The number of billion-dollar weather disasters in the United States has more than doubled in recent years, as devastating hurricanes and ferocious wildfires that experts suspect are fuelled in part by climate change have ravaged swaths of the country, according to government data released today.

Since 1980, the United States has experienced 241 weather and climate disasters where the overall damage reached or exceeded US$1 billion, when adjusted for inflation, according to data from the National Oceanic and Atmospheric Administration. Between 1980 and 2013, according to NOAA, the nation averaged roughly half a dozen such disasters a year. Over the most recent five years, that number has jumped to more than 12.

"We had about twice the number of billion dollar disasters than we have in an average year over the last 40 years or so," Deke Arndt, chief of the monitoring branch at NOAA's National Centres for Environmental Information, told reporters.

NOAA said 14 separate weather and climate disasters, costing at least US$1b each, hit the United States during 2018. The disasters killed at least 247 people and cost the nation an estimated US$91b ($133b). The bulk of that damage, about US$73b, was attributable to three events: Hurricanes Michael and Florence and the collection of wildfires that raged across the West.

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Yet 2018 did not set the record for the most expensive year for such disasters. That distinction belongs to 2017, when Hurricanes Harvey, Irma and Maria combined with devastating Western wildfires and other natural catastrophes caused US$306b in total damage. They were part of a historic year that saw 16 separate events that cost more than US$1b each.

But the most recent numbers continue what some experts call an alarming trend toward an increasing number of billion-dollar disasters, fuelled, at least in part, by the warming climate.

"There's this knot in your stomach where you know there is some big piece of this that is probably coming from climate change, but at the same time, there are a lot of moving parts," said Solomon Hsiang, a public policy professor at the University of California at Berkeley, who has studied how natural disasters affect societies.

Many factors contribute to the cost of any one disaster. For instance, a hurricane that hits a heavily populated area, such as Hurricane Sandy in 2012 or Hurricane Harvey in 2017, is likely to have a far higher economic impact than one that hits a less crowded part of the country.

The nation's growing population, inconsistent building codes and the fact that many cities and infrastructure sit near coasts or along rivers also play a role. But increasingly, experts say, so does climate change.

"The recent past is likely prologue," said Mark Muro, a senior fellow at the Brookings Institution, who has studied the economic impact climate change is likely to have on different parts of the country in the coming decades.

THE FOURTH-WARMEST YEAR


Separately today, the National Aeronautics and Space Administration and NOAA released data that officially made 2018 the fourth-warmest year since 1880.

The last four years have been the warmest on record, and nine of the 10 warmest years have been since 2005.

Analyses from Nasa and NOAA also show that in most or all of these years, the Earth was at least 1 degree Celsius warmer than it was in the preindustrial era of the middle to late 1800s.

"It was quite clearly the fourth warmest year in our record, which goes back to 1880, and probably was warmer than many hundreds of years before that," said Gavin Schmidt, director of the Goddard Institute for Space Studies at Nasa, which produces the temperature record.

The agencies' data also showed that 2018 was the wettest in the past 35 years in the US, and the third wettest since record keeping began in 1895.

Hsiang said that climate models predict that the country can expect more of the most catastrophic and costly events over time - namely, more powerful hurricanes slamming into the East and Gulf coasts and more intense wildfires in the West. Scientists also have predicted that a warming climate will fuel more severe droughts, longer wildfire seasons and more frequent floods.