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Earth hottest in 5,000 years, study suggests
Sept. 25, 2006
Courtesy NASA
and World Science staff
Temperatures on Earth are hotter than they have been in several thousand years, according to a report in Monday’s early online issue of the
research journal Proceedings of the National Academy of Sciences.
A further increase of 1° Celsius (1.8° Fahrenheit) will produce
dangerous sea level rises and species exterminations,
the authors wrote.
The study, led by James Hansen of NASA’s Goddard Institute for Space Studies in New York, found
that warming over the past three decades has pushed Earth past the hottest
levels in the current interglacial period, or time between
ice ages. The current period has lasted nearly 12,000 years. The previous record temperatures during
this period are estimated to have occurred around five or six millennia ago.
Recent warming is forcing species of plants and animals to move toward the north and south poles, the report
said.
The study used temperatures around the world taken during the last century. Scientists concluded that these data showed the Earth has been warming at what they called a remarkably quick rate of about 0.36° Fahrenheit (0.2° Celsius) per decade for the past 30 years.
“This evidence implies that we are getting close to dangerous levels of human-made pollution,” said Hansen.
Human-made “greenhouse gases” are causing global warming, according to scientists. Greenhouse gases trap heat in the Earth’s atmosphere and warm the surface. Some greenhouse gases, which include water vapor, carbon dioxide, methane, nitrous oxide, and ozone, occur naturally, while others are due to human activities.
Further global warming “of more than 1°C, relative to 2000, will constitute “dangerous” climate change as judged from likely effects on sea level and extermination of species,” the scientists wrote. The report extends a recent finding that Earth is currently hotter than at any time in the past
400
years.
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Temperatures on Earth are hotter than they have been in several thousand years, according to a report published in Monday’s early online issue of the journal pnas. The study, led by James Hansen of NASA’s Goddard Institute for Space Studies, in New York, found that, because of a rapid warming over the past three decades, the Earth is passing through the warmest levels in the current interglacial period. which has lasted nearly 12,000 years. An “interglacial period” is a time in the Earth’s history when the area of Earth covered by glaciers was similar or smaller than at the present time. The previous record temperatures during that period are estimated to have occurred around five or six millennia ago. Recent warming is forcing species of plants and animals to move toward the north and south poles, the report added. The study used temperatures around the world taken during the last century. Scientists concluded that these data showed the Earth has been warming at what they called a remarkably quick rate of about 0.36° Fahrenheit (0.2° Celsius) per decade for the past 30 years. “This evidence implies that we are getting close to dangerous levels of human-made pollution,” said Hansen. In recent decades, human-made greenhouse gases have become the largest climate change factor, according to scientists. Greenhouse gases trap heat in the Earth’s atmosphere and warm the surface. Some greenhouse gases, which include water vapor, carbon dioxide, methane, nitrous oxide, and ozone, occur naturally, while others are due to human activities. Further global warming “of more than 1°C, relative to 2000, will constitute “dangerous” climate change as judged from likely effects on sea level and extermination of species,” the scientists wrote. The report extends a recent finding that Earth is currently hotter than at any time in the past 400 years.