WASHINGTON: A paper published this week during the American Geophysical Union (AGU) fall meeting in San Francisco points to new evidence of human influence on extreme weather events.

Three researchers from Lawrence Berkeley National Laboratory (Berkeley Lab) are among the co-authors on the paper, which is included in "Explaining Extreme Events of 2015 from a Climate Perspective," a special edition of the Bulletin of the American Meteorological Society (BAMS) released December 15 at the AGU meeting.

The paper, "The Deadly Combination of Heat and Humidity in India and Pakistan in Summer 2015," examined observational and simulated temperature and heat indexes, concluding that the heat waves in the two countries "were exacerbated by anthropogenic climate change."

While these countries typically experience severe heat in the summer, the 2015 heat waves--which occurred in late May/early June in Indiaand in late June/early July in Pakistan--have been linked to the deaths of nearly 2,500 people in India and 2,000 in Pakistan.

"I was deeply moved by television coverage of the human tragedy, particularly parents who lost young children," said Michael Wehner, a climate researcher at Berkeley Lab and lead author on the paper, who has studied extreme weather events and anthropogenic climate change extensively.

The research team also found that, despite being close in location and time, the two heat waves were "meteorologically independent." Even so, Wehner emphasized, "the India/Pakistan paper confirms that the chances of deadly heat waves have been substantially increased by human-induced climate change, and these chances will certainly increase as the planet continues to warm."