Scientists have proven that current global warming is different from other climate shifts that have occurred on the planet over the past 2000 years. Previous cold snaps and warming were not planetary, but regional, caused by natural forces. Whereas at the end of the 20th century (the 21st century was not studied), the temperature on 98% of the Earth's territory turned out to be the highest for the entire study period. This near global warming is unique to the modern era.
Moreover, the rate at which the temperature rises today far exceeds any previous fluctuations. These fluctuations were mainly caused by natural causes, including powerful volcanic eruptions, rather than anthropogenic greenhouse gas emissions. These are the findings, voiced in three papers published in the journal Nature and Nature Geoscience, Science News reports.
Using all available sources and data, researchers from the University of Bern and other world scientific centers analyzed how the temperature on Earth has changed since the first year of our era. Further, international teams prepared more than 15,000 different climatic reconstructions of past global changes. Then the researchers studied the exact timing of the warming and cooling of 4 previously identified "climatic eras": the warm "Roman" period - from about 1 to 300, the cold period of the Middle Ages from 400 to 800, the warm period from 800 to 1200 and the Small Ice Age period from 1300 to 1850.
They found that those past climatic eras were not simultaneous global events that spanned the entire planet. For example, during the Little Ice Age, the central and eastern Pacific Ocean reached their minimum temperature as early as the 15th century, while northwest Europe and southeast North America cooled to a minimum two centuries later, by the 17th century.
The next study revealed what natural forces could be behind the huge regional fluctuations in temperature, again why did the Little Ice Age happen? It turned out that powerful volcanic eruptions were the main driver of such large-scale temperature fluctuations. The eruptions initially led to a cooling and climate change, and then a recovery period, when the planet warmed up again. This recovery coincided with the start of the Industrial Revolution, in which greenhouse gases became the main driver of modern global warming.
The authors of the works state that the research results do not "discover America." But this time, different groups of scientists conducted independent analyzes and came to a common opinion: modern global warming looks unusual, the temperature rise occurs simultaneously everywhere and its rate is higher than in previous millennia. In addition, this time, researchers have created unique models that can synthesize and reproduce the temperatures of the past 2,000 years.