Coastal Disruptions from Climate Change Threaten Agriculture
Over the last few decades, rising sea levels are starting to have an impact on people and/or economic activity which are located in coastal communities around the world as well as many island nations that have little or no elevation above sea level. According to the National Aeronautic and Space Administration (NASA), global average sea levels have risen 8-9 inches since 1880. Their research indicates that about one third of the increase is due to the thermal expansion of ocean water as it has gotten warmer, and about two-thirds is due to meltwater flowing back to the ocean as glaciers and ice sheets on land melt. These effects are occurring as a result of climate change.
While that overall average is quite modest, it conceals a great deal of variability that matters in certain regions. For example, local sea level is rising much more quickly than average in areas along the Gulf of Mexico, as local agriculture and other businesses (like oil and natural gas drilling) are pumping water out of aquifers much more quickly than it can be replenished naturally, resulting in soil compaction and the ground sinking and settling. Scientists have determined that the sea level around Grand Isle, Louisiana (which is 109 miles south of New Orleans), has risen by 24 inches since 1950, and that rate of rise has accelerated over the last decade, now rising by over 1 inch every 2 years.
Recognizing the risk that rising sea levels present to their populations, leaders of a group of small island nations have banded together to push the rest of the world for aggressive actions to combat climate change. At the meetings that led to the Paris Accord in 2015, this group insisted that the threshold that the world should strive to maintain was remaining below the 1.5 degrees Celsius increase above pre-industrial levels that would minimize the environmental impacts of climate change.
That grouping known as small island developing states (SIDS) includes 39 island nations such as Barbados and Haiti in the Caribbean Sea, Timor L’Este and Tuvalu in the Pacific Ocean, as well as 19 regions which are part of larger sovereign nations, such as the U.S. and British Virgin Islands and New Caledonia (a French territory 900 miles east of Australia). At the current rate of sea level rise projected over the next several decades, some of the more low-relief islands, such as the Maldives (Indian Ocean) and Kiribati in the Pacific Ocean could be rendered uninhabitable by 2050. Collectively, these SIDS members have about 65 million people living in their territories, and many of them are at risk of being forced to leave their homes due to the envelopment of the sea as a result of climate change. That surge would nearly triple the number of current refugees worldwide, from the current estimate of 36.4 million to more than 100 million. Such an increase, even if realized over a period of multiple decades, would place an enormous burden on the world’s humanitarian institutions. FAO data indicates that those countries also produced $19.7 billion worth of agricultural goods on average between 2017 and 2021, which would need to be replaced on the world market if those island nations had to be abandoned.
More locally, agricultural land along the Atlantic Coast in the United States has also been experiencing saltwater intrusion in recent decades as a result of sea-level rises. Scientists at the National Oceanic and Atmospheric Administration (NOAA) predict that sea levels along the East Coast will rise by about a foot over the next 30 years. In the last few years, researchers at the University of Maryland have been evaluating this problem, both by mapping its impact on coastal fields in the Eastern shore areas of Delaware and Maryland and looking at ways to help farmers cope with these changes.
A 2019 article in Bioscience by a number of University of Maryland researchers (Tully et al.) found that many fields along the Eastern Shore with common cash crops planted — like corn and soybean — suffer from observed salinity levels equivalent to 3.8 parts per trillion (ppt), which is roughly double the level at which crop growth is known to be substantially impaired.
The USDA Climate Hub that is focused on agriculture in the U.S. Northeast is also collecting and sharing data and research on the saltwater intrusion issue. At a USDA research facility near Cape May, New Jersey, scientists are developing plant and conservation solutions for farmers in coastal zones to address saltwater intrusion and other environmental issues.
The increase in saltwater intrusion in coastal areas around the world is due to a range of factors–some naturally occurring, such as droughts, infiltration of seawater into groundwater aquifers that are near the coast, and increased frequency of storm surges and higher tides that bring seawater further inland. Other factors are primarily human-induced, such as the use of water management practices such as irrigation and how water control structures are connected.
A farmer in New Jersey is finding ways to continue to use his land even after saltwater intrusion has occurred. In a February 2024 article in Civil Eats, Mr. John Zander describes his intention to plant test plots of various tidal grasses. Since such species can survive in salty conditions, he plans to use the biomass for animal bedding and weed control, and also hopes to sell some of the plants as living ‘plugs’ to neighboring farmers to help them establish field buffers and also to local conservation groups.
Other farmers are opting to enroll such fields in USDA conservation programs such as the Conservation Reserve Enhancement Program (CREP) or the Agricultural Conservation Easement Program (ACEP), to either help to mitigate the damage or take the affected fields out of production entirely.
