Climate Change – A new study from the National Academy of Sciences has definitively linked extreme weather events to climate change, just as scientists had long predicted.

In the past, scientists had been hesitant about attributing such events as Hurricane Katrina or Superstorm Sandy due to the many number of factors that impact violent storms.

Scientists have instead said that individual events can’t be definitively linked to climate change, but the new study says that’s not the case anymore. Instead, scientists can at least determine the probability of these kind of events occurring, according to a statement from Penn State.

Climate science has progressed so much that experts can accurately detect global warming’s fingerprints on certain extreme weather events, such as a heat wave, according to a high-level scientific advisory panel.

For years scientists have given almost a rote response to the question of whether an instance of weird weather was from global warming, insisting that they can’t attribute any single event to climate change. But “the science has advanced to the point that this is no longer true as an unqualified blanket statement,” the National Academies of Sciences, Engineering and Medicine reported.

Climate Change 2High precipitation and drought conditions caused by warming temperatures are most problematic for WNC.

Rising temperatures make up only part of Western North Carolina’s biggest weather threats as the region’s climate changes, scientists say.

Across the Southeast, the number of extreme weather events has increased too, said Deke Arndt, climate monitoring branch chief at the Asheville office of the federal National Centers for Environmental Information.

Measuring climate change involves far more than tracking average high temperatures. Increases in morning lows, for example, hold impact as well. And those have been happening across the Southeast.

Higher morning lows and afternoon highs are critical factors in generating more extreme weather, Arndt said.

Climate Change Data Show: Extreme Southeast weather events on the rise
Climate Change Data Show: Extreme Southeast weather events on the rise

He and his NCEI colleagues define the Southeast as Alabama, Florida, Georgia, North Carolina, South Carolina and Virginia.

Climate change in WNC has made the region more susceptible to drought and to intense rain storms, he said.

“It may seem counterintuitive that we are witnessing both an increase in drought and also in the number and magnitude of rainy days,” Arndt said.

“But it represents an overall increase in the water cycle. More rain is getting delivered in large doses, leaving room for more dry-down periods,” said Arndt, whose Asheville office serves as headquarters for the National Oceanic and Atmospheric Administration’s four NCEI locations.

The others are in Boulder, Colorado; Silver Spring, Maryland; and Stennis, Mississippi.

Daily low temperatures in the Southeast have become higher since 1990, Arndt said. That has a larger impact on everyday life, such as energy costs, he said.

“The daily minimum temperature, especially in the summer, affects more than the daily maximum temperature,” Arndt said.

Another measurement that affects climate in the Southeast is the extremes in days with and without precipitation.

Data show that fluctuations in the Southeast between extremes in precipitation for days, whether wet or dry, have exceeded the expected 10 percent of the Southeast the majority of the time since 1971.

That means greater portions are enduring weather extremes.

One-day extremes in precipitation encompassing more than 10 percent of the Southeast has leapt since 1990. Ten percent is the amount climate scientists expect each year.

Drought also has worsened in the Southeast, scoring on the extreme of the spectrum nine times since 1999, according to NCEI data.

Variabilities in extremes give people and policymakers their greatest challenges in WNC, said Jim Fox, director of the UNCA National Environmental Modeling and Analysis Center.

For example, that variability will affect power generation by Duke Energy plants that supply energy to WNC, Fox said.

And it will affect apple growers in places such as Henderson County, he said.

Those farmers have had to cope with more hail storms, late frosts, period of intense rain and longer droughts.

“It’s really hard for them to maintain sustainability over time,” Fox said.

But as the data show and Arndt emphasized, it’s the water supply for high-population centers such as Buncombe County that are most at-risk from climate-change affected weather patterns.

“Buncombe County relies on water from the sky for all its needs,” Fox said. “That means that in times of drought, (government officials) have to find ways to store water. We’re a lot more susceptible to drought than people think.”

So building local resilience – from additional lines from Duke power plants, to buildings constructed above the flood plain, such as those in Biltmore Village and the River Arts District’s New Belgium brewery is critical, he said.

Due to its isolation in the mountains, Asheville and the surrounding region are also is at risk if a weather event causes a disruption in highway access, Fox said.

The landslide that cut off access to Asheville from Interstate 40 and the problems caused by Hurricane Ike are examples, Fox said.

The landslide forced trucks to take 100-mile detour to get to Asheville, he said.

And while Ike never hit WNC, it disrupted Gulf Coast gas refineries, which supply the region with fuel, Fox said.

Weather extremes increasing in the Southeast

• In 18 of the 25 years from 1990 through 2015, more than 10 percent of the Southeast experienced extremes in one-day precipitation events. Scientists set 10 percent as what should be expected.

• In 10 of the years from 1990 through 2015, more than 10 percent of the Southeast experienced hotter extremes in minimum temperatures. In six other years during that period, some percentage recorded hotter than normal minimum temperatures.

• In 19 of the years from 1990 through 2015, more than 10 percent of the Southeast experienced one-day extremes with precipitation. Extremes in one-day precipitation occurred in 11 of those years.

• Extremes in drought severity have become more common since 1999. In nine of the years from 1999 through 2015, more than 10 percent of the Southeast has experienced severe drought. And in three other years, more than 10 percent of the Southeast recorded severe precipitation. The severity of drought and precipitation demonstrate that extremes on both ends of the spectrum are increasing, climate scientists say.

Source: Asheville office of the National Centers for Environmental Information, National Oceanic and Atmospheric Administration.

Mike Cronin, mcronin@citizen-times.com

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