"The accumulation of greenhouse gases in the atmosphere is causing substantial changes to Earth’s climate and ecosystems. As governments take action to mitigate greenhouse gas emissions, the effectiveness of these actions must be validated by atmospheric measurements to independently confirm reported emissions. This proposal will study the emissions of carbon dioxide (CO2) from fossil fuel combustion in two regions that have enacted progressive policies to reduce emissions: California and the UK. It will integrate the applicant, Dr. Heather Graven, into the European community as a lecturer at Imperial College London in the UK from her current post as a postdoctoral researcher at Scripps Institution of Oceanography in the US. Critical contributions of the CIG funding will be its support for travel to maintain and expand her collaborative network in the US, Europe and abroad, and its support for her initial investments to establish an innovative research program in Europe. The project involves cooperation across sectors, bringing together universities, government agencies and private firms, and it makes strong international connections between complementary research being conducted in the US and across Europe, in particular with the European Integrated Carbon Observing System (ICOS) and the American Carbon Monitoring System (CMS). The quality and leadership of the applicant, demonstrated by publications in high impact journals, outreach in the news media and the award of a significant grant to support part of her research programme over the integration period, will contribute to the excellence and impact of European research."