When it comes to the planetary scale, we may seem like puny creatures individually. Yet collectively we have awesome powers over the Earth, for better or worse. Not only are we driving countless species ever closer to the edge of extinction through wanton destruction or heedless negligence. We’ve also been changing the seasons.
According to a team of climate researchers from Lawrence Livermore National Laboratory at the University of California, Berkley, and several other institutes, humans are causing seasonal temperatures to tilt out of balance, thereby altering traditional seasonal weather patterns. They have published their findings in the journal Science.
After using satellite data and computer modelling to size up our global “fingerprint” on the climate, they have reached the conclusion that human activities are markedly affecting seasonal temperature cycles in the troposphere, the lowest layer of Earth’s atmosphere that extends from the planet’s surface to some 16 kilometers into the atmosphere at the tropics and 13 kilometers at the poles. The troposphere is responsible for weather patterns globally.
“[A] human-caused signal in the seasonal cycle of tropospheric temperature can [now] be measured,” the researchers say. The culprit is our excessive carbon dioxide emissions, which are strengthening the planet’s seasonal “heartbeat.” This planetary heartbeat regulates the differences in temperatures between frigid winters and sweltering summers.
The scientists found by help of their computer model simulations that at mid-latitudes the extent of the seasonal temperature cycle increases markedly as a result of increased warming in each hemisphere’s summer season. As average temperatures rise around the planet, summers are becoming warmer more rapidly than other seasons, especially in the Northern Hemisphere.
“Our results suggest that attribution studies with the changing seasonal cycle provide powerful and novel evidence for a significant human effect on Earth’s climate,” Benjamin Santer, the lead author of the study, said in a press release.
Then again, much of this will not comes a surprise to many people. Anecdotal evidence has abounded that the seasons are not what they used to be like around much of the planet. Summer heat records are also being broken with increasing regularity across the Northern Hemisphere. This new bit of research now provides solid scientific evidence that our hunch about the changing of seasons has been right all along.