Letter: The case for climate change
Three recent letters (Feb. 28, March 3, July 11) express skepticism of, or disbelief in, the phenomenon called global warming. I would like to counter that with one letter of belief.
Although trained as a scientist, my abilities to independently analyze mountains of data have faded over the years. These days, I place my faith in those younger scientists who have spent many years studying atmospheric science. For this reason I give a very high weight to the reports of the Intergovernmental Panel on Climate Change (IPCC).
Since its formation in 1988, the IPCC has digested the mountains of data, and new data as it becomes available. The IPCC has also assessed the work of science groups that apply chemistry, physics and mathematics looking for cause and effect. The IPCC has issued four assessment reports. A summary of the last report, published in November 2007, is at http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr_spm.pdf.
One of the first statements in the report is: "Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level." To me, unequivocal means there is no doubt.
Another major statement in the summary report is: "Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations. It is likely that there has been significant anthropogenic warming over the past 50 years averaged over each continent (except Antarctica)." They go on to say that, if emissions had stopped in 1950, there would likely have been global cooling.
The summary report goes on to: 1) make predictions on temperature and sea level out to 2100; 2) point out ways in which mankind can adapt to these changes; 3) possibilities for, and costs of, reducing emissions.
I feel that the case has been made, and we should move ahead with actions to reduce greenhouse gas emissions.
Earl O. Knutson