Beyond all the hype and all the anxiety about climate policymaking, the upbeat newsmaking about energy transitions and the growing dread of civilisational collapse, what have we learned about the climate system in the last year? Here are some key observations drawn from research and data published in 2022.
1. Record emissions
Covid supply-chain disruption and the war in Ukraine have distracted from the task of rapid emissions reductions and contributed to inflation, falling real wages and a political focus on cost-of-living pressures. The war has disrupted energy markets, driven a return to coal whose use is at an all-time high, prompted an increase in emissions-intensive arms production and use, and become an excuse for governments to delay climate action.
Atmospheric levels of all three main greenhouse gases reached record highs in 2022. Carbon Monitor reported emissions data for full year 2022 as: “Global CO2 (carbon dioxide) increased by +1.6% in 2022 (+8.0% than 2020, and +2.1% than 2019)”, an all-time record. In November 2022, the Global Carbon Project had estimated carbon emissions from fossil fuels in 2022 would reach 37.5 billion tons of carbon dioxide, the highest ever recorded. The latest International Energy Agency (IEA) projections show that global carbon emissions from energy are still growing and may peak in 2025, but are likely to plateau at a high level after that for a decade or more, rather than decline in any significant manner.
Likewise, the UNFCCC estimated that total global greenhouse emissions, taking into account implementation of the latest commitments by nations, would in 2030 be “50.8% higher than in 1990, 10.6% higher than in 2010, and 0.3% lower than in 2019, as well as 1.9% lower than the estimated level for 2025, indicating the possibility of global emissions peaking before 2030”. Note that in this statement, emissions peaking by 2030 is judged a “possibility,” not a high probability.
2. The 1.5°C target
The warming trend will reach 1.5°C around 2030, irrespective of any emission reduction initiatives taken in the meantime, according to the IPCC’s Sixth Assessment Working Group 1 Summary for policymakers (Table SPM.1); and the UN Environment Program said there is no longer a credible path to holding warming below 1.5°C in the short term (without deploying immediate cooling interventions, which are nowhere on the policymaking agenda).
Prof. Bill McGuire says “continuing to argue for the viability of 1.5°C is misleading and raises false hopes”, and The Economist editorialised that “the world is going to miss the totemic 1.5°C climate target”. Matthews and Wynes concluded that human activities have caused global temperatures to increase by 1.25°C and “the current emissions trajectory suggests that we will exceed 1.5°C in less than 10 years”.
In 2022, Prof. Will Steffen wrote that “the only reasonable conclusion… is that the lower Paris target of 1.5°C is now out of reach… past inaction, and in particular, failure to begin significant emission reductions before 2020, have cost us dearly”. And Australian scientists said that:
The latest science, viewed alongside continuing increases in global greenhouse gas emissions, suggests that limiting warming to 1.5°C is now almost certainly infeasible. It would now require not only rapid emission reductions, but also the large-scale removal of carbon dioxide from the atmosphere. There is no evidence that this can be achieved at sufficient scale to meet the 1.5°C target.
3. What about overshooting 1.5°C and cooling back to that level by 2100?
Most policy talk about achieving the 1.5°C target is somewhat a sleight-of-hand; it is actually about “overshooting”, in which the temperature exceeding 1.5°C, perhaps significantly and for decades, with carbon drawdown helping reduce atmospheric greenhouse gas and temperature levels back to 1.5°C in the latter part of the century.
The Washington Post reported on work which examined 1200 future emission paths, and found that only 112 get warming back down to 1.5°C or less by 2100, once unrealistic near-term emission reduction assumptions are excluded. [As noted above, greenhouse emissions are still increasing, not reducing.] Of the 112 paths, 86 were identified as “high” overshoot which involve “spending decades above 1.5°C” which is “an unsettling prospect” because “it raises the possibility, for instance, of the world experiencing dangerous tipping points and even calamities such as the irreversible loss of the West Antarctic ice sheet”. [In fact there is convincing evidence that several such tipping points have already been passed, and scientists have warned that warming in the 1.5–2°C range risks “a cascade of feedbacks could push the Earth System irreversibly onto a ‘Hothouse Earth’ pathway”.]
The 26 “low” overshoot scenarios remaining have varying assumptions about the level of technological development of carbon drawdown methods. The Potsdam Institute has characterised such technology use as having “speculative,” “challenging” or “reasonable” assumptions. When those 26 scenarios remaining were assessed under the “reasonable category” for all the five main drawdown methods — carbon capture and storage, land-based removal, carbon intensity, energy demand and less methane — no path was left. If, instead, technologies identified as “challenging” are considered, there are 11 scenarios available of the 1200 examined. What makes these 11 scenarios work? The Post reported:
One common theme is much more dramatic carbon removal from the atmosphere, storing it either underground or in forests and agricultural landscapes. The majority of these scenarios require us to be able to subtract over seven billion tons per year from the atmosphere by 2050. This will require a huge scale up of interventions like carbon capture and storage, which only has an estimated capacity of about 43 million tons per year today. Capacity has roughly doubled in the past decade, but a far faster pace of change would be needed to achieve this outcome.
4. Likelihood of achieving the 2°C target
As noted above, the IEA has reported that emissions from energy may peak in 2025, but are likely to then plateau at a high level after that for a decade or more. And The Economist reported that emissions slashed today won’t slow warming until mid-century.
To keep warming to 2°C means achieving a 50% reduction in global emissions by 2030 according to the “carbon law”, which on the basis of equity means zero emissions by 2030 for high-per capita emitting nations. Clearly, given the emissions data and projections, the world is not going to get anywhere near this. Current models, reported in the 2021 IPCC report, project around 0.3°C warming between 2020 and 2030, and more than 2°C by mid-century for the medium- and high-emissions scenario paths that the world is currently on. Current climate models show that the Earth likely will reach 2°C of global warming by the 2040s without significant policy changes, and significant players including big oil are backtracking on previous commitments, whilst central bankers express scepticism about having a climate role to play.
“Global warming of at least 2°C is now baked into Earth’s future,” wrote former NASA climate chief James Hansen in the memo co-authored with Makiko Sato and Pushker A Karecha: “That level of warmth will occur by mid-century.” And there are warnings that the rate of global warming over the next 25 years could be double what it was in the previous 50 years, in part due to the aerosol “Faustian bargain”. [Short-lived atmospheric sulfate aerosols are a by-product of burning fossil fuel and have a cooling effect which has been masking up to 1°C of global warming. Reduced emissions of greenhouse gases and clean air policies will also reduce this aerosol cooling, so there is little prospect that decarbonisation policies will significantly bend down the temperature curve over the next two decades.]
In addition, the paleoclimate evidence is that the last time CO2 levels were similar to today, there were sea level fluctuations of 20-40 metres associated with global temperature variations between today’s temperature and 3°C warmer.
It should be noted here that 2°C is not a reasonable target. In a chapter in a book published in 2022, Steffen pointed out that even the current level of warming is dangerous:
It is clear from observations of climate change-related impacts in Australia alone – the massive bushfires of the 2019–2020 Black Summer; the third mass bleaching of the Great Barrier Reef in only five years; and long-term cool-season drying of the country’s southeast agricultural zone – that even a 1.1 °C temperature rise has put us into a dangerous level of climate change.
…. to be continued.