How La Niña and El Niño change earth's temperature

Various climate-related disasters such as floods, droughts, and cyclones are quite natural phenomena. However, it seems that these disasters are becoming more severe over time. There is now excessive rainfall during the rainy season, leading to sudden floods. Recently, we have witnessed sudden floods in Dubai due to excessive rainfall, and in June 2022, the Sylhet region experienced severe flooding.

Another issue that is being discussed is heatwaves. I have never seen schools or colleges giving holidays due to excessive heat during my academic life, but I have seen it this year. This excessive heat has raised concerns and curiosity among us. We wonder, what is the reason behind this increased level of heat? Will the earth's temperature continue to rise day by day?

The change in the state of natural disasters is primarily due to the changes in the earth's climate, which are occurring due to the overall global warming caused by greenhouse gas emissions. We are constantly emitting greenhouse gases, the characteristic of which is to trap heat. This means that some of the heat energy that comes from the sun during the day is trapped by greenhouse gases at night, and as a result, the earth's overall temperature, including water and land, increases.

In the past century, the average global temperature has increased by one degree Celsius. The rate of temperature increase has been particularly alarming since 1970, when industrialization began on a large scale. Since then, the rate of temperature increase has been steadily increasing.

Every element of a system is interconnected or dependent on each other. If one element of the system changes, then changes occur in other aspects of the system accordingly. Global climate is a system, and due to various human-created factors, its equilibrium has been disrupted, leading to changes in various natural disasters.

To understand this topic easily, consider a family. Suppose the family is financially stable, meaning they have high financial resources. In such a case, the family members will use premium quality goods in every aspect of their life, be it food, clothing, appliances, or anything else. Now, if for any reason, the financial stability of this family is shattered, will they be able to maintain their previous lifestyle? The answer is no. It means that the family will change their lifestyle according to their economic condition.

Similarly, due to the increase in global temperature, changes are occurring in the global climate, and as a result, various types of natural disasters are changing. One of these is heatwaves or excessive heat.

When the topic of thermohaline circulation arises, so do the phenomena of El Niño and La Niña, both of which significantly influence global weather patterns. The rising temperature of the waters in the Pacific Ocean, observed after the phenomenon known as El Niño, is juxtaposed with the presence of the Coriolis force, which causes winds to blow from east to west due to the Earth's rotation on its axis. Consequently, warm water accumulates on the western side of the Pacific Ocean, particularly in regions adjacent to Australia or South Asia, resulting in increased evaporation and the formation of rain clouds.

Conversely, in regions along the coast of Peru or South America, the ocean water remains cooler, leading to reduced rainfall and drought conditions. When these natural occurrences intensify, meaning a greater amount of warm water than usual moves from east to west, it is termed La Niña. Conversely, if warm water from the surface levels of the Pacific Ocean moves from west to east, contrary to the normal pattern, it is termed El Niño. This results in areas like Australia or South Asia experiencing warmer ocean waters, leading to increased evaporation and subsequent rainfall.

The interplay between El Niño and La Niña affects global weather patterns by altering oceanic circulation patterns, which in turn influence atmospheric conditions. Where heavy rainfall might not typically occur, there may be excessive precipitation, while areas that usually experience rain may encounter drier conditions.

Now, the question arises: why do El Niño and La Niña occur? The movement of warm water on the surface levels of the Pacific Ocean from one place to another is a natural occurrence, primarily driven by oceanic currents. However, the current intensification of El Niño and La Niña is concerning. Since the late 20th century, instances of both El Niño and La Niña have become more severe. The reasoning behind this lies in global warming, which is causing these phenomena to become more intense.

As of 2022, countries like China, the United States, India, the European Union, Russia, and Brazil collectively account for 61.6% of global greenhouse gas emissions. Qatar leads the charge in per capita carbon dioxide emissions, while Burundi emits the least amount of carbon dioxide per capita. Bangladesh emits approximately 1.62 tons of carbon dioxide per capita annually. Generally, developed countries emit higher amounts of greenhouse gases. It is estimated that by 2050, the Earth's average temperature will rise by 1.5 degrees Celsius, with potentially dire consequences if greenhouse gas emissions are not curbed.

Currently, Bangladesh is experiencing extreme heatwaves due to the intensified El Niño effect, compounded by various local factors, primarily deforestation. Deforestation reduces the number of trees available to absorb greenhouse gases, leading to increased atmospheric carbon dioxide levels and contributing to global warming. Additionally, fewer trees mean less shade, exacerbating the heat felt by individuals, which is evident in the current heatwave conditions.

Despite experiencing intense heatwaves last year and this year, the highest recorded temperature in Bangladesh's history was on May 18, 1972, at 45.1 degrees Celsius. However, people might not have felt that heat as severely then, perhaps because Bangladesh had abundant forests, rivers, and water bodies, which mitigated the effects of the heat. But nowadays, the resulting environmental changes due to the heat are making life unbearable for people.

Not only heat, but also various natural disasters in more devastating forms will come before us if we cannot curb global warming. Now the question arises: what should we do in this regard?

At the personal level, we should focus on planting trees and being aware of environmental pollution. At the national level, we should focus on forest conservation, preventing river encroachment, eliminating water pollution, raising awareness about environmental pollution, refraining from development activities that destroy nature, and exerting strong opposition to greenhouse gas emissions in developed countries.

The responsibility for our future generations lies with us. If we cannot leave a beautiful, habitable Earth for them, it will be our ultimate failure and indifference towards future generations. Currently, among the billions of planets and satellites in this vast universe, we have only one habitat, and that is Earth. Just as you keep your own home clean and tidy, you should also keep our planet clean and tidy for your own sake.

Md. Jomman Bhuiyan: Content creator and teacher