Imagine sudden movements of the tropical monsoons, a decrease in Northern Hemisphere rainfall, and the strengthening of Atlantic storm paths within decades. These are some of the effects that climate scientists expect if the Meridional Overturning Circuit (AMOC), which redistributes heat from equatorial regions to the Northern Hemisphere, h -suddenly entering a deep state as a result of global warming. The effects would dramatically change conditions for agriculture, biodiversity and the economy in large parts of the world.
A model study by Johannes Lohmann and Peter D. Ditlevsen from Ice Physics, Climate, and Earth, The Niels Bohr Institute, University of Copenhagen, Denmark, is now proposing the AMOC, and may sub- other climatic systems approaching tip tension points. long before expected due to rate hikes. The work, published today in PNAS is part of the TiPES project funded by the EU Horizon 2020.
Time is of the essence
There is growing concern among climate scientists that several climate subsystems could inevitably and suddenly turn to a new state if atmospheric CO2 levels are pushed past unknown thresholds . These subsystems include the Antarctica and Greenland ice sheets, the Amazon rainforest, the Asia-Australia monsoon, the Arctic ocean ice, and the AMOC.
In addition, it is not yet certain whether tidying effects arising from a stage may occur. These effects manifest themselves as the system ‘s transition to a new state even before a theoretical threshold is reached in the external conditions (such as atmospheric CO2 levels). In rate-driven tidying, the rate of change – not the magnitude of the change – is the important factor. This is because tidying up happens more easily when the system settings change very quickly.
To study rate fluctuations in the climate system Dr. Johannes Lohmann studies the phenomenon in a complex ocean model, Veros.
It’s unbelievable
First, the model’s rapid threshold at the slow rise of the Atlantic freshwater input was identified. Then, a series of experiments were performed, in which freshwater input was increased at different levels, but only to levels below the tension level. The results clearly demonstrated the features of rate tidying.
In particular, when the ocean model was subject to an increase in freshwater inputs into the Atlantic Ocean, which was similar to the acceleration of melting from the Greenland ice sheet over time periods of 10 to 150 years, there was a bias strong at the AMOC to go into a deep state before it was used a threshold was reached.
It also seemed that due to the chaotic dynamics of the ocean model, the rate-driven heap was very sensitive to momentary changes in the initial conditions and the rate of change of melt water rise. This makes the slick threshold fuzzy. So the qualitative boldness of ocean circulation, ie whether it will collapse or remain as it is today, remains unbelievable.
Worry, if that’s true
The emergence of rate-driven waste in a global ocean model provides important evidence that one or more of the climate subsystems may be pushed prematurely as a result of global warming. Whether this actually exists remains to be seen across more models in the climate model hierarchy.
However, the findings identify fundamental limitations in climate forecasting and emphasize the need to limit CO2 emissions in order to stay away from dangerous and unpredictable emissions.
“It’s worrying news. Because if this is true, it will reduce our safe workplace,” said Johannes Lohmann.
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The TiPES project is a European science collaboration, exploring points of tension in the Earth System. The TiPES project has received funding from the European Union’s Horizon 2020 research and innovation program.
TiPES Podcast: https: /
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