I Thought They Left Something Out. Gaping Holes in the IPCC Climate Report.

Yesterday's report of the Intergovernmental Panel on Climate Change was pretty jarring with its dire warning that we had just a dozen years to cut our carbon emissions by almost half or face catastrophic global warming.

But, hey, I did try to warn you that, coming from the IPCC, what you read was a "best possible scenario" outlook.

As I read through it I noticed something was missing. If anything that was to be expected from the IPCC. So what didn't make it into the report?

Tipping points, positive feedback loops, all the ways that nature itself has already become a major player in driving climate change. It's one thing to warn that human civilization is driving us to the edge of a cliff. It's another thing entirely when you include this powerful natural force now pushing us from behind. We are not the only player any longer.

Think of disappearing Arctic sea ice, the decline of major ice caps and glaciers, the warming Arctic Ocean, the increasing volumes of water vapour in the atmosphere, changes in the major oceanic currents, the thawing of permafrost releasing methane into the atmosphere, the accelerating loss of Antarctic ice, on and on and on.

The IPCC report sets out the world’s current knowledge of the impacts of 1.5C of warming and clearly shows the dangers of breaching such a limit. However, many scientists are increasingly worried about factors about which we know much less. 

These “known unknowns” of climate change are tipping points, or feedback mechanisms within the climate system – thresholds that, if passed, could send the Earth into a spiral of runaway climate change. 

Tipping points merit only a few mentions in the IPCC report. Durwood Zaelke, founder of the Institute for Governance and Sustainable Development, said: “The IPCC report fails to focus on the weakest link in the climate chain: the self-reinforcing feedbacks which, if allowed to continue, will accelerate warming and risk cascading climate tipping points and runaway warming.”

...Bob Ward, of the Grantham Institute, said: “The IPCC summary for policymakers only mentions the west Antarctica and Greenland tipping points, which we may already have reached.”

...One of the problems with tipping point thresholds is that we may not know when they are reached. Robert Larter, of the British Antarctic Survey, called polar ice sheets “sleeping giants”, which if they pass a tipping point will cause devastation.

...Further unknowns include the effects of climate change on carbon sinks, such as soils and forests: higher temperatures could dry out some soils, causing them to release stored carbon into the air. But increased rainfall – a symptom of climate change in some regions – could in other areas be making it harder for forest soils to trap greenhouse gases such as methane.

Mario Molina, who shared the Nobel prize in chemistry in 1995 for his work on depletion of the ozone layer, said: “The IPCC report demonstrates that it is still possible to keep the climate relatively safe, provided we muster an unprecedented level of cooperation, extraordinary speed and heroic scale of action. But even with its description of the increasing impacts that lie ahead, the IPCC understates a key risk: that self-reinforcing feedback loops could push the climate system into chaos before we have time to tame our energy system, and the other sources of climate pollution.”

...While governments have the means to affect how much CO2 gets released through policies that radically cut the use of fossil fuels, it would be much harder to get a grip on thawing permafrosts, mass forest collapses or the loss of polar sea ice.

By failing to get a grip on a thing that’s feasibly under your control, we end up risking the release a whole gang of other monsters that we can’t.

As a co-author of the IPCC report, professor Will Steffen, of the Australian National University and Stockholm Resilience Centre, knows too well what's missing - feedback loops, knock-on effects, cascades - the whole dark side of climate change.

For those who understand the idea of a carbon budget – where scientists have calculated how much CO2 you could emit before hitting certain temperature rises – it looks even meaner than before if Steffen and his colleagues are right. 

But as they also point out, several of these feedbacks might have “tipping points” that then set off a cascade of other issues. Steffen says:

“Even at the current level of warming of about 1C above pre-industrial, we may have already crossed a tipping point for one of the feedback processes (Arctic summer sea ice), and we see instabilities in others – permafrost melting, Amazon forest dieback, boreal forest dieback and weakening of land and ocean physiological carbon sinks. 

And we emphasise that these processes are not linear and often have built-in feedback processes that generate tipping point behaviour. For example, for melting permafrost, the chemical process that decomposes the peat generates heat itself, which leads to further melting and so on.”

I expect by now you've had enough. I'll leave the interwoven challenges such as overpopulation and over consumption of the planet's resources for now. Yet the identified omissions in the IPCC report, the emerging dark side of climate change that is not under human control, is what makes me leery that we actually have until 2030 to cut our carbon emissions by half. 

This has become a race between humanity and nature to avert runaway global warming and that is going to be decided well before we reach 2030.