A ‘perfect example’ of the effects of global warming


Since mid-December 2022, California has been experiencing unprecedented weather conditions, with episodes of rain and at least five storms in more than a month, particularly due to “vapor corridors”. The rains have killed at least 19 people. Ecohistorian Christophe Roncato, lecturer at Grenoble Alpes University, analyzes the Tounsi phenomenon and its consequences.

RFI: How do you analyze these different episodes of heavy rain in California? ?

Christophe Roncato Tounsi: I think it is important to emphasize the recurring nature of precipitation in California as rain or snow. Since December 26, no less than four or five consecutive waves have swept the state. And, of course, this is caused by global warming and red-colored temperatures, high humidity in the atmosphere, which reinforces the exceptional nature of this precipitation.

There is a lot of talk about atmospheric rivers these days. Can you explain what it is? ?

It’s a term that’s been around since the 90s. In the context of California, we hear a lot about it, and it manifests itself in higher humidity in the atmosphere, which leads to rain and snow, which is equivalent to the great rivers of the planet. Amazon or Nile. As a result, it causes significant damage to infrastructure, population, vegetation…

► Also read: United States of America: A series of deadly floods occurred in California

Also called steam corridors. Is it the same?

Yes, these are the same phenomena underlying the current precipitation.

Is there human responsibility in these events?

I believe it is double. Of course, these are human activities as a whole, associated with various economic sectors, which, as everyone knows, emit a certain amount of greenhouse gases. Thus, it is not California-specific liability, but systemic and collective liability. But we can also point to certain liabilities in California, such as our tendency to build in flood-prone areas. This is something California’s public policy needs to work on to prevent flooding from causing disproportionate damage.

Because the current water storage infrastructures, dykes, artificial lakes are no longer adapted to today’s world?

Infrastructures are adapted to the climate of the 20th century, not the 21st. Thus, in the current context, extremes are becoming stronger and infrastructures are struggling to resist.

With the addition of ongoing drought throughout the American West, particularly in California, the soils are therefore extremely dry and unable to absorb as much water. Can we make a connection with global warming?

Climatologists have long said that global warming will exacerbate extremes. There we have a perfect example of what is happening globally. I think we should make a connection. We see that the transition in the American media is not carried out systematically.

Does this mean these extreme events will happen again and again?

Absolutely. A new normal is emerging in these extreme hot, extreme rain, extreme snow scenarios. And yet scientists working on these climate changes tell us. We are dealing here with what some call climate shocks, which are sudden environmental consequences. We are also talking, for example, about the erosion of banks by discharged water.

From a human perspective, who suffers repeatedly from these events?

Everyone is affected. We have counties like Santa Cruz that are quite affluent, with populations that can work in large high-tech industries. These people were impressed.

But in fact, on the contrary, minorities, not so poor people, cannot cope…

Taking San Francisco as an example, we certainly understand that it is the people who live outside who are most at risk. And then we also know that certain areas south of San Francisco to Los Angeles are going to have a harder time rebuilding their infrastructure because they’re often underfunded.

California, it has been repeated all too regularly, is at the forefront of the fight against global warming with a Democratic governor. What is actually being done? Is that enough?

California has a reputation for being proactive on environmental issues, and rightfully so. If we take a closer look at the climate, we will see that in the 2000s, a climate turnaround took place with the impetus of Governor Arnold Schwarzenegger. Since 2007, 2008, very serious scenarios have emerged under the influence of science. Is that enough or not? This is a question that needs to be asked. However, we can be interested in some aspects of these scenarios that want to stay on track in terms of economic growth.

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