New Climate Change Projections Highlight Eastern Shore’s Vulnerability

A Salisbury Daily Times article (2018-12-20) discussed the challenges the Eastern Shore faces from climate change according to the latest projections released by the University of Maryland’s Center for Environmental Science.

The Center’s projections incorporated findings from the Intergovernmental Panel on Climate Change Fifth Assessment (2014) and regional factors, such as subsidence and ocean currents. The Center provided three outlooks based on growing greenhouse gas emissions, stabilizing emissions, and meeting the emissions caps under the Paris Agreements. Maryland law requires the projections be updated every five years.

From the summary of the Center’s report:

The Likely range (66% probability) of the relative rise of mean sea level expected in Maryland between 2000 and 2050 is 0.8 to 1.6 feet, with about a one-in-twenty chance it could exceed 2.0 feet and about a one-in-one hundred chance it could exceed 2.3 feet. Later this century, rates of sea-level rise increasingly depend on the future pathway of global emissions of greenhouse gases during the next sixty years. If emissions continue to grow well into the second half of the 21st century, the Likely range of sea-level rise experienced in Maryland is 2.0 to 4.2 feet over this century, two to four times the sea-level rise experienced during the 20th century. Moreover, there is a one-in-twenty chance that it could exceed 5.2 feet. If, on the other hand, global society were able to bring net greenhouse gas emissions to zero in time to meet the goals of the Paris Climate Agreement and reduce emissions sufficient to limit the increase in global mean temperature to less than 2°Celsius over pre-industrial levels, the Likely range for 2100 is 1.2 to 3.0 feet, with a one-in-twenty chance that it would exceed 3.7 feet. …

These probabilistic sea-level rise projections can and should be used in planning and regulation, infrastructure siting and design, estimation of changes in tidal range and storm surge, developing inundation mapping tools, and adaptation strategies for high-tide flooding and saltwater intrusion.

The report cautioned more recent research has indicated that the rate of 100-year sea level rise may be more rapid than the report’s projections without immediate and significant emission reductions.

The Daily Times article focused on the particular effects on the Eastern Shore, which is particularly at risk due to: (1) the Shore’s ongoing land subsidence; (2) long shorelines; (3) low-lying land areas; and (4) water backing up in the Chesapeake Bay if the Gulf Stream slows as the planet warms. From the article:

“The Chesapeake Bay region is one of the places that is ground zero on the planet for sea level change,” said Michael Scott, director of the Eastern Shore Regional GIS Cooperative.

Some of Maryland’s over 3,000 miles of tidal shoreline will experience near daily flooding by 2100 regardless of human’s choices. …

These most recent predictions include measurements for Cambridge and Ocean City that show a .2 and .3 foot higher rise than Baltimore by the end of the century.

The Center’s data projections have stabilized over its last several reports, providing greater certainty to local governments in likely outcomes. In the article, Scott noted that both planning for the changes and mapping affected areas is critical, both for tidal flooding and storm surges.

A two feet rise in sea level is unlikely to reach homes in most of the Eastern Shore, says Scott, because they are typically built higher above sea level with the exception of extremely low-lying Dorchester County.

However, storm surges that already affect many Chesapeake Bay communities would intensify with the added water.

The Center’s report noted that climate change will lead to more frequent and severe storms (but not hurricanes) and storm surges could reach 10 feet.

Another challenge noted in the article is dealing with water being pushed from urban areas and lands with “hardened” water defenses such as bulkheads and sea walls. These defenses will force more water onto shorelines without such protections.

Sea-Level Rise Projections for Maryland 2018 (Center for Environmental Science)