24 February 2023

Faster, higher, hotter: What we learned about the climate system in 2022 (3)

Third in a 3-part series  |  Part 1  |  Part 2

by David Spratt

So far this series has looked at:

  1. Emissions trends
  2. The 1.5°C target
  3. Overshooting and cooling back to 1.5°C
  4. The likelihood of achieving the 2°C target
  5. 2°C degrees is not a point of system stability
  6. We are heading towards 3°C or more
  7. System-level change and tipping points are happening faster than forecast

This post looks at cascading risks, climate extremes and necessary actions.

8    Risks are cascading, and underestimated 

Climate system feedbacks can drive abrupt, non-linear change that is difficult to model and forecast, with the Earth moving to dramatically different conditions. Such changes may be irreversible on relevant time frames, such as the span of a few human generations. Major tipping points are interrelated and may cascade, so that interactions between them lower the critical temperature thresholds at which each tipping point is passed.

Climate models do not yet incorporate key processes, and therefore are deficient, especially when projecting abrupt change, system cascades, and changes in the cryosphere and in the carbon cycle. Whether it be permafrost, Greenland or West Antarctica (and hence sea-level rises), the story is the same. Current climate models are not capturing all the risks, such as the stalling of the Gulf Stream, polar ice melt and the uptick in extreme weather events. Thus Earth system and Integrated Assessment Model projections, and their use in determining carbon budgets, are not reliable. It is important that observations, semi-empirical models, expert elicitations, and lessons from past climates are given more weight, given current model deficiencies.

22 February 2023

Faster, higher, hotter: What we learned about the climate system in 2022 (2)

Second in a 3-part series  |  Part 1   |  Part 3

by David Spratt

The first part in this series looked at:

  1. Emissions trends, 
  2. The 1.5°C target, 
  3. Overshooting and cooling back to 1.5°C, and 
  4. The likelihood of achieving the 2°C target.

This post looks at system stability at 2°C, warming at 3°C, and feedbacks and cascades.

5    2°C degrees is not a point of system stability

Even sharp reductions in emissions will not be enough to avoid crossing the 1.5°C threshold, nor the 2°C threshold, given the record-breaking use of fossil fuels in 2022 and the forecasts.

Yet it is a big mistake to think we can stabilise or “park” the Earth System at around 2°C and expect it to stay there, says Will Steffen.  Earth’s climate history shows 2°C is not a point of system stability, but a signpost on a road to a hotter planet. 

When projections in late 2021 showed future warming of around 2.7°C, Potsdam Institute Director Johan Rockström responded: “I barely even want to talk about 2.7°C… If we go beyond 2°C, it’s very likely that we have caused so many tipping points that you have probably added another degree just through self-reinforcing changes. And that’s without even talking about extreme events.” 

20 February 2023

Faster, higher, hotter: What we learned about the climate system in 2022 (1)

First in a 3-part series  | Part 2 Part 3

by David Spratt

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. 

01 February 2023

Will Steffen’s crucial climate ideas on “Hothouse Earth”, tipping cascades and non-linearity

By David Spratt 

The eminent Australian climate scientist, and former Labor government advisor and head of climate at ANU, Will Steffen, who died early this week from complications following cancer surgery, will be remembered for some of the big, crucial ideas he and his collaborators contributed to the understanding of the Earth System, particularly planetary boundaries, climate tipping point vulnerabilities and cascades, risk and nonlinearity, and the “Hothouse Earth” scenario. 

Particularly in the last few years, Steffen was very clear and forthright in communicating the threat and the dynamics of the climate system, and the trajectory towards collapse:

"Given the momentum in both the Earth and human systems, and the growing difference between the ‘reaction time’ needed to steer humanity towards a more sustainable future, and the ‘intervention time’ left to avert a range of catastrophes in both the physical climate system (e.g., melting of Arctic sea ice) and the biosphere (e.g., loss of the Great Barrier Reef), we are already deep into the trajectory towards collapse … That is, the intervention time we have left has, in many cases, shrunk to levels that are shorter than the time it would take to transition to a more sustainable system.”