The projection of global temperature for the year 2100 is most alarming. The Intergovernmental Panel on Climate Change (IPCC) shows that temperatures are set to surpass the maximum temperatures in the 11,300-year period known as the Holocene — under all plausible greenhouse gas emission scenarios.
This is of particular interest because the Holocene spans the entire period of human civilization.
According to the researchers, history shows that over the past 5,000 years, the Earth on average cooled about -17C (1.3F) — until the past 100 years, when it warmed by -17C (1.3 F).
The largest changes were in the northern hemisphere, specially Asia. Climate models project that global temperature will rise another -16.7 to -11.3C (2.0 to 11.5F) by the end of this century, largely dependent on the magnitude of carbon emissions. "What is troubling is that this warming will be significantly greater than at any time during the past 11,300 years," researchers said. Results of the study, by researchers at Oregon State University and Harvard University, were published in the journal Science.
Lead author Shaun Marcott says previous research on past global temperature change has largely focused on the last 2,000 years. Extending the reconstruction of global temperatures back to the end of the last Ice Age puts today's climate into a larger context.
"We already knew that on a global scale, Earth is warmer today than it was over much of the past 2,000 years. Now we know that it is warmer than most of the past 11,300 years," Marcott said. Peter Clark, co-author said, "When you just look at one part of the world, the temperature history can be affected by regional climate processes like El Nino or monsoon variations. But when you combine the data from sites all around the world, you can average out those regional anomalies and get a clear sense of the Earth's global temperature history."
According to the team, the most important natural factor affecting global temperatures during the last 11,300 years is a gradual change in the distribution of solar insolation linked with Earth's position relative to the sun.
"During the warmest period of the Holocene, the Earth was positioned such that Northern Hemisphere summers warmed more. As the Earth's orientation changed, Northern Hemisphere summers became cooler, and we should now be near the bottom of this long-term cooling trend — but obviously, we're not," they said.
According to Marcott the earth's climate responds tremendously to carbon dioxide and solar insolation.
Anda sedang membaca artikel tentang
In 2100, Earth will be hottest in 11,300 years
Dengan url
http://pijitwajah.blogspot.com/2013/03/in-2100-earth-will-be-hottest-in-11300.html
Anda boleh menyebar luaskannya atau mengcopy paste-nya
In 2100, Earth will be hottest in 11,300 years
namun jangan lupa untuk meletakkan link
In 2100, Earth will be hottest in 11,300 years
sebagai sumbernya
0 komentar:
Posting Komentar