America is already experiencing the beginning stages of the severe consequences of climate change. Our nation has seen unheard of weather extremes, supers storms and severe widespread drought. The last decade has seen record heat in seven of the last ten years. The Polar Ice Cap and Greenland's ice field almost vanished last summer.
"Future generations of Americans can expect to spend 25 days a year sweltering in temperatures above 100F (38C), with climate change on course to turn the country into a hotter, drier, and more disaster-prone place.
The National Climate Assessment, released in draft form on Friday , provided the fullest picture to date of the real-time effects of climate change on US life, and the most likely consequences for the future.
The 1,000-page report, the work of the more than 300 government scientists and outside experts, was unequivocal on the human causes of climate change, and on the links between climate change and extreme weather.
"Climate change is already affecting the American people," the draft report said. "Certain types of weather events have become more frequent and/or intense including heat waves, heavy downpours and in some regions floods and drought. Sea level is rising, oceans are becoming more acidic, and glaciers and Arctic sea ice are melting."
The report, which is not due for adoption until 2014, was produced to guide federal, state and city governments in America in making long-term plans."
Goldenberg writes that the affects of change is already hitting America hard:
Some of those changes are already evident: 2012 was by far the hottest year on record, fully a degree hotter than the last such record – an off-the-charts rate of increase.
Those high temperatures were on course to continue for the rest of the century, the draft report said. It noted that average US temperatures had increased by about 1.5F since 1895, with more than 80% of this increase since 1980.
The rise will be even steeper in future, with the next few decades projected for temperatures 2 to 4 degrees warmer in most areas. By 2100, if climate change continues on its present course, the country can expect to see 25 days a year with temperatures above 100F.
Night-time temperatures will also stay high, providing little respite from the heat.
Certain regions are projected to heat up even sooner. West Virginia, Maryland and Delaware can expect a doubling of days hotter than 95 degrees by the 2050s. In Texas and Oklahoma, the draft report doubled the probability of extreme heat events.
Those extreme temperatures would also exact a toll on public health, with worsening air pollution, and on infrastructure increasing the load for ageing power plants.
But nowhere will see changes as extreme as Alaska, the report said.
"The most dramatic evidence is in Alaska, where average temperatures have increased more than twice as fast as the rest of the country," the draft report said. "Of all the climate-related changes in the US, the rapid decline of Arctic sea ice cover in the last decade may be the most striking of all."
Other regions will face different extreme weather scenarios. The north-east, in particular, is at risk of coastal flooding because of sea-level rise and storm surges, as well as river flooding, because of an increase in heavy downpours."