12 April 2023

The case for climate cooling, and some eye-watering charts


by David Spratt

Recently I had the opportunity to do one of the MEERTALKS, organised  by Mirrors for Earth's Energy Rebalancing (MEER), a network of researchers and advocates established by Ye Tao which focusses on mirror-based cooling solutions. The topic was the recent Breakthrough paper Faster, higher hotter on some takeaways from climate research in 2022. But equally it could have been called "The case for cooling".

A video of the event is now available

In the talk I also included some slides not in the original paper, and each is startling in its own way.

The first, from the US Energy Information Administration, shows projected energy-related carbon dioxide emissions for the US to 2050. In the reference (middle) case, emissions in 2050 are still more than 80% of the current figure.  No sign of net-zero anywhere on the horizon here!

The second from Wood Mackenzie and published by the Financial Times shows projected fossil fuel gas (LNG) liquefaction capacity of the world's three largest LNG exporters — USA, Qatar and Australia — out to 2030.  It projects a doubling from these three exporters in just eight years, from around 240 million tonnes a year to 480 million tonnes by 2030.  Whilst coal production is falling, gas is going in the opposite direction, which suggests fossil fuel emissions may plateau, but not drop substantially over the next decade.

The third by Leon Simons shows global shipping sulphur dioxide emissions (grey) and the Earth's absorbed solar radiation anomaly (or Earth's energy imbalance or EEI) over the North Atlantic, North America and North Pacific (brown). While there may be other factors at work, the relationship appear clear. Bunker oil used for shipping has been high in sulphur, which when burned produces sulphur dioxide, a short-lived atmospheric aerosol which has a strong but temporary cooling effect because it blocks incoming solar radiation, but it also causes acid rain. Agreements to clean up bunker fuel have seen a sharp decrease in the sulphur emissions with a drop of more than three million tonnes a year as the chart illustrates. And the consequence of losing the cooling mask has been a rapid increase in incoming solar radiation and hence in the energy imbalance (in general terms, warming still to come) over the world's major shipping routes in the Pacific and Atlantic north of the Equator.  The increase in the anomaly of more than three watts per metre square is equivalent to an eventual temperature rise of more than 2°C over the area measured, which is about one quarter of the Earth's surface.  That is roughly another half a degree of warming on a global basis, which is consistent with Jim Hansen's comments (see below) about a recent doubling in EEI.

The fourth chart comes from a recent newsletter from Jim Hansen and his former colleagues at NASA, showing global temperatures and their projection (in yellow) to 2050 of an increased rate of warming of approx. 0.25°C per decade or more. Hansen has been saying this for some time, arguing that the reduction in sulfate aerosol cooling, either from reduced fossil fuel use, and/or from cleaning up the fuel as in the shipping example above, would drive faster warming. In his December 2022 newsletter, Hansen wrote that Earth's Energy Imbalance (EEI) has doubled "mainly being increased growth rate of greenhouse gases and a reduction of human-made aerosols (fine particles in the air that reflect sunlight and cool the planet)" and that "increased EEI is the basis for our projection that global warming will accelerate by as much as 50-100% in the few decades following 2010. The length of this period of accelerated warming will depend on the path humanity follows in its continuing changes of atmospheric composition." This projection shows the warming trend reaching 2°C in the 2040-2050 range, the result depending on the level of future fossil fuel emissions and the extent of the aerosol masking.

And lastly, some data which has only just come out from the Copernicus Climate Change Service/Copernicus Atmosphere Monitoring Service, and tweeted here.  With the La Niña (which tends to result in a slightly lower global average temperature) ending and an El Niño developing, global average warming for the month of March 2023 was 1.5°C warmer than the pre-industrial baseline, and the fifth time that has happened in the last eight years. Now figures from a few months don't constitute a long-term trend, but if a strong El Niño takes hold, we may soon be looking at figures where 1.5°C+ is more than an odd monthly occurrence.