Cold weather doesn’t prove global warming is fake, despite what President Trump and other climate change deniers have tweeted for years. Climate scientists have spent considerable time and energy attempting to explain how, as National Geographic reported last year, “an atmosphere changed by rising levels of gases like carbon and methane leads to more climate changes than just warming.”
While it remains true that increasing levels of dangerous gases have multiple impacts on our weather, a new study conducted by researchers in Sweden and Norway, and published in the journal Nature Climate Change, would upend the long-established narrative that daily weather is distinct from long-term climate change, The Washington Post reported Thursday. The study also implies that we’ve been underestimating the human impact on extreme weather events like storms, floods and hurricanes.
Researchers used statistical models of weather patterns around the globe and climate modeling to simulate temperature and humidity variations worldwide. In doing so, the authors write in the study’s introduction, “we detect the fingerprint of externally driven climate change, and conclude that Earth as a whole is warming.”
With help from machine learning, researchers pinpointed signals of human-induced global warming on a single day of observations. They concluded that the first signal of human impact on global warming occurred in 1999.
The researchers also concluded, per the Post:
… that the spatial patterns of global temperature and humidity are, in fact, distinguishable from natural variability, and have a human component to them. Going further, the study concludes that the long-term climate trend in global average temperature can be predicted if you know a single day’s weather information worldwide.
Reto Knutti of ETH Zurich’s Institute for Atmospheric and Climate Science, a co-author of the study, told the Post, “We’ve always said when you look at weather that’s not the same as climate.” That remains true in terms of local weather, but, Knutti continued, “Global mean temperature on a single day is already quite a bit shifted. You can see this human fingerprint in any single moment.”
“This … is telling us that anthropogenic climate change has become so large that it exceeds even daily weather variability at the global scale,” Michael Wehner of Lawrence Berkeley National Laboratory wrote in an email to the Post. He called the study results “profoundly disturbing.”
Researchers are calling for a more holistic view of climate change. “Uncovering the climate change signal in daily weather conditions calls for a global perspective, not a regional one,” Sebastian Sippel, a postdoc working with Knutti, explained in a statement.
Read the full study here.