On an unusually sunny October day on Brighton beach in southern England, a severe drought triggered the first extinction of plants and birds in the Tablas de Daimiel and the government of the Canary Islands suspended classes in the islands’ schools because of the high temperatures, according to the scientist David Armstrong McKay (Surrey, United Kingdom, 34 years old) placed his forearm horizontally in front of his face to explain what climate tipping points are: “It’s like a seesaw.” If you push a ball toward the center, the seesaw stays put in the same position as long as it does not reach the pivot point, and the ball returns to the start. Once you stop applying force, continue. However, if this threshold is exceeded, the tilt of the pivot will cause the ball to roll downhill and continue to do so even after you stop pushing. At this point in the explanation, the University of Exeter researcher rotates his forearm until his fingertips point to the ground.
Can this happen in different parts of the planet if global warming reaches a certain level?
There are many different complex systems that exhibit this behavior. And one example of this is actually the climate system. There are various components and parts of it that can represent these thresholds, beyond which there will be self-sustaining changes that move them to a new state, even if we keep global warming stable just after that point is crossed and even if we can reduce it through massive removal of carbon dioxide to make temperatures slightly lower (which is currently technically impossible).
Give an example.
The Greenland ice sheet is melting, especially on the sides, but because it is still very high [ahora mismo, de media, tiene más de 2.000 metros de altura], it’s still quite cold up there. It’s like climbing a mountain: it’s cold at the top, but as you go down the atmosphere naturally gets warmer. As it melts due to warming, the ice layer becomes smaller and the height of the upper part drops to areas where the air becomes warmer and warmer. At some point it will reach a point where there is no longer enough snow on the summit to keep it stable, so it will basically start melting everywhere all the time. And there will be nothing that can be done to save them.
And what will be the consequences?
Well, this whole process would take a long time, probably hundreds or thousands of years, but in the end it would raise sea levels by seven meters, which would affect the billions of people who live in this area on the coasts of the world. the world. All of these cities would have to move. Even in this century, it would significantly accelerate and even double sea level rise [de velocidad]if such processes were started in both Greenland and Antarctica.
Is this the point that worries you the most?
Actually, I’m worried about everyone. The process [de no retorno] Ice sheet rise, particularly in West Antarctica, could occur earlier and faster than in Greenland, meaning a sea level rise of three meters over hundreds of thousands of years. But the collapse of the subpolar vortex [una de las piezas de la circulación de vuelco meridional del Atlántico, AMOC, la principal corriente oceánica que regula el clima] It can happen in a few decades, so pretty quickly – it’s not clear, but some models suggest it could happen with a two degree rise in temperature – and that would cool the region by a few degrees and change climate patterns a lot . Consequently, it would destroy everything that depends on them, such as agriculture, which would be chaotically different in Europe. Even without considering the negative socioeconomic impacts, the mere loss of coral reefs would be a tragedy for life on Earth.
Armstrong McKay, in Brighton. In the background an offshore wind farm seen from the coast. Manuel Vazquez
Armstrong McKay speaks as he drinks a coffee and milk on one of the terraces on the promenade of one of England’s most famous beaches. On one side is an old, half-sunken dock. on the other side, a still standing one that houses an amusement park, and in the background a row of windmills that appear on the horizon in the sea. He is wearing a checked shirt and jeans and has his long hair tied back in a ponytail. He is one of many young scientists struggling not to give up in the face of uncertainty before securing a permanent position at a university or research institute. He has a degree in geophysics and has extensive knowledge in the study of paleoclimate, Earth’s resilience and its interrelationship with human dynamics. He admits he was surprised by the impact of the study he presented last September on climate change points: “It’s been a bit of a rollercoaster.” While working with the Stockholm Resilience Center, Armstrong McKay suggested to his current boss in Exeter, Professor Timothy Lenton, proposed to update the work that pioneered the tipping point research field in 2008. After summarizing the results of more than 200 studies to estimate the warming thresholds for each of these points, they published along with eight other colleagues in the journal Science wrote the article entitled “Exceeding 1.5 °C of global warming could trigger multiple climate tipping points.” Lenton signed the last place and Armstrong McKay signed the first place.
He now speaks about this work with the care and patience of a generation of scientists who are convinced that it is not enough just to “do science and publish it in good journals in the hope that political leaders will read it.” , but that we must make an effort to “explain the information to people in a way that they can understand it and do something with the information.” For this reason, it focuses on a central theme, the Amazon rainforest, whose warming threshold to reach the point of no return still appears to be a long way off.
What would a world be without the Amazon rainforest?
First of all, as with reefs, it would be simply tragic to lose this incredible feature of the planet; Although they have evolved over millions of years, some species that have been around for many millions of years are now threatened with extinction. It seems to me to be something like a cosmic crime. But if some vulnerable parts of the Amazon rainforest were to disappear, around 30 billion tons of carbon would be released beyond that, equivalent to several years’ worth of human emissions. That, without being a gigantic amount compared to what the fossil fuels that continue to burn produce, would increase warming by 0.1 degrees, which we cannot currently afford, considering we are at 1.2 and moving towards 1.3, and we should also keep things so that they do not exceed 1.5…
The problem is that the calculations, no matter how good they are, always have a high degree of uncertainty, meaning we don’t really know whether we’re past the point of no return.
