Potential climate change impacts: a global, multi-sectoral assessment

Recent graduate Anna Feeney is currently working at CEH, helping us to prepare content for our new website (more on that in the New Year!). Anna has been getting to know our science by reading some of the recent peer-reviewed outputs authored by CEH scientists. Here she describes one paper which caught her eye:

“A new paper recently published in the journal Climatic Change explores some future climate change scenarios, and translates projected changes in meteorological conditions into a range of different impacts that might affect the day-to-day lives of millions of people.

The work was led by Professor Nigel Arnell from the University of Reading. It uses a “pattern-scaling” technique to capture the main features of available climate models from around the world including the IMOGEN model developed by CEH’s Dr Chris Huntingford, who is also a co-author of the article. The research team used 21 climate models and four possible socio-economic tracks to examine a whole host of sectors such as water resources and agriculture.

According to the authors it is potentially one of the most multi-dimensional, wide-ranging studies into climate change impacts to date.

The four socio-economic pathways represent potential future societal habits, each taking into account possible changes in consumption patterns, socio-economic behaviour and corresponding levels of carbon emissions. After combining this information with the 21 different climate change models, changes to climate could be estimated at regional levels at three different milestones: 2020, 2050, and 2080.

Aerial views during an Army search and rescue mission show damage from Hurricane Sandy to the New Jersey coast, Oct. 30, 2012. US Air Force photo by Master Sgt Mark C Olsen (in public domain).

Under one projection for 2050, a sea level rise of 12-32cm is projected which could lead to about 450 million people potentially struggling with increased river flooding, about 1 billion other people possibly feeling increased water stress, and each year an extra 1.3 million of those living near the coast could be flooded.

The authors conclude that a planet that is on average 2.2C warmer would mean that more energy would be consumed in cooling efforts, although that increase in consumption would be offset by reduced need for heating during the colder seasons. Of particular note is that most areas would experience a fall in crop productivity, with implications for the global food supply chain.

A striking conclusion of the report is that, for many impacts, differences between driving climate models are actually more significant than the difference between the socio-economic forcing scenarios. This is mirrored in the IPCC reports, where although all models agree on at least some level of global warming, when it comes to expected changes in rainfall patterns (a key determinant for many impacts of concern) there are large parts of the world with very little agreement. It is hoped that increased data availability will be able to narrow down predictions of global water systems and that the overall uncertainty will eventually become much smaller.

For the present at least, however, adaptation policy determining how to live with climate change will have to keep in mind the complex nature of climate models and their current uncertainties, as well as the multiple potential scenarios based on how much fossil fuel is burnt in to the future.”

Anna Feeney

The open access paper can be read online.

Full paper reference: Arnell, N. W., Brown, S., Gosling, S. N., Gottschalk, P., Hinkel, J., Huntingford, C., ... & Zelazowski, P. (2014). The impacts of climate change across the globe: A multi-sectoral assessment. Climatic Change, 1-18. doi: 10.1007/s10584-014-1281-2

Staff page of Dr Chris Huntingford, CEH

When climate models get it wrong

Guest post by Dr Chris Taylor, Meteorologist, NERC Centre for Ecology & Hydrology

Our recent paper on how rainfall processes are represented in climate models (‘Afternoon rain more likely over drier soils’ published online in Nature this week) led to some interesting headlines around the globe including "Shock. Climate models are too alarmist" (Andrew Bolt’s column in the Melbourne Herald Sun). This is not exactly how I’d express the meaning of the paper!

A key result of our work is that the current models are getting the relationship between rainfall and local soil moisture incorrect, and therefore can end up in a vicious circle of drying soil and reduced rainfall. Representing the processes by which clouds and rain develop within computer models in order to make climate projections over the entire globe for decades hence is tremendously difficult. Until now we didn't have a global observational basis for testing how well the models were predicting this particular aspect of climate. The paper attempts to do this using data from across six continents. Both the paper itself and our press release  go to considerable efforts to provide a balanced report on the research. 

We have a saying in the UK that you shouldn't throw the baby out with the bath-water. There are plenty of people around who jump on any evidence that the models aren't as good as we would like, and instantly move to reject the whole enterprise of climate modelling. We all know the models have to get better, and to get better, scientists need to identify aspects where the models fail. Sometimes communicating that process isn't easy.

Christopher M. Taylor, Richard A. M. de Jeu, Françoise Guichard, Phil P. Harris & Wouter A. Dorigo ‘Afternoon rain more likely over drier soils’ was published in Nature on 12 September 2012.  DOI 10.1038/nature11377