Warmer surface temperatures over just a few months in the Antarctic can splinter an ice shelf and prime it for a major collapse, NASA and university scientists have reported. The process can be expected to become more widespread if Antarctic summer temperatures increase. Above: The Larsen B ice shelf, which collapsed in 2000. Photo credit: NASA
Scientists agree the Earth's climate is being directly affected by human activity, and for many people around the world, these changes are having negative effects. Records show that 11 of the last 12 years were among the 12 warmest on record worldwide.
The just-released Intergovernmental Panel on Climate Change (IPCC) Summary for Policy Makers — the first volume of the IPCC's 4th Assessment Report — states that scientists are more than 90% confident that human industrial activity is driving global temperature rises. (add your thoughts on the report at RealClimate.org)
Carbon dioxide levels today are nearly 30 percent higher than they were prior to the start of the Industrial Revolution, based on records extending back 650,000 years.
According to NASA, the polar ice cap is now melting at the rate of 9 percent per decade. Arctic ice thickness has decreased 40 percent since the 1960s.
The current pace of sea-level rise is three times the historical rate and appears to be accelerating.
The number of Category 4 and 5 hurricanes has almost doubled in the last 30 years. The IPCC 4th Assessment Report said that this trend would likely continue.
Droughts in the Sahel during the 1970s and 1980s were found to be caused by warmer sea surface temperatures, and the current drought in the Amazon is suspected to be a result of rising ocean temperatures.
Poverty and food insecurity has also been tied to climate variability.