The effects of climate change in Maryland
Effects of climate change are visible in Maryland now. Noticeable effects include:
Increasingly severe storms
When air temperature increases, more water vapor can be held in the air. Combined with the extra energy available to storms that arise over the warming ocean, the additional water vapor in the air causes more rainfall and increasingly severe winds. The impact of Hurricane Sandy was a tragic illustration of this deadly combination. In the Northeast (including Maryland), much more rain is falling as downpours now than in the past (see fig below).
This can cause flash flooding and tremendous soil erosion in regions where stormwater is not carefully managed. In addition, severe inland storms such as the derecho of 2013 are expected to become more common. Derechos occur when extremely hot air in the southern US collides with colder air in the north. The high winds that resulted from this collision caused wind speeds of 60-80 mph in the 2013 derecho; the storm moved 600 miles in just 10 hours.
Sea level rise
The Mid-Atlantic is particularly vulnerable to changing sea level and is likely to see more rise than the global average. Given Maryland’s miles of coastline and the impact of rising season tidal flow in Chesapeake Bay, communities on the Eastern Shore and the Bay are beginning to face the need for adaptation strategies with help from Maryland’s Department of the Environment and MD Sea Grant. The nuisance flooding from storms that used to occur periodically in Baltimore and Annapolis is now increasingly frequent and is likely to get worse in coming years. Baltimore had an average of 1.3 floods per year between 1957 and 1963, while Annapolis had 3.8 annually. However, from 2007 to 2013, Baltimore had on average 13.1 flood days per year, while Annapolis had more than 39 such days.
Increased sea level also makes storm surge during extreme weather on the coast much more serious, impacting not only coastal communities, but also communities on the bay through increased tidal flux. Storm surge causes extensive flooding and damage to properties, and is responsible for many injuries during severe storms.
Increasingly strange weather
Climate change leads to not only an increase in the average air temperature over time, but is associated with much greater variability in temperature. During the past few years in Maryland, it has become common to have temperatures fluctuate by 20-30 degrees within a single week. The extreme weather is not just limited to heat: In the winters of 2014 and 2015, we had record cold temperatures and half of the largest snowstorms on record in the region have occurred since 2003. This extreme winter weather has caused some to doubt the reality of global warming, although on a global level, 2014 was the warmest year ever recorded. Although apparently paradoxical, the extreme winter cold in the Midwest and Mid-Atlantic is a likely byproduct of climate change, caused by rapidly warming temperatures in the Arctic that have disturbed circumpolar wind patterns and caused the jet stream to dip southward over North America east of the Rockies.
Health impacts of climate change
Earlier springs and longer summers allow many insect species to produce additional generations in a year, while warmer winters increase their overwintering survival. This combination of longer summers and warmer winters is increasing the risk of Lyme disease in the Mid-Atlantic. First, the population size of the black-legged tick increases over the summer but is not reduced by cold winter weather. Warmer winters also provide more food and more benign conditions for overwintering deer and white-footed mice, the two major wild reservoirs of the Lyme disease bacterium, Borrelia bergdorferi.