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Today's Climate More Sensitive to Carbon Dioxide Than in Past 12 Million Years
Last edited Wed Jun 6, 2012, 05:25 PM - Edit history (1)
(Please note, National Science Foundation press release, copyright concerns are nil.)
http://www.nsf.gov/news/news_summ.jsp?cntn_id=124393
[font face=Serif]Press Release 12-107
[font size=5]Today's Climate More Sensitive to Carbon Dioxide Than in Past 12 Million Years[/font]
[font size=4]Geologic record shows evolution in Earth's climate system[/font]
June 6, 2012
[font size=3]Until now, studies of Earth's climate have documented a strong correlation between global climate and atmospheric carbon dioxide; that is, during warm periods, high concentrations of CO2 persist, while colder times correspond to relatively low levels.
However, in this week's issue of the journal Nature, paleoclimate researchers reveal that about 12-5 million years ago climate was decoupled from atmospheric carbon dioxide concentrations. New evidence of this comes from deep-sea sediment cores dated to the late Miocene period of Earth's history.
During that time, temperatures across a broad swath of the North Pacific were 9-14 degrees Fahrenheit warmer than today, while atmospheric carbon dioxide concentrations remained low--near values prior to the Industrial Revolution.
The research shows that, in the last five million years, changes in ocean circulation allowed Earth's climate to become more closely coupled to changes in carbon dioxide concentrations in the atmosphere.
The findings also demonstrate that the climate of modern times more readily responds to changing carbon dioxide levels than it has during the past 12 million years.
"This work represents an important advance in understanding how Earth's past climate may be used to predict future climate trends," says Jamie Allan, program director in the National Science Foundation's (NSF) Division of Ocean Sciences, which funded the research.
…[/font][/font]
[font size=5]Today's Climate More Sensitive to Carbon Dioxide Than in Past 12 Million Years[/font]
[font size=4]Geologic record shows evolution in Earth's climate system[/font]
June 6, 2012
[font size=3]Until now, studies of Earth's climate have documented a strong correlation between global climate and atmospheric carbon dioxide; that is, during warm periods, high concentrations of CO2 persist, while colder times correspond to relatively low levels.
However, in this week's issue of the journal Nature, paleoclimate researchers reveal that about 12-5 million years ago climate was decoupled from atmospheric carbon dioxide concentrations. New evidence of this comes from deep-sea sediment cores dated to the late Miocene period of Earth's history.
During that time, temperatures across a broad swath of the North Pacific were 9-14 degrees Fahrenheit warmer than today, while atmospheric carbon dioxide concentrations remained low--near values prior to the Industrial Revolution.
The research shows that, in the last five million years, changes in ocean circulation allowed Earth's climate to become more closely coupled to changes in carbon dioxide concentrations in the atmosphere.
The findings also demonstrate that the climate of modern times more readily responds to changing carbon dioxide levels than it has during the past 12 million years.
"This work represents an important advance in understanding how Earth's past climate may be used to predict future climate trends," says Jamie Allan, program director in the National Science Foundation's (NSF) Division of Ocean Sciences, which funded the research.
…[/font][/font]
http://news.sfsu.edu/sea-temperatures-less-sensitive-carbon-dioxide-levels-13-million-years-ago
[font face=Serif][font size=5]Sea temperatures less sensitive to carbon dioxide levels 13 million years ago[/font]
[font size=3]In the modern global climate, higher levels of carbon dioxide (CO[font size="1"]2[/font]) in the atmosphere are associated with rising ocean temperatures. But the seas were not always so sensitive to this CO[font size="1"]2[/font] "forcing," according to a new report. Around 5 to 13 million years ago, oceans were warmer than they are today -- even though atmospheric carbon dioxide concentrations were considerably lower.
The unusual mismatch between sea temperatures and CO[font size="1"]2[/font] levels during this time period hints that the relationship between climate and carbon dioxide hasn’t always been the same as it is today, said Petra Dekens, assistant professor of geosciences and a co-author of the new study published in the journal Nature.
"There was a transition, from the Earth’s climate system being not as sensitive to changes in atmospheric carbon dioxide to becoming more sensitive to these changes," Dekens said. "What’s interesting is that we can see this transition happening within the last 13 million years."
The connection between modern-day ocean warming and increased levels of atmospheric carbon dioxide produced by human activities has been confirmed in numerous studies, many of them collected in the most recent report of the Intergovernmental Panel on Climate Change.
…[/font][/font]
http://dx.doi.org/10.1038/nature11200[font size=3]In the modern global climate, higher levels of carbon dioxide (CO[font size="1"]2[/font]) in the atmosphere are associated with rising ocean temperatures. But the seas were not always so sensitive to this CO[font size="1"]2[/font] "forcing," according to a new report. Around 5 to 13 million years ago, oceans were warmer than they are today -- even though atmospheric carbon dioxide concentrations were considerably lower.
The unusual mismatch between sea temperatures and CO[font size="1"]2[/font] levels during this time period hints that the relationship between climate and carbon dioxide hasn’t always been the same as it is today, said Petra Dekens, assistant professor of geosciences and a co-author of the new study published in the journal Nature.
"There was a transition, from the Earth’s climate system being not as sensitive to changes in atmospheric carbon dioxide to becoming more sensitive to these changes," Dekens said. "What’s interesting is that we can see this transition happening within the last 13 million years."
The connection between modern-day ocean warming and increased levels of atmospheric carbon dioxide produced by human activities has been confirmed in numerous studies, many of them collected in the most recent report of the Intergovernmental Panel on Climate Change.
…[/font][/font]
