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2020: Hottest Year On Record

NASA data show that 2020 was the hottest year on record.

The image below shows that high temperature in 2020 hit Siberia and the Arctic Ocean.

In above images, the temperature anomaly is compared to 1951-1980, NASA’s default baseline. When using an earlier baseline, the data need to be adjusted. The image below shows a trendline pointing at an 0.31°C adjustment for a 1900 baseline. 

Additional adjustment is needed when using a 1750 baseline, while it also makes sense to add further adjustment for higher polar anomalies and for air temperatures over oceans, rather than sea surface temperatures. In total, a 0.78°C adjustment seems appropriate, as has been applied before such as in this analysis. For the year 2020, this translates in a temperature rise of 1.8029°C.

Three trends: blue, purple and red

Will the global temperature rise to 3°C above 1750 by 2026? The blue trend below is based on 1880-2020 NASA Land+Ocean data and adjusted by 0.78°C to reflect a 1750 baseline, ocean air temperatures and higher polar anomalies, and it crosses a 3°C rise in 2026.

The trend shows a temperature for 2020 that is slightly higher than indicated by the data. This is in line with the fact that we’re currently in a La Niña period and that we’re also at a low point in the sunspot cycle, as discussed in an earlier post. Such variables show up more in trends based on shorter periods.

The second (purple) trend is based on a shorter period, i.e. 2006-2020 NASA land+ocean (LOTI) data, again adjusted by 0.78°C to reflect a 1750 baseline, ocean air temperatures and higher polar anomalies. The trend approaches 10°C above 1750 by 2026. The trend is based on 15 years of data, making it span a 30-year period centered around end 2020 when extended into the future for a similar 15 year period. The trend approaches 10°C above 1750 in 2026.

The trend is displayed on the backdrop of an image from an earlier post, showing how a 10°C rise could eventuate by 2026 when adding up the impact of warming elements and their interaction.

The stacked bars are somewhat higher than the trend. Keep in mind that the stacked bars are for the month February, when anomalies can be significantly higher than the annual average.

Temperature rise for February 2016 versus 1900.

In the NASA image on the right, the February 2016 temperature was 1.70°C above 1900 (i.e. 1885-1914). In the stacked-bar analysis, the February 2016 rise from 1900 was conservately given a value of 1.62°C, which was extended into the future, while an additional 0.3°C was added for temperature rise from pre-industrial to 1900.

Later analyses such as this one also added a further 0.2°C to the temperature rise, to reflect ocean air temperatures (rather than water temperatures) and higher polar anomalies (note the grey areas on the image in the right).

Anyway, the image shows two types of analysis on top of each other, one analysis based on trend analysis and another analysis based on high values for the various warming elements. Does the stacked-bar analysis reflect a worst-case scenario? Well, an even faster rise is illustrated by the next trend, the red line.

The third (red) trend suggests that we may have crossed the 2°C treshold in the year 2020. The trend is based on a recent period (2009-2020) of the NASA land+ocean data, again adjusted by 0.78°C to reflect a 1750 baseline, ocean air temperatures and higher polar anomalies.

As said, we’re currently in a La Niña period and we’re at a low point in the sunspot cycle. Such variables show up more when basing trends on shorter periods. The red trend indicates that we could be facing even higher temperatures over the next few years. 

Where do we go from here?

It’s important to acknowledge the threat constituted by a possibly very steep temperature rise over the next few years. The threat is illustrated by the image below. 

At a 3°C rise, humans will likely go extinct, while most life on Earth will disappear with a 5°C rise, and as the temperature keeps rising, oceans will evaporate and Earth will go the same way as Venus, a 2019 analysis warned.

Steep rise in temperature

A steep rise in temperature could take place due to oceans keep taking up less heat, thus leaving more heat in the atmosphere. The danger is illustrated by the image below. 

The white band around -60° (South) indicates that the Southern Ocean has not yet caught up with global warming, featuring low-level clouds that reflect sunlight back into space. Over time, the low clouds will decrease, which will allow more sunlight to be absorbed by Earth and give the world additional warming. A recent study finds that, after this ‘pattern effect‘ is accounted for, committed global warming at present-day forcing rises by 0.7°C.

Ocean stratification contributes to further surface warming, concludes another recent study

“The stronger ocean warming within upper layers versus deep water has caused an increase of ocean stratification in the past half century. With increased stratification, heat from climate warming less effectively penetrates into the deep ocean, which contributes to further surface warming. It also reduces the capability of the ocean to store carbon, exacerbating global surface warming. Furthermore, climate warming prevents the vertical exchanges of nutrients and oxygen, thus impacting the food supply of whole marine ecosystems.”

“By uptaking ~90% of anthropogenic heat and ~30% of the carbon emissions, the ocean buffers global warming. [The] ocean has already absorbed an immense amount of heat, and will continue to absorb excess energy in the Earth’s system until atmospheric carbon levels are significantly lowered. In other words, the excess heat already in the ocean, and heat likely to enter the ocean in the coming years, will continue to affect weather patterns, sea level, and ocean biota for some time, even under zero carbon emission conditions.”

As the above map also shows, the temperature rise is hitting the Arctic Ocean particularly hard, while there are at least ten tipping points that are affecting the Arctic, as described in an earlier post, including the latent heat tipping point and the methane hydrates tipping point, as illustrated by the image below, from an earlier post.
The danger is that greater ocean stratification, in combination with stronger winds, will contribute to the formation of a lid at the surface of the North Atlantic Ocean that enables more heat to move into the Arctic Ocean and cause methane to erupt from the seafloor, thus contributing to cause the 1,200 ppm CO₂e cloud tipping point to get crossed, resulting in an extra 8°C rise, as an earlier post warned.

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

Links

• Climate Plan

https://arctic-news.blogspot.com/p/climateplan.html

• NASA Global Land-Ocean Temperature Index

https://data.giss.nasa.gov/gistemp

• What are El Niño and La Niña?
https://oceanservice.noaa.gov/facts/ninonina.html

• Multivariate El Niño/Southern Oscillation (ENSO) Index Version 2 (MEI.v2)
https://psl.noaa.gov/enso/mei 

• Greater committed warming after accounting for the pattern effect – by Chen Zhou et al. 

• Upper Ocean Temperatures Hit Record High in 2020 – by Lijing Cheng et al. 
https://link.springer.com/article/10.1007/s00376-021-0447-x

• Methane hydrates tipping point threatens to get crossed
• Cold freshwater lid on North Atlantic

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