Understanding Climate Risk

Science, policy and decision-making

Posts Tagged ‘Drought

Food Security and Climate Change

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An excellent briefing from Paul Rogers of the Oxford Research Group on food security and climate change is updating the current global  situation with respect to recent climate events (Hat tip to Jamie Doughney). I’ll reproduce it below after making a few comments.

Most of the briefing concentrates on the conditions of the 1974 food crisis to add a historical perspective. Globally, the US and North America is in the second year of drought, looking at greatly reduced maize production and other other crops. The southwest Indian monsoon is somewhat late and currently at 17% below the 50-year average after a poor year last year. The Horn of Africa is in a delicate recovery stage after last year’s disaster, and efforts to build resilience in the region are ongoing. A recent report from scientists at the UK’s Met Office and the USA’s National Oceanographic and Atmospheric Administration (NOAA) found that the number of below average rainy seasons in East Africa could have been attributable to warming in the Indian and Western Pacific Oceans.

Rogers states that economic growth has been patchy, so that the proportion of people under food stress has not changed greatly since the 1970s. This time around though, he nominates climate change as making a significant contribution to that stress. I agree. One part of that is the asymmetric impact of warming on land affecting drier regions. This is pretty well known. The other is that he suggests climate change is accelerating:

The loss of Arctic sea in recent summers has exceeded forecasts using climate modelling and some recent events have been startling in their intensity, including the extent of the thawing of surface layers of the Greenland ice cap during the early part of July.

This is because climate change is strongly non-linear, and there is increasing evidence that the world, or at least much of the  northern hemisphere, is in a warming episode similar to that experienced in 1997-98. The idea that extremes should change gradually on a smoothly changing mean climate is seriously wrong, and if the world continues to adapt based on that assumption, millions of people will continue to be at risk through insufficient adaptation efforts.

I’m champing at the bit to get back to this research because I use different methods to those of mainstream climate science (but also have a truckload of other work to do). However, both lines of research are pointing to a strong climate change signal in recent extreme events, thereby increasing scientific confidence in its conclusions.

Rogers’ briefing is reproduced below.

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Nothing grows in Texas

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The Sacred Cowboys sang nothing grows in Texas. Last summer it came true. The Texan drought of 2011 was hotter and drier than any of the great droughts of the 1930s. Is it possible to diagnose what role climate change may have played? State Climatologist for Texas John Nielsen-Gammon asked this question last year in a preliminary post on the drought.

He concluded there was a strong anthropogenic evidence for warming but little evidence for its influence on the extremely low rainfall. The following analysis was developed without seeing his summary and happily, they have much in common. The big difference is the explicit treatment of non-linear warming.

I applied the methods for analysing step changes and attributing regional warming developed for SE Australia to the Texan climate. Was it possible to estimate the relative contributions of global warming for a single season? The results were more successful than I had anticipated. Tmax was 86% more likely to be due to anthropogenic warming and Tmin 95%. The method is unorthodox, so may be controversial. Details over the fold.  Read the rest of this entry »

Written by Roger Jones

March 12, 2012 at 12:40 am