Most Americans now recognize the scientific community's consensus that human activity is fueling the climate crisis, according to polls—but for those who are still unconvinced of the conclusion reached by 97 percent of climate scientists, a new study makes an even more definite assertion.

Scientists at the Lawrence Livermore National Laboratory in California found that the information available can now be classified as "five-sigma"—a standard in the scientific community meaning that there is a one-in-a-million chance that the same data would be observable if humans were not causing the planet to grow warmer through activities like fossil fuel extraction. The classification represents a "gold standard" level of certainty.

"The narrative out there that scientists don't know the cause of climate change is wrong," Benjamin Santer, who led the study, told Reuters. "We do.”

Scientists applied the same "five-sigma" measure to research confirming the existence of the Higgs boson subatomic particle in 2012, a finding that was received with applause from the science community and the press.

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The report, which was published in the journal Nature Climate Change, builds on the United Nations' Intergovernmental Panel on Climate Change (IPCC) report from 2013, which found that it was "extremely likely" that humans were causing the climate crisis—with a 95 percent chance.

In recent years, although President Donald Trump and other Republican lawmakers have attempted to cast doubt on the scientific consensus that human activity is causing global warming and the climate crisis, the American public has increasingly believed scientists.

In a 2018 survey by the Yale Program on Climate Change Communication, 62 percent of Americans believed that man-made climate change was taking place, versus just 47 percent convinced that was the case just five years earlier.

The Nature Climate Change study also comes on the heels of reports that the melting of ice in Antarctica and the warming of the ocean are both occurring much faster than previously thought; that the last four years have been the hottest on record; and that the warming of the globe could cause clouds to disappear from the sky in the next generation, leading to an 8º Celsius (14.4º Fahrenheit) jump in temperature.

"Humanity cannot afford to ignore such clear signals," the authors of the most recent study wrote in Nature Climate Change.