From the IPCC Report Summary For Policy Makers:
Observed increases in well-mixed greenhouse gas (GHG) concentrations since around 1750 are unequivocally caused by human activities. Since 2011 (measurements reported in AR5), concentrations have continued to increase in the atmosphere, reaching annual averages of 410 ppm for carbon dioxide (CO2), 1866 ppb for methane (CH4), and 332 ppb for nitrous oxide (N2O) in 2019. Land and ocean have taken up a near-constant proportion (globally about 56% per year) of CO2 emissions from human activities over the past six decades, with regional differences (high confidence).
And:
Each of the last four decades has been successively warmer than any decade that preceded it since 1850. Global surface temperature8 in the first two decades of the 21st century (2001-2020) was 0.99 [0.84- 1.10] °C higher than 1850-1900. Global surface temperature was 1.09 [0.95 to 1.20] °C higher in 2011– 2020 than 1850–1900, with larger increases over land (1.59 [1.34 to 1.83] °C) than over the ocean (0.88 [0.68 to 1.01] °C). The estimated increase in global surface temperature since AR5 is principally due to further warming since 2003–2012 (+0.19 [0.16 to 0.22] °C). Additionally, methodological advances and new datasets contributed approximately 0.1ºC to the updated estimate of warming in AR6.
Some assessments from around the globe:
HUMANS ARE TO BLAME - FULL STOP
The Intergovernmental Panel on Climate Change (IPCC) used its strongest terms yet to assert that humans are causing climate change, with the first line of its report summary reading: "It is unequivocal that human influence has warmed the atmosphere, ocean and land."
And:
WEATHER IS GETTING EXTREME
Weather extremes once considered rare or unprecedented are becoming more common -- a trend that will continue even if the world limits global warming to 1.5C.
Severe heat waves that happened only once every 50 years are now happening roughly once a decade. Tropical cyclones are getting stronger. Most land areas are seeing more rain or snow fall in a year. Severe droughts are happening 1.7 times as often. And fire seasons are getting longer and more intense.
We are locked into 30 years of worsening climate impacts no matter what the world does.
The world has already warmed about 1.1 degree Celsius (about 2 degrees Fahrenheit) since the 19th century. The report concludes that humans have put so much carbon dioxide and other greenhouse gases into the atmosphere that this warming will continue at least until the middle of the century, even if nations take immediate steps today to sharply cut emissions.
That means some of the noticeable effects the world is seeing now — like extreme droughts, severe heat waves and catastrophic downpours and flooding — will continue to worsen for at least the next 30 years.
Some other impacts will continue for far longer. The enormous ice sheets in Greenland and West Antarctica will continue to melt at least through the end of the century. Global sea level will continue to rise for at least 2,000 years.
We can thank decades of science denial from our friends across the political aisle for this.
