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Friday is Earth Day, and the planet is running a fever.

The global thermometer shows that 2016 is on track to be the world’s warmest year since modern record-keeping began in 1880, topping the record set just last year. Boosted by El Nino and climate change, March was the 11th consecutive warmest month, and it deviated from normal more than any previous month.

Some of the other recent entries on Earth's medical chart:

In the past six years in the USA, states have set monthly records for warmth 132 times. There have been only four coldest months.

In the past six months, three freakishly intense tropical storms in the Pacific and Indian oceans, spawned by record warm waters, have generated peak winds of 173, 185 and 215 miles per hour.

Thanks to heat and drought, wildfire season is starting earlier and ending later in the USA and abroad.

Recent research suggests that the huge West Antarctic ice sheet might disintegrate within decades, raising sea levels and inundating coastal cities. The extent of Arctic sea ice, meanwhile, hit new lows this January and February.

Just this week, the temperature reached 89 in Seattle, breaking the record for hottest April day by four degrees, and Houston had record rainfall, with nary a hurricane or tropical storm in sight.

Can any single extreme weather event like these be blamed on global warming? No.

Are these the types of extreme events that become increasingly likely because the Earth is heating up, and warm air holds and releases more water? Yes.

Get politics out of climate debate: Opposing view

There’s no quick or easy cure for what ails the planet. The Paris climate accord, to be signed by more than 130 nations Friday at the United Nations, represents the most ambitious international effort to date to head off catastrophic warming. But even if all countries keep to their emission-reduction promises, the pledges made aren’t nearly enough to meet the Paris target of keeping the planet “well below” 3.6 degrees Fahrenheit of warming.

Further progress will depend in large part on advances in green-energy technology — and on U.S. leadership, which in turn will depend in large part on the results of November’s presidential election.

So far, the top two candidates for the Republican nomination have shown frighteningly little awareness of the threat posed by climate disruption. Donald Trump has said that he’s “not a big believer” in human-caused climate change. Ted Cruz has called climate change a liberal plot to control the economy, the energy sector and “every aspect of our lives.” Both vow they’d slash funding for the Environmental Protection Agency.

While there's plenty of room for the next president to insist that other countries live up to their commitments to curb greenhouse gas emissions, there's no excuse for the science denial being spouted on the campaign trail.

The GOP candidates are like doctors who tell patients that an illness is all in their heads — and that even if there is a problem, we can’t afford to do anything about it.

Actually, given the growing mountain of evidence that greenhouse gas emissions are making the Earth sicker by the day, we can’t afford not to treat the patient.

USA TODAY's editorial opinions are decided by its Editorial Board, separate from the news staff. Most editorials are coupled with an opposing view — a unique USA TODAY feature.

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