The Earth is now in its warmest period in the history of modern civilization and it is "extremely likely" humans are causing the rise, according to a sweeping new special report by scientists working for the U.S. government that paints a grim picture for the future of the climate.
Released Friday afternoon, the report notes that the Northeast and Atlantic coast could be in for an especially difficult time ahead — particularly with flooding and heavy storms.
"The last few years have also seen record-breaking, climate-related weather extremes, and the last three years have been the warmest years on record for the globe," says the report by the U.S. Global Change Research Program.
The strongly worded report, almost dire at times, comes at a time the Trump administration is denying a link between human activity and climate change. Officials did not try to stop the release of the report, which is part of the government's National Climate Assessment and is mandated by law.
The report is "designed to be an authoritative assessment of the science of climate change" and is a joint effort between the National Oceanic and Atmospheric Administration, NASA, and the Department of Energy.
Scientists say global average surface air temperatures have increased by about 1.8 degrees Fahrenheit (1 Celsius) in the last 115 years.
"This assessment concludes, based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century," the report states. "For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence."
The report notes that "thousands of studies" carried out by researchers around the world have documented temperature change in both the atmosphere and oceans, melting glaciers, less snow, rising sea levels, and ocean acidification.
The seas have risen between 7 and 8 inches since 1900, the findings state. Half of that has come since 1990. Humans, through the burning of fossil fuels and other activity, "made a substantial contribution" to that rate, which is faster than in any other century in the last 2,800 years.
And it's having a real impact. Daily tidal flooding in 25 Atlantic and Gulf Coast cities is accelerating. Several more inches of sea rise are expected within 15 years. At a minimum, the seas will rise 1 to 4 feet by the end of the century. An 8-foot rise, which could be catastrophic, is not ruled out.
Among other findings:
Heavy rainfall will increase – especially in the Northeast, which is already seeing the largest observed changes.
Heatwaves, more prevalent since the 1960s, could become common. By 2050, annual average temperatures are expected to rise 2.5 degrees.
Large forest fires in the west and Alaska, also now more common, will further increase.
Water resources could be impacted, with trends showing earlier spring melts and reduced snowpack in the west.
Chronic drought could occur by the end of the century.
"The magnitude of climate change beyond the next few decades will depend primarily on the amount of greenhouse gases (especially carbon dioxide) emitted globally," the report states. "Continued growth in CO2 emissions over this century and beyond would lead to an atmospheric concentration not experienced in tens to hundreds of millions of years."
The report concludes that the changes could become "potentially large and irreversible."