As
reported last week by the BBC, the 50,000 member American Geophysical Union (AGU) has updated its policy position, first adopted in 2003, on
Human Impacts on Climate. The policy position, "revised and reaffirmed" in December 2007 begins by stating:
The Earth's climate is now clearly out of balance and is warming. Many components of the climate system—including the temperatures of the atmosphere, land and ocean, the extent of sea ice and mountain glaciers, the sea level, the distribution of precipitation, and the length of seasons—are now changing at rates and in patterns that are not natural and are best explained by the increased atmospheric abundances of greenhouse gases and aerosols generated by human activity during the 20th century.
Here's James J. McCarthy, then president-elect of the American Association for the Advancement of Science (AAAS), writing in March 2007 in a
published letter to the New York TimesTo the Editor:
The National Academy of Sciences, the American Geophysical Union, the American Meteorology Society and the American Association for the Advancement of Science have all issued statements stating that climate change is: a) occurring, b) largely caused by humans and c) likely to continue with large negative consequences for natural and human socioeconomic systems unless we rapidly decarbonize our global energy systems.
People who have evidence that contradicts these statements can publish their findings in scientific journals, after which the public might expect to see this work discussed in Science Times. In the meantime, if you feel obligated to publish what are simply opinions, please use the opinion pages rather than the science section.
James J. McCarthy
Cambridge, Mass.
The writer is the president-elect of the American Association for the Advancement of Science.
The current AAAS position is summarized in the
AAAS Board of Directors Statement on Climate Change:
The scientific evidence is clear: global climate change caused by human activities is occurring now, and is a growing threat to society. Accumulating data from across the globe reveal a wide array of effects....
The statement was approved on 9 December 2006 and released on 18 February at the AAAS Annual Meeting in San Francisco.
I was at that AAAS Annual Meeting in San Francisco, and attended the plenary lecture by Susan Soloman, Senior Scientist at NOAA and co-chair of the
IPCC Working Group I which "assesses the physical scientific aspects of the climate system and climate change." At the conclusion, I recall feeling that the evidence would certainly convince any reasonably thinking person. My notes from that meeting include:
- The IPCC doesn't do science; it assesses.
- The review process included two reviews, and 600 reviewers; there were 30000 comments received.
- We must distinguish between weather and climate; climate is non-local, and deals in averages.
- Analysis of: tree rings, corals, bore holes
- Attribution: Natural forcings that hold out anthropogenic causes do not match the observed data; when anthropogenic causes are included, the models match the data.
- Key Conclusions:
1. Warming of the climate system is unequivocal
2. It is very likely (>90%) that this warming is due to greenhouse gasses
If you want to check out the science, I'd start with the
IPCC's Working Group I report,
The Physical Science Basis, in particular the
Summary for Policymakers (
pdf) and
Technical Summary (
pdf).
Michael Shermer (founder of the Skeptics Society) wrote a column in the June 2006
Scientific American titled
The Flipping Point: How the evidence for anthropogenic global warming has converged to cause this environmental skeptic to make a cognitive flip.
My own view is as follows:
At this point, the debate over anthropogenic climate change appears to me to have taken on the pattern of the creation-evolution debate, which I've been following for -- has it been 30
years now?!? By that I mean, at its core, it has ceased to be much of a scientific debate, but is rather a social issue. Yes, there is (some) uncertainty, but science is a very conservative enterprise, and yet there is broad and deep scientific consensus on this issue. It strains credulity to imagine a scientific cabal of this magnitude mindlessly worshiping Al Gore.
Anti-evolutionists chip around the edges of what is at this point one of the most strongly confirmed theories of science. The anti-anthropogenic climate change (aacc?) arguments seem to me to similarly chip at the fringes where there is debate and admitted uncertainty.
And again, it's not as if the science for this grew
ex nihilo from atmospheric scientists after repeated viewings of
An Inconvenient Truth. The IPCC was established 20 years ago. I've got
Science News articles (yes, hard copy, in a manilla folder!) related to ozone layer depletion and global warming dating back to 1992.
There will be "greenwashing." There will be lazy and hyped reporting from the "
Beast Without a Brain." But in the end, we should heed Richard Feynman's famous conclusion to his report on the shuttle Challenger accident: "For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled."