Coastal areas have the highest amounts of precipitation within the Northeast region. Some of these heavy precipitation events will be in the form of severe storms (e.g. hurricanes and winter northeasters).
Studies have found that there could be as much as a 50 percent increase in severe storm occurrences over the next century given the current rate of climate change. The intensity of hurricanes in the Atlantic will increase along with warming ocean waters: for each 1.8°F increase in tropical sea surface temperatures the rainfall rates of hurricanes could increase by 6-18% and the wind speeds of the strongest hurricanes could increase by about 1-8%.
Heavy precipitation events, particularly winter northeasters and hurricanes, are accompanied by storm surges, which can exacerbate near-shore flooding. A shallow slope will potentially produce a greater storm surge for the same storm than a steep shelf. Storm surge will have greater impact as sea levels rise, including a greater extent of inundation.
The Intergovernmental Panel on Climate Change (IPCC) and US Global Change Research Program predict that flooding associated with 100 year storms (major storms that currently have a 1 percent chance of occurring, on average, in a given year) will become more frequent; in the northeastern US such flooding levels could occur as often as every 20 years in some locations.
Seasonal variations are also expected. More winter precipitation will fall as rain, and less as snow; this is due in part to warmer winter air temperatures. Under one of the climate change scenarios an average of 5%-20% increase in winter precipitation is expected by 2100.
The predictions for seasonal precipitation used by the Commonwealth of MA (MA EOEA 2011) are shown in Table 1. The effects of these possible changes on shellfisheries are not well understood. For example, while heavy precipitation events may decrease salinity levels in near-shore embayments, sea level rise may increase salinity levels. Thus, changes in salinity (and other aspects of water chemistry) may occur in pulses, having to do with the timing of tides and runoff from precipitation events.
|Current Conditions||2050 Prediction||2100 Prediction|
|Annual Precipitation||41 inches||43-44 inches
(+5% to +8%)
(+7% to +14%)
|Summer Precipitation||11 inches||11 inches
(-1% to -3%)
(-1% to no change)
|Winter Precipitation||8 inches||8.4-9.3 inches
(+6% to +16%)
(+12% to +30%)
Table 1. Predictions for seasonal precipitation used by the Commonwealth of MA (MA EOEA 2011).
Heavy Precipitation Change Impacts Relevant to Shellfishing
Implications for Shellfishing
Heavy Precipitation Changes in Wellfleet Harbor may :