Arctic News: Carbon dioxide growing rapidly

Thursday, August 22, 2024

Carbon dioxide growing rapidly

The image below shows NOAA monthly mean concentration of carbon dioxide (CO₂) recorded at Mauna Loa, Hawaii, from 2020 through July 2024. The inset shows that CO₂ was 425.55 parts per million (ppm) in July 2024, an increase of 3.72 ppm from July 2023, when CO₂ was 421.83 ppm. This 3.72 ppm growth is higher than the 3.36 ppm annual growth in 2023, the highest annual growth on record.

The image below shows the same data, with a trend added based on August 2009 through July 2024 data.

The above trend points at 430 ppm CO₂ getting crossed in February 2025, which would constitute a jump of 10 ppm in two years time (from 420 ppm in February 2023 to 430 ppm in February 2025). Despite numerous warnings and despite politicians' pledges to act decisively, the concentration of CO₂ in the atmosphere is growing rapidly.

If this trend continues, 1200 ppm CO₂ could be crossed in early 2035, as illustrated by the image below.

In other words, the clouds tipping point could get crossed in early 2035 due to rising CO₂ alone.

There has been some debate as to when the clouds tipping point would get crossed. The above image points at carbon dioxide in the atmosphere crossing 1200 ppm in 2035. Someone argued that, when calculating the carbon dioxide equivalent (CO₂e) for different gases, counting should start from the year 1750, implying that the clouds tipping point would not be at 1200 ppm CO₂ but would instead be reached by an increase of 1200 ppm above the CO₂ concentration in the year 1750, which was 278 ppm. Adding 1200 ppm to 278 ppm makes 1478 ppm. The image below illustrates that, if the trend would continue, this higher value of 1478 ppm could be crossed in 2036.

[ from earlier post ]

Rising emissions could originate from many sources, the more so as more sinks turn into sources.

[ from earlier post ]

The clouds tipping point is at 1200 ppm CO₂e (carbon dioxide equivalent), so it could be crossed even earlier when also taking into account more methane, nitrous oxide, etc. The above image, from an earlier post, warns that a trend (added to NOAA globally averaged marine surface monthly mean methane data from April 2018 to November 2022) points at 6000 ppb methane in 2027. The image further warns that this could cause the clouds tipping point to get crossed due to methane alone, and illustrates this by comparing 6000 ppb methane with 1200 ppm CO₂e while using a Global Warming Potential (GWP) of 200.

Not all equivalents are equal

There are several ways to measure the impact of methane. In the above image, methane parts are taken as equivalent to carbon dioxide parts, while using a GWP for methane of 200. Not all equivalents are equal, so here's another way to compare CO₂'s and methane's impact.

The image on the right, by Eric Fisk, shows contributions to 2010–2019 warming relative to 1850–1900 in °C. The whiskers show likely ranges, indicating that methane's impact may rival, if not exceed carbon dioxide's impact, and there are reasons why this may be the case.

[ from FAQ ]

Methane concentrations have risen strongly since 2010-2019.

Methane's immediate GWP may exceed 200, much higher than the values that are often used when applying horizons of 20 years or 100 years.

Methane's lifetime extends as more methane is released, due to hydroxyl depletion, as illustrated by the graph on the right, based on data by Isaksen et al. (2011).

Indirect effects include more stratospheric water vapor and tropospheric ozone. Carbon dioxide is produced when methane is broken down. Methane's lifetime also extends as more water vapor enters the atmosphere, as temperatures rise.

The study by Isaksen et al. calculates that a scenario of 7 times current methane (image below, medium light colors) over 50 years would correspond with a radiative forcing of 3.6 W m⁻².

[ from FAQ ]

At the time of the study, little was known about the clouds tipping point, let alone that it could be crossed due to methane alone at concentrations much lower than 7 times the methane in 2011. Even when using a lower value for methane's impact, there is a growing potential for the amount of methane in the atmosphere to increase dramatically, as a result of methane releases from permafrost, as temperatures keep rising, which would strongly contribute to cause the Clouds Tipping Point to get crossed. This increases the urgency to take climate action. The images below illustrate the danger.

The above image, adapted from Copernicus, shows a methane forecast for August 22, 2024 03 UTC (run 00 UTC). Note that the scale goes up to 10 ppm or 10,000 parts per billion (ppb).

The above image shows that high methane concentrations (around 2400 ppb) were recently recorded at the observatory in Utqiagvik (Barrow), Alaska.

As discussed in an earlier post, peak daily average methane is approaching 2000 ppb at Mauna Loa, Hawaii. Local peaks can be much higher, as illustrated by the image on the right that shows that a methane peak of 2739 ppb was recorded at 399 mb by the NOAA 20 satellite on August 22, 2024 AM.

Methane levels are particularly high at latitudes higher than 60°N, where they can often exceed 2000 ppb, even at relatively low altitudes.

The next image on the right shows methane as recorded by the NOAA 20 satellite on August 13, 2024 AM at 1000 mb, which corresponds with the lowest altitude available.

The next image on the right shows methane on August 23, 2024 AM at 840 mb, where the NOAA 20 satellite recorded levels as high as 2418 ppb.

When using a GWP of 200 for methane, a concentration of 2000 ppb may correspond with 400 ppm CO₂e, as discussed above. Together with a daily peak CO₂ concentration of 430 ppm, this would add up to a joint CO₂e peak of 830 ppm, i.e. only 370 ppm away from the clouds tipping point at 1200 ppm CO₂e. This 370 ppm CO₂e could be added almost instantly 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 carbon and methane contained in vulnerable sediments at the seafloor of the Arctic Ocean, as discussed above and in earlier posts such as this one, and at the threat page.

[ image from the Extinction page ]

There are further emissions and developments such as tipping points and feedbacks that should be taken into account. The above image, from an earlier post, illustrates the mechanism how multiple feedbacks can accelerate the temperature rise of the atmosphere.

Several feedbacks can also constitute tipping points. Decline of Arctic sea ice comes with loss of albedo and loss of the Latent Heat Buffer, and the joint loss can abruptly and dramatically increase temperatures in the Arctic Ocean.

Further increase of heat in the Arctic Ocean can in turn cause the Seafloor Methane Tipping Point to get crossed, resulting in destabilization of methane hydrates contained in sediments at the seafloor of the Arctic Ocean, as discussed in many earlier posts such as this one.

Self-amplifying feedbacks and crossing of tipping points, as well as further developments (such a as loss of the aerosol masking effect and sunspots reaching a peak) could all contribute to cause a temperature rise from pre-industrial of over 10°C, in the process causing the clouds tipping point to get crossed that can push up the temperature rise by a further 8°C.

Altogether, the temperature rise may exceed 18°C from pre-industrial by 2026, as illustrated by the image on the right.

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.

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