Scientists tie climate change to extreme global events

12/16/2016

A major scientific report issued in San Francisco on Thursday has documented more correlations between climate change and extreme weather risk, asserting there’s stronger evidence that greenhouse gases are making the planet’s heat, drought, and storms much worse than they would be without as many of the man-made pollutants in the atmosphere.

This week’s unusually cold temperatures across the upper half of the continental United States might make people forget about the number of global heat records set worldwide in recent years, with 2016 expected to set another.

But in the fifth edition of Explaining Extreme Events from a Climate Perspective, a team of 116 scientists from 18 countries attempt to make connections that many of their colleagues avoid.

They specialize in the emerging genre of science known as “extreme event attribution” — that is, trying to prove that certain major events are either caused by or made worse by climate change.

This year’s report focused on extreme events of 2015, from heat waves in India, Pakistan, Europe, East Africa, East Asia, and Australia to an unusual lack of snow in the Pacific Northwest.

The Great Lakes region was not specifically part of this year’s study, even though 2015 was Lake Erie’s worst year on record for algal blooms.

Scientists such as Martin P. Hoerling of the National Oceanic and Atmospheric Administration’s Earth Systems Research Laboratory, though, agreed climate change is a big reason why Lake Erie’s most dominant form of algae, microcystis, is on the rise globally. He said public officials trying to combat it should realize that climate change has been making storms that push algae-growing nutrients into the water more frequent and intense.

“We are in a warmer world that’s warming rather rapidly,” Mr. Hoerling told reporters covering the report’s rollout at the American Geophysical Union’s fall gathering in San Francisco. “We are ramping up the frequency of extreme rain events in the continental United States.”

According to the report, climate change was behind the “sunny day” tidal flooding of South Florida in September, 2015. Researchers found the odds of flooding from unexplained sea level-surges on calm days has risen 500 percent since 1994.

“Even without a cloud in the sky or a storm on the horizon, the Miami, Florida, region is more likely to experience tidal flooding because of long-term sea level rise cause by global warming,” the report said.

It attributed the 2015 “snowpack drought” in the Cascade Mountains to “unprecedented warmth that caused cold-season precipitation to fall as rain rather than snow on the mountains,” and said Alaska’s wildfires were made worse by climate change.

The report, published Thursday in a special edition of the Bulletin of the American Meteorological Society, was based on 25 peer-reviewed research papers.

It found linkages between climate change and heat waves, record-low Arctic sea ice in March, 2015, extreme drought in southwestern Canada, extreme May rainfall in southeast China, and record winter sunshine in the United Kingdom.

But it ruled out climate change as a source or contributor to outbreaks of extreme cold in the eastern United States and Canada that year, the late onset of Nigeria’s spring rainy season, and heavy precipitation in December of Chennai, India.

“As we get better at distinguishing the influence of climate change from natural variability, the local significance and impacts of this global phenomenon are becoming clearer,” said Stephanie C. Herring, a scientist with NOAA’s National Centers for Environmental Information.

Earlier this week at the AGU gathering, Ohio State University’s Field to Faucet water quality program director, Jay Martin, presented research intended to help western Lake Erie region farmers achieve the watershed’s goal of a 40 percent reduction in algae-forming nutrients.

The research team he represented, which also includes scientists from the University of Michigan, East Carolina University, and other OSU departments, calls for more fertilizer to be injected underground, and for a wider use of cover crops and buffer strips. The Journal of Great Lakes Research published the results.

They found 39 percent of farmers were already applying fertilizer below the soil surface; 22 percent were already growing cover crops, and 35 percent were already using buffer strips. Each of those categories falls about 20 percent short of what’s needed for targeted phosphorus reductions, according to their report.

Contact Tom Henry at: thenry@theblade.com, 419-724-6079, or via Twitter @ecowriterohio.