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 2007. In 2009 he presented a speech to COP 15 – the UNFCCC Conference of Parties event in Copenhagen.