The White House announced on Jan. 29 that the federal government will reduce its greenhouse gas (GHG) emissions by 28% by 2020. The announcement comes on the heels of President’s Obama’s pledge on Jan. 28 that the United States would reduce GHG emissions by 17% by 2020 as part of an international climate agreement. The Jan. 29 announcement follows up on an executive order signed by the president this fall, which required federal agencies to set sustainability goals by Jan. 4. The 28% reduction target is the aggregate of 35 federal agency self-reported targets required by the executive order. Among
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.