Climate Variability

Is it a wet year or a dry year?

The answer to this question determines much of how the Bay fares from season-to-season and year-to-year.

Whether spring rains send copious amounts of nutrients and sediment rushing into the estuary often predicts how well underwater grasses will survive. Whether flows of nutrient-rich runoff trigger abundant algal blooms can forecast the extent to which the Bay's bottom waters will be starved of oxygen when these algal cells die and decompose.

Extreme events, such as the floods caused by Tropical Storm Agnes in 1972 or Hurricane Isabel in 2003, sharpen our awareness of climate variability and its effects on the Bay ecosystem. These storms remind us of the dynamic nature of the estuary and the sensitivity of its shorelines and living resources to waters and winds.

Climatic cycles, such as those related to the El Niño Southern Oscillation (ENSO) or the North Atlantic Oscillation (NAO) may also impact the Chesapeake watershed. El Niño years tend to be wetter, especially in the southern part of the watershed, while La Niña years are drier. The NAO, which occurs on a cycle of a decade or more, usually brings warmer wetter conditions along the entire eastern seaboard.

Climate change is a persistent signal that underlies annual cycles of climate variability, escalating the amplitude of the effects that we see. There is a real prospect that the Chesapeake region will witness a shift in climate during the 21st century due to an increase in greenhouse gases in the Earth's atmosphere. As a result of warming temperatures and land subsidence, sea level will continue to rise. Low-lying areas along the Bay's shoreline will face more tidal flooding, especially during storms, and entire islands could be inundated.

Useful Links

Climate Change Initiatives
Projects to help communities confront the impacts of climate change

Ready for Rising Waters?
Chesapeake Quarterly, Volume 9, Number 4, 2010

Global Warming and the Bay
Chesapeake Quarterly, Volume 5, Number 3, 2006

Five Hundred Feet Above the Bay: New Tools for Tracking Changes in the Chesapeake
Chesapeake Quarterly, Volume 3, Number 2, 2004

A Tale of Two Years
Chesapeake Quarterly, Volume 3, Number 2, 2004

Living Chesapeake: Habitat

Climate Action Plan (pdf)
Maryland Commission on Climate Change