Climate change now detectable from any single day of weather at global scale

We’ve always said when you look at weather that’s not the same as climate. That’s still true locally, if you are in one particular place and you only know the weather right now, right here, there isn’t much you can say. However, on a global scale, that is no longer true. Global mean temperature on a single day is already quite a bit shifted. You can see this human fingerprint in any single moment.

Reto Knutti, study co-author of ETH Zurich

• States that for generations, climate scientists have educated the public that ‘weather is not climate’, and climate change has been framed as the change in the distribution of weather that slowly emerges from large variability over decades
• States, however, that weather when considered globally is now in uncharted territory
• Detects—on the basis of a single day of globally observed temperature and moisture—the fingerprint of externally driven climate change, and concludes that Earth as a whole is warming
• Detects the fingerprint of climate change from any single day in the observed global record since early 2012, and since 1999 on the basis of a year of data
• Finds that detection is robust even when ignoring the long-term global warming trend
• This complements traditional climate change detection, but also opens broader perspectives for the communication of regional weather events, modifying the climate change narrative: while changes in weather locally are emerging over decades, global climate change is now detected instantaneously