By Helena Wright
When the landmark report by the UN Intergovernmental Panel on Climate Change (IPCC) came out in 2018, there was widespread media coverage of the headline that we have 12 years to avert climate catastrophe.
Where does the ‘12 years’ headline come from? This is based on the number of years we have left until the carbon budget is used up for 1.5°C of warming — the level needed to save most of the world’s coral reefs.
However, the headline might have given people a false sense of security. In my opinion, ‘12 years’ is too optimistic. We are facing an emergency, as groups like Extinction Rebellion point out.
Global emissions need to peak immediately and then fall dramatically each year to achieve the 1.5°C goal. We do not have the luxury of 12 years left: we must immediately halt further fossil fuel use.
As this chart from the IPCC shows, there is a remaining carbon budget of about 420 GtCO2 for a two-thirds (66%) chance of limiting warming to 1.5°C, and 580 GtCO2 for a 50% chance.
Source: IPCC SR15 CH2. TCRE = transient climate response to cumulative carbon emissions
Right now, the world has warmed 1°C above pre-industrial levels. Global emissions are roughly 42 GtCO2 (gigatonnes of carbon dioxide) per year. If emissions carry on at this rate, the carbon budget for a 66% chance of below 1.5C will be used up in 10 years, whilst the budget for a 50% chance will be gone in 14 years. This is an average of 12 years.
That’s not the same thing as saying we have 12 years. Global emissions need to peak right now, without delay, and fall dramatically to meet the 1.5°C goal (see figure below).
As the IPCC points out, by 2050, the world will need to reach ‘net zero emissions’ — where human-caused emissions are in balance with reductions — to achieve 1.5°C.
That means, frankly, we do not have 12 years to wait for technological or political solutions. The world must peak global emissions now and get them down to ‘net zero’ as soon as we can.
Reaching 1.5°C requires a monumental global effort for a 66% chance — almost a wartime effort — with extremely steep reductions each year including shutdown of fossil fuel assets (see below).
Source: Global Carbon Project 2018
Since this is extremely difficult, it will also require CO2 removal (of which a huge programme of tree-planting is probably most realistic) to suck emissions out of the atmosphere. Scientist Glen Peters has described reaching 1.5°C as ‘highly unlikely’.
Can 50%, or even 66%, be considered a reasonable chance of reaching 1.5°C? The risks of exceeding 1.5°C are already too high, but we are where we are.
Saying we have‘12 years’ is too optimistic as we need to halt emissions now and reach net zero by mid-century to give critical ecosystems a chance of survival. We should have started steep reductions of global emissions years ago.
Managed decline of fossil fuels
What the IPCC report fails to explain succinctly is there’s no space in the global carbon budget for any expansion of fossil fuel infrastructure. Research has shown to reach 1.5°C, we cannot build any new fossil fuel power plants or pipelines.
To have a chance of reaching the goal, all fossil fuel infrastructure — power plants, pipelines, vehicles, etc — needs to be replaced with zero-carbon alternatives at the end of their lifetimes.
Overall the framing of ‘12 years left’ might have given people false hope that we have longer than we really do to avert crisis. At the same time — framing it as a ‘12 year’ cut-off point may create a feeling of hopelessness.
Some argue creating a sense of ‘panic’ may not help us respond. But when the situation is dire, like Extinction Rebellion, I would argue for the truth — and the truth is perhaps we do need to panic.
Why is 1.5°C important? Is it really an emergency?
The Paris Climate Agreement committed countries to keeping global warming to below 2°C and to “pursuing efforts” to limit the temperature increase to 1.5°C above pre-industrial levels.
As the IPCC explains, 1.5°C commits the world to around 0.26 to 0.77 metres of sea level rise by 2100, severely affecting many island nations and coastal regions, and would damage almost 70–90% of coral reefs.
At 2°C, coral reefs will be almost completely damaged (99%). Since coral reefs support 25% of marine life in the ocean, this could result in extinction for many species. For ocean ecosystems, it is already an emergency situation.
As Johan Rockstrom has noted, the ambitious 1.5°C target was initially seen as a political concession to small island states who are facing severe impacts from rising seas. But even if we miss the 1.5°C target, we will need to galvanize more effort to avoid further impacts.
The longer we leave it, the worse it will get, but it is important to note that the 1.5°C (or 2°C) target is not a cut-off point that would lead to irreversible changes or a point-of-no-return, because we cannot be sure where those points are.
As David-Wallace explains in his book ‘uninhabitable earth’, one of the most frightening risks is that we will cross tipping points in the earth’s climate system.
Scientists project some of these tipping points could be crossed at 2°C, and any increment higher increases the risk of destabilising the system and triggering irreversible changes.
Whilst some have criticised the use of the word ‘extinction’, there is a risk the earth’s life support systems are disrupted to an extent that leaves many parts of the world uninhabitable.
That’s why groups such as Extinction Rebellion have been calling for direct action.
In the face of such an emergency, rapid and urgent measures are needed by people at every level — by governments, local communities, and individuals — including a moratorium on new fossil fuel expansion.
The situation we are facing can be overwhelming to comprehend— but we need to face the truth. Humanity is at an absolutely critical time to stop catastrophe from unfolding.