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For the past 3 million years, the Arctic has never been as hot as it is now

We have painfully watched the cycle that pleases humanity: every mid-September, the amount of ice covering the Arctic Ocean plummets. This year, the ice covers only 3.74 million square kilometers, the second lowest measurement in 42 years, since scientists used satellites to track the ice here. Ice covers only about 50% of the area compared with 40 years ago.

As the Intergovernmental Panel on Climate Change has pointed out, the level of carbon dioxide in the atmosphere is now higher than at any time in human history. Three million years ago, during the Pliocene-Upper New World, Earth last witnessed the current dense CO2 atmosphere.

Data collected over 42 years (except for 2012) show that the minimum Arctic ice level is decreasing by the end of each summer.

According to geologists studying Earth’s developmental landmarks as well as the climate’s ability to support life, the changes in the Arctic are a sign that climate change will change the planet. this. If greenhouse gas emissions continue to rise, Earth’s climate could be the same as three million years ago, with higher sea levels, unstable weather and a state of both natural and social. people change.

Arctic of the Pliocene

The team led by Julie Brigham-Grette and Steve Petsch – professor and associate professor of geological sciences from the University of Massachusetts Amherst – analyzed the cores of sediment taken from Lake El’gygytgyn in Russia, to better understand the Arctic climate in the Pliocene, a time when the atmosphere contained a lot of CO2. Samples of fossil pollen hidden in sedimentary cores show that the Arctic of 3 million years ago was very different from today.

We know the Arctic is a tree-free plain, with here it is tundra vegetation like grass, water spleen and a species of wild flower. But the pollen in the sediment core, dating back millions of years, comes from trees such as deciduous pine, spruce, pine, and poison pines. This shows that the northern forest was once abundant in the cold soil.

For the past 3 million years the Arctic has never been as hot as it is now | Explore

Boreal forest.

Because the Arctic was much warmer during the Pliocene, the Greeland ice sheet did not exist. Small glaciers that run along the hilly western region of Greenland are one of the few places with year-round ice cover. Only the Arctic was the most icy point on Earth during the Pliocene.

In the past, the sea was warmer and there were no major ice sheets in the Northern Hemisphere, so the sea level was 9-15 meters higher than today. The coast is not what it is today, many bays are deep in surface water. Warm winter also makes it less snowy.

Why is the atmosphere in the Pliocene so much CO2?

Natural events that take place throughout Earth’s history release a lot of CO2 into the atmosphere, while many other processes absorb CO2. The main system that keeps CO2 levels in balance and regulates the Earth’s climate is a “natural temperature stabilizer” in the form of reactive rocks that absorb CO2 in the air.

In soil, some rocks absorb CO2 to decompose into other matter. These chemical reactions take place faster with high temperatures and heavy rainfall – that’s Earth’s climate as greenhouse gases keep increasing.

The other natural temperature stabilizer has its own conditioning mechanism. As CO2 and temperature increase, rock decay rate increases due to absorbing more CO2 in the air. If the amount of CO2 drops to a certain level, the global temperature decreases and the chemical reaction of the rock slows down, the amount of CO2 drops slowly.

For the past 3 million years the Arctic has never been as hot as it is now | Explore

Pliocene scene in the eyes of a 19th century painter.

The rock decomposition reaction occurs faster in the areas where there are many exposed minerals. Examples are places with high erosion, or periods of Earth’s geological plate fluctuations, pushing soil up into steep slopes.

From a geological point of view, the temperature stabilizer operates slowly. For example, at the end of the Dinosaur Era (about 65 million years ago), it was estimated that the CO2 concentration in the air was extremely high (between 2,000-4,000 ppm), and it took 50 million years for the CO2 to naturally drop to reach. levels like the Pliocene, with a density of about 400 ppm (“ppm” unit refers to 1 million parts of air there is 1 part CO2).

Because the rate of change of CO2 in the air is slow, the Earth’s climate also changes slowly. The ecosystem has had millions of years to adapt and recondition itself to suit the general climate.

Will we soon face a climate similar to the Pliocene?

Human activities today create a large amount of CO2, which makes natural CO2 absorption not keep up. At the beginning of the Industrial Age in 1750, the amount of CO2 in the air reached 280 ppm. It only took humans 200 years to bring Earth back to an unprecedented concentration of CO2 in millions of years.

Most of the changes in CO2 density take place since World War II. It is normal that the CO2 density increase by 2-3ppm per year; The Earth therefore heats up at a rapid rate. Since 1880, the Green Planet has warmed by 1 degree Celsius, a rate of increase several times faster than the warming waves that have taken place in the past 65 million years.

For the past 3 million years the Arctic has never been as hot as it is now | Explore

In the Arctic alone, ice and snow reflect the sunlight, making the growth even higher. Therefore, the ice in the Arctic Ocean tends to decrease more and more. Researchers estimate that within two decades, the Arctic will have no ice in the summer.

This is not the only evidence that the Arctic is warming. The melting speed of the Greenland Ice Sheet is remarkably fast. In early August, Canada’s remaining ice shelf broke and fell into the sea. Many sub-arctic seas have witnessed sporadic high temperatures.

If the Earth’s climate is similar to what happened in the Pliocene, coastal cities and agricultural regions near the sea are at great risk. This gloomy future can be completely avoided by minimizing the use of fossil fuels, and turning the thermostat back on to let the Earth cool down a bit.

Check out The Coversation

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