Floods, heat waves, and air pollution: New report details how the Upstate will be impacted by climate change

Illustration by MHJ/iStock.

A scientific report recently issued by 13 federal agencies paints a troubling picture of what could await the Upstate if significant steps aren’t taken to address climate change.

The 1,600-page report is the second volume of the Fourth National Climate Assessment (NCA4), which reviews the science of climate change and details the devastating effects it could have on communities across the United States. It was produced by the U.S. Global Change Research Program, a consortium of more than 300 government and independent scientists, including a social environmental geographer at the University of South Carolina

Ultimately, the report, which was mandated by Congress, “concludes that the evidence of human-caused climate change is overwhelming and continues to strengthen, that the impacts of climate change are intensifying across the country, and that climate-related threats to Americans’ physical, social, and economic well-being are rising.”

NCA4 co-author Brenda Ekwurzel said the report “makes it clear that climate change is not some problem in the distant future. It’s happening right now in every part of the country.” Ekwurzel is a senior climate scientist with the Union of Concerned Scientists, a nonprofit advocacy organization based in Washington, D.C.

“When people say the wildfires, hurricanes, and heat waves they’re experiencing are unlike anything they’ve seen before, there’s a reason for that, and it’s called climate change,” she said. “In light of the report’s findings, it’s critical that federal, state and local governments take aggressive action to protect U.S. residents by both reining in emissions and helping communities adapt to the climate impacts that are now inevitable.”

As the report notes, climate change will have a number of impacts on the country, including dwindling water supplies, agricultural declines, infectious disease outbreaks, destructive sea-level rise, an increase in certain natural disasters, and billions of dollars in economic losses. One segment of the report is dedicated to how climate change may impact the Southeast if steps aren’t taken to address the issue.

Here are some ways the Upstate could be impacted over the next few decades:

Heat Waves:

South Carolina’s geographic position gives it a humid, subtropical climate with hot summers and mild winters. But the increased presence of carbon dioxide and other greenhouse gas emissions in the atmosphere could result in unprecedented warming by the end of the 21st century, including more intense heat waves during the summer months, according to the NCA4.

“Sixty-one percent of major Southeast cities are exhibiting some aspects of worsening heat waves, which is a higher percentage than any other region of the country,” the report says. 

A state climate summary by the National Centers for Environmental Information (NCEI) shows that average temperatures across South Carolina have already increased about 0.5 degrees Fahrenheit since the beginning of the 20th century.

In the Upstate, the average annual temperature at the National Weather Service station at Greenville-Spartanburg International Airport has increased by more than 3 degrees Fahrenheit since 1980, according to public data.

The NCA4 warns that the region’s rising temperatures will increase risks for outdoor jobs and activities.

“Workers in the agriculture, forestry, hunting and fishing sectors together with construction and support, waste, and remediation services work are the most highly vulnerable to heat-related deaths in the United States,” the report says. 

In addition to heat waves, the NCA4 notes that the number of days with high minimum temperatures (nighttime temperatures that stay above 75 degrees Fahrenheit) has been increasing across the Southeast, and some areas could see an additional 100 “very warm nights” per year by the end of the century.

South Carolina has experienced an “above average” number of very warm nights since the early 1980s, according to the NCEI. The highest number of very warm nights occurred from 2010 to 2014, with an average of eight nights per year, more than double the long-term average.

“Exposure to high nighttime minimum temperatures reduces the ability of some people to recover from high daytime temperatures, resulting in heat-related illness and death,” the NCA4 says. “This effect is particularly pronounced in cities, many of which have urban heat islands that already cause elevated nighttime temperatures.”

Rising temperatures also have the potential to increase the transmission of vector-borne diseases, which are spread by the bite of an animal such as a mosquito or tick.

Dr. Michael Reiskind, an assistant professor of entomology at North Carolina State University, told the Greenville Journal earlier this year that higher temperatures not only cause some mosquitoes to feed more frequently but also allow them to develop faster and the viruses they carry to replicate faster, meaning an infected mosquito is able to transmit whatever disease it has to more animals and humans before its life cycle ends.

An analysis from Climate Central, a nonprofit news organization that reports on climate change, found that rising temperatures and humidity since the 1980s have already driven an increase in the number of days each year with ideal conditions for mosquitoes. In Greenville, for instance, the mosquito season has increased from 113 days to 137 days since 1989, an increase of 24 days.

For more information, visit https://bit.ly/2OpqY1P.


While future changes in precipitation remain uncertain, extreme precipitation is projected to increase across South Carolina and other parts of the Southeast due to climate change, according to the NCA4.

“Extreme rainfall events have increased in frequency and intensity in the Southeast, and there is high confidence they will continue to increase in the future,” the report says.

