One of the most important news items this past month, in my opinion, was the February 2 release of a report by the United Nations Intergovernmental Panel on Climate Change (IPCC). This was the panel’s fourth report. Here is an overview of the report’s conclusions from the Wikipedia entry on the IPCC:

• Warming of the climate system is unequivocal
• Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely (greater than 90% likely) due to the observed increase in anthropogenic (human) greenhouse gas concentrations
• Hotter temperatures and rises in sea level “would continue for centuries” no matter how much humans control their pollution.^[9], although the likely amount of temperature and sea level rise varies greatly depending on the fossil intensity of human activity during the next century (pages 13 and 18)^[10]
• The probability that this is caused by natural climatic processes alone is less than 5%
• World temperatures could rise from anywhere between 1.1 and 6.4°C (1.98 to 11.52°F) during the 21st century (table 3) and that:
  • Sea levels will probably rise by 18 to 59cm (7.08 to 23.22in) [table 3]
  • It is more than 90% certain that there will be frequent warm spells, heat waves and heavy rainfall
  • It is more than 66% certain that there will be an increase in droughts, tropical cyclones and extreme high tides.
• Both past and future anthropogenic carbon dioxide emissions will continue to contribute to warming and sea level rise for more than a millennium.
• Global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values over the last 650,000 years.

Pundits continue to weigh in on the topic of climate change, of course. I will say only this: be wary of those who cite a scientist here or a report there in opposition to the panel’s conclusions. My layman’s impression is that the vast majority of scientists agree with the report’s strong statements regarding the grave consequences of global warming and the likelihood that it is caused by human activity. Now the most important question is what to do about our warming planet.

Note: Each IPCC report is a compilation of many scientific reports. As such, they are based on the work of a large number of scientists.

This entry was posted on Monday, February 26th, 2007 at 1:16 pm and is filed under Environment and Ecology, Politics.