By; Rodney Hunter
Over the past two decades, the 2 degrees Celsius number has emerged as a critical threshold for global warming. In the 2015 Paris accord, international leaders agreed that the world should act urgently to keep the Earth’s average temperature increases “well below” 2 degrees Celsius by the year 2100 to avoid a host of catastrophic changes.
The potential consequences are daunting. The United Nations Intergovernmental Panel on Climate Change warns that if Earth heats up by an average of 2 degrees Celsius, virtually all the world’s coral reefs will die; retreating ice sheets in Greenland and Antarctica could unleash massive sea level rise; and summertime Arctic sea ice, a shield against further warming, would begin to disappear.
But global warming does not heat the world evenly.
Today, more than 1 in 10 Americans — 34 million people — are living in rapidly heating regions, including New York City and Los Angeles. Seventy-one counties have already hit the 2-degree Celsius mark. Alaska is the fastest-warming state in the country, but Rhode Island is the first state in the Lower 48 whose average temperature rise has eclipsed 2 degrees Celsius. Other parts of the Northeast — New Jersey, Connecticut, Maine and Massachusetts — trail close behind.
While many people associate global warming with summer’s melting glaciers, forest fires and disastrous flooding, it is higher winter temperatures that have made New Jersey and nearby Rhode Island the fastest warming of the Lower 48 states.
America’s hot spots
Nationwide, trends are clear. Starting in the late 1800s, U.S. temperatures began to rise and continued slowly up through the 1930s. The nation then cooled slightly for several decades. But starting around 1970, temperatures rose steeply.
At the county level, the data reveals isolated 2-degree Celsius clusters: high-altitude deserts in Oregon; stretches of the western Rocky Mountains that feed the Colorado River; a clutch of counties along the northeastern shore of Lake Michigan — home to the famed Sleeping Bear Dunes National Lakeshore near Traverse City.
Along the Canadian border, a string of counties from eastern Montana to Minnesota are quickly heating up.
The topography of warming varies. It is intense at some high elevations, such as in Utah and Colorado, and along some highly populated coasts: Temperatures have risen by 2C in Los Angeles and three neighboring counties. New York City is also warming rapidly, and so are the very different areas around it, such as the beach resorts in the Hamptons and leafy Westchester County.
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