Extreme weather left its mark across the planet in 2016, the hottest year in recorded history. Record heat baked Asia and the Arctic. Droughts gripped Brazil and southern Africa. The Great Barrier Reef suffered its worst bleaching event in memory, killing large swaths of coral.

Now climate scientists are starting to tease out which of last year’s calamities can, and can’t, be linked to global warming.  In a new collection of papers published Wednesday in the Bulletin of the American Meteorological Society, researchers around the world analyzed 27 extreme weather events from 2016 and found that human-caused climate change was a “significant driver” for 21 of them.

To judge whether global warming made a particular extreme weather event more likely to occur, scientists typically compare data from the real world, where rising greenhouse gases have heated the planet over the past century, against a modeled counterfactual world without those rising emissions. This technique has gained broader acceptance among climate scientists in the past decade.

• Record temperatures around the world: Last year, Earth reached its highest temperature on record, beating marks set in 2015 and 2014.

•Coral bleaching in the Great Barrier Reef: Over the past two years, unusually warm waters in the Pacific have caused bleaching on the Great Barrier Reef, a phenomenon in which coral expel vital algae from their tissue and take on a ghastly white appearance.

• Drought in Africa: In the first few months of 2016, severe droughts and heat waves spread across much of southern Africa, triggering local food and water shortages that affected millions.

•Wildfires in North America: In 2016, wildfires burned about 8.9 million acres of western Canada and the United States, including a particularly destructive fire in Alberta that forced mass evacuations and destroyed 2,400 homes.

• The warm “blob” in the Pacific Ocean: Over the past few years, a large patch of unusually warm water has appeared off the coast of Alaska, popularly known as “the blob.” These warm waters have allowed toxic algae blooms to spread across the region, killing seabirds by the thousands and forcing local fisheries to close.