An international team of researchers led by the Australian National University claims that climate change is not a recent phenomenon. It turns out that human activity has been causing global warming for the past 180 years.
According to lead researcher Nerilie Abram, an associate professor from the Australian National University (ANU), global warming started during the early part of the Industrial Revolution. The signs were first seen in the Arctic and tropical oceans during the 1830s. This date is earlier than what scientists previously speculated.
“In the tropical oceans and the Arctic in particular, 180 years of warming have already caused the average climate to emerge above the range of variability that was normal in the centuries prior to the Industrial Revolution,” points out the associate professor.
The research team studied records of climate variations of oceans and continents, as well as results of climate model simulations. This analysis also included climate history indications in cave decorations, ice cores, tree rings and corals.
During the 1800s, humans only caused small increases in the atmospheric level of greenhouse gases. However, the planet’s climate responded rapidly even with the tiny increase of carbon emissions.
After the global warming affected tropical oceans and the Arctic, it affected Europe followed by Asia and North America. The Antarctic, on the other hand, experienced delay in climate change. Experts believe this is caused by the ocean circulation, which pushes warm water away from the south and toward the north.
Major volcanic eruptions that occurred in the early 1800s were also studied. However, these events did not play a big role in the start of global warming.
The study was conducted as part of the international Past Global Changes 2000 year (PAGES 2K) Consortium, with the collaboration of 25 scientists from Europe, Asia, Australia and the US. The findings are now available in the journal Nature.