The target of limiting the global temperature increase to 1.5°C above pre-industrial levels has been a totemic threshold ever since the 2015 Paris Agreement, indicating whether climate change is within manageable limits, whatever the political rhetoric.
In June 2023, the global temperature temporarily passed the threshold, with heatwaves, wildfires and flooding affecting every part of the world.
With COP28 approaching, scientists, journalists, and politicians are proclaiming either ‘keep 1.5 alive’, ‘1.5 is dead’, or ’every fraction of a degree matters’.
However, both the ‘keep 1.5 alive’ and ‘1.5 is dead’ narratives may be missing the point.
1.5°C matters – it represents a level of heating beyond which critical ‘tipping points’ may be breached. But the threshold was set at a time when climate change impacts were still a future risk of harm, and when little mandate for change existed in any country.
Climate impacts are now real, present and growing worse. The world’s citizens, increasingly harmed by climate change, may soon demand action that is not measured by its influence on an abstract target. Instead, powerful new societal forces could emerge demanding transformational change. A new plan for that eventuality is required.
How close are we to 1.5°C?
The IPCC estimates that, under a moderate emissions scenario, the world is likely to surpass 1.5°C in 2030. And, for a 50 per cent chance of limiting temperature to 1.5°C with limited to no overshoot, emissions will need to peak before 2025.
Yet with emissions reaching a recent all-time high, and the start of 2025 around the corner, it is no wonder some are saying ‘1.5 is dead’.
Temperature increases may be accelerated – at least temporarily – due to the El Niño-La Niña cycle, which has recently flipped from providing an unusually long period of cooling (La Niña), to what may become a strong warming period (El Niño).
The change has contributed to the World Meteorological Organization (WMO) predicting a 66 per cent likelihood that between 2023 and 2027 1.5°C will be surpassed for at least one year.
From an abstract target to real world impacts
On the current global trajectory, within a decade or two, climate change impacts may exceed communities’ ability to adapt.
Crossing the 1.5°C threshold may lead to an acceleration of these impacts as critical climatic and earth system tipping points are crossed.
Recent IPCC climate models show a cluster of such abrupt ’tipping points’ occurring between 1.5°C and 2°C (though with considerable uncertainty).
Exceeding 1.5°C therefore risks creating runaway climate change, where climate impacts grow in a non-linear manner.
But wait, might breaching 1.5°C be temporary?
In September 2023, the UN will publish an assessment of global progress towards meeting the Paris Agreement goals. This Global Stocktake report will likely be peppered with language around planning for ‘temporary overshoot’ of 1.5°C.
Temporary overshoot will require removing carbon dioxide from the atmosphere, or ‘negative emissions’, and carbon capture utilization and storage (CCUS) to supress emissions from the continued burning of fossil fuels.
The two negative emission technologies most heavily relied upon are bioenergy with carbon capture and storage (BECCS), and direct air (carbon) capture (DAC). These technologies are complex and unproven at the scale needed.
All carbon capture technologies also require significant energy input. In a world prioritising secure, affordable energy, this cost may pose a major barrier to their large-scale deployment. Further, BECCS, DAC and CCUS facilities are only likely to be deployed at scale from 2035 or 2040 onwards.
As such, there may well be a significant overshoot in the 1.5°C temperature limit before fossil emissions can be captured at scale and negative emissions kick in. By then, tipping points may have already been triggered.
Future promises of negative emissions may actually deter or delay faster decarbonization now. This deter and delay effect could actually lead to an additional temperature rise of up to 1.4 °C.
Is the 1.5°C narrative still valuable?
The likelihood is that the ‘keep 1.5 alive’ narrative will be worthless within two political cycles, or less.
The counterargument is that if the ‘1.5 is dead’ narrative replaces it, we risk a race to the bottom, where countries pursue a ‘burn-baby-burn’ fossil fuel agenda to gain competitive advantage over those that try and limit emissions.
However, perhaps both narratives are increasingly redundant.
Climate change is no longer a bogeyman of the future. Climate impacts are here causing harm every day. The lived experience of everyone on Earth will increasingly suggest the problem is immediate, growing, and not being managed.
As the costs of climate change mount, it is possible that the abstract politics of the Paris Agreement will be revolutionized by citizens’ demands for effective, urgent action, creating a political tipping point where countries compete to decarbonize at the fastest rate. Should that occur, a new plan will be required.
What does a new plan of action need to succeed?
In the short term three actions should be pursued. First, the world needs to prevent lock-in to high emission fossil fuel assets. Many large investment firms have hired climate risk analysts recently, and there is a clear path towards emphasizing to this cohort the climate risks their investment portfolios must avoid.
Second, building on this, the messaging and speed of climate impact attribution should be amplified, robustly ascribing a probability that extreme weather events are being caused by anthropogenic climate change.
These rapid assessments enable societies, the media, businesses and governments to relate experienced harm to current climate change.
Third, net zero will have to be reformed so that incumbents do not plan to ‘net off’ their emissions in the future and continue as usual in the meantime. The focus must be on emissions reductions (getting as close as possible to zero emissions).
Negative emissions (the net part) should be constrained to what is truly feasible and limited to hard-to-abate sectors like steel, cement and shipping.
In the medium term, there should be a refocus on the fastest acting emission reduction mechanisms.
Large infrastructure projects take decades to be deployed, but with sufficient societal concern and buy-in, behaviour change can be enacted far more quickly.
Demand-side measures are most crucial in counties with the highest per capita consumption and emissions.