I have to apologize to Peter Hadfield (better known as Potholer54) as I am not sure I have found the source of the talking point that we only have 12 years. Science journalist Hadfield always encourages real skeptics to check claims by searching for the source in the scientific literature. The best solution to the riddle I found is really disappointing, but independent of the source, the claim is terrible.
How much warming is seen as acceptable is a political compromise between how hard it is to change the energy system (against powerful vested interests) and how much damages people see as acceptable. All world leaders have agreed in the Paris climate agreement on the following compromise.
Holding the increase in the global average temperature to well below 2°C [3.6°F] above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C [2.7 °F] above pre-industrial levels, recognising that this would significantly reduce the risks and impacts of climate change.Previously the political compromise used to be to keep the warming below 2°C and most scientific work thus focused on the impacts of 2°C warming and on possible ways to make the transition that fast. After Paris politicians asked scientists to study how much the damages from climate change would be reduced and how much harder it would be to limit warming to 1.5°C.
The Intergovernmental Panel on Climate Change (IPCC) thus brought all the research on this topic together and in October published a report on the difference between 1.5°C and 2°C warming. In the media reporting a frequent talking point somehow was that we only have 12 years to stop climate change.
How much CO2 can we still emit?
Before looking into it I had guessed the claim would be based on the carbon budget. How much CO2 we can still emit until we reach the amount that will likely warm the Earth by 1.5°C. Note that CO2 accumulates in the climate system and the warming is determined by the total historical amount we emit. I sometimes worry people think that when global warming becomes too devastating we can stop emitting CO2 and the problem is solved. When the French stopped dumping salt in the Rhine and Meuse the water quality quickly became better. CO2 is not like that. When we stop emitting CO2 warming will even continue for some time, it will not go back to the temperature we used to have and many consequences (such as sea level rise) will keep getting worse, just slower.
The Earth has already warmed by about 1°C since the end of the 19th century.* Based on past emissions alone we would not reach the 1.5°C warming level yet, according to the IPCC report. A part of the carbon budget is still left. This is a bit more than 10 times how much we currently emit per year and could thus have been the source of the talking point. The Summary for Policy Makers of the IPCC states:
Limiting global warming requires limiting the total cumulative global anthropogenic emissions of CO2 since the pre-industrial period, that is, staying within a total carbon budget (high confidence). By the end of 2017, anthropogenic CO2 emissions since the pre-industrial period are estimated to have reduced the total carbon budget for 1.5°C by approximately 2200 ± 320 GtCO2 (medium confidence). The associated remaining budget is being depleted by current emissions of 42 ± 3 GtCO2 per year (high confidence). The choice of the measure of global temperature affects the estimated remaining carbon budget. Using global mean surface air temperature, as in AR5, gives an estimate of the remaining carbon budget of 580 GtCO2 for a 50% probability of limiting warming to 1.5°C, and 420 GtCO2 for a 66% probability (medium confidence).This would have been a better reason for the talking point than the possible reason below, but even then we do not have 12 years, we should do more NOW. We cannot wait 12 years and then suddenly stop all emissions. We are already doing a lot, half of all new electrical generation capacity in the world is already renewable power, but we need to do more and do this now. The only time better than now is decades ago.
On the other hand, the Earth does not explode in 12 years, any action reduces damages and adaptation costs. If we do not manage to limit the warming to 1.5°C, it would be better to limit it to 1.6°C than to 1.7°C, and so on. There is no brick wall we crash into, there is no cliff we fall into, there is no "deadline", CNN. Any limitation of the warming makes life on Earth better. Being lied into one Iraq war is catastrophic, but still better than 2 or 3 wars.
Any analogy is imperfect, but a better analogy would be that climate change is like crossing a busy street without looking, it is a irresponsible risk and the farther you go the higher the risk. Another analogy is walking into a mine field as Michael Mann often says. We do not know when the mines will explode, better walk into the field as little as possible and not 12 meters.
Reducing CO2 emission means changing our energy system and agriculture. This is a big task, and not something we will not be finished within 12 years. When we do more now, we would also have more time than 12 years to finish the task.
It is much better to say that to achieve the climate goals we have set ourselves in the Paris climate agreement we have to be at zero emissions in a generation. Or that we have to half emissions in 2030.
I would vote for that, but considering the resistance to change of the establishment, Gavin Schmidt is probably realistic when writing on RealClimate:
Can we avoid going through 1.5ºC?
IPCC has to use a few circumlocutions to avoid giving a direct answer to this question (for reasonable and understandable reasons). I’m not quite so constrained…
There are many issues related to the feasibility question of which physical climate-related issues are only one. The basic issue is that the effort to reduce emissions sufficiently to never get past 1.5ºC would require a global effort to decarbonize starting immediately that would dwarf current efforts or pledges. This seems unlikely (IMO).
...
So my answer is… no.
I get that there is reluctance to say this publically – it sounds as if one is complicit in the impacts that will occur above 1.5ºC, but it seems to me that tractable challenges are more motivating than impossible (or extremely unfeasible) ones – I would be happy to be proven wrong on this though.
The craziness begins
However, the press articles and TV segments on the IPCC report do not talk about the carbon budget. In most cases they do not explain at all where the 12 years comes from. The Guardian headline is: "We have 12 years to limit climate change catastrophe, warns UN." Given that English is the global language, the difficulty of the English have understanding international relations is rather surprising. The IPCC is not the UN. More importantly for this post, the headline is not explained anywhere in the article.The most surprising place to see the claim is Fox News**: "Terrifying climate change warning: 12 years until we’re doomed." That is some contrast to their evening television opinion shows operating as the PR arm of the Republican party. This article was on their homepage, in the science section, under the category "Doomsday" and republishing an article written by the New York Post. Again I cannot find a justification for the headline in the article.
