Climate crisis intensifies the era of extreme events – 02/25/2023 – Reinaldo José Lopes

The tragic paradox of the dozens of deaths on the coast of São Paulo during the last Carnival is that they are, at the same time: 1) the pure juice of “more of the same” and 2) harbingers of the world to come. Far from contradicting each other, these things interact with and reinforce each other. And, as usual, the most vulnerable pay the price.

The “more of the same” should have been obvious to everyone for decades: how real estate speculation, inequality and the lack of urban planning push millions of Brazilians into risk areas – which collapse and swallow families one year in and the other also.

Therefore, I would like to focus on item 2 above. This is the most complicated task, because it is almost impossible to directly attribute a specific disaster to the current climate crisis – a crisis that, it never hurts to remember, is due to human action.

The difficulty is due to the fact that the climate system is influenced by a wide variety of factors, which operate on different space and time scales and produce different types of natural variability. This means that the so-called extreme weather events (among which almost 700 mm of rain from one day to the next, like the recent one) certainly will happen every now and then naturally.

The crucial issue here, however, has to do with the frequency of these events. And, in this regard, we have every reason in the world to believe that the increase in global temperature will be bad news in many ways, especially for a country where torrential summer rains are already common, like ours.

Imagine that the atmosphere is a bank account. The water vapor that “fits” in it, according to this analogy, is an overdraft limit – which can increase a lot according to a simple variable: the temperature. A warmer atmosphere is able to “hold” more water vapor in it. And, of course, increased heat alone tends to cause more water to evaporate from oceans and rivers.

Notice, therefore, that turning a single “key” of the climate system, increasing the average temperature of the planet, is capable of messing up a wide variety of elements of this system, such as the intensity of the formation of rain clouds – which are nothing more than water vapor. ‘concentrated water–, with impacts both on storms in the Brazilian tropics and on blizzards in temperate countries. (Yes, a warmer world can, also paradoxically, generate more snow under certain conditions, since winter keeps happening every year.)

And the simple fact that megastorms tend to be more common in this context could end up concentrating rainfall –the moments when some water falls from the skies– in more spaced and violent episodes. That is, too much rain at certain times would even increase the likelihood of severe droughts at other times of the year.

(It is probably not by chance that São Paulo ceased to be the “land of drizzle” in the middle of the last century to become the homeland of floods today. The brutal increase in the number of paved areas and channeled rivers certainly contributed to this , but rare is the rain in São Paulo today, which does not go beyond the drizzle phase.)

In addition to facing the planetary challenge of preventing even more serious increases in temperature, it is also possible to think locally: learn to prepare for the worst. It’s better to keep in mind at all times that the rains and droughts that happened “once a century” will appear every five or ten years. There is no other way.

PRESENT LINK: Did you like this text? Subscriber can release five free hits of any link per day. Just click the blue F below.