Dengue fever and more snakes? S.C. braces for hotter climate

Michael Cobb, captain/owner of the shrimp boat “Family Thing,” offloads some of the smaller brown shrimp he caught during the first day of commercial shrimp season Tuesday June 10, 2003. Cobb was docked behind the Wando Shrimp Company on Shem Creek.

It’s going to get hotter, and sooner than most folks might expect.

That’s the conclusion of a recent peer-reviewed study that pegged 2047 as the date when average yearly temperatures in South Carolina will be consistently higher than in any year since 1860 because of climate change.

By 2047, it should become pretty clear how accurate that study was, because some parts of the globe are predicted to reach “climate departure” in just seven years. Parts of Indonesia get to go first.

In subtropical South Carolina, consistently warmer years could mean more heat-related deaths, impacts on agriculture and wildlife — particularly aquatic animals, such as striped bass and brown shrimp — and the rise of tropical diseases such as mosquito-borne Dengue fever.

“A major concern is tropical diseases moving north,” said Robert Ball, College of Charleston and Medical University of South Carolina public health professor.

The potential effects of consistently higher temperatures are understood, and it’s well documented that average temperatures have been rising. As with the rise in sea levels, the variables are how much of an increase, and how fast.

Questions about how to best respond remain mired in politically polarized disputes about the science.

Published in the journal Nature by University of Hawaii biological geographer Camilo Mora and colleagues, what the study did was run simulations from 39 computer models, and put firm dates on when higher average annual temperatures will likely become the norm in different parts of the world.

Worldwide, and specifically on the Atlantic coast of the United States, that year is 2047, give or take a few years to account for the margin of error. Specific places elsewhere have dates ranging from 2020 in parts of Indonesia to 2071 in Anchorage, Alaska.

Ball said the impacts of a warmer climate already are being seen. Dengue fever cases are turning up along the Gulf Coast in Texas and in Florida, which has had more cases this year than ever previously reported.

A barracuda caught recently off South Carolina poisoned the couple who ate it, because it was tainted with harmful algal blooms associated with tropical waters, Ball said.

Medical University of South Carolina researchers are now studying “an explosion of these harmful algal blooms, and they are moving north from Florida as the water temperatures increase,” said Eric Lacy, director of the Marine Biomedicine and Environmental Sciences Center.

For some species, a relatively small change in temperature can be crucially important. Take the Eastern brook trout, for example, which is currently found in Upstate streams where the water can reach 68 to 70 degrees during the summer.

“Brook trout typically do not occur in streams where maximum temperatures exceed 70 (degrees),” an S.C. Department of Natural Resources report said this year. “Any increase in stream temperature as a result of climate change likely would result in the loss of the species in South Carolina.”

For people, illness, injuries or deaths due to heat, air pollution, extreme weather and water-borne pathogens all are among the potential problems studied by neighboring North Carolina as part of a federal Centers for Disease Control and Prevention program, in which South Carolina did not participate.

“What the public now considers to be an exceptional (heat) event could become routine across much of the country,” a related CDC study said.

That CDC study looked at potential impacts from higher average temperatures due to climate change. As with the University of Hawaii study, different levels of climate-changing emissions were considered, producing different scenarios.

“Under the higher emissions scenario, by the late part of this century, people in New Hampshire would experience a summer climate close to the current norm for North Carolina, while those in Illinois would experience a climate like that currently experienced in Louisiana or Texas,” the CDC study said.

The University of Hawaii study projections assume that emissions of carbon dioxide and other gases continue to increase worldwide. If emissions were reduced, the study said, the worldwide “year of climate departure” could be as late as 2069.

Georgia Tech climate scientist Judith Curry, who has repeatedly criticized the conclusions and methodology of the United Nations Intergovernmental Panel on Climate Change, said on her blog Climate Etc. that the University of Hawaii study made much more sense than studies that looked only at more recent temperature trends.

“To me, it makes much more sense to look at the historical variability since 1860, than merely to look at the period 1986-2005,” said Curry, who fits somewhere in between the scientific consensus on climate change and the conservative groups that insist it’s a hoax.

The Heartland Institute, which regularly publishes reports such as “Polar bears thriving as Artic ice recedes,” dubs Curry a “lukewarmist” while touting her criticism of the IPCC.

Curry said that “sounding the ‘alarm’ based on this paper seems misguided, since this paper seems markedly less alarming than what was reported in the AR5 (the latest IPCC report).”

The authors of the University of Hawaii study acknowledge that it was limited by the relatively short span of historical records on climate variability. But the study also is skewed by the effects of greenhouse gases on modern records, they said.

Regardless of what date proves to be the “year of climate departure” the changes already are underway. As just one example, bird species such as the Gulf Coast white pelican are now showing up in South Carolina, while “native” species such as purple finches are in dramatic decline.

This is a subject the S.C. Department of Natural Resources recently studied extensively. The resulting report on the effects expected from climate change was controversially withheld from the public, initially, then released after some of the language about global warming was toned down.

The report says climate warming is “a threat-multiplier that could create new natural resource concerns, while exacerbating existing tensions already occurring as a result of population growth, habitat loss, environmental alterations and overuse.”

If the University of Hawaii study proves correct and South Carolina’s annual temperatures will be forever hotter in less than 40 years, that doesn’t mean it will be hot every day, or that it won’t ever be cold. It means the average temperature for the entire year will be elevated.

Currently, the state’s average annual temperature is about 61 degrees, according to the state DNR report, ranging from around 55 degrees in the mountains at Caesars Head to 66 degrees along the southern coast.

One of the largest impacts researchers worry about as temperatures rise involves winter temperatures. Without enough cold days during a South Carolina winter, species that can’t handle cold weather could move north from Florida, including large constrictor snakes and tropical fish species.

The report also echoes Ball’s concerns: “Increased temperatures, changes in rainfall and other environmental factors affected by climate shifts can create ideal conditions for proliferation of invasive plant and animal species, including parasites and pathogens.”