As we face yet another year marked by unprecedented weather events, the field of attribution science is crucial in highlighting how climate change is both contributing to and exacerbating these extremes.
Essentially, attribution science measures and quantifies the human impact on climate change and its associated effects. This research has laid the groundwork for understanding climate change over the past three decades and has become key to the United Nations’ Intergovernmental Panel on Climate Change (IPCC) reports, which are recognized globally for consensus on climate science. These studies are retrospective, focusing on the role of climate change and causation, unlike time series studies or future projections of climate impacts.
Attribution science encompasses four interrelated areas: trend, source, impact, and extreme event attribution, each offering different insights into climate change consequences. This article will specifically explore the role of extreme event attribution and discuss how to effectively communicate its findings and limitations.
A brief history of extreme event attribution
Did climate change make this heatwave more likely?
Did climate change intensify this downpour?
Extreme event attribution (EEA) seeks answers to such questions. Over time, attribution research has evolved, enabling scientists to investigate new queries about fossil-fueled climate change impacts.
The first EEA study examined a severe heatwave in Europe in 2003, which resulted in 35,000 excess deaths and prompted the development of extreme heat warnings across Europe. Research by Peter Stott and colleagues in 2004 revealed that human influence more than doubled the likelihood of this event, showcasing a major methodological breakthrough in isolating climate change’s role in individual events.
Over the past two decades, the field has rapidly advanced, enhancing our understanding of climate change’s role in extreme weather. Research has shown that during Hurricane Harvey, climate change tripled the likelihood of extreme rainfall and increased total rainfall by at least 19%, with a best estimate of 37%. Similarly, studies on extreme heat have found that climate change made the 2021 Pacific Northwest heatwave up to 3.6°F hotter.
Occasionally, research indicates that climate change did not influence a specific extreme event. For example, a study on May 2023 extreme rain in northern Italy found no impact from climate change on the event’s likelihood or severity. Such results underscore the rigor of this science, though they are rare due to fundamental atmospheric changes.
EEA studies have become vital evidence in IPCC assessment reports, supporting conclusions like:
“Human-caused climate change is already affecting many weather and climate extremes globally” and “It is virtually certain that hot extremes (including heatwaves) have increased in frequency and intensity across most land regions since the 1950s, driven by human-induced climate change.”
Every statement and figure in the Summary for Policymakers section of IPCC reports (such as those quoted above) is approved by all participating countries alongside the report’s scientific authors. Thus, the inclusion of EEA research in IPCC reports and summaries emphasizes the strong methodology behind these studies and their role in shaping the consensus on climate change.
Innovative research propelled the EEA field forward in 2025, with two notable studies examining the emissions of the Carbon Majors, the largest fossil fuel producers and cement manufacturers globally, and their contributions to extreme heatwaves.
One study linked the economic costs of several extreme heatwaves to emissions from the Carbon Majors, finding that Chevron’s emissions alone led to $791 billion to $3.6 trillion USD in heat-related losses over 31 years.
Another study systematically attributed 231 heatwaves to the Carbon Majors’ emissions, concluding that these emissions were responsible for half of the increase in heatwave intensity over 120 years, and that 16 to 53 of these heatwaves would not have occurred without emissions traced to these entities. Like the 2004 Stott study, these works mark major advancements in extreme event attribution and hint at promising future research.
Ease of attributing the role of climate change depends on event type and geography
Extreme event attribution research is built on decades of peer-reviewed science. However, the data and methodology available mean that scientists can attribute some event types with higher confidence, while studies are predominantly concentrated in the Global North.
Events most confidently attributed are those closely linked to temperature increases, like heatwaves. In contrast, complex events like convective storms present challenges in isolating climate change’s influence, resulting in varying confidence levels in different event types, as reflected in the literature. The IPCC clearly articulates this, while also affirming the rigor and confidence in studies where conclusions are more robust.
Geographically, extreme event attribution research is unevenly distributed, with a focus on events in the Global North and fewer studies on those in the Global South. Bridging this gap is challenging due to systemic issues, such as the availability of long-term data sets more accessible in the Global North, which has significant equity implications as attribution science becomes crucial in accountability and litigation contexts.
EEA research is a vital tool among many for understanding climate change. Recognizing its limitations and striving to address them is essential as the field progresses.
