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How to Save the World in 15 Years – Part Two: Net Zero is Not Enough

Just as we underestimated the speed and scale of climate change, Nafeez Ahmed argues, our narrow, linear ways are leading us to underestimate the scope of potential solutions

An iceberg melting in Antarctica. Photo: Anna Berkut/Alamy

How to Save the World in 15 YearsPart TwoNet Zero is Not Enough

Just as we underestimated the speed and scale of climate change, Nafeez Ahmed argues, our narrow, linear ways are leading us to underestimate the scope of potential solutions

The new Intergovernmental Panel on Climate Change (IPCC) report published this month, synthesising the work of thousands of scientists and representing the agreement of 195 countries, goes further than any other report in suggesting that the Paris Agreement net zero target is based on a colossal self-deception: the assumption that, if we can progressively reduce emissions down to net zero over the next 30 years, we will be able to avoid entering the climate danger zone that occurs once the Earth breaches the 1.5-2 degrees Celsius ‘safe limit’. 

It is now clear that the net zero targets will still guarantee dangerous climate change, given that every scenario – including the IPCC’s most optimistic – sees the world breaching the critical 1.5C threshold within the next 20 years.

In fact, emerging evidence not directly included in the new IPCC report suggests that the situation is worse – with new data suggesting that the Earth has breached a total of six out of nine planetary boundaries necessary to sustain a habitable human civilisation, and that other major tipping points described by the IPCC already appear to be at risk of flipping.

The Tipping Points We Could Be Triggering Today

Because the IPCC needs to reach a consensus, it can often exclude analysis of climate tipping points where some of the greatest risks can be found, due to the higher uncertainties around when and how they might be triggered.

Its new report continues to assume that the 1.5-2C temperature range is a viable target to avoid the risk of dangerous climate change. While this may well be the case, a wide range of evidence suggests that this ‘safe limit’ may not be safe at all. 

The report has set out at least 12 key tipping points which are at risk of crossing the threshold – including the melting of polar ice sheets, methane release from melting permafrost, and the die-out of tropical forests. The report acknowledges that the risks of these tipping points being triggered goes up with every ton of carbon dioxide added to the atmosphere. Yet, it tends to project the risks as being of most significance after the 1.5C threshold.

But more and more evidence is emerging that we are at risk of starting to cross these tipping points right now.

More than a quarter of the Amazon rainforest, for instance, is now releasing more carbon than it absorbs, indicating that the Earth may already be about to breach an irreversible tipping point here. 

A recent study in Science Advances found that, at the current pace of global warming, by 2040, forests will take up only half as much carbon dioxide from the atmosphere as they do now. At this point, the land system would increasingly act to accelerate climate change rather than slow it down. The scientists behind the study described the results as “conservative”. 

Commenting on the findings, Phil Duffy of the Woodwell Climate Research Centre said that they challenge the idea that the 1.5-2C limit is truly safe: “It calls into question the assumption that the climate would even be stable at those levels of warming if all human greenhouse gas emissions were to cease. It might be at those levels of warming, emissions from vegetation would be sufficiently large to result in continued increases in atmospheric CO2 and hence continued warming.”

The key danger with such tipping points is that, in many cases, once crossed too far, there is no going back. Once a tipping point is well and truly breached, even if we reduce carbon emissions, the cycle of amplifying feedbacks that is kicked-off as a result would continue regardless.

The Danger Zone is Here 

One of the most dangerous tipping points relates to the Gulf Stream – the Atlantic ocean current which helps regulate global temperatures, particularly in western Europe.

In March, scientists found that the Gulf Stream is moving slower than it has in thousands of years and is on track to breach a tipping point by the end of the century. This would make a chaotic mix of rising seas, severe heat waves, devastating storm patterns, and unprecedented cooling a new normal from northern Europe to the eastern United States.

But more recent research suggests that we could breaching that tipping point far, far earlier. According to a study in Nature Scientific Reports published two months later, the dangerous breaching of climate tipping points can take place not simply due to reaching a certain threshold of CO2 in the atmosphere, but also due to the rate of change being too fast for the system to evolve gradually. Modelling the Gulf Stream, the study found that, if CO2 levels increase at an unprecedented rate – as is happening right now – this could trigger an abrupt regime-shift, leading to dangerous knock-on effects on global temperatures and climate. 

The study corroborated findings by a separate study in the Proceedings for the National Academy of Sciences, which also concluded that even “small-amplitude changes in the forcing, if the rate of change is fast enough” could induce a catastrophic collapse in global ocean circulation currents. 

By August, a further study in Nature Climate Change identified alarming warning signs that the recent decline in the Gulf Stream “may be associated with an almost complete loss of stability over the course of the last century”. According to one scientist, the research indicated that the Gulf Stream might be closer to a collapse tipping point than we think.

“These results indicate that climate tipping is an imminent risk in the Earth system,” said Scientific Reports co-author Professor Michael Ghil of the atmospheric and oceanic sciences department at the University of California. “Even the safe operating space of 1.5 or 2 degrees above present generally assumed by the IPCC might not be all that safe. According to the precautionary principle, we must consider abrupt and irreversible changes to the climate system as a real risk – at least until we understand these phenomena better.” 

