Climate: it's going to get even hotter. How long will we hold out?

Last summer, it was very hot all over the world. We remember the heat waves in France, the giant fires in California, the suffocation of the Australians. But that's nothing compared to what's ahead of us. A study published this week warns us: record heat waves will happen again and what seemed exceptional will now become the norm. This announcement comes amidst a barrage of alarming climate information that now clearly raises the question of our ability to adapt to an increasingly unbearable world.

Aeteorologists, if not climatologists, don't know which saint to devote themselves to when they observe the thermometer climbing and climbing again. The first days of June were rather cool and rainy in France. But in the rest of the world, temperatures reached alarming figures for a spring.

Rain of records

In the northern hemisphere, stifling heat has hit several regions of the planet, particularly the major population centres.

On Monday, it was 48°C in New Delhi, the capital of India; a temperature never seen before in June. In some parts of India, the mercury even rose to 50°C, the highest level ever reached by the country.

On the other side of the hemisphere, in San Francisco, the temperature climbed to 37.8°, an all-time record. The heat was not confined to the so-called "temperate" zones of the hemisphere. It rose in a perfectly abnormal way far north, to the borders of Scandinavia. Meteorologists in Helsinki, Finland, have said that the temperatures of these days have never been recorded since the weather has existed in that country. In mid-May, temperatures exceeded 30°C in Russia, from Kazakhstan to the White Sea and the Urals. On the edge of the Arctic Ocean, 31.2°C was recorded in Koynas, a city of 350,000 inhabitants located at 65° N latitude. More than 30° C inside the Arctic Circle, an unprecedented temperature at this time of the year.

In Japan, at the end of May, an unprecedented heat wave broke dozens of records, including the highest temperature ever recorded in the Japanese archipelago during the month of May: 39.5° C.

Last summer, exceptional heat affected 22 percent of the populated and agricultural regions of the northern hemisphere between May and July. The United States had its warmest May on record, California had its warmest July on record and many European cities recorded their warmest temperatures on record, while cities in Asia, the Middle East and Africa also reached new milestones. In France, in 2018, the average annual temperature was the highest ever recorded: 13.9°C. This is 1.4°C above the averages for the period 1981-2010. While a difference of 1.4°C may seem tiny, it actually represents the thermal difference between Paris and Toulouse. A similar situation was observed in Germany, Austria, Poland and Switzerland, which all recorded their annual temperature record in 2018.

The study just published by published the scientific journal Earth's Future has been looking at these extreme temperatures to see if these heat waves will become more widespread. The researchers are adamant: " We have entered a new climate regime with extraordinary heat waves of a magnitude and force never seen before. ». Thanks to modelling studies, Swiss and British researchers predict an intensification of heat waves in the coming years. Last summer's heat waves are only a foretaste. And yet they are unprecedented, with researchers claiming they have never encountered them in their historical analyses: "We have never seen them before. They are unprecedented before 2010 ".

"Lethal Heat"

Scientists from several countries have assessed the consequences of temperature rises in major metropolises. They come from published their work in Earth's Future.

The impact of climate change is specifically felt in countries with tropical climates characterized by high humidity and extreme temperatures. In addition, the socio-economic development and high urbanization of countries in these regions, particularly in Africa, is leading to an explosion in urban population growth. The combination of these two factors has a strong impact on the living conditions of people living in African cities, particularly in terms of extreme temperatures, and even death. « We consider that the critical threshold is 40.6 degrees Celsius in perceived temperature, i.e. taking into account humidity. ", notes Guillaume Rohat, a researcher at the Institute of Environmental Sciences (ISE) of the UNIGE. Indeed, high outside humidity disturbs our ability to thermoregulate, which can have deadly consequences.

Scientists have introduced a new term: " lethal heat ». The temperatures recorded and those to come clearly put human health at risk. This is a logical consequence; humans, like all mammals, are thermal engines. They operate in relation to the temperature of the ambient air; this must be low enough for the air to act as a refrigerant, drawing heat from the skin so that the engine can continue to pump. In some equatorial areas of the planet, the predicted warming is expected to reach 7° C. The ambient air is too hot for the human body's heat engine to operate. In addition, in tropical regions, there is extreme humidity. In Costa Rica, for example, temperatures could exceed 45°C with a humidity level of 90 %. Moving outside can be fatal.

