Arctic News: Have feedbacks taken over?

Sunday, June 2, 2024

Have feedbacks taken over?

For about one year now, global temperature anomalies have been extremely high, as illustrated by the image below, created with a screenshot from Copernicus, showing an anomaly from 1991-2020 of 0.86°C on June 1, 2024.

What could be behind these persistently high temperatures? Many causes such as El Niño and sunspots have been discussed in earlier posts. How much do emissions contribute to these high temperatures?

Despite pledges by politicians to ensure that temperatures would not cross 1.5°C above pre-industrial, the growth rate of the concentration of carbon dioxide in the atmosphere appears to be accelerating, as illustrated by the image below, adapted from NOAA and showing concentration of carbon dioxide at Mauna Loa, Hawaii.

Have feedbacks taken over as the dominant driver of the temperature rise? The image below shows NOAA March 2009 through May 2024 monthly CO₂ concentration at Mauna Loa (black) with a trend (magenta) added for a joint 30-year coverage. The trend shows how CO₂ could cross the clouds tipping point at 1200 ppm (parts per million) in 2038, which in itself would push up temperatures by a further 8°C.

What could cause such a steep rise? Many studies point at organic carbon and inorganic carbon releases from soils that could further raise both CO₂ concentrations and temperatures. A recent study by Weiskopf (2024) finds that biodiversity declines from climate and land use change could lead to a global loss of up to 103.14 GtC for a global sustainability scenario and up to 145.95 GtC for a fossil-fueled development scenario, indicating a self-reinforcing feedback loop where higher levels of climate change lead to greater biodiversity loss, in turn leading to greater carbon emissions.

The clouds tipping point is actually at 1200 ppm CO₂e (carbon dioxide equivalent), so it could be crossed even earlier when also taking into account more methane, nitrous oxide, etc. As discussed in an earlier post, the daily mean CO₂ on April 26, 2024, was 428.59 ppm, while peak daily average methane is approaching 2000 parts per billion (ppb) at Mauna Loa, Hawaii. A methane concentration of 2000 ppb corresponds, at a Global Warming Potential (GWP) of 200, with 400 ppm CO₂e. Together with the daily average CO₂ concentration of 428.63 ppm this adds up to a joint CO₂e of 828.63 ppm, i.e. only 371.37 ppm away from the clouds tipping point.

This 371.37 ppm CO₂e could be added almost immediately by a burst of seafloor methane less than the size of the methane that is currently in the atmosphere (about 5 Gt). There is plenty of potential for such an abrupt release, given the rising ocean heat and the vast amounts of methane present in vulnerable sediments at the seafloor of the Arctic Ocean, as discussed in earlier posts such as this one and at the threat page.

There are many further developments and feedbacks that should be taken into account. Furthermore, note that anomalies in the image at the top are calculated from a 1991-2000 base. The temperature rise and the resulting feedbacks are even larger when anomalies are calculated from a pre-industrial base.

[ from earlier post ]

[ from Moistening Atmosphere ]

The above image, created with NASA content, shows that the February 2024 temperature was 1.76°C above 1885-1915, which could be as much as 2.75°C above pre-industrial (bright yellow inset right).

A 2.75°C rise corresponds with almost ⅕ more water vapor in the atmosphere, as the extinction page points out. The increase in water vapor in the atmosphere is a self-amplifying feedback, since water vapor is a powerful greenhouse gas, further accelerating the temperature rise.

Surface precipitable water reached a record high of 27.139 kg/m² in July 2023, as illustrated by the image below, adapted from NOAA.

[ from earlier post ]

Worryingly, data for the first four months of 2024 are way higher than they were in 2023 at the same time of year, which raises fears that surface precipitable water will reach an even higher peak in 2024 than was reached in 2023. The situation is depicted even more clearly on the image below, created with the same data.

As said, more water in the atmosphere further accelerates the temperature rise. Furthermore, high relative humidity also makes high temperatures more unbearable. The human body can cool itself by sweating, which has a physiological limit that was long described as a 35°C wet-bulb temperature, i.e. once the wet-bulb temperature reaches 35°C, one can no longer lose heat by perspiration, even in strong wind, but instead one will start gaining heat from the air beyond a wet-bulb temperature of 35°C.

A 2022 study (by Vecellio et al., 2022) finds that the actual limit is lower — about 31°C wet-bulb or 87°F at 100% relative humidity — even for young, healthy subjects. The temperature for older populations, who are more vulnerable to heat, is likely even lower. In practice the limit will typically be lower and depending on circumstances could be as low as a wet-bulb temperature of 25°C, as discussed in an earlier post.

Temperature in either °C or °F and the relative humidity for spots on Earth can be viewed at nullschool, and then the associated wet-bulb temperature can be calculated here.

North Atlantic

There are numerous tipping points and non-linear, self-amplifying feedbacks that can all contribute, interact and start to kick in with greater ferocity, amplifying and further accelerating the rise, as discussed at the feedbacks page.

What could push up temperatures dramatically is loss of Arctic sea ice, as discussed in earlier posts such as this one. Ominously, the North Atlantic sea surface temperature anomaly has risen strongly recently, as illustrated by the images below.

The maps below, adapted from Climate Reanalyzer, show sea surface temperatures (left) and sea surface temperature anomalies (right) on June 2, 2024.

North Atlantic sea surface temperatures keep rising, as illustrated by the image below that highlights temperature anomalies from 1951-1980 for May 2022, May 2023 and May 2024.

[ click on images to enlarge ]

Climate Emergency Declaration

The situation is dire and the precautionary principle calls for rapid, comprehensive and effective action to reduce the damage and to improve the situation, as described in this 2022 post, where needed in combination with a Climate Emergency Declaration, as discussed at this group.