Blasting Through Planetary Boundaries

A key theme of the new IPCC report is that, as we continue to pump carbon dioxide into the atmosphere, we increase the risk of crossing ‘tipping points’ – regional or global thresholds beyond which climate impacts accelerate to the point that they become irreversible. 

But, in addition to climate tipping points, scientists have also identified a total of nine ‘planetary boundaries’ in the Earth system, the stability of which is critical to maintain the balance by which the Earth’s atmosphere, oceans and ecosystems allow human civilisations to flourish. 

Recent scientific evidence suggests that we may be overshooting these boundaries far deeper than we previously believed. According to earth systems scientist Professor Will Steffen of the Stockholm Resilience Centre in an interview published in June in the journal Globalizations, the latest data suggests that more than half – six out of nine – planetary boundaries appear to have now been crossed by human civilisation. This has increased from the four boundaries his team found had been crossed back in 2015.

The planetary boundaries framework, first established in 2009, identifies the complex equilibrium of nested ecosystems which, if disturbed out of their natural balance which has existed for hundreds of thousands of years, will shrink what scientists call the ‘safe operating space’ for humanity: as we push through these boundaries, the planet will become less and less habitable for human civilisation.

Six years later, Prof Steffen and his team’s research confirmed that the Earth is already crossing the planetary boundaries of land-system change, biosphere integrity, biogeochemical flows, and climate change. A further six years on, the situation has further deteriorated. “The two additional boundaries that probably have been transgressed are ocean acidification and freshwater use,” he told Globalizations

At this rate – crossing two boundaries every six years – we would cross a total of eight out of nine planetary boundaries as early as 2027; with only one planetary boundary, the ozone layer, remaining. The ozone is in fact the only boundary where we have seen continued improvements over the Past decades. In effect, this means that the Earth is on track to blast our way through all of the key planetary boundaries the stability of which are critical for human survival well within this decade.

Indeed, a comprehensive scientific assessment of the rate at which we are disturbing key planetary boundaries and tipping points, published in July in BioScience, concluded ominously that “we are nearing or have already crossed tipping points associated with critical parts of the Earth system, including the West Antarctic and Greenland ice sheets, warm-water coral reefs, and the Amazon rainforest”.  

This is what is happening at the current level of around 1.25C of warming – and it suggests that the idea we can safely continue emissions up to 1.5C if not beyond is seriously mistaken. It also suggests that the IPCC goal of breaching 1.5C in two decades, and staying there for several more decades while attempting to reduce back down to 1.4C by 2100, is a recipe for continued ecological catastrophe.

According to Wolfgang Knorr, a senior climate scientist at Lund University, conservative estimates of the impact of Earth system feedbacks suggest that the carbon budget (the amount of carbon we can continue to safely emit while avoiding 1.5C) will be exhausted in as little as four years. And, if a larger range of such feedbacks are taken into account, along with past investments in fossil fuel infrastructure, the carbon budget could already have been effectively exhausted. 

Similarly, ecological economist Professor Tim Jackson of the University of Surrey calculates that, if emissions fall too slowly, the UK’s carbon budget could be exhausted as early as 2023


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In the Zone

If we are already in the climate danger zone, then even if we reduce carbon dioxide emissions to zero immediately, this does nothing about the existing stock of carbon currently accumulated in the atmosphere – which has now reached dangerous levels at risk of pushing the climate system across major tipping points that could trigger further irreversible warming events. 

In a landmark study published around a decade ago in Earth System Dynamics, atmospheric scientist Professor Timothy Garrett of the University of Utah warned that, given the correlation between the expansion of industrial civilisation, global economic growth and increases in carbon dioxide emissions, the scale and speed at which we need to reduce CO2 is so colossal that it implies that civilisation and the global economy must completely collapse in order to avert disaster.

He observed: “If civilisation does not collapse quickly this century, then CO2 levels will likely end up exceeding 1000 ppmv [parts per million by volume]; but, if CO2 levels rise by this much, then the risk is that civilisation will gradually tend towards collapse… Ultimately, civilisation appears to be in a double-bind with no obvious way out. Only a combination of extremely rapid decarbonisation and civilisation collapse will enable CO2 concentrations to be stabilized below the 450ppmv level that might be considered as ‘dangerous’.”

At first glance, our predicament appears intractable. But, just as we under-estimate the speed and scale of climate change, our narrow, linear ways of looking at the world are also leading us to under-estimate the scope of potential solutions to climate change. What if the fossil fuel system underpinning industrial civilisation as we know it, was, indeed, likely to collapse? But what if this did not mean the end of civilisation – but the birth of a completely new system?

This year, I was involved in a new research study published just days before the IPCC’s report. According to the San Francisco-based think tank RethinkX, the rapid phase-out of carbon-intensive industries is achievable within as little as 15 years. But, instead of a haphazard approach that involves doing anything and everything while hoping they work for the best, we need a focused, strategic approach based on targeting the most problematic sectors – energy, transport and food – and leveraging the most promising technologies.

Doing so has the potential to transform the entire human system and its relationship to our environment. 

In the third and final part of this series, Nafeez Ahmed will examine the emerging evidence that we have all the tools we need to solve environmental crises, and that change is coming faster than anyone thought possible

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