In yet another year defined by record breaking weather events, attribution science can play an important role in articulating how climate change is both contributing to and worsening extremes.
In broad strokes, attribution science identifies and quantifies human contributions to climate change and its related impacts. Attribution research has provided foundational understanding about climate change for over 30 years and has been a cornerstone of the United Nations’ Intergovernmental Panel on Climate Change (IPCC) assessments, which serve as the global authority on consensus climate change science. These studies are retrospective and distinct from climate impact time series because they isolate the role of climate change and address questions of causation. Similarly, they are separate from projection studies that model the impacts of climate change into the future.
Attribution science includes four interrelated subfields—trend, source, impact, and extreme event—which provide different kinds of insight into the consequences of climate change. This blog, however, will focus specifically on what extreme event attribution can tell us about our world and discuss strategies to communicate both its findings and its limitations.
A brief history of extreme event attribution
Did climate change make this heatwave more likely?
Did climate change make this downpour more intense?
Extreme event attribution (EEA) answers research questions like these. Like so many scientific disciplines, attribution research has evolved over time, allowing scientists to answer new questions about the impacts of fossil-fueled climate change.
The first EEA study focused on a devastating heatwave that occurred in Europe in 2003, that led to 35,000 excess deaths and the creation of extreme heat warning programs in countries across Europe. The study, published by Peter Stott and colleagues in 2004, found that human influence had more than doubled the likelihood of this event. While attribution methods had previously shown how climate change had contributed to trends like rising global average surface temperatures, this study represented a huge methodological advance by isolating the role of climate change in an individual event for the first time.
Over the past 20+ years, the field has evolved rapidly, increasing our understanding of how climate change is driving extreme weather. This type of 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, research on extreme heat has shown that climate change made the 2021 Pacific Northwest heatwave up to 3.6°F hotter.
Sometimes this research finds that climate change did not play a role in a given extreme event. A study focused on May 2023 extreme rain in northern Italy, for instance, found that climate change didn’t affect the event’s likelihood or severity. Results like these affirm the rigor of this methodology, but are also rare given the fundamental changes to our atmosphere.
EEA studies have also become critical evidence in IPCC assessment reports, supporting key findings like:
“Human-caused climate change is already affecting many weather and climate extremes in every region across the globe” and “It is virtually certain that hot extremes (including heatwaves) have become more frequent and more intense across most land regions since the 1950s, with high confidence that human-induced climate change is the main driver of these changes.”
Each statement and figure included in the Summary for Policymakers section of IPCC reports (like those quoted above) are approved by every country that participates in the IPCC in collaboration with the report’s scientific authors. As a result, the inclusion of EEA research in IPCC reports and the Summaries for Policymakers underscores the robust methodology that underlies these studies as well as their role in shaping the consensus understanding of climate change.
Innovative studies moved the field of EEA forward in 2025, with two high profile studies that addressed research questions about the contributions of emissions from the Carbon Majors, the largest fossil fuel producers and cement manufacturers in the world, to extreme heatwaves.
One study attributed the economic costs of several extreme heatwaves to the emissions of the Carbon Majors, finding that the emissions of single emitter, Chevron, have led to between $791 billion to $3.6 trillion USD in heat related losses over a 31 year period.
Another study systematically attributed 231 heatwaves to emissions from the Carbon Majors, finding that their emissions contributed to half of the increase in heatwave intensity over the last 120 years, and that between 16 and 53 of these heatwaves would not have occurred without emissions traced to these entities. Like the Stott study in 2004, these studies highlight major developments in extreme event attribution and foreshadow the exciting research on the horizon.
Ease of attributing the role of climate change depends on event type and geography
Extreme event attribution research builds on decades of peer-reviewed science. The available data and methodology, however, mean that scientists can attribute some types of events with higher confidence and that the geographic spread of these studies skews heavily towards events in the Global North.
The events that can be attributed with the most confidence are those that are most closely tied to temperature increases, like heatwaves. Isolating the contribution of climate change can be more complicated for more complex events, like convective storms that involve more complex processes. This translates to different levels of confidence in the attribution of certain types of events, which is reflected in the published literature about these topics. The IPCC is very clear about this while also affirming the confidence and rigor of studies and event types where scientists have stronger confidence in their conclusions.
