Environment

Climate disasters in 2021 reveal weather divide across globe

Published on: 23 December 2021 12:15 PM
by KnowESG
Wildfires that swept through Sequoia National Forest in California in September 2021 were so severe they killed ancient trees that had adapted to survive fires.

A Brief Summary

Climate change in 2021 left no clue for scientists who study them, In Europe, extreme flash floods wreaked havoc across the continent kill more than 200 people. In Asia, rainfall inundated major cities. Heatwaves touch records in the pacific northwest, Europe and the Arctic. Most of the disasters have been linked to human-caused climate change.

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Along with a lingering global pandemic, the year 2021 was marked by a slew of climate disasters, some of which startled even climate scientists. Rainstorms developed into violent flash floods that rushed through European mountain communities, killing more than 200 people. Excessive rain-drenched large areas across Asia, flooding subway stations in China. In the Pacific Northwest, Europe, and the Arctic, heatwaves obliterated records. California, Canada, Greece, and Australia have all seen wildfires. That was just a sampling of the extremes, Damage from the worst climate and weather disasters is predicted to exceed $100 billion in the United States alone by 2021.

Many of these extreme weather phenomena have been connected to human-caused climate change, and they provide a preview of what to expect in a world that is fast warming. Something ,in particular, jumped out in the United States: a clear national precipitation gap, with one side of the country being overly wet and the other being too dry. Here's what happened with precipitation in the United States in 2021, and why similar events are expected to occur again in the future.

The weather gap between east and west. In 2021, the eastern United States had storm after storm. In August, Tennessee had record rains, which resulted in fatal flash flooding. Days after Hurricane Ida slammed Louisiana, the remnants of Hurricane Ida mixed with another front and became so powerful that they broke rainfall records and flooded subway stations and underground residences in New York and Pennsylvania, causing widespread devastation.

Meanwhile, almost the whole West was experiencing dryness, which fueled wildfires that spread through woods and towns.

La Nina, a periodic occurrence caused by Pacific Ocean temperatures that tends to leave the Southwest drier than normal and the North and much of the eastern half of the United States wetter, can exacerbate this type of east-west weather gap. But there's more: global warming is fueling both drought and excessive rains. In August 2021, flash floods in Tennessee washed away cars and destroyed homes.

When the globe heats, three things happen to precipitation in particular.

1) Increased precipitation as a result of global warming.

Evaporation from the Earth's surface increases as the temperature rises. It also enhances the capacity of the atmosphere to hold moisture by around 7% for every degree Celsius that the earth heats. Global precipitation is predicted to increase as more moisture evaporates, but this increase will not be uniform.

2) Climate change causes more intense precipitation.

More moisture is required to reach the condensation level and generate precipitation at higher temperatures. Light precipitation will be less common as a result. However, when storm systems do form due to higher moisture in the atmosphere, the increased humidity causes heavier rainfall events.

Storms are also driven by latent heat, which is the energy released into the atmosphere when water vapour condenses into liquid water. Increased moisture in the atmosphere also boosts latent heat in storm systems, causing them to become more intense.

Heavy precipitation events have grown in frequency and intensity over most geographical areas since the 1950s, according to research.

In September 2021, the aftermath of Hurricane Ida inundated subway stations in New York City.

3) As the world warms, moist locations become wetter and dry places become dryer.

Because of the global atmospheric circulation pattern, precipitation does not fall evenly around the globe. This global circulation transports moisture to places where winds converge, such as the tropics, where the majority of the world's rainforests are found, and away from places where winds diverge, such as the mid-latitudes, where the majority of the world's deserts are found.

Increases in evaporation and moisture will imply more moisture is moved from dry areas to wet areas and into storm tracks at higher latitudes, assuming no significant changes in global wind patterns. Global warming may also alter the global circulation pattern, creating a shift in the world's wet and dry zones.

In June 2021, a California farmer removed almond orchards due to a lack of water to irrigate them. The east-west divide, mountains, and moisture local circumstances, such as the form of the land, the types of plants that grow on it, and the existence of major water bodies, all influence these dynamics. except for the West Coast, the western United States is dry due to its location in the rain shadow of mountains. The western mountain ranges force the westerly wind from the Pacific Ocean higher. The air cools as it rises, and precipitation occurs on the mountain's windward side. The moisture has already rained out by the time the wind reaches the leeward side of the mountains. The air warms as it descends the mountains, lowering the relative humidity even further.

In July 2021, the 'bathtub ring' encircling Lake Mead indicated record low water levels in this vital Colorado River reservoir. The reservoir's capacity dropped below 35%, resulting in water restrictions.

The easterly trade wind, on the other hand, brings moisture from the North Atlantic and the Gulf of Mexico to the eastern United States. Increased temperature means more moisture in the atmosphere, which leads to greater precipitation and stronger storms with abundant moisture supply.

This is what years of precipitation data indicate, as well as what climate models predict for future precipitation. With global warming, both show a drop in yearly precipitation in the West, implying more protracted spells of drought, and an increase in the East.

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