To bolster the falsehood of lingering scientific doubt, some people have pointed to things like the Global Warming Petition Project, which urged the United States government to reject the Kyoto Protocol of 1997, an early international climate agreement. Questioning consensus remains a common talking point today, and the 97 percent figure has become something of a lightning rod. Frank Luntz, a Republican consultant, explained the rationale in an infamous 2002 memo to conservative lawmakers: “Should the public come to believe that the scientific issues are settled, their views about global warming will change accordingly,” he wrote. Many pushed the narrative that scientists still hadn’t made up their minds about climate change, even though that was misleading. So where did we get the idea that there’s still debate about climate change? A lot of it came from coordinated messaging campaigns by companies and politicians that opposed climate action. In the United States, daily record highs now outnumber record lows two-to-one. Land areas have warmed more than the sea surface and the Arctic has warmed the most - by more than 4 degrees Fahrenheit just since the 1960s. Together, these data all tell the same story: Earth is getting hotter.Īverage global temperatures have increased by 2.2 degrees Fahrenheit, or 1.2 degrees Celsius, since 1880, with the greatest changes happening in the late 20th century.

Later, scientists began tracking surface temperatures with satellites and looking for clues about climate change in geologic records. We know this is true thanks to an overwhelming body of evidence that begins with temperature measurements taken at weather stations and on ships starting in the mid-1800s. Ever since, human activities have been heating the planet. However, during the Industrial Revolution, people started burning coal and other fossil fuels to power factories, smelters and steam engines, which added more greenhouse gases to the atmosphere. This greenhouse effect is important: It’s why a planet so far from the sun has liquid water and life! These gases make up just a small fraction of the atmosphere but exert outsized control on Earth’s climate by trapping some of the planet’s heat before it escapes into space. For more than a century, scientists have understood the basic physics behind why greenhouse gases like carbon dioxide cause warming.

Earth thousands of years later