Communicating about climate change and extreme events
Attribution science is a vast field, with EEA research emerging as its flagship, partly due to the efforts of World Weather Attribution, which conducts rapid attribution studies using peer-reviewed methods, gaining significant media attention. Although these studies have raised awareness of fossil-fueled extreme events, they have also caused confusion about the scope of questions attribution science can address.
Attribution science addresses questions like: did climate change make this event more frequent or severe?
It does not address the question: was climate change the sole cause of this event?
Similarly, an attribution study will not be available for every event. Yet, even without one, climate science—particularly trend attribution research—can guide our understanding of climate change’s potential role.
For instance, hurricanes are highly complex phenomena, and modeling tropical cyclone formation is notoriously difficult. Currently, no EEA studies demonstrate how climate change influenced the formation of a specific hurricane. However, extensive research has established the link between climate change and extreme precipitation associated with hurricanes.
Additionally, robust trend attribution research demonstrates how climate change contributes to rising sea surface temperatures, potentially leading to rapid storm intensification. Similarly, sea level rise attributed to climate change can worsen hurricane flooding. When discussing hurricanes without an EEA study, emphasizing these critical points is important for contextualizing climate change’s impact. This distinction is vital because scientific integrity demands clarity about what is known and unknown. We can confidently state that climate change is warming oceans and raising sea levels (both exacerbating hurricane impacts) while acknowledging that other factors remain less certain. Clearly presenting this information strengthens the science.
Wildfires provide another example. Attributing individual wildfire events to climate change is extremely difficult due to various influencing factors, such as the historical banning of cultural burning by Indigenous communities, forest management practices, and ignition sources. However, trend attribution science offers valuable insights into climate change’s role. A 2016 study showed that climate change-induced dryness nearly doubled the burned area in western North American forests between 1986 and 2015. This study examined numerous wildfires collectively to assess climate change’s influence.
Following the devastating January 2025 wildfires in Los Angeles, a rapid attribution study determined that climate change increased the likelihood of the extreme fire weather that fueled the wildfires’ rapid spread by 35%. Collectively, this research illustrates that while event attribution studies can quantify climate change’s specific impact on an event, a broad array of other scientific research can demonstrate how climate change affects our communities and ecosystems.
Moving forward: Five things to keep in mind when talking about attribution science
As attribution science advances and finds new applications—from IPCC assessments to courtroom evidence and city planning—how we discuss it is crucial. Here are key considerations for communicating about EEA and attribution science more broadly:
1. Be precise about the questions EEA can answer. Extreme event attribution reveals how climate change influenced an event’s likelihood or severity, not whether it was the sole cause. This distinction is important when framing EEA as answering “did climate change make this more likely or severe?” rather than “did climate change cause this?” and avoids overstating while still conveying meaningful information about climate change’s role.
2. Acknowledge varying confidence levels without undermining the science. Confidence in attribution findings varies by event type. Heatwaves, which closely correlate with temperature increases, can be attributed with high confidence. More complex events like extreme precipitation or hurricanes involve additional factors, complicating the isolation of climate change’s contribution. Attribution science still provides significant insights into most event types, but transparently communicating these differences enhances credibility while affirming the robust methodology underpinning the research. These methodological constraints present opportunities for further development.
3. Absence of an attribution study doesn’t mean absence of a climate connection. Not every event will have a dedicated attribution study, and that’s acceptable. Trend attribution research can inform our understanding even when specific studies are unavailable. For hurricane formation and intensification, for example, robust science on rising sea surface temperatures and sea level rise can contextualize climate change’s role without needing a specific EEA study for each storm.
4. Extreme event attribution exists within the broader attribution science research field. Extreme event attribution is one of four interrelated subfields, alongside trend, source, and impact attribution. Presenting EEA as part of this broader toolkit underscores that multiple lines of evidence can inform conclusions about climate change’s contributions, even when one type of study isn’t available.
5. Attribution science is robust and continues to evolve. From the initial 2004 European heatwave study to the 2025 Carbon Majors research attributing economic costs and heatwave occurrences to specific emitters, EEA has rapidly expanded the questions it can answer. Highlighting these advances signals that attribution science is dynamic and continues to develop new tools for understanding climate impacts.
Attribution science has made significant strides over two decades and continues to progress. By clearly and constructively communicating its findings and limitations, we can ensure this research continues to inform the decisions, policies, and accountability efforts shaping our climate future.
