Post by louise on Jan 15, 2011 10:13:38 GMT 1
From www2.ucar.edu/news/3628/earth-s-hot-past-could-be-prologue-future-climate
"Earth’s hot past could be prologue to future climate
The magnitude of climate change during Earth’s deep past suggests that future temperatures may eventually rise far more than projected if society continues its pace of emitting greenhouse gases, a new analysis concludes. The study, by National Center for Atmospheric Research (NCAR) scientist Jeffrey Kiehl, will appear as a “Perspectives” piece in this week’s issue of the journal Science.
Building on recent research, the study examines the relationship between global temperatures and high levels of carbon dioxide in the atmosphere tens of millions of years ago. It warns that, if carbon dioxide emissions continue at their current rate through the end of this century, atmospheric concentrations of the greenhouse gas will reach levels that last existed about 30 million to 100 million years ago, when global temperatures averaged about 29 degrees Fahrenheit (16 degrees Celsius) above pre-industrial levels.
Kiehl said that global temperatures may gradually rise over the next several centuries or millennia in response to the carbon dioxide. Elevated levels of the greenhouse gas may remain in the atmosphere for tens of thousands of years, according to recent computer model studies of geochemical processes that the study cites.
Because carbon dioxide is being pumped into the atmosphere at a rate that has never been experienced, Kiehl could not estimate how long it would take for the planet to fully heat up. However, a rapid warm-up would make it especially difficult for societies and ecosystems to adapt, he says.
If emissions continue on their current trajectory, “the human species and global ecosystems will be placed in a climate state never before experienced in human history,” the paper states."
My emphasis in last para.
This is a small exerpt from a larger article - well worth reading.
"Earth’s hot past could be prologue to future climate
The magnitude of climate change during Earth’s deep past suggests that future temperatures may eventually rise far more than projected if society continues its pace of emitting greenhouse gases, a new analysis concludes. The study, by National Center for Atmospheric Research (NCAR) scientist Jeffrey Kiehl, will appear as a “Perspectives” piece in this week’s issue of the journal Science.
Building on recent research, the study examines the relationship between global temperatures and high levels of carbon dioxide in the atmosphere tens of millions of years ago. It warns that, if carbon dioxide emissions continue at their current rate through the end of this century, atmospheric concentrations of the greenhouse gas will reach levels that last existed about 30 million to 100 million years ago, when global temperatures averaged about 29 degrees Fahrenheit (16 degrees Celsius) above pre-industrial levels.
Kiehl said that global temperatures may gradually rise over the next several centuries or millennia in response to the carbon dioxide. Elevated levels of the greenhouse gas may remain in the atmosphere for tens of thousands of years, according to recent computer model studies of geochemical processes that the study cites.
Because carbon dioxide is being pumped into the atmosphere at a rate that has never been experienced, Kiehl could not estimate how long it would take for the planet to fully heat up. However, a rapid warm-up would make it especially difficult for societies and ecosystems to adapt, he says.
If emissions continue on their current trajectory, “the human species and global ecosystems will be placed in a climate state never before experienced in human history,” the paper states."
My emphasis in last para.
This is a small exerpt from a larger article - well worth reading.
