Global temperatures will reach unprecedented levels in 50 million years by the end of the century if greenhouse gas emissions are not significantly reduced, a study warned.
German and American experts have analyzed tiny fossils of nuclei drilled from the bottom of the sea to reconstruct the Earth's climate history in the time of the dinosaurs. During this 66 million year period, the planet has seen four distinct climatic states – which scientists have called “hothouse”, “warmhouse”, “coolhouse” and “home.” ÅicehouseÃ¢ â¬. Each of these states is characterized by special concentrations of greenhouse gases and the extent of ice that is stored at the Earth's poles.
For most of the last three million years, the Earth has been in a state of “icehouse” – one characterized by alternating glacial and interglacial periods. However, greenhouse gas emissions and other human activities are now pushing the climate into “warmhouse” and “hothouse” states, experts have warned.
Heat conditions were last seen in the Eocene, which ended about 34 million years ago and in which there were no polar caps. During this time, global average temperatures were 9-14 degrees Celsius higher than they are today.
“The projections of the intergovernmental group on climate change for the year 2300 in the scenario of 'normal emissions' will bring the potential of global temperature to a level that the planet has not seen in 50 million years,” he said. the author of the work James Zachos.
Also in their study, Professor Zachos and his colleagues created a “climate reference curve” called CENOGRID, which shows the global temperature changes from the past to the present and includes various predictions for the future based on emission levels.
“Now we know exactly when it was warmer or colder and we have a better understanding of the underlying dynamics and the processes that drive them,” said the author and the geologist. sailor Thomas Westerhold. Ã¢ â¬ ÅThe time from 66 to 34 million years ago – when the planet was much warmer than it is today – is of particular interest, as it represents a parallel in the past with what it could lead to future anthropogenic change, âhe added.
“We have long known that glacial-interglacial cycles are marked by changes in Earth's orbit,” said Professor Zachos, who conducts research at the University of California, Santa Cruz. These cycles, he added, “change the amount of solar energy that reaches the Earth's surface, and astronomers have calculated these orbital variations back in time.”
Prof. Zachos' previous research has established that a period of rapid global warming about 50 million years ago, which led to climate change in a greenhouse state, was caused by a massive release of carbon in the atmosphere. Similarly, at the end of the Eocene, with the fall of atmospheric carbon dioxide, ice sheets began to form in Antarctica, and the climate shifted to a state of cooling.