Human Activity Impacts Vertical Structure of Atmospheric Temperature: Implications for Weather

Human activity is affecting our climate. Now, though, scientists have found out how else we're impacting our world. It turns out that human activity is influencing the vertical structure of atmospheric temperature, which could have implications for weather patterns in the future.

In order to find out exactly how human activity might be impacting temperatures in our atmosphere, scientists employed observational satellite data and computer model-predicted response to human influence. It turns out that both the satellite data and the model prediction have a common latitude/altitude pattern of atmospheric temperature change. More specifically, the scientists saw a global-scale tropospheric warming and a stratospheric cooling. The troposphere is the lowest portion of Earth's atmosphere, while the stratosphere lies just above it.

Natural internal fluctuations in the climate are generated by interactions of the coupled atmosphere-ocean system, such as the well-known El Niño. External influences, in contrast, include greenhouse gases and stratospheric ozone. These influences all have a unique "fingerprint" in the detailed latitude/altitude pattern of atmospheric temperature changes.

"Human activity has very different effects on the temperature of the upper and lower atmosphere, and a very different fingerprint from purely natural influences," said Benjamin Santer, one of the researchers, in a news release. "Our results provide clear evidence for a discernible human influence on the thermal structure of the atmosphere."

In fact, the scientists found that current climate models are highly unlikely to produce the distinctive signal pattern that they found by internal variability alone. Instead, it's likely that the temperature changes were caused by human-caused increases in greenhouse gases. That said, there are other influences that can cause these changes, such as major volcanic eruptions, though it's unlikely that they're solely to blame.

"During the recovery from such eruptions, tropospheric warming and stratospheric cooling also occur," said Celine Bonfils, one of the researchers, in a news release. "But in contrast to volcanic influences, human-caused atmospheric temperature changes affect all latitudes and last longer. This suggests that the recent changes in temperature are not simply a recovery from past volcanic events."

The findings are published in the journal Proceedings of the National Academy of Sciences.