The past says abrupt climate change in our future

December 13, 2001

San Francisco - Past climates changed abruptly, suggesting that abrupt changes in the future will also occur, according to a Penn State geoscientist.

"When we look at records of the past, climate often changed abruptly rather than smoothly," says Dr. Richard B. Alley, the Evan Pugh professor of geosciences at Penn State. "This is true wherever and whenever you look."

Alley, who is currently chairing the National Academy of Science Committee on Abrupt Climate Change: Science and Public Policy, told attendees today (Dec. 13) at the fall meeting of the American Geophysical Association in San Francisco, that while studies of ice cores, sediments and other relics of the past indicate these abrupt changes, the models currently used by those predicting the future of climate change do not do a good job of simulating abrupt changes in the past.

"If we look at what we know about climate, there is much we don't understand," says Alley. "However, we do know that abrupt change occurred in the past."

The abrupt changes are especially notable in temperature near the north and south poles and in precipitation away from the poles. In the near term, nature sometimes changes smoothly, sometimes remains the same and sometimes changes all at once. In the long term, abrupt change appears to be the norm. Current models all tend to change smoothly and do not capture abruptness.

"It is possible that climate change in the future will include abruptness, even though the current models do not show this," says Alley.

The Penn State geoscientist suggests that climate change includes a process of approaching and crossing a series of thresholds. Climate forcing factors are like a tower of blocks. Building the tower, blocks can be added, and the tower remains stable, but eventually the block height crosses the threshold of stability and the tower abruptly topples. With climate, the thresholds in the past have sometimes been reached in as few as 10 years.

"It will be a long time, if at all, before we are really good at predicting climate change and it may not be easy," Alley says. "Any reality may be very different from the predictions and we need to anticipate changes and surprises. We need to build uncertainty into our models of dealing with climate change."
-end-


Penn State

Related Climate Change Articles from Brightsurf:

Are climate scientists being too cautious when linking extreme weather to climate change?
Climate science has focused on avoiding false alarms when linking extreme events to climate change.

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.

Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.

Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.

Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.

Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).

Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.

Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.

Read More: Climate Change News and Climate Change Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.