There Is 'No Doubt' Humans Are Causing Climate Change, Scientists Say in New Report
While the planet has undergone rising and falling temperature changes throughout its history, a series of studies published this week in Nature and Nature Geoscience set out to refute any notion that the increasing temperatures seen over the last century are simply a normal part of nature’s cycle.
Researchers looked at records of trees, ice, sediment, corals, cave deposits and other evidence from the last two millenniums to determine that Earth has never experienced the quick and widespread temperature changes it has seen in just over the last 150 years.
Warming and cooling periods before have occurred on the planet before, such as the Little Ice Age between 1300 and 1850 CE, and the Medieval Warm Period between 800 and 1200 CE. But a team from the University of Bern found the fluctuations in temperature during these periods varied from location to location and affected less than half the planet at any one time, according to The Guardian, citing the team’s study in Nature.
In comparison, the rise in temperatures over the last century have been felt over 98 percent of Earth’s surface. The only exception is Antartica, where “contemporary warming has not yet been observed over the entire continent,” ABC of Australia noted.
“There is no doubt left — as has been shown extensively in many other studies addressing many different aspects of the climate system using different methods and data sets,” said climate scientist Stefan Brönnimann of the University of Bern, according to the Guardian.
“This paper should finally stop climate change deniers claiming that the recent observed coherent global warming is part of a natural climate cycle,” added Mark Maslin, professor of climatology at University College London. “This paper shows the truly stark difference between regional and localized changes in climate of the past and the truly global effect of anthropogenic greenhouse emissions.”
In the report published in Nature Geoscience, researchers found evidence that over the course of the last 2,000 years, the planet saw its fastest temperature rise in just the second half of the 20th century.
Before 1850, temperature variations on the planet were typically caused by volcanic eruptions, which sent debris into the atmosphere, blocking out portions of the sun, according to NBC.
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But after 1850, decades into the Industrial Revolution — which saw cars and factories transform humans’ way of life — the planet’s warming is found to be largely attributed to greenhouse emissions released by human activity.
“The familiar maxim that the climate is always changing is certainly true,” Scott St. George, a physical geographer at the University of Minnesota in Minneapolis, wrote in a companion piece to the report in Nature.
“But even when we push our perspective back to the earliest days of the Roman Empire, we cannot discern any event that is remotely equivalent — either in degree or extent — to the warming over the past few decades,” St. George continued. “Today’s climate stands apart in its torrid global synchrony.”