The 20th Century has been like no other. With human population jumping from 1.6 to 6 billion between 1900 and 2000, there have been more people vulnerable to climate change than ever before. Moreover, during this same period, carbon dioxide concentrations in the atmosphere have risen from 290 parts per million (ppm) to 369 ppm, with strong evidence pointing to the burning of fossil fuels as a primary cause of these increases. Many climate researchers and policy makers are concerned that increased in population and rising standards of living will lead to ever higher levels of carbon dioxide and other greenhouse gases. See the Intergovernmental Panel on Climate Change (IPCC), Etheridge, et. al., 1998 and U.S. EPA Global Warming.
During the 20th Century there were two world wars, numerous hurricanes and typhoons, influenza breakouts, droughts and famines... and at virtually every step of the way climate played some role in the events.
There has also been increased cloud cover, particularly in the Northern Hemisphere during the past century (Groisman, 1999). While water vapor is the most abundant greenhouse gas, low clouds also shade and cool the surface. Currently the role that water vapor and clouds play in warming or cooling the Earth's climate system is being investigated by scientists.
The 20th century has experienced
catastrophic climate events. The worst tropical storm of the 20th century
occurred in Bangladesh
in November 1970 where 300,000-500,000 people were killed due to winds
coupled with a storm surge.
swelling populations and human activities such as the burning of fossil
fuels lead to warmer temperatures and global warming? Research shows that
global temperatures have in fact risen by .6 degrees Celsius over the
past 100 years and the National Academy of Sciences indicate that the
increase is due in large part to human activity. (See Whitehouse briefing from June 11, 2001.) According Mann
et. Al, 1999, the 20th century warming counters a millennial-scale
cooling trend which is consistent with long-term astronomical forcing.
Also see Paleo
Perspective Global Warming for more on human impact on climate.
Click here to view Putting the 20th Century in Perspective
Downloaded Sunday, 30-Aug-2015 02:09:10 EDT
Last Updated Wednesday, 20-Aug-2008 11:22:39 EDT by email@example.com
Please see the Paleoclimatology Contact Page or the NCDC Contact Page if you have questions or comments.