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Climate target of 1.5 °C – everybody is called upon!

On 8 October, the Intergovernmental Panel on Climate Change (IPCC) published its special report on the 1.5 °C climate target. The tenor of the report: it’s urgent! The conclusion of science is that in order to keep global warming well below 2 °C, everybody is called upon to do their bit. Governments, the economy and citizens must act now. Prof. Astrid Kiendler-Scharr, Director of the Jülich Institute of Energy and Climate Research, contributed to the report as an expert. We asked her for her assessment.

Interview with Prof. Kiendler-Scharr (in German)

What was your motivation to contribute as an expert to the IPCC special report on the 1.5 °C target?

Prof. Kiendler-Scharr: I am convinced that the climate issue is a huge challenge we have to resolve, and this motivates me. We must not always think in terms of individual publications and hope that the results will somehow come together. This is why the IPCC reports are so important because they pool the knowledge of the global research community on climate change. For example, the scientific facts are made available to the politicians so that they can then take the appropriate decisions.

In the Paris Climate Agreement, the international community of states agreed to limit global warming to well below two degrees, preferably to 1.5 °C. Is that even possible anymore?

Prof. Kiendler-Scharr: We need a strong shift in energy technology towards renewable energy sources to achieve this ambitious goal. The fact that coal and other fossil fuels are not conducive to the climate is – at least in Germany and the majority of other nations – completely undisputed. Nevertheless, the urgency with which measures for climate protection would have to be taken is not yet clear to politicians and the wider public, or the necessary steps have not yet been implemented.

Is the 1.5 °C question the right one in order to achieve more effective climate protection?

Prof. Kiendler-Scharr: Setting a temperature target, which was part of the Paris climate agreement, was in this case definitely a paradigm shift. Before that, the climate question had been discussed from the emissions point of view: which concentrations of which greenhouse gases may still be emitted until a certain limit is exceeded? These climate targets and their implementation, however, were obviously not a success story. By 2020, for example, emissions from Germany are to fall by 40% compared with 1990 levels. This will be difficult to achieve now, in 2018. It remains to be seen whether the temperature target is a stronger aspect to actually take binding action – or whether it is seen as a political way out to push aside climate or emission targets.

And how does the paradigm shift affect research?

Prof. Kiendler-Scharr: There is clearly an increased expectation on science. It must now make clear statements as to which atmospheric composition, which greenhouse gas and air pollutant concentrations are associated with which temperature increase. This gives more attention to details, such as the effects of long-lived greenhouse gases and short-lived climate drivers. For example, all current calculations show that we have to actively remove CO2 from the atmosphere in order to avoid a temperature increase of more than 1.5 °C.

Why that?

Prof. Kiendler-Scharr: CO2 belongs to the long-lived greenhouse gases. Once it is in the atmosphere, it will stay there practically forever. Even if CO2 emissions could be reduced to zero today, natural sinks such as forests and oceans would not be sufficient by far to significantly reduce the CO2 share within a few decades. The situation is different with short-lived trace gases and air pollutants.

verschneiter Wald von oben fotografiertNatural sinks such as forests and oceans would not be sufficient by far to significantly reduce the CO2 share within a few decades.
Copyright: CC0 Public Domain

What role do these short-lived substances play in climate change?

Prof. Kiendler-Scharr: Short-lived climate drivers, such as atmospheric ozone or aerosols, that is airborne particles, have a clearly limited residence time in the atmosphere. If the 1.5 or 2 °C goal is to be achieved, one needs to seriously turn to these short-lived fabrics. Ground-level ozone is formed by anthropogenic air pollutants. It is not only harmful to humans and the environment, but also a powerful greenhouse gas. Measures to improve air quality, therefore, have a direct effect on the climate.

Are aerosols not considered cooling agents for the climate?

Prof. Kiendler-Scharr: Yes and no. The situation with aerosols is complicated. The totality of all aerosols leads to a cooling in net terms, but some aerosol types like soot can also have a warming effect. At the same time they act as cloud nuclei. Clouds, in turn, have a cooling or warming effect depending on their composition, altitude and the time of day. If we can get to understand these complex relationships better, there is a chance of achieving success in climate change in the near future. This knowledge, in turn, could be used as a transitional phase until the reduction of CO2 is further advanced.

Von Dürre gezeichneter BodenCopyright: C00 Creative Commons

What, then, has to happen in the short term?

Prof. Kiendler-Scharr: All processes that cause greenhouse gases to rise should be minimised as far as possible. This includes, for example, industrial production, agriculture or livestock farming. In the developed countries, in particular, a fundamental change of our way of life is necessary. We must feel good when we act sustainably in all areas. This requires a new awareness of our lifestyle based on knowledge and conscience. Politically, a path is usually viable via subsidies or tax concessions: Cycle paths, local public transport, storage facilities for renewable energies – these are projects where politicians can take action and make climate protection more attractive for everyone.

Will the present 1.5 °C special report increase the pressure on politicians?

Prof. Kiendler-Scharr: First of all, it should be noted that the report was requested by politicians. This gives science the opportunity to enter into a very direct dialogue with politics. In my view, the special report reflects very well the current state of scientific knowledge on global warming and the resulting climate effects. All in all, it is an impressive example of the scientific community’s worldwide cooperation. However, it is not the task of research to conduct politics and that is a good thing. Science has presented the facts and pointed out the consequences – politics must now decide how appropriate solutions can be found – be it by promoting renewable energy sources and their storage or by actively reducing CO2 from the atmosphere. It is not enough, by any means, to plant a tree once in a lifetime.

Brigitte Stahl-Busse

CO2 yesterday and today

For at least 800,000 years, before the beginning of industrialisation280 particles of CO2 per million particles (ppm) were in the air.
In 1996the share was: 362 ppm
In 2018the share rose to: 403.3 ppm
Such a high CO2 concentration of over 400 ppm last existed three to five million years ago. Temperatures on Earth at that time were 2 to 3 °C higher, the Greenland ice sheet and the ice in western Antarctica had melted. Sea levels were 10 to 20 metres higher than today.

(Source: WMO)