Michael Roderick Awarded 2009 Australasian Science Prize for Climate Change Research. (October 27, 2009)

The Australian scientist who overturned some "obvious" assumptions regarding climate change was today awarded the 2009 Australasian Science Prize.

Dr Michael Roderick “has raised questions of global significance”; he is a joint Fellow in The Australian National University’s Research School of Earth Sciences and Research School of Biology.

Dr Roderick’s research was based on a deceptively simple experiment that measures the rates of water evaporation from about 300 standardised pans distributed around Australia and more overseas. Counterintuitive the pans reveal that although the world has been warming, evaporation has been declining. He explains the paradoxical evidence: London receives about 600 mm of rainfall every year, and the surrounding landscape is green and wet. On average, Canberra also receives around 600 mm each year but the surrounding landscape is much drier and largely brown. The landscape differences are largely due to the different rates of evaporation. Evaporation is much higher in Canberra than London.

Needless to say, there has been a widespread expectation that evaporation would increase as air temperature rises with global warming. It has been anticipated, for example, that wet and green places like London would become more like Canberra should global temperatures rise.

There was surprise amongst the global scientific community when confronted with observations showing that the evaporation of water from pans has been, on average, declining over the last 30–50 years just as global temperatures have been rising. Understanding and unravelling the ‘pan evaporation paradox’ underpins the whole question of how water availability has changed and might change.

Dr Roderick has shown that several factors are at work simultaneously, with declining wind speed and/or declining radiation being the major global factors behind declining evaporation.

However, Dr Roderick’s research has been published since the mid-2006 cut-off date for the Intergovernmental Panel on Climate Change’s Fourth Report (2007) and therefore updates the IPCC’s models, particularly in relation to rainfall forecasts.

Earlier in the year Dr Roderick and PhD researcher Wee Ho Lim released the Atlas of the Global Water Cycle. These maps, averaged from a number of the IPCC’s climate models, show the history of rainfall in regions of Australia and overseas and outline the best rainfall projections, with uncertainties stated.

A separate study of the water-stressed Murray–Darling Basin (MDB), released exclusively with this announcement, finds “fundamental differences” between public beliefs about climate change and scientific observations. The study by Dr Roderick and Professor Graham Farquhar, a plant physiologist at the ANU, finds that “the public perception is that it will get drier, whereas the scientific basis is that it will rain more on a global average basis. When averaged across all models, a robust prediction is for global precipitation to increase annually by 17 mm for every 1°C of warming.”

The study finds that some regions will become wetter while others will become drier. “We should not give up on agriculture and water resources in the MDB and other once-productive regions,” Dr Roderick remarks. “The future is not necessarily as bleak as appears from the recent and continuing drought.”

According to Dr Roger Gifford, Chief Research Scientist in CSIRO’s Plant Industry: “Observations and conclusions like Dr Roderick’s will improve climate change predictions and lead to more realistic assumptions about the nature of human-induced climate change that sit behind a great deal of climate change impacts and adaptation research. He is a scientist’s scientist.”

Dr Thomas Barlow, a research policy specialist, adds: “This is curiosity-led science that has raised questions of global significance. He starts with very simple but important questions and answers them with extraordinary rigour and originality. In my mind this is truly inspirational stuff – science at its best.”