According to the president’s report, the Northeast has experienced a greater recent increase in extreme precipitation than any other region of the U.S.: between 1958 and 2010, the Northeast saw a jump of more than 70 percent in the amount of precipitation falling in “very heavy events” (defined as the heaviest 1 percent of all daily events).

Since 1900, Earth has seen a 1.3-degree increase in the mean global temperature, owing primarily to an exponential increase in atmospheric carbon dioxide levels caused by emissions from farms, factories, power plants and vehicles. That falls far outside the natural warming and cooling cycle, which rises and falls fractionally over millennia, according to the International Panel on Climate Change. We could see the planet warm by as much as 7.2 degrees by 2100, the IPCC says.

Do the math: If we’ve seen a 70 percent increase in really big rainstorms since the mid-20th century and the result is Irene and Sandy, among others, what might we see if the global mean temperature were to rise nearly 6 degrees more? What might Long Island look like?

If temperature were to rise by a mere 2 degrees, we could see our shoreline flooded regularly. This is why scientists tell us that we could see a storm the size and strength of Sandy strike the Atlantic Coast every two years by the end of the century.

The president’s climate assessment was not prepared by a handful of his closest advisers. Scientists and policymakers from every major federal agency contributed, including the Agency for International Development, the Environmental Protection Agency, NASA, the National Science Foundation, the Smithsonian Institution and the departments of agriculture, commerce, defense, energy, health and human services, state, interior and transportation.

We should take this report very, very seriously. This isn’t the United Nations telling us that climate change is coming. This is our federal government –– our president –– telling us that it’s already arrived.