Just 2 Degrees Of Warming Could Trigger ‘Climate Domino Effects,’ New Study Reveals – Forbes
The relationship between five massive Earth systems could be destabilized by even moderate climate change, leading to cascading effects of accelerated sea level rise and species loss, a new study has warned.
Climate phenomena such as the melting of Antarctic ice sheets can lead to dangerous “domino effects” that lead to knock-on impacts on other global systems, such as the flow of water in the Atlantic Ocean and the drying of the Amazon rainforest, a team of researchers at the Potsdam Institute for Climate Impact Research (PIK) found.
“We’re shifting the odds, and not in our favour,” said Ricarda Winkelmann, lead of PIK’s FutureLab on Earth Resilience in the Anthropocene. “We are making long-term choices today that the next generations will have to live with.”
Winkelmann said that the risk of climate domino effects occurring rises between warming of just 1 to 3 degrees Celsius—potentially within the limits for global warming set by the Paris Agreement.
The Potsdam study, published in the journal Earth System Dynamics, attempts to understand the large-scale, real-world mechanics of climate change. The researchers looked at the relationships between five huge global elements: Greenland and the West Antarctic Ice Sheets, the Atlantic Meridional Overturning Circulation (a system of ocean currents that carries warm water from the southern Atlantic northward), the El-Niño Southern Oscillation (an irregular system of winds and sea temperatures in the eastern Pacific ocean) and the Amazon rainforest.
MORE FOR YOU
Winkelmann told me how her team used millions of simulations to show how the elements can impact one another.
“While these mechanisms are well-known, the dynamics brought about by the interactions of these tipping elements were not,” she said. “In our study, using a novel network approach, we provide a risk analysis of potential climate domino effects, where the tipping of one element triggers further tipping processes.”
One interaction analyzed, Winkelmann said, begins with ice loss occurring at the Greenland Ice Sheet. As the gigantic mountains of ice in Greenland lose their mass they begin to sink to lower elevations where the air is warmer. “This, in turn, can lead to more melt, and so on and so forth,” she explained. “So once a critical threshold in the surface temperature is crossed, this can set in motion the destabilization of large parts of the ice sheet.”
In turn, Winkelmann explained, the inundation of fresh water from melting ice brings changes in salt levels and temperature that can slow down the Atlantic overturning circulation system, which transmits heat from the warm subtropics to the polar regions, leading to further accelerated melting of Antarctic ice.
And the domino effect does not stop there: the Atlantic overturning circulation could eventually impact on another weather system, the El-Niño Southern Oscillation, and significantly lower rainfall in the Amazon. In combination with deforestation by humans and further warming, this could accelerate a phenomenon that could cause up to 50% of rainforest to become tropical savanna or dry forests, as revealed in 2016 by Brazilian scientist Carlos Nobre.
Winkelmann said the simulations revealed for the first time that such domino effects could take place at relatively low levels of global warming.
“The risk of triggering such domino effects increases significantly between 1 and 3 degrees Celsius of global warming,” she said. “Indeed I was surprised to see that in one third of our simulations, the domino effects happen already at warming levels up to 2 degrees.”
One of the key takeaways from the research, paradoxically, is not so much that it shows what will happen, but that it reveals more about how much we don’t know. It demonstrates that climate change implies an increasingly chaotic future, in which human activity has induced vast forces to interact in ways that will have multiple impacts and consequences for which we are unlikely to be prepared.
“The very existence of tipping points, and the inherently highly-nonlinear behaviour of parts of the climate system, also mean that we have to deal with the associated uncertainties,” Winkelmann said. “We need to shift our thinking towards considering the Earth system as a whole, with all its interconnected parts—including us humans as its most powerful driver of change.”
“In the end, it is our burning of coal and oil that determines ongoing and future greenhouse gas emissions and, therefore, if and when climate tipping points are crossed,” she concluded.