More than 99 percent of climate scientists affirm global warming is caused by human activity. Despite this, a loud and very small minority of scientists, and some politicians in the United States (notably Donald Trump), loudly deny the existence of global warming.
The majority scientists, however, recently reported that evidence for man-made global warming has reached a "gold standard" level of certainty, meaning it's now all but irrefutable.
This certainly puts pressure on politicians and policymakers to act urgently to cut greenhouse gases emissions to limit rising temperatures.
"Humanity cannot afford to ignore such clear signals ..." of satellite measurements confirming rising temperatures over the past 40 years, said a report published in the journal Nature Climate Change.
The report said confidence that human activities are boosting the heat at the Earth's surface had reached a "five-sigma" level. Five-sigma is a statistical gauge which means there is only a one-in-a-million chance the signal will appear if there was no warming.
Five-sigma, which is also considered the "gold standard" for certainty, was applied in 2012 to confirm the discovery of the Higgs boson subatomic particle. This particle is a basic building block of the universe and is responsible for the creation of baryonic matter as we know it.
The findings released Monday by researchers in the United States, Canada and Scotland said evidence for global warming reached the five sigma level by 2005 in two of three sets of satellite data widely used by researchers. It reached third in 2016.
Study lead author Benjamin Santer at the Lawrence Livermore National Laboratory in California said he hopes the five-sigma findings will convince skeptics and spur action.
"The narrative out there that scientists don't know the cause of climate change is wrong," he said. "We do."
Mainstream scientists say the burning of fossil fuels is causing more floods, droughts, heat waves, and rising sea levels. In addition, 62 percent of Americans polled in 2018 believe that climate change has a human cause compared to 47 percent in 2013, according to the Yale Program on Climate Change Communication.
