We usually imagine the climate change like an endless ascending line: more heat, melted glaciers and more acidic oceans. However, science has just put on the table a hypothesis that is not very intuitive: under certain extreme conditions, global warming does not end in hell, but in a real freezer. And the plankton, which seems harmless, has a lot to say in this regard.
The identified. A team of researchers from the University of California, Riverside (UCR) and the University of Bremen has identified an instability in the carbon cyclea “glitch” in Earth’s climate operating system, suggesting that an ocean that is too warm and depleted of oxygen can trigger massive global cooling.
The geological thermostat. To understand this finding, we must first look at how the Earth regulates its temperature in the long term. The classic mechanism is silicate weathering. Which basically means that when there is a lot of CO₂ in the atmosphere along with heat, it rains more and this rain dissolves the silicate rocks, dragging the carbon and the nutrients it stores to the sea, such as phosphorus.
That’s where plankton uses that carbon to build their shells and, when they die, they sink, trapping CO₂ on the seabed. And although it may seem like good news that they store this gas that is seen as a great enemy on the seabed, the fact of reducing its concentration It means that the temperature drops.
A paradigm shift. Until now, scientists saw this as a stable “thermostat”: if it is hot, the system works to cool the environment, and if it is cold it works less intensely.
But now something radical arises: the thermostat has a catastrophic failure mode. According to their simulation models, when the system is coupled to the cycle of marine nutrients and biological productivity, the regulation can be unstable. And this is where the ideas of a future ice age begin.
The plankton trap. For researchers, if we continue with extreme warming on our planet, erosion will increase to bring nutrients to the ocean. Something that will undoubtedly be appreciated by the phytoplankton and the algae that will accumulate it and when it dies, it will create an area in the water where there is not a hint of oxygen.
In an ocean without oxygen, phosphorus once again dominates sea water which will create a vicious cycle where the algae They will consume large amounts of oxygen. The result is that the ocean floor begins to ‘suck’ CO₂ from the atmosphere at breakneck speedwhich is much faster than volcanoes or human activities can replenish it.
The result is clear: a thermal collapse that can lead to a severe glaciation similar to what the Earth has experienced in the past.
We had other fears. Right now on the table we had the suspicion that the collapse of the AMOCthe ocean currents that move water between various locations, will lead us to this situation. And they have a very important function: moving warm water from the tropics towards the north through the surface and cold, dense water towards the south through the depths. Something that a priori regulates global temperature.
Global warming. A priori, anyone might think that continuing to emit greenhouse gases into the atmosphere is the solution to this. But the authors issue a warning: geological times are not human times.
We are talking about a mechanism that operates on scales of hundreds of thousands of years, and that is why it will not cool the planet either in this century or the next. In fact, researchers suggest that if this mechanism were activated today, it would be an excessive correction that will occur long after we have suffered the consequences of global warming.
The fragility of the system. The carbon cycle is not a simple scale that stays in balance, but is quite dynamic and complex. This is somewhat difficult, since it can easily become unbalanced. The idea that the planet can “overreact” to heat by causing extreme cold reminds us that the Earth has regulatory mechanisms that are indifferent to the survival of human civilization.
Images | Javier Miranda Alberto Restifo
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