A new study reveals that humans caused the last 16 record-breaking years in terms of high heat levels. Furthermore, our impact on global climate change stems back as far as 1937, when industrialized areas burned coal to give power to their factories and emerging technologies, suggesting that the recent hot summers and years would not have occurred were it not for human activity.
"What we found was that we could actually detect human influence on extreme events a lot earlier than we'd thought," said Daniel Mitchell, who participated in the research.
The team also reveals that until recently, the effect found in the study had been masked by the widespread use of industrial aerosols, which diminish temperatures and likely had a cooling effect that spanned the globe.
"Everywhere we look, the climate change signal for extreme heat events is becoming stronger," Andrew King, lead author of the study, said. "Recent record-breaking hot years globally were so much outside natural variability that they were almost impossible without global warming."
During the course of the study, the team looked at weather events that existed outside of the range of natural variability and used climate modeling to compare them to a hypothetical world without human-induced greenhouse gases. The team found that record-breaking hot years can be attributed to climate change; these years are: 1937, 1940, 1941, 1943-44, 1980-1981, 1987-1988, 1990, 1995, 1997-98, 2010 and 2014.
"In Australia, our research shows the last six record-breaking hot years and last three record-breaking hot summers were made more likely by the human influence on the climate," King said. "We were able to see climate change even more clearly in Australia because of its position in the Southern Hemisphere in the middle of the ocean, far away from the cooling influence of high concentrations of industrial aerosols."
When aerosols exist in high concentrations, they are able to reflect more heat into space, which subsequently leads to a decrease in temperatures in the areas where they are most congregated. Conversely, in areas where these aerosols exist in low amounts, the warming effect is more apparent.
Aerosol concentrations were found to be the likely cause of cooling periods in central England, central United States, central Europe and East Asia during the 1970s. In addition, the team claims that aerosol-related cooling is responsible for the delayed emergence of warming in all regions except for Australia.
"It's just kind of scary that we've been influencing the climate for a very long time, and we haven't really done anything substantial to limit our emissions," King concluded. "We've just made the problem worse and worse."
The findings were published in the March 7 issue of Geophysical Research Letters.