Extreme event attribution research is also not well distributed geographically, with lots of studies focused on events in the Global North and far fewer studies on events in the Global South. Systemic issues can make bridging this gap difficult. For example, long term data sets required to establish a baseline in this type of research are often more readily available the Global North, which carries important equity implications as attribution science becomes important in the accountability and litigation spaces.
EEA research is one important tool among many for understanding climate change. However, remaining cognizant of its limitations and working to overcome them will be key as the field continues to develop.
Communicating about climate change and extreme events
Attribution science is a broad field of research, but EEA research has become its poster child, in part, due to the work of World Weather Attribution which conducts rapid attribution studies using peer reviewed methods, often resulting in broad media coverage. While these studies have increased awareness of fossil fueled extreme events, they have also led to confusion about what types of questions attribution science can and can’t answer. answer.
Attribution science answers questions like: did climate change make this event more frequent or intense?
It does not answer the question: was climate change the sole contributor to this event?
Similarly, we’re never going to have an attribution study for every event. But even without one, climate science—particularly trend attribution research—can inform our thinking about how climate change may have played a role.
For example, hurricanes are super complex events, and tropical cyclone formation is notoriously hard to model. As a result, I’m not aware of any EEA studies that demonstrate how climate change contributed to the formation of a specific hurricane. As discussed above, much research has established the connection between climate change extreme precipitation associated with hurricanes.
However, we also have robust trend attribution research that shows the key role of climate change in rising sea surface temperatures, which can allow storms to rapidly intensify. Similarly, sea level rise attributed to climate change can exacerbate flooding from hurricanes. When talking about hurricanes in the absence of an EEA study, highlighting these key pieces of information is key in contextualizing how climate change may be contributing to these events. This distinction matters because scientific integrity requires us to be clear about what we know and what we don’t. We can state with confidence that climate change is warming oceans and raising sea levels (both of which worsen hurricane impacts) while acknowledging that other aspects remain less certain. Being precise about this strengthens, rather than weakens, the science.
Wildfires represent another example of this. As individual events, they are incredibly difficult to attribute to climate change due to the range of factors that play a role like historical banning of cultural burning practices by Indigenous communities, forest management, and ignition source. But we have amazing trend attribution science that can allow us to say a lot about the role of climate change in these events. A 2016 study, for example, showed that climate change via increased dryness nearly doubled burned area in forests of western North America between 1986 and 2015. This study looked at many wildfires in aggregate to understand the role of climate change.
Following the devastating January 2025 wildfires in Los Angeles, one rapid attribution study found that climate change made the observed extreme fire weather—that drove the rapid spread of wildfires in the region—35% more likely. Together, this research shows that while event attribution studies allow us to quantify the specific contribution of climate change to a given event, we have a wide range of other science we can rely on to show how climate change is impacting our communities and ecosystems.
Moving forward: Five things to keep in mind when talking about attribution science
As attribution science continues to grow and find new applications—from IPCC assessments to courtroom evidence to help with city planning—how we talk about it matters. 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 tells us how climate change influenced an event’s likelihood or intensity, not whether climate change was the sole driver of an event. This distinction matters when framing EEA as answering “did climate change make this more likely or severe?” rather than “did climate change cause this?” and avoids overclaiming 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 tie closely to temperature increases, can be attributed with high confidence. More complex events like extreme precipitation or hurricanes involve additional factors that complicate isolation of climate change’s contribution. Attribution science still has a lot to say about most event types, but communicating these differences transparently strengthens credibility while still affirming the robust methodology underlying the research. These methodological constraints represent opportunities for the research to further develop.
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 okay. Trend attribution research can inform our understanding even when event-specific studies don’t exist. For hurricane formation and intensification, for example, we can point to robust science on rising sea surface temperatures and sea level rise to 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. Communicating EEA as part of this broader toolkit helps highlight 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 first 2004 European heatwave study to 2025 Carbon Majors research attributing economic costs and heatwave occurrence to specific emitters, EEA has rapidly expanded the questions it can answer. Pointing to these advances signals that attribution science is dynamic and continues to develop new tools for understanding climate impacts.
Attribution science has come a long way in two decades and continues to develop. By communicating its findings and its boundaries clearly and constructively, we can help ensure this research continues to inform the decisions, policies, and accountability efforts that shape our climate future.