Why the wilder storms? It’s a ‘loaded dice’ problem
Torrential rainfall lashed Japan in July. A cloudburst in August submerged entire villages in south India. In September, Hurricane Florence burst dams and lagoons, with coal ash and pig waste spilling into the waterways of North Carolina. On the other side of the planet, a typhoon walloped the Philippines and ravaged the country’s staple crop, rice.
Climate scientists can’t say where or when the next big storm will hit, but all the evidence points to this: Global warming is bringing the planet into an era of wilder, more dangerous rains with ruinous and long-lasting consequences.
“Where it rains, it’s raining heavier,” said Raghu Murtugudde, a professor of Earth systems science at the University of Maryland who edited a recent book on extreme weather in the tropics. “It’s the classic loadeddice analogy.”
The dice, he said, are “throwing up some numbers more often” in the form of extreme weather. How? The greenhouse gases humans have already injected into the atmosphere have heated up the planet and now pack so much moisture into the air that they heighten the risk of more extreme precipitation.
The good news is that floods and storms don’t kill as many people as they once did.
Early warning systems are in place. So are shelters. People have learned to evacuate from danger zones, including in flood-prone places like the lowlands of Bangladesh, where individual storms once killed tens of thousands of people. In the Philippines this year, Typhoon Mangkhut left a death toll of 100, sharply lower than the 6,000 fatalities from Haiyan, one of the strongest storms ever recorded, which hit the country in 2013.
The bad news is everything else. Even after floodwaters recede, the ruin from a storm can be felt for a very long time.
A study of more than 6,500 cyclones found that tropical storms, especially if they struck frequently, could substantially alter a country’s economic trajectory. Researchers found that in countries hit by the storms, national incomes hadn’t caught up to their previous pace of growth even 15 years after the disaster.
Storms have struck the Philippines very frequently. And they have affected how the country feeds itself.
Between 2006 and 2013, the Philippines was pummeled by 76 natural disasters, primarily floods and tropical storms, with an estimated $3.8 billion in losses to the country’s agricultural sector over that eight-year period, according to the U.N. Food and Agriculture Organization.
This year, because of Typhoon Mangkhut, which struck the country’s rice belt, the Philippines is expected to import much more rice than it otherwise would have.
On average, floods and storms have displaced nearly 21 million people every year over the last decade, according to the Internal Displacement Monitoring Center. That is three times the number displaced by conflict.
Worldwide, according to Munich Re, the world’s largest reinsurer, damaging floods and storms have more than tripled in number since the early 1980s. Their economic losses have risen sharply, too, with two record years in the last decade in which damages topped $340 billion. The company said 2017 was “a wake up call.”
“The slow speed of adaptation to the higher risks is my biggest issue,” said Ernst Rauch, chief climatologist at Munich Re. “We all know, we should know, the risks are changing.”
Preparing for that future of wilder storms, climate scientists acknowledge, is especially difficult when it’s hard to pinpoint, when, where and how often extreme weather will strike, except to warn that it will.
In the United States, heavy downpours in most parts of the country have increased “in both intensity and frequency since 1901,” a report by the National Oceanic and Atmospheric Administration concluded in 2017. The largest increases were in the Northeast.
NOAA also said 2017 was a record year for high-tide floods. And 2017 was a particularly nasty hurricane year, in part because of the warming of the Atlantic Ocean, with six major hurricanes with wind speeds of at least 111 mph.
“The problem is how much money am I willing to spend for how much protection when I know only that we need more protection but not how much,” said Anders Levermann, a climate scientist at Potsdam University in Germany.
The cost of doing nothing is likely to be steep. Levermann’s team concluded that river floods alone would result in global economic losses of approximately 17 percent worldwide in the next 20 years.
Climate change, though, doesn’t just bring more rain. While some of the wettest parts of the world are seeing heavier and more unpredictable precipitation, scientists say, some drier parts of the planet are becoming measurably drier.
The combination can be dangerous.
In India, for instance, even as total annual rainfall has dipped slightly, bursts of intense rain are becoming more powerful, one recent study concluded. Another group of researchers drilled down to find that, in the center of India between 1950 and 2015, there was a threefold increase in what were once rare cloudbursts, those that dump 150 millimeters, or nearly 6 inches, or more of rain on a single day.
Lisa Goddard, director of the International Research Institute at Columbia University, compared the atmosphere to “a big giant sponge” that grows heavy with moisture and, at some point when it’s too heavy, has to be squeezed out, resulting in intense rains.
The results can be overwhelming. If emissions continue to rise and global temperatures grow by 2 degrees Celsius, the mighty Ganges River could double in volume, with devastating consequences for the hundreds of millions of people who live in its basin.
All that unpredictability creates painful choices for government officials who manage reservoirs and dams: Whether to store water in case of drought, or release it to avert floods.
Even the best forecasts, Murtugudde pointed out, are only as good as the people who use them. To avert the worst impacts of disaster in the age of wild rains, it’s not just the science that matters, he said, but the ability of climate experts to persuade the people to follow the science.
“You have to get them to trust the forecast,” he said.
“The slow speed of adaptation to the higher risks is my biggest issue. We all know, we should know, the risks are changing.”
– ERNST RAUCH, CHIEF CLIMATOLOGIST AT MUNICH RE