Africa to take a "quantum leap" in climate forecasting

| Monday December 6, 2010 00:00

CORDEX, an initiative by the World Climate Research Programme, will help downscale the global climate model climate change projections being prepared for the next assessment report of the Intergovernmental Panel on Climate Change (IPCC) so as to predict, for instance, what impact higher global temperatures might have on Lagos, Nigeria, until the end of this century.

This detailed information will feed into the IPCC's fifth assessment report, expected to be published in 2013 or 2014.

'The priority area for CORDEX is Africa, as it is historically under-researched,' said Hewitson, who is also the co-lead author of the chapter on regional contexts in the report by IPCC Working Group II, which will look at impact, adaptation and vulnerability.

Projecting the impact of climate change requires studying changes in the long-term averages of daily weather patterns and many other factors, and can be a tricky business.

Thinking big on climate change modelling Scientists use climate models that simulate the possible impact of variables like radiation, moisture content, and the movement of air and temperature over a given period of time to help project what could happen.

To make forecasting the possible effects of climate change as comprehensive as possible, and also make the connection between current events and future consequences clearer, scientists and academics have been expanding the list of variables to include sea level rise and even food price increases and malnutrition statistics.

A climate model works by calculating what the climate is doing, say, in terms of wind, temperature and humidity at a number of points on the earth's surface and in the atmosphere or ocean, according to an explanation on the website, climateprediction.net. The website is backed by the University of Oxford, the Rutherford Appleton Laboratory and The Open University, all based in the UK. Climate models are systems of differential equations based on the basic laws of physics, fluid motion, and chemistry.To 'run' a model, scientists divide the planet into a 3-dimensional grid, apply the basic equations, and evaluate the results. Atmospheric models calculate winds, heat transfer, radiation, relative humidity, and surface hydrology within each grid and evaluate interactions with neighboring points 'These points are laid out as a grid covering the surface of the Earth, dividing it up into a lot of little boxes. The more boxes there are, the finer the resolution of the model and the smaller-scale climate features it can represent. From this point of view, the best climate model would be the one with the finest resolution.'  Previous climate change models for Africa have typically worked at 200 km resolution - the distance covered by each box in the grid - said Hewitson, who heads the Climate Systems Analysis Group at the University of Cape Town (UCT) in South Africa. The target for Africa is to predict climate changes for every 50 km, but some modellers might take it down to even 25 km, said Hewitson.

Fourteen climate modelling groups have already begun work, taking into account climate data from as far back as 1950 and looking beyond into 2100. Because of a lack of capacity in Africa, only two groups - one at UCT, led by Hewitson, and the other being the Council for Scientific and Industrial Research (CSIR) in Pretoria, South Africa - are based on the continent.

The 12 other groups are led by the Abdus Salam International Centre for Theoretical Physics in Trieste, Italy, the Swedish Meteorological and Hydrological Institute, the Danish Meteorological Institute and the University of Iowa, which are among the world's foremost climate modelling institutions.  The climate data generated by the modelling groups will be processed by regional teams in Africa led by African scientists, as part of the CORDEX initiative. They will be mentored by top global climate modellers such as Bill Gutowski of Iowa State University, who has been involved in efforts to build a climate research community in Africa for the last decade.

The regional teams will then use the data from the 14 climate modelling groups to develop projections, for instance, of flood frequency in a particular catchment area.

'The focus [of the modelling in Africa] is on areas that are urban, agricultural, water catchments, and other regionally important aspects,' said Hewitson.

The mentors will assist the regional teams in developing projections and writing analyses that will meet the requirement of countries wanting information on the effect of climate change on their food security, health, economic growth and a host of other sectors.  The regional teams will be finalized by the end of 2010 and data processing will start in 2011 - IRIN