Global carbon emissions from power plants may be headed for a record high this year after summer droughts and heatwaves boosted coal- and natural gas-fired generation.

The jump in fossil fuel use pushed emissions from electricity production up 1.7%, or 133-million tons, in the first eight months of this year, climate think-tank Ember said in a report Wednesday. Most of the increase was in July and August, as fossil generation was unchanged in the first half from a year earlier.