When everything tips over

Earth's climate is racing toward dramatic heating - what are the consequences, what do tipping points mean, and why are increasingly shrill warnings unhelpful?

By Juliane Schumacher

[This article posted on 6/20/2023 is translated from the German on the Internet, https://www.akweb.de/ausgaben/694/wenn-alles-kippt-klimawandel-kipppunkte-planetare-grenzen-wo-stehen-wir/.]

New York skyline shrouded in orange smoke

Heat waves, droughts, floods: Extreme weather events are on the rise. And are delivering increasingly apocalyptic images, as in New York City on June 7. Because of wildfires in Canada, the city was shrouded in orange smoke.

The fact that tipping points play such a prominent role in the current discussion about climate change basically goes back to a misconception. For many decades, one image dominated the Western conception of the Earth: that the climate system was stable. Geographers drew climate zones on maps: Depending on latitude, east or west coast location, cold or warm ocean currents, the assumption was that every place on Earth had a particular climate, with an average temperature and a particular distribution of precipitation.

When concerns about human-induced global warming led researchers to look more closely at climate history, and new technologies made it possible to look further back than the short period of human civilization, this picture began to crack. It became clear that the fact that climate was considered to be something stable was mainly due to the fact that, in terms of geological history, humans are very young - and that the last 10,000 years in particular can be regarded as unusually stable in terms of climate.

The climate, however, is anything but stable, and there is no such thing as a "natural" climate to which the earth would permanently settle. The amount of solar radiation that provides energy to the Earth is not always the same; what portion of it is converted into heat and how much escapes into space - all this depends on many factors that have led to different climatic states of the planet. For much of Earth's history, it was much hotter than it is today, and ice did not even exist at the poles; at other times, the Earth froze over completely. For the last hundreds of millions of years, longer ice ages alternated with shorter warm periods, triggered by fluctuations in the Earth's orbit around the Sun and the associated changes in solar radiation.

How the climate changes

More significant for the policy debate were two other findings: First, these climate changes did not occur uniformly over millions of years. Again and again in the history of the Earth, there were relatively abrupt regional and global changes in which temperatures rose or fell briefly - in the course of a few hundred or thousand years. On the other hand, it became clear that in the complex system of global temperature regulation there are feedbacks that can weaken or strengthen processes.

While many scientists initially assumed that certain feedbacks would counteract warming - for example, stronger plant growth due to more carbon dioxide in the air - the state of research today is that these are too weak or act too slowly to slow down short-term warming. Mechanisms such as the long-term carbon cycle through weathering and volcanic activity are most likely responsible for the Earth's recovery from even very hot and very cold states. However, these processes take place over periods of many millions of years.

In the short term, on the other hand, the feedbacks that seem to be most effective are those that further amplify a warming process once it has been set in motion. This also applies to the global warming currently being observed, triggered by the large quantities of greenhouse gases that humans have been introducing into the atmosphere for about 200 years, primarily through the use of fossil fuels.

The melting of Greenland ice alone would raise sea levels by several meters.

Some of these feedbacks have long been known: for example, the influence of albedo, the planet's reflectivity, which determines what part of the sun's radiation is reflected by the surface and what is converted into heat. Ice reflects almost all of it - when there are more patches of ice, it gets colder, more ice forms, and the cooling is further enhanced. Conversely, melting ice causes more solar radiation to hit water or dark ground - and thus more of it is converted to heat, further amplifying the warming.

Closely related to the system of feedbacks is the principle of tipping points: This refers to the fact that changes in such systems are not linear - that is, that a steady increase in greenhouse gases does not lead to a steady melting of a glacier's ice. Instead, there are points at which self-reinforcing processes begin, causing the entire system to change relatively abruptly. These changes - the melting of a glacier, for example - continue through the feedbacks even when the original trigger is removed. It is difficult to impossible to return the system to its previous state.

What do we actually know about tipping points?

Climate scientists* have warned more and more forcefully in recent years that systems exist around the world that are being driven by current warming to a state that is irreversible - and some of these points may already have been passed. One of the best-known examples is the Greenland Ice Sheet, which has been measured to be melting at an increasing rate in recent years, and the West Antarctic Ice Sheet, where further increases in temperature could also trigger melting. Melting of the Greenland ice sheet alone would raise sea levels by several meters.

