Some people are still unaware that the global warming we are currently experiencing is unprecedented on Earth. However, there have been many instances of global warming and climate change on our planet throughout history. What is important to note is that no previous global warming event has occurred in such a short period as the current one. In other words, it is human activity, through polluting practices, that is accelerating the global warming process due to greenhouse gas emissions.
Around 56 million years ago, Earth experienced a fairly abrupt period of global warming known as the Paleocene-Eocene Thermal Maximum (PETM). Want to know what caused this pronounced global warming?
Global warming 56 million years ago
At that time, human beings had not yet appeared, so we could not be the cause of such global warming. For those who think that this is natural and that the Earth suffers from time to time global warming that lead to climate changes, and that this is normal, it is not.
It is true that for millions of years, the Earth has experienced unexpected temperature increases and climate changes, but these have occurred over periods of thousands of years. In our current climate change, only about 250 years have passed since the start of the Industrial Revolution and the emission of greenhouse gases began. To better understand the causes of these phenomena, it is helpful to analyze the origins of global warming.
Around 56 million years ago, a massive release of carbon dioxide (CO2) into the atmosphere significantly raised global temperatures. The Paleocene-Eocene Thermal Maximum is undoubtedly the fastest and most extreme naturally occurring global warming event our planet has experienced in the last 66 million years. This global warming lasted approximately 150.000 years, and global temperatures increased by at least 5 degrees Celsius, a rise comparable to some of the predictions for the modern climate beyond the end of this century.
Reason for global warming
This global warming was very abrupt and was not caused by humans. So, what could have triggered such a rise in temperatures worldwide? It has been suggested in the scientific community that it was caused by the injection of carbon into the ocean and atmosphere ; however, the definitive trigger, the source of this carbon, and the total amount released have so far remained unknown.
However, where could such large quantities of CO2 have come from, enough to raise the average global temperature by 5°C? Research conducted by Marcus Gutjahr's international team, formerly at the University of Southampton in the UK and now at GEOMAR (Helmholtz Centre for Ocean Research) in Kiel, Germany, suggests that it may have been due to gas emissions from volcanic eruptions. For a more detailed analysis of global warming in relation to volcanoes, you can visit the Natural Atmospheric Particles section.
To this day, volcanoes are not responsible for the increase in the concentration of greenhouse gases, so it is normal to think that in the past neither. However, it must be taken into account that volcanic activity so many millions of years ago was much more frequent and intense than today.
Research and measurements
To understand the cause of CO2 emissions, a combination of new geochemical measurements and global climate modeling was used. This determined that this extreme global warming was caused by a geologically rapid doubling of atmospheric CO2. When we say "rapid," we mean a period of less than 25.000 years (which is why we cannot compare this global warming to the current one, not at all), with volcanoes being the direct cause of these emissions.
Furthermore, this can also be corroborated by the fact that this period roughly coincided with the formation of vast expanses of basalt ocean floor, thanks to large quantities of lava that spread across the seabed. This occurred when Greenland began to separate from northwestern Europe, creating the North Atlantic Ocean. To learn more about the implications of global warming on the oceans, you can consult the article on the Caspian Sea.
