Wednesday, September 16, 2020

Temperatures threaten to become unbearable

Many people could face unbearable temperatures soon. 

Temperature anomalies on land in the Northern Hemisphere (red) are spread out much wider and they are more than 0.5°C higher than global land+ocean anomalies (blue).


The pale green and grey trends are both long-term trends based on January 1880-August 2020 NOAA data. The short-term red and blue trends, based on January 2013-August 2020 NOAA data, are added to show the potential rise due to El Niño, changes in aerosols and feedbacks kicking in more strongly as tipping points get crossed.

The image below, updated from an earlier post, shows two such tipping points.


The August 2020 ocean temperature anomaly on the Northern Hemisphere was 1.13°C above the 20th century average. The image shows a trend based on January 1880-August 2020 NOAA data. The latent heat tipping point is estimated to be 1°C above the 20th century average. Crossing the latent heat tipping point threatens to cause the methane hydrates tipping point to be crossed, estimated to be 1.35°C above the 20th century average.

Keep in mind that above images show temperature anomalies from the 20th century average, which is NOAA's default baseline. As an earlier analysis points out, when using a 1750 baseline and when using ocean air temperatures and higher Arctic anomalies, we may have already crossed both the 1.5°C and the 2°C thresholds that politicians at the Paris Agreement pledged would not get crossed.

Currently, we are in a La Niña period, which suppresses air temperatures. Only a thin layer of sea ice is left in the Arctic, with extent almost as low as it was in 2012 around this time if year, as discussed in the previous post. When an El Niño event returns, things will get a lot worse. 


The temperature rise is strongest in the Arctic, as illustrated by the zonal mean temperature anomaly map below. The map shows anomalies as high as 4.83°C or 8.69°F in the Arctic. The North Pole is at the top of the map, at 90° North, the Equator is in the middle, at 0° and the South Pole is at the bottom, at -90° South. And yes, NASA's default baseline is 1951-1980, so anomalies are even higher when using a 1750 baseline. 


As said, there are further tipping points and feedbacks kicking in more strongly as they get crossed. At least ten tipping points apply to the Arctic, as discussed in an earlier post.

The situation is dire and calls for immediate, comprehensive and effective action, as described in the Climate Plan.


Links

• NOAA Global Climate Report - August 2020
https://www.ncdc.noaa.gov/sotc/global/202008

• Multivariate El Niño/Southern Oscillation (ENSO) Index Version 2 (MEI.v2)