Extreme weather such as heavy rain, flooding, heat waves, droughts and the intensity of storms are increasing. Sea levels rise by up to 80 centimetres.
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Research
1.5 degree target concerns us all!
Research
1.5 degree target concerns us all!
Prof. Astrid Kiendler-Scharr, Director of the Institute of Energy and Climate Research (IEK-8), considers the IPCC reports important because they pool the knowledge of the global research community on climate change. She herself is researching the role of aerosols in climate change. These are the smallest particles that serve as cloud nuclei, for example. She was involved as an expert in the current IPCC report on the 1.5 degree target.
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In early October, the Intergovernmental Panel on Climate Change (IPCC) published its special report on the 1.5 degree climate target. The bottom line: it’s urgent! In order to keep global warming well below two degrees Celsius, everyone is called upon: governments, the economy and the citizens. Climate expert Prof. Astrid Kiendler-Scharr was involved as an expert in the report. We asked her for her assessment.
In the Paris Climate Agreement, the international community of states agreed to limit global warming to well below two degrees, preferably to 1.5 degrees. Is that still possible at all?
The report shows that it is difficult, but indeed possible. 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.
Image above: Prof. Astrid Kiendler-Scharr, Director of the Institute of Energy and Climate Research (IEK-8), considers the IPCC reports important because they pool the knowledge of the global research community on climate change. She herself is researching the role of aerosols in climate change. These are the smallest particles that serve as cloud nuclei, for example. She was involved as an expert in the current IPCC report on the 1.5 degree target.
What steps would that be?
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. Also important: we need a new awareness of our lifestyle, based on knowledge and conscience. It is not enough to plant a tree once in your life. We must feel good when we act sustainably in all areas. Politically, a viable path is usually via subsidies or tax breaks: cycle paths, local public transport, storage facilities for renewable energies – these are projects in which politicians can take action, thus making climate protection more attractive for everyone.
Has the special report increased the pressure on politicians?
First of all, it should be noted that the report was requested by politicians. Science has presented the facts and revealed the consequences. However, it is not the task of research to conduct politics. And that’s a good thing. It is not science, but politics that must now decide how appropriate solutions can be brought about. In any case, the report has brought the issue of climate change to the fore again.
Do you already see consequences in politics?
This will have to be seen in the next few months. The decision of the EU ministers of the environment to lower the limit values for carbon dioxide emissions of new cars by 35 per cent, not leaving them at 30 per cent, could be an indication. However, numerous measures are needed to achieve ambitious climate targets, as the report points out. All current calculations show, for example, that we have to actively remove CO2 from the atmosphere in order to avoid a temperature increase of more than 1.5 degrees.
What if ...?
Worldwide increase in temperature and its consequences in 2100
Weather extremes are even more frequent. The Arctic is ice-free in summer. Sea levels rise by up to 90 centimetres. Researchers fear a tipping point. This leads to the melting of the ice sheets of Greenland and of West Antarctica. This would cause the sea level to rise by several metres over the course of the following centuries.
The global distribution of water is changing drastically. Already dry regions are becoming even drier, southern Africa, the south-west of the USA and the Mediterranean region being especially prone to droughts. The frequency of extreme floods is increasing on half the earth’s surface. Sea levels rise by up to 1 metre.
Sea levels rise by up to 2 metres locally. Large areas near the coast are flooded, megacities such as Miami in the USA or Guangzhou in China are on the verge of at least partial evacuation. All ice sheets are melting. A further massive increase in sea levels begins.
Sources: IPCC reports, 4-degree World Bank report, articles in journals such as Nature and PNAS et al.
As scientific assessments differ, for example, on the stability of the ice sheets in the various temperature scenarios, the data on sea-level rise fluctuate.
Why that?
CO2 is one of the long-lived greenhouse gases. It takes over a hundred years for it to dissolve. The combustion of fossil raw materials since the beginning of industrialisation, however, has released far more CO2 into the atmosphere than the earth could have absorbed again in the same period. Even if CO2 emissions were reduced to zero today, natural sinks such as forests and oceans would be far from sufficient to significantly reduce the proportion of CO2 within a few decades. This could only be achieved if it were actively removed from the atmosphere. The situation is different with short-lived trace gases and air pollutants.
What role do these short-lived substances play in climate change?
Short-lived climate drivers are, for example, atmospheric ozone, methane or aerosols, that is, airborne particles. The time they stay in the atmosphere is clearly limited. If we want to achieve the 1.5 or 2 degree target, we have to turn seriously to these short-lived fabrics. Ground-level ozone, for example, is formed by anthropogenic air pollutants. It is not only harmful to humans and the environment, but also a powerful greenhouse gas. Here, therefore, measures to improve air quality have a direct effect on the climate.
Are aerosols not considered cooling for the climate?
Yes and no. The situation with aerosols is complicated. The net total of all aerosols leads to a cooling, but some aerosol types like soot can also have a warming effect. At the same time, they act as cloud nuclei. Clouds, on the other hand, have a cooling or warming effect depending on composition, time of day and altitude. If we better understand these complex interrelationships, there is a chance of achieving success in climate change in the near future. This knowledge could be of use in the transition phase until the reduction of CO2.
Adherence to the CO2 reduction targets has not seemed to work properly so far. Is the 1.5 degree target better suited to achieving effective climate protection?
In any case, setting a temperature target is a paradigm shift that was first agreed in the Paris climate agreement. Previously, the climate issue 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? However, these climate targets and their implementation were obviously not a success story. By 2020, for example, emissions in Germany should fall by 40 per cent compared with 1990 levels. Now, in 2018, this will be difficult to achieve. It remains to be seen whether the temperature target will actually lead to mandatory measures being taken or whether it will be used as an excuse not to have to commit to unpopular concrete emission targets.
And how does the paradigm shift affect research?
There is a clear increase in expectations towards science. It must now make clear statements as to which atmospheric composition, greenhouse gas and air pollutant concentrations are associated with which temperature increase. This means that more attention is paid to details such as the effects of long-lived greenhouse gases and short-lived climate drivers. There is therefore not only a lot of work to be done in politics, but also in science.
Interview: BRIGITTE STAHL-BUSSE
The Paris Climate Agreement
In the 2015 Paris Climate Agreement, 196 countries decided to limit the rise in the global average temperature to “well below 2 degrees” by 2100, but if possible even to 1.5 degrees Celsius above the pre-industrial level. This is to significantly reduce the risks and impacts of climate change. The UN commissioned the Intergovernmental Panel on Climate Change (IPCC) to conduct a study on whether and how this goal can be achieved. This special report on the 1.5 degree target has been available since 8 October 2018.
Greenhouse gases …
Proportions of the 909 million tonnes of total emissions 2016 in Germany in CO2 equivalents *
* CO2 equivalent describes the warming potential of a gas compared to the corresponding amount of CO2.
** Hydrogen-containing chlorofluorocarbons, perfluorocarbons, sulfur hexafluoride.Source: German Environment Agency
… and how effective they are
Comparison of effectiveness and lifetime
ImageS: Forschungszentrum Jülich/Sascha Kreklau, Petr Kovalenkov, Graphic: SEITENPLAN GMBH