Exeter University LogoProfessor Peter Cox
Met Office Chair in Climate System Dynamics
Room 338, Harrison Building
School of Engineering, Computer Science and Mathematics
University of Exeter

Email: P.M.Cox@exeter.ac.uk

Tel (work): 01392 269220




26th September 2007


Ref: Global Cooling Project


Dear Mr Taylor,


I have looked over the 21-7-07 drafts of the global cooling project proposal and the accompanying science dossier. I am happy that the review covers the field and provides a cogent case to support the project proposal.


The proposal that you are making is bold and timely. It is now recognised that global warming requires immediate action to minimise the extent of climate change by the end of this century (“mitigation”) and to adapt to the inevitable climate change that is already frozen into the system over the next few decades (“adaptation”).


Your proposal aims to increase soil moisture through rainwater harvesting in semi-arid areas, where there is believed to be a possibility of two climate-vegetation states (“green” and “arid”). Planting in these regions has the potential to flip the local landscape into the “green” state, as vegetation can significantly enhance rainfall in these regions. Something similar, though without significant human-intervention in that case, seems to have occurred in the Western Sahel about 5,500 years ago.


The greening of regions which are currently semi-arid is possible based on our  understanding of the interactions between the land-surface and the climate (e.g. as studied in the “CLASSIC” centre that I lead). It promises to massively improve local climatic conditions and thereby water availability and crop yields, and would surely make the local human-populations much more resilient to climate change. Your proposal therefore provides a potential mechanism for adaptation to climate change in areas where people are typically most vulnerable.


In addition, you suggest that rainwater harvesting has the ability to offset global warming by enhancing reflective cloud cover, and you back this up effectively by reference to the renowned work of Ramanathan and Pielke, amongst others. Rainwater harvesting will almost certainly increase cloud cover locally and would therefore most likely reduce local temperatures at the Earth’s surface.  The impact on the global mean temperature is less clear, so I am pleased to see that your proposal includes some climate modelling work to ascertain where it would be best to carry-out a re-vegetation and the impact that this is likely to have on the local and global climate. The required modelling tools already exist to a large extent, and you have already engaged many of the key experts in this field.


Overall I applaud the boldness of your proposal, which puts-forward the most benign way for vulnerable peoples to be assisted in adapting to climate change, as well as contributing to the slowing-down of global warming itself.


Some information on my professional background:


Prof Peter Cox  holds the position of “Met Office Chair in Climate System Dynamics” at the University of Exeter, UK.  He is also director of the “CLASSIC” Earth Observation Centre of Excellence (http://classic.nerc.ac.uk/) which uses EO data to quantify interactions between the land-surface and climate. Until September 2006, Prof Cox was the Science Director – Climate Change at the Centre for Ecology and Hydrology, and prior to that he was at the Hadley Centre for Climate prediction and Research (1990-2004). His personal research has focussed on interactions between the land-surface and climate, and he led the team that carried-out the first climate projections to include vegetation and the carbon cycle as interactive elements. Prof. Cox, is a founding member of the Coupled Climate-Carbon Cycle Intercomparison Project (C4MIP), and is a lead-author on the IPCC Fourth Assessment report. He has published over 50 peer-reviewed papers in scientific journals, including one of the most highly-cited papers on global warming in the last ten years.


Yours Sincerely


Professor Peter Cox