It’s important to talk about uncertainty. In our work last year, we displayed the minimum estimates in yellow in the charts. The color gradually changed to red when it became more likely, and finally became very red when it was very likely. From there, we use the most common values to calculate, for example, that the ice sheet’s balance will probably tip over to 1.5 degrees of warming. But it could happen at 0.8 degrees, which obviously would have already happened. Here’s the thing: We don’t actually know exactly when the turnaround will happen, but we do know that the likelihood increases as the embers are stoked. And it could already be happening.
And in 10, 15, 20 years we will know for sure…
We need some time before we can be really sure. It’s like walking through a minefield: the further you go, the more likely you are to hit a minefield, but you don’t know exactly when that will happen. In this environment of uncertainty, some politicians might be tempted to say, “If we don’t know exactly when it’s going to happen, should we really worry or focus on the things we know for sure?” But we know for sure : The warmer it gets, the closer we are to catastrophic events, which should be reason enough to keep the temperature increase as low as possible so as not to exceed these thresholds.
Is this why you think the climate tipping point approach is so successful?
It is worth emphasizing that climate change is already bad. We don’t need tipping points that motivate us to limit global warming to 1.5 degrees. But climate tipping points give us the measure of the change we cause in the long term; We could change the system in ways that will make life difficult for our descendants for many, many generations. Many people seem surprised when you explain that climate change is no longer largely reversible; They seem to think: Well, at some point something will be invented that will solve everything, maybe we can suck out all the carbon dioxide and get back to zero. But even in the unlikely event that this happens, moving past these tipping points will not reverse change.
It’s an extremely serious situation that you scientists keep trying to explain. But you also talk about positive turning points.
This is true. When I give talks, I sometimes play the bad cop and focus on the bad news, while another colleague plays the good cop and explains the positive social turning points. This is what some of my colleagues in Exeter are working on a lot more: they are looking for positive spaces from a social, economic and technological perspective… For example, solar technology or electric cars are so widespread that even though governments have abolished the subsidies, prices would not rise and mass acceptance would continue. Or how the protest that Greta Thunberg started in 2018 gave birth to a self-sustaining social movement.
But beyond social turning points, there are also those who talk about climatic turning points that can have positive effects, such as the greening of the Sahel region in Central Africa.
It’s interesting, but it’s not entirely clear. It may objectively be seen as a good thing that the Sahel can become a greener place, but it is much more complex. First of all, it wouldn’t be the entire region: some western parts would dry out, and the Gulf of Guinea in West Africa, where there is currently rainforest, would probably tend to dry out somewhat. In addition, there are also biodiversity systems in the rest of the region that have their own value, to which their inhabitants have adapted and in which changes can take place – in some places the jump is currently even taking place from a dry savannah to a kind of bush invasion further destabilize an already quite unstable area.
It seems that there is a current that tries to incorporate positive elements into the message about climate change, perhaps because there are those who simply stop listening when everything is negative.
Yes, and that’s why I think it’s important to talk about social turning points. I also try to contribute to this change by accurately disseminating climate tipping points. Because there are a lot of very fatalistic people who say, “There’s nothing we can do now.” And yes, we can, even if some really dramatic tipping points happen – sea levels rise and reefs disappear, for example – it won’t be a game- Over situation because it doesn’t significantly increase global warming, and we can still try it. Limit it so that no more turning points are crossed.
Okay, in this complex environment full of uncertainty, what can you do to improve the situation instead of giving up?
The main message must be: the lower we can keep warming, especially the maximum peak, the better. This reinforces the Paris Agreement to limit warming to 1.5 degrees and the need to reduce greenhouse gas emissions to zero. This would mean a rapid phase-out of the fossil fuel industry – about two-thirds of emissions come from it – which is not happening yet. Other things that we already know are important, having to do with changing the way land is used and farmed, are not important either. Therefore, it would also be very important to start planning for adaptation to those changes that can trigger tipping points. We need to start thinking about extreme scenarios where, for example, maritime defense will no longer be sufficient by the end of the century. And adaptation can occur not in anticipation of a flat, gradual process, but also in thinking about the worst possible possibilities. Let’s go back to the Amazon. It is undoubtedly threatened by climate change, which brings more droughts and fires, but also by deforestation [causada por el hombre] And if Amazon countries band together to stop it, the situation could improve significantly. At the same time, ecological reforestation could also be seriously addressed: a new rainforest will not be the same as the old one in a few decades, it will no longer be as diverse or functional, but it can probably receive some of its feedback, especially that Ability to create its own rain. So if some of these forests could be restored, protected and agroforestry promoted as an alternative industry to livestock, one of the climate tipping points could be eliminated.
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