The impacts of El Niño are expected to be more violent in a warmer climate

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According to the work of an international team of researchers, the events The boy of the future will be responsible for more virulent climatic fluctuations than in the past. In particular, the temperature and precipitation anomalies induced by the phenomenon should become sharply accentuated. Significant results published in the journal Geoscience of nature this April 15.

The boy – the oceanic part of the natural oscillation named ENSO – is a climatic fluctuation which occurs irregularly every 2 to 7 years and which results from a coupling between the ocean and the atmosphere in the equatorial Pacific. It consists of an abnormal warming of the waters along the equator, which induces an upheaval of the rain regimes in the tropics and whose influences even diffuse towards the middle latitudes.

Extracting oneself from the complexity to better understand the evolution ofThe boy

For these reasons, The boy affects the socio-economic sector as well as those related to the environment or health, from the regional scale to the global scale. Understanding how this phenomenon is changing with global warming is therefore a major issue. However, the nature of the underlying physics makes the problem particularly difficult.

Indeed, the mechanisms bring into play feedback loops that even the most powerful models still struggle to represent in detail. However, the research efforts carried out in recent years have made it possible to make significant progress. In particular, it appeared that the reaction of the phenomenon was controlled by some basic physical concepts such as the relation of Clausius-Clapeyron. A property that allows you to avoid part of the complexity. In this context, a recent study reports that climate disruption and the accompanying impacts The boy will increase in a warmer climate.

Numerical simulation results showing the response in temperature, wind (top) and humidity (middle) during a The boy present (left) and future (right). Red indicates high temperature or humidity, vice versa for blue. Finally, the lower figure shows the amplitude of theThe boy used for simulations (identical for comparison). Credits: IAP / Kaiming Hu et al. 2021.

The key role of latent heat influences

“The saturated vapor pressure increases exponentially with temperature, so the same air temperature anomaly will lead to a larger saturated vapor pressure anomaly in a warmer climate,” details Hu Kaiming, main author of the paper. “Therefore, with global warming, even if the sea surface temperature remained unchanged, the wet reaction of the low troposphere tropical climate at ENSO will increase, which will in turn a major reorganization of temperature, atmospheric circulation and precipitation.

In summary, the climatic fluctuations associated with The boy will be magnified in a warmer world. We can, for example, think of a stronger influence on global temperature anomalies or more massive redistributions of atmospheric water (rain, drought) and mass (pressure, wind). Thus, latent heat influences seem to add a notable constraint on the evolutions of tropical variability modes such asENSO. A dimension that differentiates them from those of higher latitudes – let us quote among others thenorth atlantic oscillation – where these influences are much weaker.

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