Human influence on climate detectable in the late 19th century

• 成果类型: Article
• 署名作者: Santer, Benjamin D.; Solomon, Susan; Thompson, David W. J.; Fu, Qiang; Keeling, Ralph F.
• 署名单位: Woods Hole Oceanographic Institution; University of California System; University of California Los Angeles; Massachusetts Institute of Technology (MIT); Colorado State University System; Colorado State University Fort Collins; University of East Anglia; University of Washington; University of Washington Seattle
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-13802
• 发表日期: 2025-06-24
• 关键词: observed variability; temperature trends; MODEL; co2; methodology; atmosphere; mystery; ozone; air

摘要

The physics of the heat-trapping properties of CO2 were established in the mid-19th century, as fossil fuel burning rapidly increased atmospheric CO2 levels. To date, however, research has not probed when climate change could have been detected if scientists in the 19th century had the current models and observing network. We consider this question in a thought experiment with state-of-the-art climate models. We assume that the capability to make accurate measurements of atmospheric temperature changes existed in 1860, and then apply a standard fingerprint method to determine the time at which a human-caused climate change signal was first detectable. Pronounced cooling of the mid-to upper stratosphere, mainly driven by anthropogenic increases in carbon dioxide, would have been identifiable with high confidence by approximately 1885, before the advent of gas-powered cars. These results arise from the favorable signal-to-noise characteristics of the mid-to upper stratosphere, where the signal of human-caused cooling is large and the pattern of this cooling differs markedly from patterns of intrinsic variability. Even if our monitoring capability in 1860 had not been global, and high-quality stratospheric temperature measurements existed for Northern Hemisphere mid-latitudes only, it still would have been feasible to detect human-caused stratospheric cooling by 1894, only 34 y after the assumed start of climate monitoring. Our study provides strong evidence that a discernible human influence on atmospheric temperature has likely existed for over 130 y.