Humans started keeping track of global temperatures around the 1880s. Almost every study on global warning has used these records to see how our climate has changed since the Industrial Revolution, driven by human activities. However, a new study published Wednesday in the journal Nature says that human-induced global warming has been going on since even before we started keeping organized records of temperatures.

Global Warming
Image Credit: Dr. Nerilie Abram / YouTube video

Sustained global warming began in the 1830s

Findings of the study will have potentially huge implications for our existing climate policies. Scientists led by Dr. Nerilie Abram of the Australian National University used paleoclimate records from the past 500 years for the study. They found that sustained global warming started in the Northern Hemisphere land masses as well as tropical oceans in the 1830s. And it was caused by man-made greenhouse gas emissions.

Abram said simply looking at the data from the 1880s on won’t give us the “full picture of how we’ve been changing the climate.” Scientists created paleoclimate reconstructions of temperatures over both sea and land based on the analysis of tree rings, microbes, coral, cave samples, ice cores, and computer simulations. These things include chemical fingerprints that offer insights into what our planet’s temperature was like hundreds of years ago.

Our climate is highly sensitive to greenhouse gases

The temperature rise in the Southern Hemisphere was delayed until around 1880s, according to the study. Scientists concluded that the human-induced global warming began when greenhouse gas emissions from burning fossil fuels were insignificant compared to now. It indicates that the climate is much more sensitive to greenhouse gases than previously thought.

The Earth warmed by 0.2 degrees Celsius between 1850 and 1880. That’s small compared to half a degree Celsius increase in global temperatures in the last 30 years. An early onset of global warming could mean a potentially worse future climate than previously estimated.