The economic effects of global warming may arrive sooner and with a bigger impact than previously thought, according to Oxford Economics in a report that compares recent scientific research with the economic literature on the costs of climate change.

In the absence of efforts to curb greenhouse gas emissions, the earth could warm by 2 degrees celsius by 2050, cutting global gross domestic product by 2.5% to 7.5%, Oxford estimates, with the worst affected countries being in Africa and Asia. Longer term, a rise in temperatures of 4 degrees by 2100 could cut output by as much as 30%.

Economist James Nixon partly based his analysis on the Intergovernmental Panel on Climate…