Climate change is here, scientists warn
Floods, droughts, heat waves and bitter cold doubled in 30 years
WE WERE warned. On June 23, 1988, James Hansen told the US Congress in Washington and the world that global warming wasn’t approaching – it had already arrived.
The testimony of the top Nasa scientist, said Rice University historian Douglas Brinkley, was “the opening salvo of the age of climate change”.
Thirty years on, it’s clear that Hansen and other doomsayers were right. But the change has been so sweeping that it is easy to lose sight of effects large and small – some obvious, others less conspicuous.
Earth is noticeably hotter, the weather stormier and more extreme. Polar regions have lost billions of tons of ice; sea levels have been raised by trillions of gallons of water. Far more wildfires rage.
Over 30 years – the time period climate scientists often use in their studies to minimise natural weather variations – the world’s annual temperature has warmed nearly 0.54ºC, according to the National Oceanic and Atmospheric Administration. And the temperature in the United States has gone up even more – nearly 1.6ºC.
Said Kathie Dello, a climate scientist at Oregon State University in Corvallis: “Climate change is here, hitting us hard from all sides.”
An Associated Press statistical analysis of 30 years of weather, ice, fire, ocean, biological and other data, every single one of the 344 climate divisions in the Lower 48US states has warmed significantly.
The effects have been felt in cities from Atlantic City, New Jersey, where the yearly average temperature rose 2.9ºC in the past 30 years, to Yakima, Washington, where the thermometer jumped a tad more. In the middle, Des Moines, Iowa, warmed by 3.3ºC since 1988.
South central Colorado, the climate division just outside Salida, has warmed 2.3ºC on average since 1988, among the warmest divisions in the United States.
And then there’s the effect on wildfires. Veteran Salida firefighter Mike Sugaski used to think a fire of 4 046 hectares was big. Now he fights fires 10 times as large.
In fact, wildfires in the US now consume more than twice the hectares they did 30 years ago.
The statistics tracking climate change since 1988 are almost numbing. North America and Europe have warmed 1.89ºC – more than any other continent. The Northern Hemisphere has warmed more than the Southern, the land faster than the ocean.
Across the US, temperatures increased. Since 1988, daily heat records have been broken more than 2.3 million times at weather stations across the nation, half a million times more than cold records were broken. The AP interviewed more than 50 scientists who confirmed the depth and spread of warming.
When you look at the globe as a whole, especially since 1970, nearly all the warming is man-made, said Zeke Hausfather of the independent science group Berkeley Earth. Without extra carbon dioxide and other greenhouse gases, he said, the Earth would be slightly cooling from a weakening sun. Numerous scientific studies and government reports calculate that greenhouse gases account for more than 90% of post-industrial Earth’s warming.
“It would take centuries to a millennium to accomplish that kind of change with natural causes. This, in that context, is a dizzying pace,” said Kim Cobb, a climate scientist at Georgia Tech in Atlanta.
Others cautioned that what might seem to be small increases in temperature should not be taken lightly. “One or two degrees may not sound like much, but raising your thermostat by just that amount will make a noticeable effect on your comfort,” said Deke Arndt, NOAA’s climate monitoring chief in Asheville, North Carolina, which has warmed nearly 1.8ºC in 30 years.
Arndt said average temperatures don’t tell the entire story: “It’s the extremes that these changes bring,” Arndt warned.
The nation’s extreme weather – floods, extended droughts, heat waves and bitter cold and snow – has doubled in 30 years, according to a federal index.
The Northeast’s extreme rainfall has more than doubled. Brockton, Massachusetts, had only one day with at least 10cm of rain from 1957 to 1988, but a dozen of them in the 30 years since, according to records. Ellicott City, Maryland, just had its second 1 000-year flood in little less than two years.
And the summer’s named Atlantic storms? On average, the first one now forms nearly a month earlier than it did in 1988, according to University of Miami hurricane researcher Brian McNoldy.
The 14 costliest hurricanes in American history, adjusted for inflation, have hit since 1988, reflecting both growing coastal development and a span that included the most intense Atlantic storms on record.
Climate scientists point to the Arctic as the place where climate change is most noticeable with dramatic sea ice loss, a melting Greenland ice sheet, receding glaciers and thawing permafrost. The Arctic has warmed twice as fast as the rest of the world.
Alaska has warmed 2.4ºC annually since 1988 and 5.4ºC in the winter. Since 1988, Utqiagvik, Alaska, formerly known as Barrow, has warmed more than 6ºC yearly and more than 9ºC in winter.
“The temperature change is noticeable. Our ground is thawing,” said Mike Aamodt, 73, the city’s former acting mayor. The amount of Arctic sea ice in September, when it shrinks the most, fell by nearly one third since 1988. It is disappearing 50 years faster than scientists predicted, said Michael Mann, a climate scientist at Pennsylvania State University.
The vast majority of glaciers around the world have shrunk. A Nasa satellite that measures shifts in gravity calculated that Earth’s glaciers lost 279 billion tons of ice – nearly 67 trillion gallons of water – from 2002 to 2017.
Ice sheets in Greenland and West Antarctica have also have shrivelled, melting about 455 billion tons of ice into water. Nasa satellites have also shown 75 millimetres of sea level rise in just the past 25 years. With more than 70% of the Earth covered by oceans, a 49mm increase is enough to cover the entire US with water about 2.7m deep. – AP
WHEN YOU LOOK AT THE GLOBE, ESPECIALLY SINCE 1970, NEARLY ALL THE WARMING IS MAN-MADE