Our evolution has chosen the ‘fight or flight’ instinct to deal with environmental changes, so like the frog’s 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 implication of gradual changes caused by a steady rise in temperature; 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 prehuman times, it is episodic, when not forced by a 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, that can be suddenly activated in response to gradual warming. These are tipping points that, once passed, can fundamentally disrupt the planet and cause abrupt, non-linear change in climate.
A game of Jenga
Think of it as a game of Jenga and the planet’s climate system as the tower. We have been slowly removing blocks for generations. But at some point we will remove a crucial blockage, such as the collapse of one of the major global ocean circulation systems, say the Atlantic Meridional Overturning Circulation (AMOC), which will cause all or part of the global climate system to fall. in a planetary emergency.
But worse, it could cause runaway damage: where the tipping points form a domino-like cascade, where breaking one violates another, creating an unstoppable shift to a radical and rapidly changing climate.
One of the most worrying tipping points is massive methane emissions. Methane can be found in frozen storage in permafrost and at the bottom of the deepest oceans in the form of methane hydrates. But rising sea and air temperatures are starting to thaw these stores of methane.
This would release a powerful greenhouse gas into the atmosphere, 30 times more powerful than carbon dioxide as a warming agent for the earth. This would drastically raise the temperature and rush us to the violation of other tipping points.
This could include the acceleration of ice thawing on all three major terrestrial ice sheets – Greenland, West Antarctica and the Wilkes Basin in East Antarctica. The possible collapse of the West Antarctic Ice Sheet is seen as a major tipping point, as its loss could ultimately raise global sea levels by 3.3 meters with significant regional variations.
In fact, we would be on the irreversible path to the complete melting of land ice, which would cause sea levels to rise by up to 30 meters, about two meters per century, or perhaps faster. Just look at the elevated beaches around the world, at the last high global sea level position, at the end of the Pleistocene, about 120,000 years ago, to see evidence of such a warm world, reaching just 2 ° C was. warmer than now.
Cut off circulation
In addition to devastating coastal lowlands around the world, melting polar ice could trigger another tipping point: an AMOC disability.
This circulation system drives a northward flow of warm, salty water on the upper layers of the ocean from the tropics to the northeast Atlantic region, and a southward flow of cold water deep in the ocean.
The sea conveyor belt has a major influence on the climate, seasonal cycles and temperature in Western and Northern Europe. It means that the region is warmer than other areas of a similar latitude.
But melting ice from the Greenland ice sheet could threaten the AMOC system. It would dilute the salty seawater in the North Atlantic Ocean, making the water lighter and less able to sink or not. This would slow down the engine that powers this ocean circulation.
Recent research suggests that the AMOC has already weakened by about 15% since the mid-20th century. If this continues, it could have a major impact on the climate in the Northern Hemisphere, but especially on Europe. For example, it could lead to arable farming in the UK being stopped.
It could also reduce rainfall over the Amazon Basin, affect monsoon systems in Asia and, by bringing warm water into the Southern Ocean, further destabilize Antarctica’s ice and accelerate global sea-level rise.
The Atlantic Meridional Overturning Circulation has a major influence 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 tipping points be reached? Nobody is quite sure. It could be centuries, millennia, or it could be imminent.
But as COVID-19 has taught us, we must prepare for the expected. We were aware of the risk of a pandemic. We also knew we were not adequately prepared. But we have not acted in a meaningful way. Fortunately, we have been able to accelerate the production of vaccines to combat COVID-19. But there will be no climate change vaccine once we get past these tipping points.
We must now do something about our climate. Pretend these tipping points are imminent. And stop thinking of climate change as a slow, long-term threat that allows us to get rid of the problem and let future generations deal with it. We need to take immediate action to fight global warming and fulfill our commitments under the Paris Agreement, and build resilience with these tipping points in mind.
We need to plan now to reduce greenhouse gas emissions, but we also need to plan for the consequences, such as the ability to feed everyone on the planet, develop plans to manage flood risks, and the social and geopolitical impacts of humans to master. migrations that will result from fight or flight decisions.
Breaking through these tipping points would be disastrous and potentially much more devastating than COVID-19. Some may not like to hear these messages, or consider them part of science fiction. But if there is a sense of urgency for us to respond to climate change as we did in the pandemic, then we need to talk more about what has happened before and will happen.
Otherwise we will continue to play Jenga with our planet. And in the end there will be only one loser – us.
Reposted with permission from World Economic Forum.