Scientists: man is obliged by the emergence to global warming
Modern forms of life arose when the temperature of the seas reached 25 degrees, which is five degrees higher than we see today.
Modern life forms originated in the time when there was a sharp jump of temperature. To such conclusion scientists from the University of Leicester, writes The Independent.
About 540 million years ago there was the so-called “Cambrian explosion” during which appeared chordates, which include people. Scientists have long suspected that it was a particularly warm period in Earth’s history, but only now they managed to get the evidence.
Scientists cannot directly measure the temperature of the sea 500 million years ago. Therefore, for the experiment they used isotopes of oxygen that are popular paleothermometers. These isotopes were extracted from a tiny fossil shells obtained using the acid from blocks of limestone. It is assumed that these shells to 515 million years.
– A careful study of these tiny fossils has shown that some of them have well-preserved shell chemical composition, which has not changed since then, as they grew up on the Cambrian seabed, said one of the study’s authors, Thomas Horning.
Studying the levels of oxygen isotopes, the scientists were able to get a clear idea about what was the temperature of the sea during the Cambrian period. Their analysis showed that in high-latitude oceans of water was heated to 25 degrees, about 5 degrees higher than now. In modern terms, the Cambrian explosion occurred on the background of global warming.
2017 was one of the warmest in the entire history of observations
The deviation in mean annual temperature from the average 1981 -2010 years was 0.5 degrees Celsius.