Climate change began long before humans started tracking it and new data taken directly from the earth's oceans and living things shows our global warming targets are off by about half a century.
While scientists previously determined climate change data from instrumental records that began in the late 1800s, a new study published in Nature on Thursday looked for telltale signs of change in coral growth, ocean sediment, ice cores, tree rings and cave stalagmites.
Lead researcher Nerilie Abram said these natural records began changing long before humans started taking measurements.
"We wanted to ask the question 'when did climate change begin?' And our direct observations were not long enough, so we turned to these natural recorders," the paleo climate scientist told The Huffington Post Australia.
"When we saw the results, it was quite astounding.
"We questioned the result. We questioned our research methods. We questioned everything but that was the result that stuck -- the effects of climate change started to be seen about 180 years ago."
Abram told HuffPost Australia the research had important implications for global climate change targets.
"It's a project we've been working on for four years of hard slog science. I's nice to step back and see what we achieved, but also to see how it fits into the bigger conversation around the world.
We're already very close to the 1.5 degree target, but this earlier component of warming that we've shown pushes us even closer.Nerilie Abram
"Scientists met in Geneva last week to talk about the [COP21 Agreement's] very ambitious target to limit warming to 1.5 degrees. We're already very close to the 1.5 degree target, but this earlier component of warming that we've shown pushes us even closer.
"Even without this contribution of extra earlier warming, we don't have long before we hit those warming targets."
Climate Council professor Will Steffen said the research was a dire warning to today's ever-increasing population.
"In the first half of the 1800s, the human population was much smaller, homes did not have electricity and coal-fired power generation was in its infancy," Steffen said.
"And yet this study finds that Earth's climate was still responding to the small increase in carbon emissions at the start of the Industrial Age.
19th century changes were small and slow compared to the massive, planet-wide changes in climate we are experiencing today.Will Steffen
"Last month was the hottest month in the history of the Earth and 2016 is likely to be the third year in a row to break global temperature records.
"This study demonstrates that human influence on the climate system can be traced back to centuries ago, but that those 19th century changes were small and slow compared to the massive, planet-wide changes in climate we are experiencing today."
Nature's watchful sentinels
Abram said the research project began at Australian National University because she had a hunch the ocean could tell climate scientists about its history.
"The oceans are really important and have been largely overlooked," she said.
"In the tropical oceans, we used coral records for information because corals grow a lot like trees and their rings, every year they put down another layer of their skeleton, and as the chemistry of the ocean changes, so too does their structure.
"It was quite hard to find the big living corals but once we had them, the living part of the coral is only on the very upper surface so what's below is all old skeleton that's been laid down and can be drilled out.
"It's challenging to go back in time more than 400 years, then we need to look at other things like sediment cores."
In the murky mud of the ocean floor are layers of tiny shell creatures, that lived their life absorbing chemicals in the ocean and kept that information encoded in their shells.
"It seems like sand and mud but these sediments contain the organisms and the chemicals they absorbed form the ocean surface while they were alive."
Ice cores in the Arctic and the Antarctic completed the picture, along with tree rings and cave systems.
"They're all telling us the same thing," Abram said.
"I hope it gives an extra push to the urgency of climate change. We need to get into tacking this problem very, very quickly."Suggest a correction