One of the most prominent examples of tipping points is the Atlantic Meridional Overturning Circulation (AMOC), a system of ocean currents that includes the Gulf Stream, which brings warm water to the northeast coast of the United States and the west coast of Europe. The horror scenario of a breakaway of the current has been the subject of Hollywood movies such as "The Day after Tomorrow." In fact, during the last ice ages, there were always periods when the current changed or reversed. The warming of the ocean, it is feared, together with the increased input of freshwater from glacial melt, could trigger just this - and cause Europe to become much colder. Other frequently mentioned "tipping point systems" are coral reefs, hardly any of which would survive a rise in global temperature of more than 1.5 degrees, or the Amazon rainforest.

But the Amazon example also shows that such predictions can hardly be limited to climate alone. It is true that climate change is very likely to contribute to alternating droughts and very wet years in the Amazon rainforest area, putting a strain on the ecosystem. However, the main problems are deforestation, forest fires and fragmentation of the forest area. Researchers have calculated that 17 percent of the forest area has already been lost, and warn that once 25 percent is lost, the ecosystem could collapse and become a savanna - further exacerbating global warming.

Whether the end of the Amazon rainforest can actually be pinned down to such a figure, however, is questionable. As with most other tipping points, it is more a matter of estimates or a range of possible values that computer models have determined, not a definitive value. Whereas climate researchers such as Stefan Rahmstorf stated until a few years ago that climate research was aware of possible tipping points but could not say exactly where they were, a radical change has recently been observed in climate communication: Recent studies are warning at ever shorter intervals not only that the tipping points are probably much lower than thought just a few years ago, but also that several of them may already have been passed.

Heat, drought, rising sea levels

One contributing factor is that the Earth has warmed more in recent years than previously thought - partly because it has not yet been possible to reduce emissions. According to the Intergovernmental Panel on Climate Change, the earth has already warmed by 1.1 degrees compared with pre-industrial times. By the end of the century, it will be two to three degrees, according to current forecasts. The goal set in Paris in 2015 of limiting global warming to 1.5 degrees is unlikely to be achieved.

For around a third of humanity, rising sea levels will have devastating consequences - low-lying areas, cities and islands will sink into the sea if they cannot be protected.

The consequences of climate change are also already clearly demonstrable: heat waves and heavy rainfall are occurring more frequently. India has experienced several heat waves since March, with temperatures briefly exceeding 50 degrees Celsius - such extreme heat waves, researchers* have calculated, have become at least 30 times more likely due to increased global temperatures. Severe flooding, like that in Pakistan last year that killed at least 1,500 people and forced 30 million to flee the consequences, has also become more likely due to climate change, as have severe droughts and other extreme weather events. Moreover, rapid warming has already caused the extinction of numerous animal and plant species; if it continues to increase, entire ecosystems could collapse.

The rise in sea level will have a particularly dramatic impact - this can already be said with certainty. According to the latest forecasts of the Intergovernmental Panel on Climate Change, sea levels are expected to rise by between 30 centimeters and one meter by 2100, and could rise by up to two meters by 2150 if emissions remain high. And the rise will continue for thousands of years as warm water continues to expand. For about a third of humanity living in coastal areas, this will have devastating consequences - low-lying areas, cities and islands will sink into the sea if they cannot be protected.

The fact that the warnings are increasingly dramatic may also have political reasons - with quite problematic effects. It is understandable when scientists, who have been warning for decades, mostly in vain, about the consequences of unchecked climate change, increase the urgency with more dramatic forecasts. Emphasizing tipping points as "boundaries that must not be crossed" may be one strategy.

The problem with disaster scenarios

Underlying such a strategy, however, is the - quite naïve - assumption that the lack of climate action is a knowledge problem. The fact that man-made climate change is taking place and is having devastating consequences has been known for decades, however, and is no longer seriously doubted by anyone. The fact that emissions have nevertheless not decreased but continue to rise is not because the urgency is not clear - but because systemic causes stand in the way, above all the economic growth compulsion of the capitalist system. However, this is an aspect that the scientists who emphasize the impending tipping points consistently ignore.

Warnings of the coming catastrophe always bear the danger of depoliticizing, and they often obscure inequalities. This is also true of the tipping point debate and that around "planetary boundaries" and the Anthropocene. Both discourses are connected - the authors* who made them popular are more or less identical. In 2009, 29 experts, almost exclusively natural scientists, mostly men, all from the Global North, presented a list of planetary boundaries and described possible tipping points of the Earth system. Since then, the concept of planetary boundaries has spread rapidly.

Warnings of catastrophe risk depoliticizing, and they obscure inequalities. This is also true of the debate about tipping points.

