Author of the Intergovernmental Panel on Climate Change: “Climate change is no longer a future scenario”

With the 6th synthesis report, the Intergovernmental Panel on Climate Change (IPCC) has created the climate standard work for the coming years. What is the difference with the last report from eight years ago?

Erich Fischer: Much is in line with the latest IPCC report, but much has become clearer. What was then still a prediction has become reality. Especially when it comes to extreme weather: heavy rainfall, heat waves and drought are a reality that we have also experienced in Switzerland. Climate change is no longer a future scenario. In addition, many of the climate aspects could now be broken down into regional scales. In this way you no longer only understand the global phenomenon, but also the effects, for example in the Alps or oceans. Measurements indicate, among other things, a 60 percent shrinkage of the glaciers and an increase of 300 to 400 meters in the zero degree limit. These are impressive figures, especially for Switzerland.

It has long been said that individual events such as heat waves are not a direct sign of climate change. What has changed?

Climate change does not cause any event, but changes its probability. It has now been shown that extreme weather events are not only more frequent, but also have an intensity never seen before. Examples include the extreme Canadian heat wave in 2021, the heavy rainfall in North Rhine-Westphalia in 2021, the unprecedented 40 degrees in England last summer and the hottest and driest summer in China. Records are always broken, sometimes by several degrees. Statistically, without climate change, there should actually be less extreme events over a long period of time, the opposite is the case.

Does that also apply to Switzerland?

In the Swiss climate scenarios for 2011 less snow, heavier precipitation, longer dry spells and more heat were predicted. This is exactly what happened in 2018 and 2022.

What triggers extreme events?

It is always a mix of several factors. During a heat wave, very warm air supplied by a high pressure area plays a role. The high pressure area continues to lead to cloudless conditions, high solar radiation, dry soil and therefore lack of evaporation. Often two or three of these factors are affected by climate change. This leads to greater intensity and frequency.

According to the report, the first effects of the climate measures implemented so far are becoming visible. Which?

It is compared with a scenario without measures. Then emissions would have risen even faster and higher than in the past. But despite the positive news about emissions slowing down, they are still rising. We haven’t reached stabilization, let alone net zero.

Right now we’re roughly on the 3 degree path. How fast should we phase out fossil fuels go to lower this path?

The CO2 we emit into the atmosphere stays there for centuries. The only global possibility is not to burn the coal, oil and gas at all and therefore not to emit any carbon dioxide at all. In all scenarios of the IPCC report, it is assumed with a probability of more than 50 percent that we will already reach 1.5 degrees of global warming by the 2030s. But that means even more for Switzerland, as we are already at 2.5 degrees. The crucial question is whether we will succeed in stabilizing globally at 1.5 degrees. The new report is clearer than the previous one. To reach net zero by the middle of this century, global carbon emissions must be halved by 2030. We haven’t even stopped the increase. So that is a very ambitious goal.

That doesn’t sound very realistic.

Physically it’s possible – and that’s my area of ​​expertise. From a socio-political point of view, it is a huge challenge. But we have seen that transformations can go very quickly. In certain countries we see an extremely fast installation of renewable energy and a very fast shift to electromobility in Scandinavian countries. But that is ambitious in a country like Switzerland, where heating oil is still being installed.

Where would you see the fastest success?

In mobility and energy supply, where it also pays off economically to apply new technologies. ETH professor Anthony Patt has shown how quickly prices for photovoltaic cells and batteries have fallen. There is also great potential in food and waste incineration, especially in Switzerland.

When the temperature on earth rises above 1.5 degrees, we speak of overshooting. It will hardly be possible to avoid this, why is climate protection still worth it?

In the 2030s, there is a good chance that we will reach 1.5 degrees. Turning back is almost impossible. But it would be totally misleading to say that all is lost in an overrun. Every tiniest amount of warming makes a difference – extreme heat, heavy rainfall, drought and melting glaciers. You can see in recent decades what just a few tenths of a degree of warming has caused in the glaciers. We currently heat our air conditioning system with a capacity of about 400 trillion watts. That corresponds to 50 billion heat pumps. This results in not only immediate but also delayed effects, such as the melting of glaciers and ice caps and rising sea levels.

But the IPCC report also says that people still have a lot in their own hands. What?

A lot. Any additional warming is caused by future emissions. Much of the climate impact depends on what we do today. The amount of greenhouse gases we emit in the future therefore depends on our behaviour. The technologies are on the table, decarbonisation is possible, we can produce renewable electricity without fossil fuels. However, this requires enormous progress. From a climate physics point of view, it makes no difference whether we achieve this through our own responsibility or through regulation and market mechanisms. So far, personal responsibility has not been enough. As a technology and industrial location, Switzerland could play a pioneering role and create the preconditions for this. Switzerland is not an island and indirectly suffers from climate effects in other countries if production chains collapse or raw materials become more expensive. Of course there are people who make money from the old technologies. But more and more are relying on new technologies.