 Complete the following phrase:  Barker has overseen a continuation of the research into the application of computing to econometric modelling, in particular the theory and application of large-scale economy-energy-environment E3 models. Using such E3 models, he has been able to apply empirical analysis to international trade theory and to policies for the mitigation of greenhouse gases. He has also held various positions, including Coordinating Lead Author CLA, under the Intergovernmental Panel on Climate Change, an organisation that won jointly with Al Gore the Nobel Peace Prize for 