The claim to define "safe" areas in which humanity can live without the danger of abrupt climatic upheavals may sound understandable. But by no means all of the systems described are irreversible processes, and the limits were based exclusively on the assessment of the experts involved. So it is not surprising that criticism starts exactly here: Whose tipping points are these, who sets the limits? Why is it only about the planet as a whole, not about the unequal consumption of resources? What about those who have long lived beyond the "limits," for whom the catastrophe is not in the future but has long been here? Finally, what policies follow from intensified warnings that planetary boundaries will soon or have already been crossed?

This discourse does have political consequences. Many actors, including powerful ones, are now aware that a crisis is imminent or already underway, and they are struggling to find ways to deal with it. Two main reactions can be identified at present: Critical actors such as the British scientist Kate Raworth have taken the proclaimed planetary boundaries as an opportunity to point to social sub-limits, that is, to emphasize the minimum that people need for a dignified life. And scientists like Jason Hickel have argued that the Global North must drastically reduce its consumption of raw materials if it is to have any chance of meeting such limits.

Climate protection in capitalism

The representatives of the Planetary Boundaries Theory go in a different direction. Since 2019, they have been conducting research as the Earth Commission, funded by the Global Commons Alliance, issuing reports and publishing in scientific journals. The Global Commons Alliance is a network of major corporate foundations and institutions, including the World Economic Forum, which organizes the annual Davos business meeting, and the World Bank's Global Environment Facility. It is not surprising, then, that the concept of planetary boundaries is aimed specifically at businesses, among others, to show them ways to best deal with the challenges. The climate models created by the IIASA research institute in Austria, which is also involved in the project, are based on economic models that calculate primarily on the basis of economic rationality and cost-benefit optimization.

The richer the CO2: Who fuels climate change

Heat waves in India and China, forest fires in Canada, floods caused by heavy rain in Italy and Congo: the disaster reports about extreme weather events have already become unmanageable this summer. It is now clear that such events are occurring more frequently - and increasingly violently - as a result of global warming. What is less well known is how blatantly unequal the responsibility for climate change is distributed around the world. In the period from 1850 to 2015, the United States alone was responsible for no less than 40 percent of global emissions, while the countries of the EU accounted for 29 percent. The Global North as a whole, which accounts for only 19 percent of the world's population, accounted for 92 percent of the damage caused by climate change. What is true on a global scale is also true individually: the richer the more damaging to the climate. Currently, according to an Oxfam study, 125 billionaires alone are responsible for as many emissions on average as one million people from the poorer 90 percent of the world's population. The richest one percent of humanity - fewer people than Germany has inhabitants - emit significantly more than the poorer half (about 4 billion people) combined. And if we look at the Global North, we can see that responsibility is extremely unequal here as well. While the poorer half of the population in Germany emitted about six tons of CO2 per year in 2019, the richest one percent emitted about 105 tons - almost 18 times as much. The richest 0.001 percent in Germany, about 800 people, emit a thousand times as much greenhouse gases as the average: 11,700 tons. Surprise: Since 1991, emissions inequality has still increased significantly. None of this is taken into account in current climate policy. The consequences of global warming, on the other hand, primarily affect the countries of the Global South, and there again predominantly the poorer people.

The Earth Commission and its organs have thus developed into an alternative, non-elected structure, beyond the UN structures, in which, as bureaucratic and inert as their institutions are, the countries of the Global South at least have an active role and a say. Even though recent reports have at least formally included the aspect of "justice," questions of structural inequality, the consequences of colonialism, or the economic system still play no role.

On the other hand, the Earth Commission has recently come out more and more clearly in favor of active Earth management: In order to prevent the planet from becoming a "greenhouse earth" through the interplay of self-reinforcing processes, as the authors warn in a 2018 study, "effective planetary stewardship" is needed to actively keep the earth within a temperature range suitable for humans: through reduction of emissions, expansion of carbon sinks, and targeted "modification of the earth's energy balance," in other words: geoengineering. The Earth Commission is silent on who exactly determines what the "right" temperature of the Earth is and what measures will be taken. One thing is certain: radical proposals that can actually reduce emissions and shape the future fairly will not come from this corner.

So it's high time for the left to break out of its shock paralysis, to start politicizing knowledge again and to develop its own models and approaches that are both bigger and smaller than the warning about the end of humanity. First, by taking into account the economic structures that have so far prevented ecological and social problems from being seriously addressed. And on the other hand, by going into the painstaking, everyday detail work and testing how, beyond abstract warnings about the demise of the planet, the transformation towards a more just world can look concrete.



Juliane Schumacher

is a scientist and journalist specializing in the environment, climate change and social movements.