Sun Sentinel Palm Beach Edition
Salt is new climate change issue
Leaching from ocean appears to poison fertile land
MIDDLETOWN, N.C. —The salty patches were small at first — scattered spots where soybeans wouldn’t grow, where grass withered and died, exposing expanses of bare, brown earth.
But lately those barren patches have grown. On dry days, salt precipitates out of the mud and the crystals make the soil sparkle in the sunlight. And on a damp and chilly afternoon in January, the salt makes Dawson Pugh furrow his brow.
“It’s been getting worse,” the farmer told East Carolina University hydrologist Alex Manda, who drove out to this corner of coastal North Carolina with a group of graduate students to figure out what’s poisoning Pugh’s land — and whether anything can be done to stop it.
Of climate change’s many plagues, saltwater intrusion in particular sounds almost like a biblical curse. Rising seas, sinking earth and extreme weather are conspiring to cause salt from the ocean to contaminate aquifers and turn formerly fertile fields barren. A 2016 study in the journal Science predicted that 9 percent of the U.S. coastline is vulnerable to saltwater intrusion, a percentage likely to grow as the world continues to warm.
Scientists are just beginning to assess the potential effect on agriculture, Manda said, and it’s not yet clear how much can be mitigated.
“We spend a lot of time and money to try to prevent salt,” Pugh said. “I worry what the future is. If it keeps getting worse, will it be worth farming?”
If farmers in coastal areas have any hope of protecting their land and their livelihoods, the first step is to disentangle the complex causes that can send ocean water seeping into the
ground beneath their feet.
With that in mind, Pugh, Manda and Andrea Gibbs, the local agriculture agent for North Carolina Cooperative Extension, convened at the edge of Pugh’s saltiest field on a recent blustery afternoon.
Pugh has spent his adult life growing soybeans, corn and cotton in North Carolina’s “blacklands,” where the dark and fertile soil is a legacy of nutrient-rich swamps that were drained to make the region arable. His father farmed here in Hyde County before him, and his grandfather before that.
Pugh felt he was prepared for the challenges he would face with the brackish Pamlico Sound within spitting distance and just the thin sandy barrier of the Outer Banks between his farmland and the open ocean.
But lately, the problems have become relentless. Hyde County has been part of a declared disaster zone during four of the past five years, Gibbs said. Heavy rainfall and strong winds have caused millions of dollars in damage. Hurricanes Matthew in 2016 and Florence in 2018 brought several feet of storm surge that inundated the area with seawater.
Science suggests that climate change plays a major role. Data from the National Oceanic and Atmospheric Administration show that sea levels near Pamlico Sound are rising at a rate of 4.4 millimeters per year — equivalent to nearly 1.5 feet over the next century. Other research has shown that
warmer oceans make Atlantic hurricanes wetter, slower and more intense, resulting in more catastrophic storms like Florence.
Pugh estimates that recent flooding — and the associated salinization — cost him $2 million in lost crops over the past five years. Last year, the field where Manda is now working became so pockmarked with barren patches Pugh stopped planting.
“No point in spending the money,” he said, “or the seed.”
And the barren patches may be growing. Most of the 4,000 acres that Pugh farms were inundated during Florence.
Gibbs, who tested salinity levels in this field after the storm, said the results scared her.
“The numbers that were on that sheet .... ” she said.
After the storm, Manda and his students placed scientific instruments in Pugh’s abandoned field: wells to monitor groundwater, probes that take salinity measurements at 10minute intervals.
Though it’s known that saltwater intrusion is linked to sea level rise caused by climate change, scientists aren’t certain how salt winds up in farmers’ fields. One hypothesis is that strong winds may blow saltwater from the sound into the canals and ditches that crisscross the county, which then leak into the soil. Another possibility is that the salt was left behind by storm-surge events and simply takes a long time to wash away.