The "murderer" that once caused mass extinction of biological species, will its "shadow" reappear on Earth in the future?

Tuchong Creative

Everyone may have a personal experience of climate change in recent years, such as frequent extreme weather phenomena, accelerated melting of glaciers, changes in the ecological environment, and the accelerated extinction of some species. Many of the causes of this abnormal climate are related to the abnormal increase in sea temperature. Among them, scientists call the abnormal sea temperature in the tropical oceans in the eastern and central Pacific the "El Niño" phenomenon.

So, what exactly is El Nino and what are its characteristics? Simply put, El Nino is a climate phenomenon characterized by an abnormal increase in sea water temperature in the eastern and central equatorial Pacific. It is an important component of the global climate system and has a significant impact on the global climate. The following are the main characteristics and impacts of El Nino:

1. Abnormal sea temperature: The core feature of the El Nino phenomenon is a significant increase in sea temperature in the eastern and central equatorial Pacific. This increase is usually caused by the weakening or reversal of easterly winds, which causes warm water to flow from the western Pacific to the eastern Pacific.

2. Changes in atmospheric circulation: Rising sea temperatures affect atmospheric circulation patterns, especially the Walker Circulation. Typically, rising sea temperatures in the eastern Pacific cause air in the region to rise, changing global wind and precipitation patterns.

3. Global climate impact: El Nino can cause climate anomalies around the world. For example, the west coast of South America may experience abnormal rainfall and flooding, while Australia and Southeast Asia may experience drought.

4. Periodicity: El Niño usually occurs every 2 to 7 years and lasts from a few months to a year. It is part of the El Niño-Southern Oscillation (ENSO), which also includes La Niña, which is an abnormally low sea temperature.

5. Ecological and economic impacts: El Niño can have impacts on ecosystems and economic activities, such as reduced fishery yields, reduced agricultural production, and increased natural disasters.

The El Niño phenomenon is an important factor in the global climate system, with profound impacts on the natural environment and human society.

If the El Nino phenomenon intensifies further and the climate becomes abnormal, it may lead to the accelerated extinction of more species, resulting in a mass extinction event. Based on the current rate of species extinction, some scientists are worried that the Earth is entering the sixth mass extinction stage.

If we look back at the first five mass extinctions in the history of life on Earth, could they also be related to abnormally high sea temperatures in a certain area near the equator, similar to the current "El Niño" phenomenon? Can we find relevant geological records?

According to the fossil records in the strata, the five confirmed mass extinctions are:

1. The Ordovician-Silurian extinction event, about 445 million years ago, mainly affected marine life.

2. The Late Devonian extinction event, about 370 million years ago, was characterized by multiple stages of extinction and also primarily affected marine life.

3. The Permian-Triassic extinction event, about 252 million years ago, was the most severe extinction event in Earth's history, with about 96% of marine species and 70% of terrestrial life becoming extinct.

4. Triassic-Jurassic extinction event, about 200 million years ago. Mainly affected terrestrial and marine organisms.

5. The Cretaceous-Tertiary extinction event, about 66 million years ago, led to the mass extinction of dinosaurs except birds, which is well known to the public.

Among the above events, the end-Permian extinction event is particularly important, not only because of its huge scale, but also because it involves complex land-sea interactions, global warming, ocean hypoxia, and higher local sea temperatures near the equator.

The event is generally believed to have been driven by multiple catastrophes, including volcanic activity (such as the Siberian lava eruptions), climate warming caused by greenhouse gases, and related ecosystem collapse.

However, among these factors, there have always been different opinions in the scientific community as to which one is the dominant factor. Recently, Chinese scientists published a paper titled "Super El Niño triggered the end-Permian mass extinction" in Science. Of course, the "El Niño" mentioned here has nothing to do with the Pacific Ocean today, but refers to the phenomenon of abnormal climate caused by abnormally high sea temperatures in a certain area near the equator.

This team of scientists combined sedimentary geochemical proxy indicators and complex Earth system science model simulations to analyze the initiation and development mechanism of the end-Permian mass extinction from the perspective of ocean-atmosphere coupling. Moreover, this "super El Niño" 2.5 years ago was also related to volcanic eruptions.

We know that large-scale volcanic activity can release large amounts of greenhouse gases, such as carbon dioxide and sulfur compounds, which can cause global warming or short-term cooling. Such climate change may affect global weather patterns, including the frequency and intensity of El Niño.

This paper uses oxygen isotope paleothermometers of conodonts, an extinct marine organism, in the strata to reconstruct the east-west latitudinal temperature difference in the paleo-Tethys Ocean. It also uses complex Earth system science models for simulation and mutual verification with sedimentological evidence to establish a new model of the ocean-atmosphere coupling process at the end of the Permian.

The results show that at the end of the Permian period, as the concentration of carbon dioxide in the atmosphere increased, the ocean temperature in a certain area near the equator seemed to be getting higher and higher. At the turn of the Permian and Triassic periods 250 million years ago, as the rise of atmospheric carbon dioxide continued to intensify, the abnormally high sea temperature in a certain area near the equator caused the reverse vibration of atmospheric pressure near the equator, resulting in climate anomalies, which first led to the extinction of terrestrial life, followed by the extinction of marine life, with a gap of about 10,000 to 70,000 years between the two.

There is still heated debate about whether future climate warming will lead to a sustained increase in the intensity and duration of the El Niño-Southern Oscillation, but the fact that El Niño often causes forest degradation, coral bleaching, and mass deaths of birds and fish is already a major practical problem.

By using the past to illustrate the present, this article reveals that the environmental effects of short-scale climate change in the context of global warming have been underestimated, which provides a reference for humans to rethink how to cope with the more variable modern climate change.

This article is a work supported by the Science Popularization China Creation Cultivation Program

Author: Xiao Long, Professor of China University of Geosciences

Reviewer: Dai Yunwei, Senior Engineer, China Meteorological Administration

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.