National Climate Assessment: The weather of the Mid-Atlantic’s future

The massive Federal review of climate change trends and projections released today documents a warming Mid-Atlantic that will grow warmer in the coming decades.  Along with soaring temperatures, we can expect more intense downpours, higher seas and stronger hurricanes, the report says.

Related: National Climate Assessment: 15 arresting images of climate change now and in the pipeline | U.S. climate report says global warming impact already severe

How intense these changes become depends on whether human emissions of greenhouse gases slow or continue unabated, the report stresses.

Below, I extract (from the report’s chapter on the Northeast and Southeast U.S.) some of the key projections and images that pertain to the Mid-Atlantic’s future weather:

Hotter temperatures

Key statements:

“…the majority of Maryland and Delaware, and southwestern West Virginia and New Jersey, are projected by mid-century to experience more than 60 additional days per year above 90°F compared to the end of last century under continued increases in emissions”


Via the report: “Projected increase in the number of days per year with a maximum temperature greater than 90°F averaged between 2041 and 2070, compared to 1971-2000, assuming continued increases in global emissions (A2) and substantial reductions in future emissions (B1).”

“The frequency, intensity, and duration of cold air outbreaks is expected to decrease as the century progresses, although some research suggests that loss of Arctic sea ice could indirectly reduce this trend by modifying the jet stream and mid-latitude weather patterns.”


Via the report: “Projected average number of days per year with temperatures less than 32°F for 2041-2070 compared to 1971-2000, assuming emissions continue to grow (A2 scenario). Patterns are similar, but less pronounced, assuming a reduced emissions scenario (B1).”

More extreme precipitation

Key statements

“The frequency of heavy downpours is projected to continue to increase as the century progresses…”


Via the report: “he map shows percent increases in the amount of precipitation falling in very heavy events (defined as the heaviest 1% of all daily events) from 1958 to 2012 for each region of the continental United States. These trends are larger than natural variations for the Northeast, Midwest, Puerto Rico, Southeast, Great Plains, and Alaska. The trends are not larger than natural variations for the Southwest, Hawai‘i, and the Northwest. The changes shown in this figure are calculated from the beginning and end points of the trends for 1958 to 2012. ” (U.S. Global Change Research Program)

“Seasonal drought risk is also projected to increase in summer and fall as higher temperatures lead to greater evaporation and earlier winter and spring snowmelt.”

“Winter and spring precipitation is projected to increase…”

“Projected changes in summer and fall, and for the entire year, are generally small at the end of the century compared to natural variations.”


Via the report: “Maps show projected percent change in precipitation in each season for 2071-2099 (compared to the period 1970-1999) under an emissions scenario that assumes continued increases in emissions (A2). Teal indicates precipitation increases, and brown, decreases. Hatched areas indicate that the projected changes are significant and consistent among models. White areas indicate that the changes are not projected to be larger than could be expected from natural variability.”

Higher sea Level

Key statements

“Sea level rise along most of the coastal Northeast is expected to exceed the global average rise due to local land subsidence, with the possibility of even greater regional sea level rise if the Gulf Stream weakens as some models suggest.”


Via the report: “The map on the left shows local sea level trends in the Northeast region. The length of the arrows varies with the length of the time series for each tide gauge location. The graph at the right shows observed sea level rise in Philadelphia, which has increased by 1.2 feet over the past century, significantly exceeding the global average of 8 inches, increasing the risk of impacts to critical urban infrastructure in low-lying areas.”(U.S. Global Change Research Program)

“Sea level rise of two feet, without any changes in storms, would more than triple the frequency of dangerous coastal flooding throughout most of the Northeast.”

“…in the Mid-Atlantic…, estimates suggest that between 450,000 and 2.3 million people are at risk from a three foot sea level rise.”


Via the report: “The map shows the relative risk that physical changes will occur as sea level rises. The Coastal Vulnerability Index used here is calculated based on tidal range, wave height, coastal slope, shoreline change, landform and processes, and historical rate of relative sea level rise. The approach combines a coastal system’s susceptibility to change with its natural ability to adapt to changing environmental conditions, and yields a relative measure of the system’s natural vulnerability to the effects of sea level rise.” (U.S. Global Change Research Program)

Shifting winter (cold season) storms

Key statements

“In the mid-latitudes, where most of the continental U.S. is located, there is an increasing trend in extreme precipitation in the vicinity of fronts associated with mid-latitude storms.”

“There is also a northward shift in storms over the U.S. that are often associated with extreme precipitation. This shift is consistent with projections of a warming world. No change in mid-latitude storm intensity or frequency has been detected.”

Severe storms/tornadoes still under investigation

Key statements

“Although these relationships are still being explored, a recent study suggests a projected increase in the frequency of conditions favorable for severe thunderstorms.”

Stronger hurricanes

Key statements

“…there is a growing consensus  based on scientific understanding and very-high-resolution atmospheric modeling that the strongest tropical cyclones including Atlantic hurricanes, will become stronger in a warmer world.”

“By late this century, models, on average, project a slight decrease in the annual number of tropical cyclones … There is some uncertainty in this as the individual models do not always agree…”

” … almost all existing studies project greater rainfall rates in hurricanes in a warmer climate, with projected increases of about 20% averaged near the center of hurricanes.”

Jason is currently the Washington Post’s weather editor. A native Washingtonian, Jason has been a weather enthusiast since age 10.
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