Scientists Have Proved The Human Influence On Global Warming
Researchers from Rutgers University (USA) found that the current global warming differs from previous major climate changes. The scientists' work is published in the journal Science Advances.
Scientists have tracked the dynamics of changes in sea level and glaciers in the Cenozoic era, which lasts on Earth for 66 million years. They studied the chemical composition of samples of deep-sea sedimentary rocks in the Pacific ocean for the content of oxygen-18 isotopes. By the presence of this substance, you can presumably find out the temperature of seawater and its oxygen saturation in the past. Scientists also analyzed the ratio of magnesium and calcium in the shell walls of single-celled foraminifera organisms to estimate the temperature in deep waters.
It is noted that the content of oxygen-18 isotopes depends on the ice cover and sea level. Scientists also knew that the level of isotopes in rocks is affected by the amount of light that reaches the Earth's surface. It differs due to fluctuations in the axis of the planet. These patterns are combined into Milankovich cycles.
The researchers found that 56-48 million years ago, The earth had a warm period, during which the atmosphere contained a large amount of carbon dioxide in the absence of ice due to increased seawater levels.
According to scientists, about 16 million years later, the first glaciers appeared, and another 30 million years later, the South and North poles were covered with ice.
The seawater level began to decline to 27,000 years ago and then began to grow at a rate of about 40 millimeters per year. Until the beginning of the twentieth century, this indicator did not change, but then again there was an accelerated growth.
The described climate changes coincided with the chronology of Milankovich cycles, except for the modern melting of glaciers. From this, scientists concluded that in the past, climate shocks were caused by changes in The earth's orbit, while the current greenhouse effect is mainly associated with human activity.