Is the IPCC creating false perceptions, again?
IPCC AR6 Report
Downplaying the temperature rise from pre-industrial
One of the first issues that comes up is the baseline. The IPCC uses 1850–1900 as a baseline, like it did before (in SR1.5). This is one out of many instances where the IPCC creates a perception that it would take many years before the 1.5°C threshold would be crossed. This 1850–1900 isn’t pre-industrial. The Paris Agreement calls for pre-industrial as a base.
Furthermore, the IPCC uses seasonally-biased data to “reconstruct” the temperature rise before its baseline, making it look as if there was no rise before its baseline.
Instead, the rise from pre-industrial to 1920 could be as much as 0.3°C (1750 to 1920) + 0.2°C (1520 to 1750) + 0.29°C (3480 BC to 1520).
|In February 2016, the temperature
was 1.70°C higher than in 1900
(i.e. 1885-1914, the 30-year period
centered around the start of 1900)
Ignoring peak peril by averaging over long periods
The map on the right shows that the average global temperature was 1.70°C higher in February 2016 than around 1900 (i.e. 1885-1914). The map also shows local anomalies as high as 15.1°C and even higher peaks were reached on specific days.
|When building a bridge, an engineer will calculate how much load it can handle by first looking at how many heavy trucks will be using the bridge at times of PEAK traffic, rather than to average the weight of all vehicles on the bridge over a 30-year period. Caption and image by Sam Carana from earlier post.|
Downplaying the near-term temperature rise
Instead, the IPCC comes up with five scenarios. The only two scenarios for which the rise remains well below 2°C are SSP1-1.9 and SSP1-2.6 (images right).
The position of methane is of vital importance in these scenarios. As a requirement for both the SSP1-1.9 and SSP1-2.6 scenarios, methane emissions would need to have fallen since the year 2015. Even for SSP2-4.5, for which 2°C does get crossed, methane emissions would need to fall.
in 2015: 1834 ppb
Such a high mean methane level by 2026 cannot be ruled out, given the rapid recent growth in mean annual methane levels and with double-digit growth sustained beyond 2020 to date. It is deceptive to assume that methane levels have fallen and will continue to fall, the more so since the IPCC doesn’t point at the most effective policies to achieve this.
A short horizon is quite appropriate given that the above trend points at the possibility of such a high level for methane getting reached by 2026.
But even with less methane, when using a short horizon for the GWP of methane and adding the impact by 2026 of further greenhouse gases (carbon dioxide, nitrous oxide, water vapor, etc.), that would cause the 1200 ppm CO₂e clouds tipping point to get crossed that results in an additional 8°C temperature rise.
Given that humans will likely go extinct with a 3°C rise, and a 5°C rise will likely end most life on Earth, the IPCC could have given a little more warning that a huge temperature rise may happen over the next few years.
Natural variability acts as a catalyst in this case. Within a few years time, sunspots will be reaching the peak of their cycle, and they are looking stronger than forecast.
An upcoming El Niño could raise surface temperatures significantly. The image below indicates that the difference between the top of El Niño and the bottom of La Niña could be more than half a degree Celsius.
As cleaner alternatives become more economic, and as calls for cleaner air become stronger, this could result in a strong temperature rise soon, as discussed at the aerosols page.
As illustrated by the bar on the right, there are many further elements that could dramatically push up the temperature soon. Altogether, the rise from pre-industrial could increase to more than 18°C by 2026.
“There is no carbon budget to divide between polluters, instead there is just a huge debt of CO₂ to be removed from the atmosphere and the oceans. Comprehensive and effective action must be taken to combat run-away warming.”
It should have been obvious by now that there is no “carbon budget”. Instead, there’s only a huge and very dangerous carbon debt. There is no room for trade-offs or offsets, and terms such as negative emissions are simply inappropriate. All efforts should be made to cut emissions, including ending current subsidies for fossil fuel and livestock, while carbon could and should additionally be removed from the atmosphere and oceans. And even then, it’s questionable whether any species, let alone humans, will be able to survive the coming decade, so additional action will need to be taken as well.
This IPCC report should be returned to be rewritten, to instead focus on the best policies to facilitate the necessary changes. The scientific evidence in favor of what needs to be done is overwhelming, from all kinds of perspectives, while it’s also simply the right thing to do. Most effective are feebates, i.e. imposing fees on polluting products while using the revenues to support rebates on better alternatives, and feebates are especially effective when implemented locally. Studies on the effectiveness of feebates were made available as early as 2005 and feebates have been discussed by the IMF, the OECD and the UN, and have been implemented in various ways, e.g. in the Clean Car Programme in New Zealand. The situation is dire and calls for the most comprehensive and effective action, as described at the Climate Plan.
• IPCC special report on the impacts of global warming of 1.5 °C above pre-industrial levels and related global greenhouse gas emission pathways (SR1.5)
• Seasonal origin of the thermal maxima at the Holocene and the last interglacial – by Samantha Bova et al. (2021)
• Changing El Niño–Southern Oscillation in a warming climate – by Wenju Cai et al. https://www.nature.com/articles/s43017-021-00199-z
• IPCC report may have underplayed risk of freak El Nino and La Nina events
• IMF: Chapter 1. What Is the Best Policy Instrument for Reducing CO2 Emissions?, in: Fiscal Policy to Mitigate Climate Change – by Ruud de Mooij et al. (2012)
of Private Motor Vehicles
• Feebates: An effective regulatory instrument for cost-constrained environmental policy – by Kenneth Johnson