Uncovering the Early Signs of Climate Change in the 19th Century
Imagine if scientists in the 19th century had access to modern tools to study the atmosphere. They might have detected the early warning signs of a major shift: human activities, such as burning coal and wood, were already impacting the climate.
A recent thought experiment by a team of Earth and atmospheric scientists suggests that by 1885, just before the invention of fossil fuel-powered cars, we could have hypothetically detected the first stages of this climate change. Their findings indicate that human influence on atmospheric temperature could have existed for over 130 years.
In reality, the discovery of the heat-trapping properties of carbon dioxide only began in the mid-1800s. Emissions of this gas were on the rise due to the Industrial Revolution in Europe. It wasn’t until the 1970s that systematic scientific studies started to reveal the role of carbon dioxide in modern climate change.
The researchers’ hypothetical scenario assumes that accurate measurements of global atmospheric changes could have been made by 1860. They used instruments like satellite microwave radiometers and estimates of carbon dioxide changes from ice cores and stratospheric balloons.
Despite the warming effect of greenhouse gases, the early warning signal of climate change would have manifested as stratospheric cooling. This cooling is a result of human emissions of carbon dioxide and ozone depletion.
Greenhouse gases trap radiation in the lower atmosphere (troposphere) and increase the reflective power of the stratosphere, causing heat to bounce back towards Earth. Ozone depletion reduces the stratosphere’s ability to absorb heat, resulting in stratospheric cooling and tropospheric warming.
The researchers suggest that by 1885, the human-caused stratospheric cooling could have been identified, even before the era of gas-powered cars. This highlights the early impact of human activities on the climate.
Unless a time machine is invented, we can only speculate on how this early detection could have altered the course of climate change. It has been over 50 years since we first understood the implications of climate change, yet we still struggle to break free from our dependence on fossil fuels.
As we stand at the brink of dangerous anthropogenic interference with climate, the choices we make in the near future will determine the trajectory of our planet. Sustainable pathways must be followed to avoid irreversible damage to our environment.
The study was published in PNAS.
