As Hurricane Nate crossed the Gulf of Mexico on Saturday, it brought with it the prospect of yet more destruction in a storm-battered year that is shaping up to be the most costly on US record.



Nate was set to be the fourth major hurricane to hit in quick succession, after Harvey, Irma and Maria devastated southern Texas, Florida, Puerto Rico and the US Virgin Islands.

According to statistics issued by the National Oceanic and Atmospheric Administration (Noaa) on Friday, the clean-up bill could be without precedent. The US government can also expect more unwelcome news about how climate change is intensifying such natural disasters.

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By the end of September, Noaa said, there had been 15 “weather and climate disaster events” in the US in which total financial losses exceeded $1bn each. That tied 2017 with the same point in 2011, by the end of which year there had been 16 $1bn weather disasters, the most for one year in Noaa records dating back to 1980.

Before the arrival of Nate, 2017 had seen two incidences of inland flooding; one drought; one episode of unseasonably freezing temperatures that decimated crops; seven severe storm events, including tornadoes; three tropical cyclones; and one wildfire. In each instance, Noaa has calculated that costs will exceed $1bn.

Play Video 1:26 Cars submerged, boats upturned: Hurricane Nate aftermath - video report

Nate has a “reasonable” chance of turning into a $1bn-plus weather event, Noaa climatologist Adam Smith told the Guardian via email. If that turns out to be the case, 2017 will tie 2011 before October is even halfway through.

The full financial impact of Harvey, Irma and Maria has not yet been estimated but early forecasts lead experts to fear that Harvey alone could prove more expensive than the catastrophic Hurricane Katrina in 2005.

Katrina is the single most expensive and deadly weather event in Noaa’s 1980-2016 statistics, claiming 1,833 lives after it hit New Orleans and costing $161.3bn, adjusted for inflation. That helped make 2005 the most expensive year on Noaa’s list, with a total cost of $214.8bn.

“There is a good chance that 2017 will tie or surpass 2011 in terms of number of $1bn-plus events and either closely match or exceed 2005 in terms of total cost,” said Smith, a Noaa applied climatologist and the primary researcher for the analysis of $1bn disasters.

This year’s hurricanes and Katrina had “incredible” impacts, he said, putting them “in a class of their own” in terms of cost.

The frequency of hugely expensive weather disasters is increasing. From 1980 to 2016, according to Noaa, the US experienced an average of five and a half $1bn-plus “weather and climate disasters” each year. From 2012 to 2016, that reached 10.6 such events a year. There were 15 $1bn-plus events in 2016.

The rise in cost is chiefly due to a combination of climate change and people spreading into vulnerable areas, especially coasts and floodplains, Noaa has reported.

“Perhaps most concerning is that climate change is playing a role – amplifying the frequency and intensity – of some types of extreme weather that lead to billion-dollar disasters,” said Smith.

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Expecting a hefty budget cut from the Trump administration, according to recent reports Noaa is feeling the pinch in its field-leading aerial monitoring of severe storms, using specialized drones and hurricane-hunting manned flights.

According to a report by Popular Mechanics, the pioneering Coyote program, which flies drones through the heart of hurricanes, has run out of money. According to a report in the Washington Post, Noaa has also had technical problems with its special hurricane-monitoring manned flights during the “most energetic month for hurricanes ever recorded in the Atlantic”.

The federal government can expect to pick up the vast majority of the cost of this year’s hurricanes, Noaa has said, citing analysis from Erwann Michel-Kerjan, a risk management expert, partner at McKinsey and former adviser to the World Bank.

The taxpayer shouldered less than 10% of the cost of Hurricane Diane in 1955 and a quarter of the cost of Hurricane Hugo in 1989, according to Michel-Kerjan. That rose to 50% of the cost of Katrina in 2005 and 80% of the cost of superstorm Sandy in 2012.