Greenhouse gas emissions have escalated, glaciers have shrunk, the atmosphere and ocean have warmed, and sea level has risen.
All because of people, a new report found.
It is "extremely likely" that human influence has been the main cause of observed warming on the climate system since the mid-20th century in regions around the globe, according to a new assessment released Friday by the U.N.-created Intergovernmental Panel on Climate Change.
"Human influence on the climate system is clear. This is evident from the increasing greenhouse gas concentrations in the atmosphere, positive radiative forcing, observed warming, and understanding of the climate system," the report said.
Scientists are "highly confident" that more than 90% of the energy accumulated between 1971 and 2010 is due to ocean warming. Each of the last three decades was subsequently warmer at the Earth's surface than any decade since 1850.
They also feel "highly confident" that the rise in the sea level since the mid-19th century has been larger than the mean rate during the previous two millennia. In addition, human activity in the past 800,000 years has caused the atmospheric concentrations of carbon dioxide, methane, and nitrous oxide to escalate.
"This is yet another wake-up call: Those who deny the science or choose excuses over action are playing with fire," U.S. Secretary of State John Kerry said in a statement Friday. "Once again, the science grows clearer, the case grows more compelling, and the costs of inaction grow beyond anything that anyone with conscience or common sense should be willing to even contemplate."
More observations and improved understanding of the climate system response and climate models have aided scientists with their new conclusion. Humans must substantially reduce greenhouse gas emissions to limit climate change in years to come.
The report, published in Stockholm, Sweden, cited more than 9,000 scientific publications and drew on millions of observations.