By Chris Johansen

How does an experienced volcanologist convey to the residents in the valley that a nearby mountain will explode in a volcanic eruption within a month? Without that person being written off as an alarmist or sending those residents into denial. And how does an experienced oncologist tell a patient with what was thought of as a benign cancer that it has suddenly worsened to the point that there will be massively increasing pain and likely death within a few months – again without being dismissed as alarmist or provoking denial?

This is a dilemma now being confronted by climate scientists who study tipping points. Climate tipping points are “thresholds at which a small change causes a larger, more critical change to be initiated, taking the climate system from one state to a discreetly different state. The change may be abrupt and irreversible on relevant time frames, possibly leading to cascading events.”

Tipping points such as glacial melt, permafrost melting releasing methane, coral reef loss, irreversible disruption of traditional weather patterns, etc. were thought to be future threats if we proceed with business-as-usual. The main thrust of the climate action movement has been to avoid reaching such tipping points, to slow and eventually reverse climate change and bring us back to the benign state of around 350 ppm CO2 (e.g.

NASA photo of Thwaites Glacier, West Antarctica Creative Commons

Not so long ago, global warming beyond pre-industrial levels of above 2°C was thought to be the critical level beyond which tipping points are likely to be triggered. Recent IPCC reports have revised this back to 1.5°C.

However, a recent review of the latest tipping point research, Climate Dominoes, indicates that several critical tipping point thresholds have already been breached, at or before the current global warming level of 1.1-1.2°C. That is, we are already on a wild roller coaster ride with most of the trajectory downhill at increasing speed. The seemingly irreversible tipping points that so far appear to have been breached are:

  • Recent evidence that West Antarctica’s Thwaites Glacier has passed a tipping point for abrupt change, likely triggering a cascade of similar events on the peninsula, making many meters of sea level rise inevitable.
  • The Arctic is warming at four times the planetary average, pushing the Greenland ice sheet past a point of system stability and causing melting of permafrost to release the more potent greenhouse gas, methane. The Arctic is warming faster because of the progressive loss of sea ice over recent decades and thus its reflectivity of incoming radiation (a cascading effect).
  • Due to both human-caused deforestation and changing rainfall patterns (which can be related to Arctic warming affecting ocean currents) there is considerable evidence that eastern Amazonia has “tipped” and is now a net source of carbon. Reforestation to the extent of it again becoming a carbon sink does not seem in prospect any time soon.
  • There is mounting evidence that rainfall, and local weather generally, has changed from historical patterns, seemingly irreversibly (e.g. 20% reduction in rainfall in south-west WA over the previous 50 years).
  • It is readily apparent that tropical coral reefs are doomed because of the increasing frequency of coral bleaching events with insufficient time between those events for coral recovery.

The cited evidence in Climate Dominoes that these tipping points have been reached and are essentially irreversible is compelling but depressing for climate activists who have been largely focussing on mitigation efforts. So how do we react to this? Options seem to be:

  • “Eat, drink and be merry for tomorrow we …..”. And generally slip into a numbed state of denial. But suggest you don’t settle into a retirement home in a Mandurah canal development, or anywhere else adjacent to current sea level.
  • Encourage further critical examination of the data confirming breach of these tipping points and their irreversibility. But it should be pointed out that publication of such data in the first place depends on thorough peer review (anonymous reviewers scrutinizing all aspects of the study). Further, multi-authored IPCC and other climate reports usually settle on the lowest common denominator of interpretation, reaching the most conservative of conclusions, thus underestimating the reality of what is going on. This is evidenced by the IPCC scaling back from 2°C to 1.5°C as the critical level for maintaining a stable climate, even though evidence was available long before that 1.5°C was more realistic. And now it appears that such critical levels for tipping points are below 1.5°C. Yes, please keep checking the data and generating new data but I doubt that will result in a more optimistic prognosis.
  • Accept that the planet is now on a trajectory to a changed climate state and that we must adapt to it. Climate activists have not concentrated very much on adaptation in the past, rather putting all of their efforts into mitigation. Of course, continued efforts in mitigation are still required – to try and slow the rate of tipping into a changed planetary state. However, at the same time we need to be thinking about how to adapt to those inevitable changes.