Over the last million years, the ice age on Earth comes approximately every 100,000 years. This cycle actually exists, and different groups of scholars at different times tried to find the reason for its existence. However, the prevailing point of view on this issue yet.
More than a million years ago was a different cycle. Ice Age gave way to global warming roughly every 40 thousand. Years. But then the frequency of occurrence of glaciers was replaced with 40 thousand. 100 thousand years before. Why did it happen?
Experts from Cardiff University offered his own explanation for this change. The results of the work of scientists published in the authoritative edition of Geology. According to experts, the main reason for changing the periodicity of the onset of ice ages - it is the oceans, or rather, their ability to absorb carbon dioxide from the atmosphere.
By studying sediments that make up the bottom of the oceans, the team found that the concentration of CO2 varies from layer to layer deposition is just a period of 100 thousand. Years. It is likely, scientists say that the excess carbon dioxide are removed from the atmosphere, the ocean surface with further binding of the gas. As a result, the average annual temperature is gradually reduced, and there comes the next ice age. And it so happened that the duration of the Ice Age more than a million years ago, has increased, and the cycle of "hot-cold" has become longer.
"Probably, the oceans absorb and release carbon dioxide, and when the ice becomes larger, the oceans absorb more carbon dioxide from the atmosphere, making the planet cooler. When the little ice, the oceans release carbon dioxide, so that the climate is getting warmer, "- says Professor Carrie Lear. "By studying the concentration of carbon dioxide in the remains of tiny creatures (here refers to sedimentary rocks), We found that in periods when the glaciers increased, the oceans absorb more carbon dioxide, so it can be assumed that in the atmosphere it becomes smaller."
Seaweed, according to experts, played a major role in the absorption of CO2, because carbon dioxide is a major component of the process of photosynthesis.
Carbon dioxide passes from the ocean to the atmosphere as a result of upwelling. Upwelling or rise - is the process by which the deep ocean water rise to the surface. The most frequently observed in the western boundaries of continents, which moves the colder, nutrient-rich water from the ocean depths to the surface, replacing the warmer, nutrient poor surface water. Also it can occur in almost any area of the world ocean.
The layer of ice on the surface prevents the carbon dioxide in the atmosphere, so that if a significant portion of the ocean freezes, it prolongs the period of the ice.
"If we believe that the oceans absorb and release carbon dioxide, then we need to understand that a large amount of ice to prevent this process. It's like a lid on the surface of the ocean "- said Professor Liar.
By increasing the area of glaciers on the ice surface not only reduces the concentration of CO2 «warming», but also increases the albedo of those regions which are covered with ice. As a result, the planet receives less energy and hence cools more rapidly.
Who on Earth interglacial warm period. The last ice age ended about 11,000 years ago. Since then, the annual average temperature and the sea level is constantly increasing, and the amount of ice on the surface of the water of the oceans decreases. As a result, scientists believe a large amount of CO2 emitted to the atmosphere. Plus, carbon dioxide and produces man, and in large quantities.
All this has led to the fact that in September, the carbon dioxide concentration in the atmosphere has risen to 400 parts per million. This figure has increased from 280 to 400 parts per million in just 200 years of industrial development. Rather, the CO2 in the atmosphere is less than the foreseeable future. All this should lead to an increase in the average temperature on Earth to try on + 5 ° C in the next thousand years.
Specialists of the Department of Climate Research in Potsdam Observatory recently constructed a model of the Earth's climate, taking into account the global carbon cycle. As shown by the model, even at minimum rates of carbon dioxide emissions into the atmosphere of the Northern Hemisphere ice sheet will not increase. This means that the onset of the next ice age could move forward at least 50-100 thousand years. So in front of us waiting for the next cycle of change "glacier-warming", this time the man is responsible for this.
DOI: 10.1130/G38636.1
Referenced Materials:
- http://www.cardiff.ac.uk/news/view/499475-the-100,000-year-problem
- http://www.crossref.org/iPage?doi=10.1130%2FG38636.1