When heavy rain hit southern Brazil last week, Moisés Alexandre Heck de Carvalho braced for shin-deep floodwaters, like the country saw a 2020 deluge. Instead, the waters rose so high that the 43-year-old grabbed his television and fled to the roof. He spent two nights there, waiting for help.
On the other side of the globe last week, winding Hong Kong streets became surging rapids. Wise Hui, a 20-year old student, said downpours tied to a typhoon came on more suddenly than she had ever seen.
Then came a torrent of rain over northeastern Libya on Monday, leaving 5,300 dead and thousands still missing after perhaps the most ferocious of a spate of recent floods that have inundated communities in countries from Japan to Greece and the United States..
This summer’s record heat helps explain the floods’ intensity and persistence, scientists say, a phenomenon that climate models have long predicted would come with rising temperatures.
Yet “I’m a little shocked at how many are coming this year,” said Michael Bosilovich, a scientist at NASA’s Goddard Space Flight Center who focuses on Earth’s water cycle.
In each case, factors leading to the disasters have varied: A stagnant weather pattern allowed storms to park over Spain, Greece, Turkey and Bulgaria. In southern China, the tail of Typhoon Haikui collided with monsoons. In Libya, as much as 16 inches of rain across desert landscapes overwhelmed reservoirs and dams.
But the globe’s remarkable warmth — especially of its oceans, most of which have been running several degrees warmer than normal for months — served as a backdrop for all of the floods.
It’s too soon to know the degree to which global warming, driven by humans’ use of fossil fuels, contributed to any single deluge. But scientists said there is no question that warmer water is more prone to evaporation, and warmer air can carry more water vapor, factors that can produce more intense rains and storms.
“As long as the average temperatures keep going up, that’s just going to continue,” said Gerald Meehl, a senior scientist at the National Center for Atmospheric Research.
At the end of what has already been a summer of extremes, floods have spanned the Northern Hemisphere with remarkable intensity in recent days.
Across Brazil, deadly floods had already hit at least eight states this year before the most recent deluged ares in the southern state of Rio Grande do Sul. Floods from nearly a foot of rain from a tropical cyclone killed at least 46 people and displaced more than 25,000 people.
Heck de Carvalho and other survivors face an uncertain recovery. “We are traumatized,” he said. “I can’t stay in a place like this. I don’t know how long we will stay at this shelter we are now, because we are surviving on donations. But I want to move away from here.”