Why Climate Science is a Trap

On the need for radical honesty, Part I

(Originally published in German as part of the book “Klima, Kollaps, Kommunikation”.)

It was the year 1992 when the assembled heads of state heralded the era of climate negotiations in Rio de Janeiro. At that time, after a short stint in theoretical physics, I had started as a climate scientist at the Max Planck Institute in Hamburg, Germany. After 27 years of inventing new models and methods and improving climate models, I couldn't take it anymore. A kind of mass apathy, the opposite of mass panic, had spread in the scientific community.

I can hear it again, the mantra uniting everyone from fossil-fuel execs to politicians to the radical climate movement: ‘1.5 is alive!’. Ever since the world's governments agreed on the goal of limiting global warming to 1.5°C, optimism has spread like wildfire. ‘Together we can do it!’ Whether it's Al Jaber, head of the last world climate conference COP28 and head of the Abu Dabi National Oil Company, the German government or Fridays-for-Future: everyone agrees that one-point-five must live on.

Yet the reality out there is a different one. 2024 was the first year officially to be declared warmer than 1.5 degrees above pre-industrial levels. We have been heating up our planet for well over 100 years, and instead of taking effective action, we are, at a global level, doing quite the opposite: greenhouse gas emissions continue to rise up to this day.

When a gulf of such a size opens between enthusiasm and reality, an uncomfortable question arises: has proclaiming the 1.5-degree target actually increased the likelihood that we will ultimately do something to avert the worst consequences of the climate catastrophe?

Climate science quickly adopted the target after it was agreed upon in 2015. This is usually done in the following way: climate models are used to produce a large number of future scenarios, and it is then determined that we can still emit X tonnes of CO2 globally until we reach the 1.5-degree threshold. In other words, the focus is on how long we can continue to do what we have been doing - and not on what we have to do to avert catastrophe.

To a certain extent, this is understandable, because we have known for a long time what needs to be done, so there isn’t really much to find out. Nevertheless, viewed from an angle of every-day experience, this kind of approach seems a little odd. Let's say I'm lying in bed with a fever of 39.8°C. Feeling sick, I set myself a temperature target of 37.3°C to be reached within 48 hours. Would that be better in any way than simply doing everything I can to get better as quickly as possible? What is the point of setting a precise numerical target anyway?

I recently asked an acquaintance - a retired Swiss doctor and former Green Party politician - what role prognoses play in medicine. He told me that they are very important, because in an emergency situation you often have to decide which patients should be prioritised. Such predictions have to be made precisely but also extremely quickly.

However, speed is certainly not something that climate science could claim for itself. Back in 1896, the Swedish physicist Svante Arrhenius calculated the expecte warming from a doubling of the atmospheric carbon dioxide content. His result, plus 4°C compared to pre-industrial temperature levels, is fully still within today’s published range. This astonishingly early realisation has not prevented CO2 levels from increasing by slightly more than 50%. From around 280 parts per million at the time of Arrhenius time to over 420 today.

It seems paradoxical: climate heating has taken off right when climate scientists started publishing their findings. Currently, warming happens at a faster rate (orange line) compared to previously (red curve). Source: Berkely Earth Land and Ocean Data (Temperature anomalies above sea ice from air temperature records.)

The figure here shows that the Earth’s global average temperature has increased significantly since Arrhenius' calculations. The climate here is shown as a 20-year running mean, and the climate trend as linear fit to the last 20 years of data. Earth’s climate is fully on its way to breaking through the assumed 1.5°C threshold. And this trend has a lot of momentum to it, because most of the heat generated by the greenhouse effect goes into the oceans, whose gigantic heat capacity greatly delays the rise in air temperatures. But maybe more importantly, there is also the inertia of human habits.

Here is a case where climate science is crystal clear: to ultimately stop the rise in temperatures, we must first stop the further increase in greenhouse gas emissions – which we still haven’t, almost ten years after the Paris Agreement. But this is only the very first step. The second step is to halt the continued rise in greenhouse gas concentrations, and for that emissions must be reduced to somewhere around half the current level. But that will still not stop the heating. Ultimately, emissions must be reduced to zero.

We know from daily experience how difficult it is to change our lifestyle, let alone our economic system or political institutions. And so it should be clear that each of these steps is an extremely difficult undertaking, especially the last one. There is no guarantee we will succeed even with the first one. And in the meantime, the Earth's temperature continues to rise.

A comparison of the red curve with the orange line also shows that the rate of warming continues to accelerate, i.e. Earth’s fever curve is pointing ever more steeply upwards in the longer term. This means that the extrapolation shown as an orange line onwards is actually too optimistic because it assumes that there will be no further acceleration of the temperature rise. We know that this is not true because we are continuing to increase the CO2 content of the atmosphere. Despite of this, our simple extrapolation brings us beyond 2°C in 2050, and to around 3.5°C by 2100, a degree of planetary warming that is generally regarded as ‘catastrophic’ and whose consequences are almost impossible to estimate. This means that massive reductions in greenhouse gas emissions — far beyond those we briefly saw during the pandemic — will be necessary to achieve an optimistic scenario that ultimately leads to a warming that will likely be catastrophic.

So far, the necessary political measures to even achieve the first step have failed to materialise. I put myself in the shoes of our friend, the doctor, and imagine the following situation: More and more of his patients come to him with chronic conditions, let's say with type II diabetes. What is there to do? Imagine our friend decides to commission a never-ending number of meticulously studied future scenarios from his epidemiologist colleagues, each one supported by complicated mathematical models. These scenarios tell him in great detail how many new cases of the disease will occur in which year and decade, in which region and within which age group. However, the underlying complex calculations differ considerably from model to model, and it is these differences that most interests our friend the doctor. What he doesn't dare to do, however, is prescribe a healthier diet for his patients.

This more or less is the state of climate science today. So is climate research perhaps a form of problem avoidance? Is the point of collecting more data to get closer to solving the problem, or is it rather a kind of escape from the realisation that we are facing a practically unsolvable task? Perhaps it is precisely the continued and never ending preoccupation with the goal of 1.5 degrees, supported by a most highly sophisticated mathematical apparatus, that inevitably gives researchers a sense of familiarity with the scenario under investigation. And that familiarity, and all the time and effort invested, makes it more and more difficult to entertain the idea that all those scenarios from the start have been utterly unrealistic. And thus the scientific community more and more lulls the wider public into a sense of security, which in turn gives politicians the license to carry on as before.