The Sunrise Movement will visit members of Congress to lobby for a Green New Deal on Monday, December the 10th and would like climate scientists, who happen to meet at the AGU Fall meeting in Washington DC, to join them. They also did not go to the source, but trusted newspapers when they write in their call for action: "the latest UN report says we have 12 years to rapidly transform our economy to protect human civilization as we know it."
As an aside, had I been in Washington, I would have been happy to join them, I feel we need to do more to reduce climate change damages, but the Green New Deal is politics, not science. So I would not show up as a scientist (in one of those stereotypical white lab coats).
We may be getting a bit closer to the solution listening to CNN. Interrupting their programming on the missing Malaysia Airlines aircraft CNN titles "Planet has only until 2030 to stem catastrophic climate change, experts warn" and says: "In Paris leaders pledge to keep the rise well below 2 degrees [Celsius]. This report now suggests we aim for 1.5°C. A benchmark we are predicted to reach in 2030."
(No, the politicians suggested we'd aim for 1.5°C.) Why does CNN think that experts warned about this? The reporting of LifeGate may give a hint:
If not curbed, this trend will lead the Earth to exceed the threshold of +1.5 degrees between 2030 and 2052 (according to the different scenarios the SR15 took into consideration). This means that in just 12 years we could reach the temperature rise that the Paris Agreement hypothesised for 2100.LifeGate is a news organization calling itself "the leading point of reference for sustainable development since 2000". They at least describe this situation is sufficient detail to have a look what the source says.
What does the IPCC say about 1.5°C, 2030 and 2052? The summary for policy makers states in their description of the current situation:
Human activities are estimated to have caused approximately 1.0°C of global warming above pre-industrial levels, with a likely range of 0.8°C to 1.2°C. Global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate. (high confidence)Chapter one of the report has the details and confirms that the period 2030 to 2052 is based on an estimate of how much the world has warmed up to now and how fast it is warming. That fits, we have warmed about 1°C and the warming is about 0.2°C per decade. So one degree more warming would be in 5 decades and half a degree warming more would be 25 years, which is the middle of the 2030 to 2052 year interval.
Figure SMP1, panel a, from the Summary for Policy Makers of the IPPC Special Report on Global Warming of 1.5°C.
This is the warming baseline WUWT & Co., Big Coal and Big Oil and the pro-torture politicians Trump, Jair Bolsonaro and Mohammad Bone Saw Salman are fighting for, which is for comparison with climate policies that benefit humanity in the remainder of the report.
The period of 2030 to 2052 is mentioned in the beginning of the report and was also mentioned early in the IPCC press conference. So it makes sense that is was noted in the press, but that they used the lower uncertainty range (12 years) and not the mean (26 years) is weird, as well as calling reaching the 1.5°C level an immediate catastrophe or deadline, while it had a different function.
Maybe I am too much of a scientist, but mentioning the lower boundary of an uncertainty range makes no sense without defining the range. The IPCC used the term "likely", which is defined as a probability between 66 and 100%. If you wanted to more sure the period contains the year we will cross the 1.5°C level, for example "virtually certain" (99-100%), the range would have been much wider and the lower bound much earlier. Scientifically speaking the "12 years" without that context is meaningless.
So what most likely happened is that we have scientists describing the progression of climate change. They give the uncertainty range and the press decides to only mention the lower boundary of this range. Then they somehow turn it into a deadline, put this in many headlines and never tell their readers where the number comes from. This made #12years a somewhat viral political meme. Chinese whispers of the worst kind. Journalists please listen to Peter Hadfield: check the source.
* If we define the pre-industrial temperature as the temperature of the second half of the 19th century, as the newest IPCC report did. The actual industrial revolution and our CO2 emissions started a century earlier. Politicians will have to clarify how they define their thresholds. It may be a good idea to convert the 1.5°C and 2°C limits into warming since a more recent period, as this is better defined due to much better observations.
** Clicking on the Fox News link may give you "Access Denied". Copy and paste works.
Related reading
Professor Myles Allen lead author of the IPCC Special Report on Global Warming of 1.5°C: Why protesters [everyone, red.] should be wary of ‘12 years to climate breakdown’ rhetoric.The Carbon Brief: In-depth Q&A: The IPCC’s special report on climate change at 1.5C
Andrew King, Ben Henley & Ed Hawkins in The Conversation: What is a pre-industrial climate and why does it matter?
Special Report: Global Warming of 1.5 ºC
There’s one key takeaway from last week’s IPCC report. Cut carbon pollution as much as possible, as fast as possible.
Largest ever group of global investors call for more action to meet Paris targets. 'The group of 414 institutional investors with $31 trillion under management say governments must take serious steps to cut emissions. ... Among specific policies, they request governments “phase out thermal coal power”, “put a meaningful price on carbon” and “phase out fossil fuel subsidies.”'
In the ongoing climate negotitions in Poland, Saudi Arabia, the US, Russia & Kuwait objected to the conference "welcoming" the IPCC Special Report on 1.5°C warming, the BBC reports. The flood of messages on this BBC article suggests that climate scientists who volunteered to write the report are not amused.