Climate change is already contributing to the deaths of nearly 400,000 people a year and costing the world more than $1.2 trillion, wiping 1.6% annually from global GDP, according to a new study. The impacts are being felt most keenly in developing countries, according to the research, where damage to agricultural production from extreme weather linked to climate change is contributing to deaths from malnutrition, poverty and their associated diseases. Air pollution caused by the use of fossil fuels is also separately contributing to the deaths of at least 4.5m people a year, the report found.

The 331-page study, entitled Climate Vulnerability Monitor: A Guide to the Cold Calculus of A Hot Planet, was carried out by the DARA group, a European NGO, and the Climate Vulnerable Forum. It was written by more than 50 scientists, economists and policy experts, and commissioned by 20 governments. By 2030, the researchers estimate, the cost of climate change and air pollution combined will rise to 3.2% of global GDP, with the world’s least developed countries forecast to bear the brunt, suffering losses of up to 11% of their GDP.