Projected average increases in the number of days with a maximum temperature greater than 95°F between 2041-2070, compared to 1971-2000 assuming continued increases in global emissions.
The draft of the Federal Advisory Committee’s National Climate Assessment was released several days ago, with dire warnings of significantly higher temperatures across the nation bringing more heat waves, deluges, droughts, and other forms of extreme weather. It also concluded that much of the climate change seen over the last 50 years was primarily driven by human activity.
But the report also had more locally relevant news for residents of Washington, D.C., which just experienced a record-breaking 11 straight days of temperatures of 95 degrees Fahrenheit this past summer. If humans continue driving up the amount of carbon in the atmosphere at their current pace, the number of days D.C. sees over that temperature threshold could increase by more than 15 days per year by mid-century:
If emissions continue to increase… warming of 4.5ºF to 10ºF is projected by the 2080s; if global emissions were reduced substantially… projected warming ranges from about 3ºF to 6ºF by the 2080s.
Under both emissions scenarios, the frequency, intensity, and duration of heat waves is expected to increase, with larger increases under higher emissions. Regional climate model simulations suggest that the southern part of the region, including large parts of West Virginia, Maryland, and Delaware could experience more than a doubling of days per year over 95ºF by the 2050s.
Much of the southern portion of the region, including the majority of Maryland, and Delaware, and southwest West Virginia and New Jersey, are projected to experience more than 15 additional days per year above 95°F, which will impact the regions vulnerable populations, infrastructure, and agriculture and ecosystems.
2012 was Washington, D.C.’s hottest year, with records going back all the way to 1871. And this past summer was the third hottest the city has seen in that time — and the two summers that beat it out were 2010 and 2011.
According to the climate assessment, the snowless winters the nation’s capital has recently experienced could become the norm as well. If greenhouse gases continue their current rapid increase, the number of days when temperatures dip below 32 degrees Farehnheit would decrease by 25 percent between now and 2050 — a total drop of 20 days.
Along with the heat, D.C. also dealt with persistent drought in 2012, leading to rainfall about 8 inches below normal. Conversely, and consistent with global warming’s tendency to drive more erratic weather, the District has also been hit with more severe flooding as recently as 2006. And the city is already adapting: Thanks to its efforts to reduce greenhouse gas emissions, Washington, D.C. was recognized in 2011 and 2012 as the number one U.S. EPA Green Power Community. The city is constructing a floodgate on the National Mall to protect its core from flooding, it surpassed 1.5 million square feet of green roofs in 2012, and it grew its tree canopy by 818 acres between 2006 and 2011 — bringing added shade, cooler temperatures, and reduced energy use.
Last February, the Washington legislature enacted a law prohibiting anyone from “
