These abnormally warm temperatures heated the oceans, intensifying monster hurricanes and deadly flash floods. They parched the land spurring devastating wildfires. They led to unprecedented and punishing hot weather extremes in booming population centers. And they continued to melt the Arctic, losing more and more ice with time.
Here we list some of the most notable and alarming heat-enhanced extreme events of 2017.
A catastrophic Atlantic hurricane season
Fueled by abnormally warm ocean water and a particularly conducive weather pattern over the Atlantic, the 2017 hurricane season was record-shattering.
Not only was it one of the most active, but also it was the most expensive season in U.S. history. Although final costs may not be known for years, estimates suggest the tab will run beyond $200 billion.
Hurricane Harvey kicked off the season in late August. The Category-4 hurricane slammed into Texas with 100-mph winds, but its torrential rainfall, up to 60 inches, and flooding was far more destructive. About 33 trillion gallons of water fell from the storm, most of which landed in a swath from Houston to Southwest Louisiana. Most estimates place Harvey ahead of Hurricane Katrina in damages — about $180 billion.
Just two weeks later, Hurricane Irma struck Florida after battering the Caribbean. The forecast for Irma was exceptionally difficult given how narrow the state is. From day-to-day, the potential track of the storm shifted — at one point Miami seemed likely to bear the brunt before it shifted to the peninsula’s west coast.
More than 16 million people lost power as Irma made landfall on Marco Island, Fla. — an outage that was clearly visible on satellite images. Millions of people had evacuated (some of them into the path of the storm), and damage estimates are expected to exceed $125 billion.
Yet, no storm in 2017 was as devastating as Hurricane Maria was to Puerto Rico. More than three months later, more than half of the island’s 3.3 million population still didn’t have power.
The official death toll remains artificially low, according to a recent investigation by the New York Times, which found that the number of hurricane-related deaths probably exceeds 1,000. The governor of Puerto Rico ordered a recount of the death toll in mid-December.
Wildfires torch California and Portugal
Abnormally hot and dry conditions aided and abetted explosive wildfires not only in California, but also in Portugal.
The two worst blazes in California were in the northern and southern parts of the state.
The Napa fires north of the San Francisco Bay area killed 42 people and destroyed over 8,400 homes and buildings in October. Then the Thomas Fire scorched over 280,000 acres in Southern California, becoming the state’s largest blaze on record.
Savage flash floods kill thousands
There are a few extreme weather phenomena that are absolutely, even inherently, tied to global warming. Among those is flooding, which took thousands of lives across the world in 2017.
These extreme flood events include:
- Peru, early 2017 — Exceptionally warm water in the eastern Pacific Ocean fueled torrential rain, which triggered flooding that killed more than 150 people.
- Sierra Leone, Aug. 13-14 — A round of torrential overnight thunderstorms caused extreme flooding and mudslides that swept through the capital city of Freetown. The disaster killed at least 1,050 people.
- Yangtze River basin, June-July — The East Asia rainy season triggered deadly flooding along the Yangtze River in China and killed 141 people. With a cost of $7.5 billion, it was the most expensive non-U. S. weather disaster in 2017, according to Weather Underground’s Jeff Masters.
From San Francisco to Shanghai, blistering heat shatters all-time records
Around the world, many cities endured hot weather extremes, sometimes unprecedented in their countries or regions. This is just a partial list:
- Dallas had never hit 90 degrees in November before, but it did so three times in four days this year.
- In late October, temperatures soared to 108 degrees in Southern California, the hottest weather on record so late in the season in the entire U.S.
- On Sept. 1, San Francisco hit 106 degrees, smashing its all-time hottest temperature.
- In July, Death Valley, Calif., endured the hottest month recorded on Earth.
- In late July, Shanghai registered its highest temperature in recorded history, 105.6 degrees (40.9 Celsius).
- In mid-July, Spain posted its highest temperature recorded when Córdoba Airport (in the south) hit 116.4 degrees (46.9 Celsius).
- In late June, Ahvaz, Iran, soared to 128.7 degrees Fahrenheit (53.7 Celsius) — that country’s all-time hottest temperature.
- In late May, the western town of Turbat in Pakistan hit 128.3 degrees (53.5 Celsius), tying the all-time highest temperature in that country and the world-record temperature for May, according to Masters.
Arctic warming and near-record low sea ice extent
Temperatures in the Arctic and its average sea ice extent ranked second lowest on record in 2017. The year began with record-low ice extent, but storminess between May and June and somewhat cooler conditions slowed the rate of summer decline.
“[The] Arctic shows no sign of returning to reliably frozen region of recent past decades,” said NOAA’s 2017 Arctic report card. “Despite relatively cool summer temperatures, observations in 2017 continue to indicate that the Arctic environmental system has reached a ‘new normal’, characterized by long-term losses in the extent and thickness of the sea ice cover, the extent and duration of the winter snow cover and the mass of ice in the Greenland Ice Sheet and Arctic glaciers, and warming sea surface and permafrost temperatures.”
The year closed with a record-warm December in Alaska, nearly 16 degrees above normal.
Editor’s note: Some of the material here is drawn from previous Capital Weather Gang stories in 2017.