Human Influence on Climate Detectable Since 1885 Study Shows

A new study published in the Proceedings of the National Academy of Sciences reveals that human-induced climate change could have been detected as early as 1885, far earlier than previously believed. Researchers used modern climate models to conduct a thought experiment, focusing on stratospheric temperature changes—specifically, the cooling signature in the upper atmosphere caused by greenhouse gas warming in the lower atmosphere. This distinctive pattern, which contrasts with natural variability, would have been noticeable even with limited Northern Hemisphere data, highlighting the robustness of climate models. The findings indicate that detectable human interference with Earth's climate has existed for over 130 years, predating the invention of gas-powered cars and the peak of industrial expansion. Scientists like Benjamin Santer and Susan Solomon expressed surprise at the clarity of the human signal in the upper atmosphere so early in the record, emphasizing the importance of tracking atmospheric layers beyond surface temperatures. This research underscores a long-standing chapter in climate science history and reinforces our understanding of the magnitude and persistence of anthropogenic climate impact.