Where things stand with climate

While the calendar has flipped and many are rejoicing that 2020 is behind us, the climate system knows nothing about the Gregorian calendar, and our climate is still in a dire state.

Atmospheric Carbon Dioxide

Despite a global shut-down mid-year, the monthly averaged carbon dioxide level at NOAA's Mauna Loa Observatory still reached its highest level ever, at 417.07 ppm in May. NOAA data also de-seasonalize carbon dioxide values (they tend to be highest in summer), and November 2020 (the most recent month with available data) had the highest de-seasonalized value ever, at 414.90 ppm. Observations of carbon dioxide at the observatory have steadily climbed since they began in 1958.

Carbon dioxide abundance in ppm over time at Mauna Loa Observatory (NOAA)

Arctic Sea Ice

The Arctic sea ice extent this year was much lower than the 1981-2010 median, and at times, it was the lowest ever.

(National Snow and Ice Data Center)

The blue line in the above graph shows 2020 Arctic sea ice extent through December 1. When we compare to the 1981 to 2010 climate normals (the grey median line in the above graph), 2020 and the past several years have had much lower sea ice extent than normal. The new climate normals for 1991 to 2020 will be released at some point soon, and it appears that the new median line and the interquartile range will be much lower than where it currently is.

To further show this pattern, here is a graph of sea ice anomalies in the Northern Hemisphere over time in January:

(National Snow and Ice Data Center)

The National Snow and Ice Data Center has lots more interesting data for other months and good visualizations, so I recommend looking at the center's website.

Temperature

For many spots in the world, 2020 was the warmest year on record. I like looking at NOAA's Global Climate Reports, which are released monthly. December's report has not yet been released, but the November report paints a clear picture that 2020 was an extremely warm year. According to the report, the Jan-Nov 2020 global temperature was 1.80 °F above average, which is the second warmest Jan-Nov period after 2016.

(NOAA)

Globally, it was certainly a warm year, but what happened locally?

As we end 2020, here's a calendar year summary of temperature, precipitation, and snowfall, suggesting a warm and dry year relative to normal. All values are based on data at the Burlington International Airport (BTV) and compared to the 1981-2010 normals. pic.twitter.com/wkwlKWOSTo

— NWS Burlington (@NWSBurlington) January 1, 2021

In Burlington, VT, it was the second warmest year on record after 2012, and we had the most days with high temperatures above 90 °F since 1988 and the fewest days with low temperatures below 32 °F since 1941, as shown in the NWS tweet above. You could pick many sites throughout the northeast and U.S., and similar trends would arise:

(NOAA/HPRCC)

Lastly, as I previously mentioned, new climate normals for the period from 1991-2020 will be released at some point in this year. 

With one month to go in 2020, the new 1991-2020 climate normal period is almost set. How is it looking compared to the previous (1981-2010) period? Not good. Only a few stations will have a cooler climate period. pic.twitter.com/cobhxNexYM

— Brian Brettschneider (@Climatologist49) December 4, 2020

Climatologist Brian Brettschneider has done some really neat work to show how the climate normals will change from what they were. In virtually every site in the world, the new climate normals will be warmer than they were for 1981-2010 and the trend is especially pronounced in Europe.

I apologize for painting a grim picture of where things stand with climate, but its what the data show. Hopefully 2021 will usher in a renewed focus on tackling climate change.