Our evolution has selected the instinct of “fight or flight” to cope with environmental change, so that, like the frog metaphor in boiling water, we tend to react too little and too late to gradual changes.
Climate change is often described as global warming, with the involvement of gradual changes caused by a steady rise in temperatures; from heat waves to melting glaciers.
But we know from multidisciplinary scientific evidence – from geology, anthropology and archeology – that climate change is not incremental. Even in pre-human times, it is episodic, when it is not forced by human-induced acceleration of greenhouse gas emissions and warming.
There are parts of our planet’s carbon cycle, the ways in which the earth and biosphere store and release carbon, which could be triggered suddenly in response to a gradual warming. These are turning points that, once overcome, could fundamentally alter the planet and cause sudden, non-linear climate change.
A game of Jenga
Think of it as a Jenga game and the planet’s climate system as the tower. For generations, we have been slowly removing blocks. But, at some point, we will eliminate a fundamental block, such as the collapse of one of the major global ocean circulation systems, for example, the southern Atlantic reversal circulation (AMOC), which will cause the total or partial collapse of the climate system. global in a planetary emergency.
But what’s worse, it can cause runaway damage: where turning points form a domino-like waterfall, where breaking one causes breaches of others, creating an unstoppable change to a radically and rapidly changing climate.
One of the most worrying turning points is the massive release of methane. Methane can be found in deep-freezing storage within the permafrost and at the bottom of the deepest oceans in the form of methane hydrates. But rising sea and air temperatures are beginning to thaw these methane reserves.
This would release a powerful greenhouse gas into the atmosphere, 30 times more potent than carbon dioxide as a global warming agent. This would drastically raise temperatures and push us towards non-compliance with other turning points.
This could include accelerating ice melting in the planet’s three major land ice sheets: Greenland, West Antarctica, and the Wilkes Basin in East Antarctica. The potential collapse of the West Antarctic ice sheet is seen as a key investment point, as its loss could raise global sea level by 3.3 meters with significant regional variations.
Beyond that, we would be on the irreversible path to total melting of the earth’s ice, causing sea levels to rise to 30 meters, at a rate of about two meters per century, or perhaps faster. Just look at the high beaches around the world, at the last rise in global sea level, at the end of the Pleistocene period, about 120,000 years ago, to see the evidence of such a warm world, which was only 2 ° C more warm than the present.
Circulation cut
In addition to devastating low-lying and coastal areas around the world, the melting of polar ice could cause another turning point: a disqualification of the AMOC.
This circulation system leads a flow of warm, salt water northward into the upper layers of the ocean from the tropics to the northeast Atlantic region, and a flow of cold water southward. to the ocean.
The ocean conveyor belt has a significant effect on climate, seasonal cycles and temperature in western and northern Europe. It means the region is warmer than other areas of similar latitude.
But melting the ice of the Greenland ice sheet could threaten the AMOC system. It would dilute the salt water of the sea in the North Atlantic, making the water lighter and less capable or incapable of sinking. This would slow down the engine driving this ocean circulation.
Recent research suggests that AMOC has already weakened by about 15% since the mid-20th century. If this continues, it could have a major impact on the climate of the northern hemisphere, but especially Europe. It can even lead to the cessation of arable agriculture in the UK, for example.
It can also reduce rainfall over the Amazon Basin, affect monsoon systems in Asia and, by bringing warm water into the southern ocean, further destabilize ice in Antarctica and accelerate rising sea levels.
South Atlantic flipping traffic has a significant effect on the climate. Praetorius (2018)
Is it time to declare a climate emergency?
At what stage and at what rise in global temperatures will these turning points be reached? No one is entirely sure. It can take centuries, millennia or it can be imminent.
But as COVID-19 taught us, we must prepare for what is expected. We were aware of the risk of a pandemic. We also knew we weren’t prepared enough. But we didn’t act significantly. Fortunately, we have been able to accelerate vaccine production to combat COVID-19. But there is no vaccine against climate change once these turning points are passed.
We must act now on our climate. Act as these turning points are imminent. And stop thinking of climate change as a slow-moving, long-term threat that allows us to take the problem forward and let future generations deal with it. We must take immediate steps to reduce global warming and meet our commitments to the Paris Agreement and build resilience by taking these basic points into account.
We need to plan now to mitigate greenhouse gas emissions, but we also need to plan for impacts, such as the ability to feed everyone on the planet, develop plans to manage flood risk, as well as manage social impacts. and geopolitics of people. migrations that will be a consequence of fight or flight decisions.
Breaking these turning points would be cataclysmic and can be much more devastating than COVID-19. Some may not enjoy listening to these messages or consider them to belong in the realm of science fiction. But if it injects us with a sense of urgency to make us respond to climate change as we did in the face of the pandemic, we need to talk more about what has happened before and what will happen again.
Otherwise, we will continue to play Jenga with our planet. And ultimately, there will only be one loser: us.
Published with permission from the World Economic Forum.