A groundbreaking study has uncovered that the human fingerprint on global warming was likely detectable in Earth’s atmosphere much earlier than previously understood. According to the research, which is detailed in a paper published in the journal Proceedings of the National Academy of Sciences, significant signs of human-caused climate change were likely visible as early as 1885—prior to the widespread use of gas-powered vehicles but following the onset of the industrial revolution.
The study employed a combination of scientific theory, modern observational data, and advanced computer models to analyze changes in the atmosphere. The researchers aimed to identify when the signs of human-induced climate change first became evident. Lead author Ben Santer and co-author Susan Solomon were surprised to discover a clear human signal in the upper atmosphere much earlier than anticipated.
Historically, the start date for detectable human influence on surface temperatures has been considered to be in the early-to-mid-20th century. However, the study focused on the stratosphere, the second layer of the atmosphere, which reacts differently to greenhouse gas emissions compared to the lower troposphere where most weather occurs. While greenhouse gases elevate temperatures in the troposphere, they cause a cooling effect in the stratosphere, particularly in its upper regions.
The researchers found that a mere 10 parts per million increase in carbon dioxide concentrations between 1860 and 1899 was enough to render the signs of climate change detectable in the atmosphere. In stark contrast, carbon dioxide levels are projected to increase by approximately 50 parts per million from 2000 to 2025, highlighting the escalating pace of climate change.
Professor Gabi Hegerl from the University of Edinburgh, who was not involved in the study, emphasized the implications of these findings, stating, “The results show it would have been detectable very quickly.” This underscores the significant influence of greenhouse gas increases on the upper atmosphere, which can serve as an early indicator of climate trends.
Andrea Steiner, a climate scientist at the Wegener Center for Climate and Global Change in Austria, noted that the study confirms the potential for earlier detection of human-caused climate change in the atmosphere compared to surface levels. She stated, “This confirms that temperature change signals of the atmosphere are effective not only for detection, but also as early indicators of the success of climate mitigation efforts.”
Both Santer and Solomon stressed the critical need for ongoing observation of the upper atmosphere, especially in light of recent budget cuts affecting scientific research. These cuts particularly target key climate monitoring programs within agencies like NOAA, NASA, and the Department of Energy. Santer highlighted the serious implications of losing the ability to measure and monitor changes in our environment, stating, “When we lose the capability to measure and monitor how our world is changing, it makes us all less safe.”
This study illuminates the historical context of human influence on climate change and underscores the urgent need for continued scientific monitoring. As global temperatures rise and the impacts of climate change become increasingly evident, understanding our past and present is crucial for effective climate action and mitigation strategies.
