IN SCHOOL

Climate change is more extensive and worse than once thought

THE DELUGEA girl crosses a river since the bridge was swept away by Hurricane Maria, in Puerto Rico.PHOTO AP

THE DELUGEA girl crosses a river since the bridge was swept away by Hurricane Maria, in Puerto Rico.PHOTO AP  

Climate scientists missed a lot about a quarter century ago when they predicted how bad global warming would be.

They missed how bad wildfires, droughts, downpours and hurricanes would get. They missed how much ice sheets in West Antarctica and Greenland would melt and contribute to sea level rise. They missed much of the myriad public health problems and global security issues.

Global warming is faster, more extensive and just plain worse than they once thought it would be, scientists say now.

International negotiators meet next week in Poland to discuss how to ratchet up the fight against climate change in what’s called the Conference of Parties . The world’s understanding of global warming has changed dramatically since the first conference in March 1995. Since then the globe on average has warmed nearly three-quarters of a degree (0.41 degrees Celsius) but that’s not even half the story.

That global annual temperature increase is slightly lower than some early 1990s forecasts. Yet more than a dozen climate scientists told The Associated Press that without the data currently available and today’s improved understanding of the climate, researchers decades ago were too conservative and couldn’t come close to realising how global warming would affect daily lives.

One scientific study this month counted up the ways both direct and indirect that warming has already changed Earth and society. The total was 467 .

“I don’t think any of us imagined that it would be as bad as it’s already gotten,” said University of Illinois climate scientist Donald Wuebbles, a co-author of the recent U.S. National Climate Assessment . “For example, the intensity of severe weather. We didn’t know any of that back then. And those things are pretty scary.”

In the 1990s, when scientists talked about warming they focussed on the average annual global temperature and sea level rise. The problem is that people don’t live all over the globe and they don’t feel average temperatures. They feel extremes heat, rain and drought that hit them at home on a given day or week, said Pennsylvania State University climate scientist Richard Alley.

“The younger generations are growing up where there is no normal,” University of Washington public health and climate scientist Kristie Ebi said, pointing out that there have been 406 consecutive months when the world was warmer than the 20th century average.

More recently economists have joined scientists in forecasting a costly future. Yale economist William Nordhaus, who won the 2018 Nobel prize for economics for his work on climate change and other environmental issues, told the Associated Press that his calculations show climate change would cost the United States $4 trillion a year at the end of the century with a reasonable projection of warming.

The way science has looked at global warming has changed over the last quarter century because of better knowledge, better computers, better observations, more data and in large part because researchers are looking more closely at what affects people most. Add to that what many scientists see as an acceleration of climate change and the picture is much bleaker than in the 1990s.

“I honestly didn’t think that in my mid-career we would be watching the impacts of climate change play out on my television” nor that they would be so strong, said Michael Mann, a prominent climate scientist at Pennsylvania State University.AP

We now know we might actually be witnessing the start of a mass extinction that could lead to our wiping out as much as half the species on Earth - Jonathan Overpeck, environment dean, University of Michigan.



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