Erik Puura: After us, the deluge?

Erik Puura: After us, the deluge?. 05.03.2025. According to legend, the French King Louis XV once said “Après moi, le déluge” to his mistress, Madame de Pompadour, which could be roughly translated as “After me, the flood.” As we know, Louis XV and his court lived a rather luxurious, even extravagant life, which ended just fifteen years after the king’s death with an event he would indeed have compared to a flood–the French Revolution. This phrase comes to mind when I observe how some individuals and interest groups resist global changes–changes that no longer threaten the court of a single nation but the very existence of humanity itself. Climate has always changed–but under what conditions? As a geologist, I am repeatedly astonished by the argument often used in climate change discussions: that the climate has changed throughout geological history and that there have been much warmer periods. This statement is undoubtedly true, but previous climate changes were caused by plate tectonics, volcanic activity, variations in solar radiation, and regular shifts in Earth’s orbit and axial tilt. In other words, these changes occurred over geological timescales, with the shortest regular cycle being the change in Earth’s axial tilt, which has a period of 23,000 years. In the past 50 years alone, humanity has burned such an immense amount of fossil fuels that it has led to a 1.5-fold increase in atmospheric carbon dioxide levels. Measurements also show that in recent decades, the Earth’s average surface temperature has been rising by approximately 0.2 degrees per year. Ice melting has intensified both in the Arctic and mountain regions, and even here in Estonia, we are experiencing increasingly early springs and warmer winters The impact of greenhouse gas emissions cannot be ignored It is often said that CO₂ is not the most significant greenhouse gas. That is true. However, without the greenhouse effect and greenhouse gases, the average surface temperature of our planet would be around -18°C. In other words, we wouldn’t exist. The problem is that when the concentration of any greenhouse gas increases, the greenhouse effect becomes slightly more potent. Now, let’s combine the previously mentioned trends and numbers. Some scientists, based on their expertise, do not believe there is a direct causal relationship between these data points. However, the overwhelming majority agree that there is a direct causal link–meaning that the current rapid and unidirectional climate changes (we are not talking about long cycles spanning tens of thousands of years) are human-induced. The leading cause is carbon dioxide released into the atmosphere by burning fossil fuels. I do not claim to be a climate scientist, but I know that neither Donald Trump nor other members of the older generation will experience anything during our lifetimes that would significantly worsen the quality of life in Estonia due to climate change. From a narrow, self-centred perspective, one could even repeat the words of the extravagant French king. However, these unidirectional changes continue because the burning of fossil fuels worldwide has not decreased. International climate conferences have been held for 30 years, yet during this time, CO₂ emissions from fossil fuel combustion have increased by 1.6 times every year. Are we thinking about the well-being of future generations? I am convinced that the severe setbacks caused by climate change will come long after I am gone. This raises the question: Do we care about the well-being of future generations? Do we have the right to say, “After us, let there be a year-round heatwave or water shortages?” Even now, we are witnessing multiple setbacks, some partially caused by climate change. If climate change is not a problem, why is there such a great interest in Ukraine’s rare earth metals and lithium? There is an intense global struggle for access to natural resources–or rather, this struggle has always been happening more covertly. In the past, oil-rich countries held dominance, but now the balance of power is shifting to those who control metal deposits, with China currently holding hegemony in this area. Returning to the first paragraph, those who attempt to deny rapid human-induced climate change by referencing geological history remind me of people who claim that solar eclipses do not exist because it is also dark at night. Rapid changes occurring over decades are not comparable to cyclic changes that have taken tens of thousands of years, let alone the distant geological past when, due to plate tectonics, continents were in entirely different locations. Humanity has also managed to improve the environment However, it is worth concluding on a more constructive note. One reason why the reality of climate change is often rejected may lie in its sheer scale. Critics of climate change may be inclined to accuse data-driven scientists of having a god complex of megalomania–how could humans possibly bring about changes of such magnitude? A great response to this comes from a success story, or at least a story with elements of success: the fight against the ozone hole over the Southern Hemisphere, which was set in motion by the 1987 Montreal Protocol. The global ban on CFCs, methyl bromide, and other ozone-depleting chemicals has stabilized the ozone hole that expands over Antarctica each spring (i.e., during the Southern Hemisphere’s spring). The stratospheric ozone layer reached its thinnest point in 1994 when the September-October average dropped below 100 DU (last year’s average was 123 DU). During the same period, the average size of the ozone hole was 27 million square kilometres in 2006; in 2024, it was only 20 million square kilometres. Data shows that the growth of the ozone hole has stopped. This means that humanity is capable of altering its environmental conditions not only for the worse but also for the better. This fact should give hope to those who lack it.