Since the start of the 21st century, South Carolina has experienced a “below normal number of extreme precipitation events,” according to the NCEI.

The NCA4, however, notes that high-intensity hurricanes are expected to become more common in the future due to climate change, potentially causing local waterways to flood and cause damage.

In the Upstate, the Reedy River is known to swell during extreme rainfall and flood areas throughout Greenville. That includes the Swamp Rabbit Trail and Cleveland Park, both of which sit in low-lying areas along the banks of the river.

Lake Conestee Nature Park, which is situated along the river, also experiences flooding during heavy rainfall. The park’s River Otter Way footbridge, for instance, was destroyed by a recent downpour. The footbridge is vital in connecting areas of the park, as well as providing important assistance to visitors with disabilities, according to Dave Hargett, founder and executive director of the Conestee Foundation, the nonprofit that manages the park. The park is looking to raise $50,000 via GoFundMe to rebuild the important structure. Those interested in donating can do so here.

An increase in extreme rainfall due to climate change could also lead to increased levels of water pollution due to stormwater runoff, which occurs when rain falls but there is more water than the land can absorb, according to the Environmental Protection Agency.

In urban or developed areas, the excess water flows across pavement and parking lots, picking up oil and other pollutants before flowing into a nearby river or stream.

Lisa Wells, a senior engineer with the city of Greenville, said stormwater runoff is one of the city’s biggest environmental threats, especially as urbanization throughout the downtown area continues to decrease the number of natural spaces capable of trapping stormwater when it rains. 

Since 2005, the city has spent more than $15 million to address stormwater runoff in several flood-prone areas of the city: the Henderson basin in the Parkins Mill area, Chick Springs, White Oaks, Broad Street, and near McAlister Square.

The city is currently implementing a new, multimillion-dollar stormwater management improvement plan, dubbed “Stormwater 2.0,” a move that will substantially reduce the amount of pollution that runs off of city streets and construction sites.

As a part of the improvement plan, the city is modeling Richland Creek and other waterways throughout the city to determine how stormwater flows and at what volume into the city’s streams and rivers, according to Wells.

For more information, visit https://bit.ly/2RBqd7S. 

Air Quality:

Some 28,000 tons of air pollutants are emitted each year across the Upstate, according to the EPA’s National Air Toxic Assessment.

Climate change, however, is expected to worsen air pollution throughout the Southeast as the concentration of ground-level ozone is stoked by heat waves and methane emissions.

“The major urban centers in the Southeast are already impacted by poor air quality during warmer months,” the NCA4 says. “Increases in precipitation and shifts in wind trajectories may reduce future health impacts of ground-level ozone in the Southeast, but warmer and drier autumns are expected to result in a lengthening of the period of ozone exposure.”

Ozone forms when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources react chemically in the presence of sunlight, according to the EPA.

At ground level, ozone is considered a pollutant that can impact children’s health and development and increase the risk of heart disease, lung cancer, and asthma attacks, according to the American Lung Association.

“Ozone especially harms children, older adults and those with asthma and other lung diseases,” said June Deen, senior vice president of public policy and health promotions for the American Lung Association in South Carolina, in a statement. “When older adults or children with asthma breathe ozone-polluted air, too often they end up in the doctor’s office, the hospital or the emergency room. Ozone can even shorten life itself.”

Nearly 13 percent of Greenville’s adult population has asthma, which is 40 percent more prevalent here than in the general U.S. population, according to data by the National Center for Health Statistics. Asthma is also Greenville’s leading cause of hospitalization for children under the age of 18, accounting for 41 percent of all emergency room visits.

Climate change creates conditions, including heat and stagnant air, which increase the risk of unhealthy ozone levels, according to the American Lung Association. These conditions also increase the risk of wildfires, a major source of particle pollution.

Particle pollution is a mixture of tiny particles and droplets made up of dirt, dust, soot, smoke, and liquid compounds. Exposure to this type of air pollution can increase the risk of serious health effects, including heart attacks and lung cancer.

The American Lung Association’s 2018 “State of the Air” report found that ozone levels and particle pollution levels increased in most cities nationwide, in large part due to higher temperatures in 2016, the second hottest year on record in the U.S.

The Greenville-Spartanburg-Anderson metro ranked 122nd for high ozone pollution days out of 227 metropolitan areas, according to the report. It ranked 32nd for short-term particle pollution days out of 201 metropolitan areas.

“The air is cleaner, but not clean enough to protect people’s health from harm. And climate change will continue to make both ozone pollution and particle pollution harder to clean up,” Deen said.


For more information, visit www.nca2018.globalchange.gov.


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