The above image, created with Climate Reanalyzer data, shows the temperature anomaly (in °C) compared to the 1979-2000 mean. In blue are the years 1979-2022 and in black and white is the year 2023 through December 3, 2023. A trend is added in pink and white, based on 2023 data. Note that the 1979-2000 mean isn’t pre-industrial, the anomaly from pre-industrial is significantly higher.

[ click on images to enlarge ]

The trend warns that temperatures could keep rising rapidly over the next few months. A number of things can contribute to such a rapid rise:

  • The chance that the current El Niño will slow down over the next few months is minimal, as illustrated by the IRI image on the right.
  • Earth’s radiation imbalance is very high, as illustrated by the NASA image below.

  • Antarctic sea ice extent is at record low for the time of year, as illustrated by the NSIDC image below, and the fall in extent is particularly steep in December. Sea ice loss results in less sunlight getting reflected back into space and instead getting absorbed by the ocean and the impact of Antarctic sea ice loss is even stronger than Arctic sea ice loss, as Antarctic sea ice is located closer to the Equator, as pointed out by Paul Beckwith in a video in an earlier post. A warmer Southern Ocean also comes with fewer bright clouds, further reducing albedo, as discussed here and here. For decades, there still were many lower clouds over the Southern Ocean, reflecting much sunlight back into space, but these lower clouds have been decreasing over time, further speeding up the amount of sunlight getting absorbed by the water of the Southern Ocean, and this ‘pattern effect’ could make a huge difference globally, as this study points out. Emissivity is a further factor; open oceans are less efficient than sea ice when it comes to emitting in the far-infrared region of the spectrum (feedback #23 on the feedbacks page).
  • There is a huge danger that ocean heat will reach and destabilize methane hydrates that are contained in sediments at the seafloor of oceans, resulting in massive methane eruptions, as discussed in many earlier posts such as this one.
  • Emissions are high and rising. On December 6, 2023, CO₂ was 420.16 ppm at Mauna Loa, Hawaii. Today’s greenhouse gas forcing of 4.6 W/m² is relative to mid-Holocene CO₂ of 260 ppm, i.e. the natural Holocene CO₂ level. Equilibrium global warming for today’s amount of greenhouse gases is 10°C, which is reduced to 8°C by today’s human-made aerosols. Warming in the past 6000 years was slowed down by aerosol cooling. Growing population, agriculture and land clearance produced aerosols and CO₂; wood was the main fuel for cooking and heating. Nonlinear aerosol forcing is largest in a pristine atmosphere. Impacts on people and nature will accelerate as global warming increases hydrologic (weather) extremes. The enormity of consequences demands a return to Holocene-level global temperature. (from: Global warming in the pipeline, by James Hansen et al.)
    Rises in methane can cause rapid warming. The image below, created with a Copernicus forecast for December 6, 2023 03 UTC, shows very high methane levels at higher latitudes north at 500 hPa.
  • Meanwhile, as emissions keep rising, politicians refuse to act, preferring to debate the size of the “carbon budget”. Sadly, the IPCC lends credibility to the idea that there was a “budget” to be divided among polluters, a “budget” that would enable polluters to keep polluting for decades to come. This adds a false sense of accountability to this “budget”, as if it was checked and verified by scientists across the world. Instead, there is just a huge carbon debt that has to be removed from the atmosphere and the oceans.
  • As more people become aware of the dire situation, widespread panic can set in, as warned about in this 2007 post. Instead of crossing a social tipping point that prompts people into action to combat the temperature rise, panic may set in that stops many people from showing up at work, resulting in a rapid loss of the aerosol masking effect, as industries that now co-emit cooling aerosols (such as sulfates) grind to a halt. People may start to collect and burn more wood, resulting in an increase in emissions that speed up the temperature rise. As temperatures rise, more fires could also break out in forests, peatlands and urban areas including landfills and waste dumps, further contributing to emissions that speed up the temperature rise. 
As said, the 1979-2000 base used in the image at the top is not pre-industrial. Anomalies would be much higher when using a genuinely pre-industrial base. The image on the right uses a 2.29°C 2020 anomaly from 3480 BC.

• Columbia Climate School, International Research Institute for Climate and Society

• NASA – Earth’s Radiation Balance

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