Greenery is critical to counterbalance the "urban heat island" effect from hotter, drier summers, when night-time temperatures remain high because of heat retained by brick and tarmac.

BBC: Time to leave the comfort zone

That began to happen during the first quarter of this year, when a rising trade imbalance proved a modest counterbalance to booming domestic demand, and its effect is intensifying as the trade deficit widens.

ECONOMIST: Is America��s economy too hot, too cold, or just right?