Energieerlebnis Schönau EN » 14 Outlook {Back to equilibrium}

14 Outlook {Back to equilibrium}

A big mistake?
When this interpretive panel was designed in 2017, most people were of the opinion that if we missed the 2-degree target slightly, the temperature rise would only be slightly higher. Depending on how much CO<sub>2</sub> humanity emits, so the assumption, the global average temperature would increase by, for example, 2.1 degrees, 2.5 degrees, or 2.8 degrees before rebalancing. But this is probably a huge factual error.

Will the system tip?
A study from 2018 (Steffen et al., 2018) shows that the entire system can tip over. With every tenth of a degree in temperature rise, the risk of chain reactions that reinforce themselves increases. Beyond a certain threshold, the tipping point, they are unstoppable.There is a whole series of such self-reinforcing processes (see PIK to tipping elements), such as:

  • The warmer it gets, the less sea ice covers the Arctic Ocean. This results in less reflection of solar radiation back into space and the sea warms up even more. A vicious circle.
  • The warmer it gets, the faster the permafrost soils in the far north thaw and release methane and CO<sub>2</sub> into the atmosphere. Both greenhouse gases in turn contribute to global warming and, among other things, to the accelerated thawing of permafrost soil.
  • The faster the climate warms up, the more ecosystems collapse as a result of more frequent heat, drought and fire. As a result, CO<sub>2</sub> stored in forests is released into the atmosphere, further accelerating global warming.
    (Up to now, forests have had a slowing effect on climate change: the increased CO<sub>2</sub> content in the atmosphere helps them grow faster, thus trees can bind and store more CO<sub>2</sub>, but that could change if forests grow more slowly or even die due to prolonged droughts.)
  • The depths of the oceans hold large amounts of frozen methane hydrates that can become unstable as the water gradually heats up. Freeing methane also contributes to global warming and thus further warming of the oceans, which in turn thaws more methane hydrates.

A domino effect
Most of these self-reinforcing processes work together and influence each other. Some react more instantly, others with a significant delay.
As long as the climate is only slightly warmed, these natural feedback effects also remain weak. But if humanity did released so much CO<sub>2</sub> that by 2100 a theoretical increase of 2 degrees due to the use of fossil fuels could be expected, it would actually get significantly warmer. According to an estimate of the research group around Steffen, the natural self-boosting processes could contribute an additional about 0.5 degrees to global warming. Thus by the end of the 21st century, it would actually be 2.5 degrees warmer already.
An extra half a degree increase in temperature might not sound like much. However, it could have dramatic consequences. For eventually the point will be reached, at which some of these self-reinforcing processes "tip": Once initiated by humans, they would continue to run by themselves, even if humanity stopped releasing greenhouse gases all together. Such tipping elements could trigger a domino effect.
The entire climate system would then collapse. A temperature jump of 4 or 5 degrees (perhaps even more) compared to the pre-industrial temperature level could hardly be prevented. The ecological, economic and social consequences of a global hot climate with submerged coastal cities would be incalculable.

We do not know enough
Many of these tipping elements are not yet well understood and insufficiently included in the IPCC (Intergovernmental Panel on Climate Change) models (Chu et al., 2018). Today, no one can say exactly where the tipping point for the entire system lays. Steffen et al. fear that the IPCC 's original 2-degree target already carries the risk of such self-perpetuation and domino effects being triggered.
 
Literature and Links:

The panel for download as pdf


To top of page
To top of page
Print Page
Print PDF
Recommend