Thursday, 4 October 2007

MEDIA RELEASE

Climate models under the microscope

Just how reliable are our climate models?

That is one of the questions asked by the United Nations Intergovernmental Panel on Climate Change and one being looked at by Dr Robert Colman from Australia's Bureau of Meteorology.

Addressing the GREENHOUSE 2007 conference in Sydney, Dr Colman said work over the past five years has improved the way climate models represent important physical processes. The models are more comprehensive than ever, for example with some now including plant responses and ocean biological and chemical interactions."

"Climate models use quantitative methods to simulate the interactions of the atmosphere, oceans, land surface, and ice. They are used for a variety of purposes from study of the dynamics of the weather and climate system to projections of future climate."

"Like the real climate, models attempt to balance incoming energy as short wave (including visible) electromagnetic radiation received from the sun with outgoing energy as long wave (infrared) radiation from the earth. Any imbalance — such as from increasing greenhouse gases – – results in a change in the average temperature of the earth," he said.

At the same time there have been improvements in simulation of many aspects of climate, including a number of important types of climate variability (such as El Niño) as well as a range of climate extremes, which increases our confidence in their use for projecting climate change.

Progress has also been made in understanding the inter-model differences in climate 'sensitivity' (or their response to greenhouse gas increases). This includes increased understanding of climate 'feedbacks' such as those from changes to clouds, water vapour and snow and ice cover.




Annual mean rainfall from observations (left) and models (right)

Dr Rob Colman 0425 795764
Media assistance: David Grant 0439 452 424