil and natural gas, but the US is going to continue to be more dependent on imports as our domestic production continues to [link|http://www.theoildrum.com/story/2006/11/15/83857/186|drop].

[image|http://www.theoildrum.com/uploads/44/cera_figure_1.jpg|0|US Oil Production|379|519]

US taxes on oil and gas should be significantly higher to make it clear that we have the will to reduce consumption and foreign imports. Price is the least-disruptive way to change consumption. Greater efficiency should be our driver - we shouldn't waste so much. We can live better while taking fewer resources if we put our minds to it and make investments in it. We should be tackling CO2 emissions from that end, not primarily because we're worried about [link|http://www.spiegel.de/international/spiegel/0,1518,395014,00.html|thinner polar bears] and so forth.

So, color me as a worried skeptic. The climate does indeed seem to be changing, and it's reasonable that our activities are contributing to that change. How much? I don't know. IMO modern civilization is in more peril due to dwindling supplies of cheap fuel than by rising global temperatures. Objectively, political change forced by rising fuel prices are likely to be much greater and harder to control than more frequent flooding in Venice and Bangladesh and other widely cited aspects of climate change.

My $0.02.

Cheers,
Scott.