Scientists can now detect the “fingerprint” of human-caused climate change in global daily weather patterns, according to a groundbreaking analysis published Thursday in the journal Nature Climate Change.
The study, Climate Change Now Detectable From Any Single Day of Weather at Global Scale, complicates the well-established narrative about the difference between weather and climate. Generally, the former refers to the conditions of the atmosphere in terms of factors like cloudiness, moisture, pressure, temperature, and wind over a short period of time while the latter is average weather in a region over longer periods.
“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,” the study says. “However, weather when considered globally is now in uncharted territory.”
A research team led by Reto Knutti, a climate professor at ETH Zurich in Switzerland, used statistical learning and climate model simulations to “show that on the basis of a single day of globally observed temperature and moisture, we detect the fingerprint of externally driven climate change, and conclude that Earth as a whole is warming.”
According to the study:
The fingerprint of climate change is detected from any single day in the observed global record since early 2012, and since 1999 on the basis of a year of data. 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.
As lead author Sebastian Sippel said in a statement from ETH Zurich, “Uncovering the climate change signal in daily weather conditions calls for a global perspective, not a regional one.”
'The signal of human-caused climate change has emerged in everyday weather, study finds'https://t.co/oo4qJ34DlH v/ @washingtonpost
'human role in contributing to extreme weather events such as heat waves and floods may be [underestimated by research to date]'#ClimateEmergency
— Cry for the Earth (@GlobalGreenDeal) January 2, 2020
Astrid Caldas, a senior climate scientist at the Union of Concerned Scientists, tweeted that “this study is something we have been expecting to see for a while.”
This study is something we have been expecting to see for a while. #GlobalWarming is not only behind changes in #Climate but its fingerprint was detected in global daily #weather. Yes, this means that super cold days ALSO bear the signal of #ClimateChange – not just hot ones. https://t.co/NBXT1NQjV4
— Astrid Caldas (@climategeek) January 3, 2020
Knutti, in the ETH Zurich statement, suggested that their findings could have broad implications for climate science.
“Weather at the global level carries important information about climate,” he said. “This information could, for example, be used for further studies that quantify changes in the probability of extreme weather events, such as regional cold spells. These studies are based on model calculations, and our approach could then provide a global context of the climate change fingerprint in observations made during regional cold spells of this kind. This gives rise to new opportunities for the communication of regional weather events against the backdrop of global warming.”
Our footprint is everywhere, all the time.
In 2013 @IPCC_CH concluded that humans are the dominant cause of long-term warming. We've just detected climate change in the global weather for every single day since then. https://t.co/2QCGPp0YDz— Reto Knutti (@Knutti_ETH) January 2, 2020
The Washington Post reported that the new study “was in part motivated by [U.S. President Donald] Trump’s tweets about how a cold day in one particular location disproves global warming.” Since taking office in 2017, Trump repeatedly has turned to Twitter to use cold weather events to cast doubt on the international scientific community’s consensus that human activity is driving the climate crisis.
When it comes to clear, timely, innovative science, @Knutti_ETH is the BEST. His new study "motivated by Trump’s tweets about how a cold day disproves global warming, shows that spatial patterns of global temp + humidity do have a human component to them." https://t.co/rXhPmsmd59
— Prof. Katharine Hayhoe (@KHayhoe) January 3, 2020
The Post spoke with multiple climate experts who were not involved with the research, including Michael Wehner of Lawrence Berkeley National Laboratory, who described some of the new findings as “profoundly disturbing,” and Stanford University climate scientist Noah Diffenbaugh, who highlighted the study’s contributions to advancing a global understanding about the impacts of climate change.
“The fact that the influence of global warming can now be seen in the daily weather around the world—which in some ways is the noisiest manifestation—is another clear sign of how strong the signal of climate change has become,” Diffenbaugh said. “This study provides important new evidence that climate change is influencing the conditions that people and ecosystems are experiencing every day, all around the world.”
There are a few “key caveats” about the new analysis, according to the Post:
The study contains uncertainties, particularly when it comes to the accuracy of computer models in simulating various climate cycles. It also does not tease out the importance of other factors that influence the climate, such as land-use change and human-made and volcanic aerosols.
Knutti notes that the use of machine-learning techniques, which can help tease out patterns in large data sets, can introduce uncertainties, as well, although he’s confident those were minimized here.
Sippel said technically the new study does not attribute the climate change trends they found completely to human activities but that there is most likely no other plausible explanation.
Even with the need for further research, reporting on the new findings Thursday has provoked fresh calls for government action to address the climate emergency. Congresswoman Veronica Escobar (D-Texas), in a tweet, tied the research to the failure of President Donald Trump and Senate Republicans to tackle the global crisis, and emphasized this year’s upcoming elections:
We know the fate of our planet is in our hands.
We also know that as long as @realDonaldTrump and the @SenateGOP have their way, our country will compound the #ClimateCrisis, not solve it.
There’s never been a more urgent election. https://t.co/Lw4sB6gsBI
— Veronica Escobar (@vgescobar) January 2, 2020
“This new development means that every day will be marked by the impacts of #climatechange,” Rep. Deb Haaland (D-N.M.) tweeted, linking to the Post’s report. “We must move forward on bills to reduce our impact on climate. #ClimateActionNow.”
Help us Prepare for Trump’s Day One
Trump is busy getting ready for Day One of his presidency – but so is Truthout.
Trump has made it no secret that he is planning a demolition-style attack on both specific communities and democracy as a whole, beginning on his first day in office. With over 25 executive orders and directives queued up for January 20, he’s promised to “launch the largest deportation program in American history,” roll back anti-discrimination protections for transgender students, and implement a “drill, drill, drill” approach to ramp up oil and gas extraction.
Organizations like Truthout are also being threatened by legislation like HR 9495, the “nonprofit killer bill” that would allow the Treasury Secretary to declare any nonprofit a “terrorist-supporting organization” and strip its tax-exempt status without due process. Progressive media like Truthout that has courageously focused on reporting on Israel’s genocide in Gaza are in the bill’s crosshairs.
As journalists, we have a responsibility to look at hard realities and communicate them to you. We hope that you, like us, can use this information to prepare for what’s to come.
And if you feel uncertain about what to do in the face of a second Trump administration, we invite you to be an indispensable part of Truthout’s preparations.
In addition to covering the widespread onslaught of draconian policy, we’re shoring up our resources for what might come next for progressive media: bad-faith lawsuits from far-right ghouls, legislation that seeks to strip us of our ability to receive tax-deductible donations, and further throttling of our reach on social media platforms owned by Trump’s sycophants.
We’re preparing right now for Trump’s Day One: building a brave coalition of movement media; reaching out to the activists, academics, and thinkers we trust to shine a light on the inner workings of authoritarianism; and planning to use journalism as a tool to equip movements to protect the people, lands, and principles most vulnerable to Trump’s destruction.
We urgently need your help to prepare. As you know, our December fundraiser is our most important of the year and will determine the scale of work we’ll be able to do in 2025. We’ve set two goals: to raise $100,000 in one-time donations and to add 1300 new monthly donors by midnight on December 31.
Today, we’re asking all of our readers to start a monthly donation or make a one-time donation – as a commitment to stand with us on day one of Trump’s presidency, and every day after that, as we produce journalism that combats authoritarianism, censorship, injustice, and misinformation. You’re an essential part of our future – please join the movement by making a tax-deductible donation today.
If you have the means to make a substantial gift, please dig deep during this critical time!
With gratitude and resolve,
Maya, Negin, Saima, and Ziggy