Future rainfall atlas created

ScienceAlert 10 Aug 09;
Australian National University

Researchers from The Australian National University have created the world’s first comprehensive visual atlas of global rainfall projections over the next 100 years based on all of the models used by the Intergovernmental Panel on Climate Change in its most recent report.

PhD researcher Wee Ho Lim and Dr Michael Roderick from ANU have created the Atlas of the Global Water Cycle, which contains some 300 pages of global maps and tables showing current and projected measures of rainfall, evaporation and runoff.

The atlas illustrate the projections of each of the 20 computer models used by different countries to forecast future water cycles – data drawn upon by the IPCC in its reporting on climate change, but not visualised in the same way and place until now.

“We know that as the world warms there is likely to be more rainfall on a global average basis,” Dr Roderick said. “But where is this increased rainfall going to occur, and which areas might get drier? These are simple questions to ask, but it is surprisingly hard for an individual to get an answer, whether they’re a farmer, civil engineer, teacher or interested citizen,” Dr Roderick said.

“As researchers active in the field we could not answer the question with certainty. In fact, until now we’ve never seen a compilation of the individual rainfall predictions made by all the different climate models.”

Dr Roderick said that the Atlas of the Global Water Cycle would make all the current best information on modelling for future rainfall more easily available so that individuals and communities could make more informed decisions about how to plan for the century to come. He said the climate models – such as the one used by the CSIRO in Australia – each take slightly different approaches to forecasting future rainfall patterns, and that there different findings tended to be averaged out for ease of communication.

“This averaging out of all these different findings is what we tend to see in reports from the IPCC and other international bodies. One problem with these kinds of visualisation for a place like Australia is that there is little consensus between the different models for what will happen to rainfall on our continent.

“The atlas means that you can now see all the different models’ predictions for Australia and the world in detail, and then come to a more informed understanding. All these models are like crystal balls for the global water cycle – but it’s a question of whose crystal ball is the best and how do we know that? I can’t answer that question, but at least by having all the information to compare people will be able to make more informed decisions.”

The Atlas of the Global Water Cycle is available for sale in hard copy or free download from ANU E press.

Original news release.