Professor of Ecosystem Science at the School of Geography.

Broadly, you research the dynamic interaction of forests and climate...
Yes. My research focuses on interactions between tropical ecosystems and the global atmosphere, with a focus on their role in global carbon, energy and water cycles, and in understanding how natural ecosystems may be shifting in response to global atmospheric change. A new focus is on the role that the potential payment for the carbon value of tropical forests (in the context of mitigating climate change) can play in protecting those forests.

How are natural ecosystems shifting in the face of climate change?
A major part of my research has been the meticulous monitoring of specific tropical forest study sites, initially in Amazonia, and more recently in the Andes, Africa and Borneo. Everywhere we look we see evidence that these forests are changing. On the positive side, the forests appear to be increasing in biomass and absorbing carbon – the rate of climate change would be about 20% faster if they weren't – but the dynamics, composition and ecology of these forests all appear to be shifting as the tropics get warmer, and we don't know how that will impact in the longer term.

What other questions interest you?
One big question is whether there is a "tipping point" – if rainforests warm or dry sufficiently, will they stop acting as brakes on climate change and become accelerators as they begin to retreat and soils begin to release carbon? In 2010 the Amazon rainforest saw its third major ("once-a-century") drought in 15 years, so this is a real threat. We have been exploring these questions using a number of approaches, including artificial drought studies and moving soils and plant material up and down the Andes to explore the effects of temperature. We feed the results into improving the models that underlie climate change predictions.

What questions do you most want to answer over the next five years?
Many tropical forests are literally disappearing before our eyes as they are chopped down for cattle ranches or soy bean farms. There's now global realisation that this cannot continue unabated. Can we slow it down and yet still encourage development in tropical forest nations? I'm involved in a number of projects trying to practically answer that question. The next 5–10 years will be crucial.

How important are trees to efforts to mitigate climate change?
Trees can be part of the solution to tackling climate change – though a far bigger part has to be finding low-carbon ways to power our societies. As individuals we can buy timber from sustainable sources, keep the pressure on our leaders to take climate change seriously and raise the next generation to be aware of how precious our planet is.