Even if we meet the Paris Accord targets of a two-degree warming, cities like Karachi and Calcutta will become almost uninhabitable and suffer deadly heat waves every year. The heat stress in New York would exceed that of present-day Bahrain, one of the hottest places on the planet. By the end of the century, the World Bank has estimated that the coolest months in South America, Africa and the Pacific are likely to be warmer than the warmest months of the late 20th century. Air-conditioning can help, but it will only aggravate the problem of CO2 emissions; furthermore, leaving aside the air-conditioned shopping centres in the Arab Emirates, it is not really plausible to air-condition all the hottest regions of the world, many of which are also the poorest. And indeed, the crisis will be most dramatic in the Middle East and the Persian Gulf, where in 2015 the heat index has already recorded temperatures of more than 50° C.

These doomsday scenarios are closely linked to the continued rise of greenhouse gases in the atmosphere. These gases - carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), the main ones - trap some of the sun's radiation in the atmosphere and return it as heat. The tragedy is that the level of CO2 in the atmosphere has never been so high in three million years. On May 11, 2019, it reached a new symbolic threshold. Its highest level in the history of mankind. Several institutes and observatories have announced that today's CO2 level is 415.26 parts per million (ppm). Scientists consider that at the dawn of the industrial revolution, the level of CO2 was around 280 ppm. In 1958, when the first measurements were taken in Hawaii, it reached 315 ppm.

These numbers seem abstract and mean little to most earthlings that we are. Yet they are a precise measure of our chances of survival. And the more accurate the measuring instruments become, the more frightening the data that appears. A post from Science of April 19, 2019 established that the warming if the atmospheric CO2 concentration doubles would be greater than previously predicted (between 2.5°C and 4.5°C). In fact, recent modelling suggests that the warming could actually exceed 5°C.

The habit of the end of the world

While the "ppms" that measure the amount of CO2 released into the atmosphere may seem abstract, the visible consequences are steadily accumulating. Extreme climatic events (giant fires, devastating cyclones, destructive floods) are multiplying and... end up blunting our sensitivity. Even among those who are the most informed about climate change, the level of alert is below reality. We can contemplate the dangers of global warming, but our imagination is, as it were, limited. Perhaps it is the accumulation of scientific data, of probabilities conscientiously established by experts, that results in watering down the seriousness of the threat. Perhaps also because our so-called advanced civilizational regions are led by groups of technocrats who believe and suggest that any problem can be solved by science and technology. Perhaps, finally, it is because the prevailing climate negationism incites caution, restraint, mistrust, if not denial. Our uncertainty about uncertainty leads us to believe, as an act of faith, that the worst will not happen; or that it will happen elsewhere, further on. Faced with a problem that proves difficult, if not impossible to solve, that puts our own annihilation into perspective, fear is not the right motor. Neither is denial.

All that's left is to get ready. Adaptation should be the key word in the face of predicted climatic shocks. Adapting to such large-scale changes requires a violent transformation of society. And it does not seem to be ready. In France, a report of the Senate calls for " bring about a real change in society "but notes that" Adaptation policies still suffer from a persistent lack of recognition and legitimacy, both in public debate and in public policies. ». Clearly, policies only look at climate issues through the sole prism of mitigation, i.e. limiting greenhouse gas emissions. This is tantamount to wishful thinking that our human efforts will succeed in correcting our mistakes and restoring the normal functioning of the packaged climate machine. Like a demiurgic complex, we think we can tame the climate beast. There are many players and ideas on all sides in this game. However, there is no one left when it comes to dealing with the consequences of climate change by limiting its negative aspects, preventing the worst, and adapting. Between " avoid unmanageable "and" deal with the inevitable As the authors of the report write, "only the first term seems to suit the minds of our contemporary decision-makers.

The urgency to adapt is crying out. Scientists are constantly reminding us of it in every way. The latest alarm was sounded on 5 June by a group of researchers from Australia, a country hard hit by climate change. The conclusions of their report don't go around saying: " it is highly probable that human civilization will come to an end... "by the year 2050. Thirty years from now. Titled "Existential climate-related security risk: A scenario approach", the report insists and warns of a " existential risk for civilization (...) with significant permanent negative consequences for humanity, which may never be reversed, by annihilating intelligent life or permanently and radically reducing its potential ». A unique situation with no historical equivalent. End of History.