More information means better predictions
CMIP5 modelling climate change and extreme weather events
In the era of ‘big data’, researchers are reaping the rewards from working with increasingly vast amounts of information about our planet. And datasets don’t get much larger than those used for modelling climatic events and simulating the impacts of global warming on the Earth’s surface.
The primary tools for modelling the climate are Atmosphere–Ocean General Circulation Models (AOGCMs). To improve the credibility of AOGCMs, the World Climate Research Programme established the Coupled Model Intercomparison Project (CMIP). This facilitates comparison of different models to identify common deficiencies and stimulate investigation into their possible causes.
CMIP5 is the fifth phase of CMIP and a multi-model framework of unprecedented scale. It incorporates many more simulations than earlier versions, including those based on historical concentrations, experiments for investigating climate sensitivity, and four emission scenarios reflecting differing potential pathways to 2100.
Use of datasets produced by CMIP5 is widespread: several thousand researchers access the CMIP5 datasets via the Earth System Grid website, and 28 modelling groups worldwide work on models that input to CMIP5 activity. Over 1000 peer-reviewed papers using the datasets have been published in a range of respected climate journals, for example: Journal of Climate (184 papers), Geophysical Research Letters (129 papers), and Climate Dynamics (122 papers).
In Australia, researchers at The Centre for Australian Weather and Climate Research, a partnership between the Bureau of Meteorology and CSIRO, have employed output from CMIP5 models to further our understanding of the current and future climate in the Pacific region.
The research, undertaken as part of the Pacific-Australia Climate Change Science Adaptation Planning (PACCSAP) program, provides insights into the current and future impacts of climate change on the Pacific and the implications for communities in the region.
The work further reinforces the strong credentials of climate research in Australia, which also boasts centres such as the ARC Centre of Excellence for Climate System Science at the University of New South Wales (see Share issue 21).
One of the research streams of PACCSAP has projected the impact of extreme weather events, such as tropical cyclones, onto the region’s future climate. The output from CMIP5 models was key to simulating the conditions for the genesis and behaviour of tropical cyclones.
“Being the latest generation, the CMIP5 models are the most valuable resource we have in the field,” says Dr Sally Lavender, Research Scientist at CSIRO’s Oceans and Atmosphere division. “The real advantage with CMIP5 is there are more models than the previous generation with a broader set of experiments, and all the models are much better in terms of sophistication. They also tend to be higher resolution and more have sub-daily time fields which, for modelling tropical cyclones, is very important.”
Dr Lavender is currently working to extend previous research using CMIP5 models to observe why and where cyclones form, and what determines their tracks. “We’re analysing the CMIP5 models to see how well they represent those processes in the real world to produce a selection of models that are good at representing tropical cyclones over the Australian region. We can then use these models to generate more informed projections of tropical cyclones under future climate scenarios.”
Research to date shows there is likely to be a reduction in the overall frequency of tropical cyclones in the Australian region; however, the proportion of high intensity cyclones is likely to increase. That needs to be taken into account in future building standards and disaster readiness planning.
This article was first published by the Australian National Data Service's Share Newsletter Issue 23, page 14 in October 2015. Read the original article here