Global carbon emissions are expected to post their biggest drop in more than 40 years this year as the global recession froze economic activity and slashed energy use around the world.

The decline comes as political leaders are struggling to come up with a common approach to dealing with climate change.

The main factor behind this year’s drop in emissions is the slowdown in industrial activity and trade around the world, according to a study due to be released in November by the International Energy Agency.

But the energy agency, which provides policy advice and research to industrialized nations, found that government actions had also contributed to the drop in emissions. The agency said it expected to see global carbon emissions fall 2.6 percent this year.