Rising temperatures have some very predictable effects: gradually worsening drought, steady sea level rise, etc. But we also run the risk of crossing a threshold where the climate aspect suddenly shifts to a new behavior. It seems that this process has taken place In part of the Arctic Ocean, There are indications that the main current flows in the Atlantic Ocean Maybe it’s almost closed.
Many attempts have been made to model the economic costs of climate change in general, but we do not yet know what crosses the tipping point that the global economy could cause. Three researchers this week attempted to explore the topic, integrating tipping point cost estimates with integrated economic/climate models. The results suggest that we may be underestimating the cost of our current carbon emissions and accepting a much higher level of financial risk than we think.
What is the tip percentage?
The climate tipping point is easy to understand on a conceptual level. At some poorly defined point in future warming, some natural systems will switch to a different kind of behavior. This behavior reduces the likelihood that the system will return to its initial state.
For example, we can turn to the ice sheets found in many sub-Arctic regions. Heating will definitely remove the “perma” from the frost, thaw the soil and maybe Release a lot of carbon stored there. Since this carbon will end up as carbon dioxide in the atmosphere, it will contribute to warming that makes permafrost regeneration impossible.
Such tipping points will have a dramatic effect on the region of the planet where permafrost is found. But it will also drive future warming, which will have far-reaching implications around the world. So while the economic costs of climate change may slowly increase with warming to a tipping point, they are likely to see a sudden jump if we pass that point.
The economic costs of climate change are usually measured using “The social cost of carbonThis puts a dollar value on every tonne of carbon we export. The price naturally goes up as we continue to emit more carbon because the buildup of carbon in the atmosphere makes it difficult to avoid higher economic costs.
Calculating the social costs of carbon is a challenge, even as warming produces increasing effects along a relatively smooth curve. Making these calculations more difficult when the effect passes a tipping point. However, the research team managed to find an attempt to estimate the cost of the eight tipping points. The researchers took these estimates and incorporated them into climate/economic models to see how they would affect the social costs of carbon.
melting ice, melting carbon
Three of the tipping points the researchers consider — melting ice sheets, releasing methane from the ocean crust, and draining the Amazon rainforest — act by putting more carbon into the atmosphere. Two more relate to the disintegration of ice sheets in Greenland or West Antarctica, which would accelerate sea level change. Three more—changes in Earth’s inversion due to loss of ice and snow, cessation of Atlantic circulation, and increased variability of the Indian monsoon—had a more subtle effect.
The above is not an exhaustive list of the climate tipping points we have identified; This is just a list of influences for which we have a precise estimate of the economic impact. So we can assume that the total impact of the turning point will be higher than the numbers generated here.
The researchers started by estimating the social costs of the carbon situation at $52 per tonne and used their model to see how each of these tipping points changed prices. Two of these—destabilizing the Atlantic circulation and altering the Earth’s inversion—really lower the social costs of carbon, though by less than 2% each. The former limits warming in the North Atlantic, and the latter results in more warming near the poles, both of which are economically beneficial.
But everything else shows a net negative. These results range from relatively small effects due to ice sheet stabilization (two and three percent increases for ice sheets) to rather dramatic effects from unstable carbon storage. The release of the ice sheet increased the social cost of carbon by more than eight percent, and the release of methane from marine crustal sediments increased by 13 percent.
If we pass all the tipping points, the social cost of carbon will rise by about 25%.
take a risk
There is a lot of uncertainty in all of these estimates, and the researchers explored them using 10,000 separate processes for their model. Runs makes it clear that while the uncertainty is large, it’s unlikely to save us, as it’s uneven on both sides of the 25 percent estimate. There is almost no chance that the total impact of this tipping point will lower the social costs of carbon. At the same time, there is a high probability that the tipping point could more than double the social costs of carbon.
Uncertainty is also uneven in time. There is a lot of uncertainty about the impact of the tipping point crossing in mid-century, in which case the effect could occur against a climate backdrop not much different from ours today. On the other hand, uncertainty about the impact will be much reduced by the end of the century, when more has gone wrong and so the social costs of carbon are likely to be very high.
Overall, this work is an early effort that builds on a limited number of studies looking at individual critical points. We would like to see more efforts to reduce uncertainty in this study, and climate impacts should be integrated with updated models and estimates in future IPCC climate reports.
At the same time, this study clearly shows that the most dangerous tipping point is one pumping a lot of extra carbon dioxide into the atmosphere. This idea alone should provide a strong incentive to monitor this effect for early warning signs, and we should study it further to make sure we know the right warning signs.
PNAS, 2021. DOI: 10.1073/pnas.2103081118 (About DOI).
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