The project, initially directed by Richard Stone, whom Barker succeeded as director in 1983, coordinated a research team including economists such as Mervyn King, Angus Stewart Deaton and Jeremy Bray.

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.

[6] Barker has stated that the climate change problem requires urgent action aimed at decarbonising the world economy[7] and his written extensively on these issues.

[8] He has been supportive of Barack Obama's Green New Deal, stating that "If all G-20 countries adopted a 'green New Deal' similar to the one proposed by President Obama, the world economy would be greatly strengthened, especially the sectors producing low-carbon technologies ... Where many current calculations get it wrong is in the assumption that more stringent [climate mitigation] measures will necessarily raise the overall cost, especially when there is substantial unemployment and underuse of capacity as there is today.