LAKE HOPATCONG, N.J. — Before climate change thawed the winters of New Jersey, this lake hosted boisterous wintertime carnivals. As many as 15,000 skaters took part, and automobile owners would drive onto the thick ice. Thousands watched as local hockey clubs battled one another and the Skate Sailing Association of America held competitions, including one in 1926 that featured 21 iceboats on blades that sailed over a three-mile course.
In those days before widespread refrigeration, workers flocked here to harvest ice. They would carve blocks as much as two feet thick, float them to giant ice houses, sprinkle them with sawdust and load them onto rail cars bound for ice boxes in New York City and beyond.
New Jersey’s average temperatures have risen nearly 2 degrees Celsius since 1895 — double the average for the Lower 48 states.
That’s because a century of climbing temperatures has changed the character of the Garden State. The massive ice industry and skate sailing association are but black-and-white photographs at the local museum. And even the hardy souls who still try to take part in ice fishing contests here have had to cancel 11 of the past dozen competitions for fear of straying onto perilously thin ice and tumbling into the frigid water.
Click any temperature underlined in the story to convert between Celsius and Fahrenheit
New Jersey may seem an unlikely place to measure climate change, but it is one of the fastest-warming states in the nation. Its average temperature has climbed by close to 2 degrees Celsius since 1895 — double the average for the Lower 48 states.
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.
A Washington Post analysis of more than a century of National Oceanic and Atmospheric Administration temperature data across the Lower 48 states and 3,107 counties has found that major areas are nearing or have already crossed the 2-degree Celsius mark.
— 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.
The freezing point “is the most critical threshold among all temperatures,” said David A. Robinson, New Jersey state climatologist and professor at Rutgers University’s department of geography.
The uneven rise in temperatures across the United States matches what is happening around the world.
Rhode Island is the first state in the Lower 48 whose average temperature rise has eclipsed 2 degrees Celsius.
In the past century, the Earth has warmed 1 degree Celsius. But that’s just an average. Some parts of the globe — including the mountains of Romania and the steppes of Mongolia — have registered increases twice as large. It has taken decades or in some cases a century. But for huge swaths of the planet, climate change is a present-tense reality, not one looming ominously in the distant future.
To find the world’s 2C hot spots, its fastest-warming places, The Post analyzed temperature databases, including those kept by NASA and NOAA; peer-reviewed scientific studies; and reports by local climatologists. The global data sets draw upon thousands of land-based weather stations and other measurements, such as ocean buoys armed with sensors and ship logs dating as far back as 1850.
In any one geographic location, 2 degrees Celsius may not represent global cataclysmic change, but it can threaten ecosystems, change landscapes and upend livelihoods and cultures.
In Lake Hopatcong, thinning ice let loose waves of aquatic weeds that ordinarily die in the cold. This year, a new blow: Following one of the warmest springs of the past century, harmful bacteria known as blue-green algae bloomed in the lake just as the tourist season was taking off in June.