Humans kickstarted climate change 200 years ago, study finds

While most experts seem to agree that human activity played a major role in bringing about climate change, the consensus has been that this is a fairly recent trend, but that is not the case at all, according to new research published in Wednesday’s edition of the journal Nature.

In fact, people have been doing things that contribute to global warming for nearly two centuries, Nerilie Abram, an associate professor from the Australian National University (ANU) School of Earth Sciences, and her colleagues discovered during the course of their research.

“It was an extraordinary finding,” Abram, who is also part of the Australian Research Council (ARC) Centre of Excellence for Climate System Science, said Thursday in a statement. “It was one of those moments where science really surprised us. But the results were clear. The climate warming we are witnessing today started about 180 years ago.”

According to the study authors, the evidence suggests that the first evidence of global warming can be traced back to the dawn of the Industrial Revolution, and signs of its impact first appear in the Earth’s oceans around the 1830s – far earlier than scientists previously thought, and contrary to the assumption that warming was not an issue until the 20th century.

Records, simulations reveal warming actually started around 1830

Abran and two dozen colleagues from Australia, Asia, Europe and the US looked at paleoclimate records starting in the year 1500. They found that the sustained industrial-era warming of oceans first arose during the middle of the 19th century, around the same time that the continents located in the Northern Hemisphere also began to experience an increase in temperatures.

They analyzed detailed reconstructions of climate over the past 500 years, reviewing records of climate variations for both continents and oceans (including those preserved in corals, tree rings and ice cores) and data collected by scientists to pinpoint when the sustained, ongoing warming trend actually began, and concluded that the 1830s were the most likely starting point.

While co-author Dr. Helen McGregor from the University of Wollongong’s School of Earth and Environmental Sciences explained that humans would have only generated slight increases in the atmospheric greenhouse gas levels during the 19th century, “the early onset of warming detected in this study indicates the Earth’s climate did respond in a rapid and measureable way to even the small increase in carbon emissions during the start of the Industrial Age.”

The Arctic and the tropical oceans where the first regions to experience the effects of warming due to increased greenhouse gas levels, Abram said. Europe, Asia and North American followed shortly thereafter, but warming appeared to have been delayed to some degree  in the Antarctic, possibly due to ocean circulation patterns preventing warmer water from reaching the continent.

“The early onset of sustained, significant warming in paleoclimate records… suggests that greenhouse forcing of industrial-era warming commenced as early as the mid-nineteenth century and included an enhanced equatorial ocean response mechanism,” the study authors wrote. “Our findings imply that… in some regions, about 180 years of industrial-era warming has already caused surface temperatures to emerge above pre-industrial values, even when taking natural variability into account.”

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Image credit: British Museum

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