Editor's Noteblook: 2020: Hottest Year on Record?

Editor's Noteblook: 2020: Hottest Year on Record?

Reflecting back on 2020, TDS' Beth Carpenter shares some weather data that puts the last year into perspective.

January 15, 2021

Nearly all of us want to close the book on 2020, and many of you in the professional snow and ice management industry would like to put the last winter -- or perhaps, the lack there of -- behind you, as well.

But weather guru and frequent Snow Magazine contributor Beth Carpenter, co-owner of Thermodynamic Solutions (TDS), has some data to consider that focuses in on 2020's record-making weather trends.Give it a read, and at the very least, share the following with your clients and educate them on the trends that influence your business.

So here Beth postulates whether 2020 as the warmest on record, and what would account for that trend.

The answer: it’s not super clear. NASA issued a press release this morning stating that 2020 was the warmest year on record, but only by a very small fraction of a degree. They then stated that due to potential uncertainty in the data that they are considering 2020 to be tied with 2016 at 1.02 degrees Celsius above normal globally. Similarly, the JMA (Japan Meteorological Agency) also considers 2020 the warmest year on record. On the other hand, agencies including NOAA, Copernicus (European), the Met Office (British), and Berkeley Earth have come to the preliminary conclusion that 2020 was second warmest on record to 2016- but just by fractions of a degree.

Click the image for a larger version.
So, why the varying results?

Weather and climate agencies around the world use different methods of measuring data, as well as different ways of comparing historical values. For example, NASA’s temperature anomaly is based on the 1951-1980 climate average, while JMA uses 1981-2010, and NOAA uses 1901-2000. To be clear, the average temperature anomaly for purposes as discussed here is the annual, global temperature departure from “normal” for the stated climate period. Average global temperatures over time, especially since the 1980s, have risen, therefore the different climate periods above will shift anomaly values and individual agency’s results cannot be directly compared.

Temperatures are measured 24/7 by automated weather stations around the world but are most prevalent in populated areas. Over the ocean, buoys can help gather this data. There are significant data gaps in the Arctic which poses difficulty for obtaining a complete global data set. Temperatures in these areas are often estimated by remotely sensed technology (satellites). Agencies determine their “best guess” estimates of temperature data using these instruments to fill in the gaps. That means that we’re adding in another potential way that agencies could come to differing conclusions.

Overall, whether 2020 was hottest on record or very close behind 2016, above normal warmth was observed across much of the globe, with the arctic areas seeing the greatest anomalies.