As the world faces another year of unprecedented weather events, the field of attribution science emerges as a crucial tool for understanding how climate change is impacting the frequency and intensity of these extremes. By isolating the human influence on climate change, attribution studies provide insights that are vital for comprehending the current climate crisis.
Attribution science is a branch of research that determines the extent of human contribution to climate change and its subsequent effects. It has been a pivotal element of the Intergovernmental Panel on Climate Change (IPCC) reports, which are regarded as authoritative assessments on climate science. Unlike time series studies that track climate impacts over time, attribution studies focus on the causation by isolating climate change’s role in specific events, distinct from future projection studies.
Within attribution science, four interconnected subfields exist: trend, source, impact, and extreme event attribution. This article will delve into extreme event attribution (EEA), exploring what it reveals about our world while discussing effective communication of its findings and limitations.
The Evolution of Extreme Event Attribution
Did climate change increase the likelihood of this heatwave?
Did climate change intensify this rainfall?
Such questions are at the core of EEA research. The discipline has advanced over time, allowing scientists to explore the repercussions of fossil-fueled climate change on extreme weather events. The first significant EEA study analyzed the 2003 European heatwave, which resulted in 35,000 excess deaths. This study, led by Peter Stott and colleagues, was groundbreaking in showing that human influence had more than doubled the likelihood of such an event.
In the past two decades, EEA research has expanded significantly, shedding light on how climate change is exacerbating extreme weather. For instance, during Hurricane Harvey, climate change tripled the likelihood of extreme rainfall and increased total rainfall by at least 19%. Similarly, the 2021 Pacific Northwest heatwave was found to be up to 3.6°F hotter due to climate change.
In some cases, EEA research has determined that climate change did not significantly impact an event. A study on May 2023 extreme rain in northern Italy found no effect from climate change. Such results highlight the robustness of the methodology, although they are rare due to the extensive changes in our atmosphere.
EEA studies have become vital pieces of evidence in IPCC reports, supporting findings such as:
“Human-caused climate change is already affecting many weather and climate extremes in every region across the globe.”
Understanding the Challenges of Attribution
Attribution science’s ability to link climate change with specific weather events varies based on event type and location. Events directly tied to temperature increases, like heatwaves, are more confidently attributed to climate change. In contrast, complex events such as convective storms pose challenges due to the intricate processes involved.
The geographic focus of EEA research has been skewed towards the Global North, with fewer studies on events in the Global South. This disparity is often due to the availability of long-term data sets necessary for establishing baselines, which are more prevalent in the Global North. Addressing these gaps is crucial as attribution science becomes integral in accountability and litigation contexts.
Communicating Climate Change and Extreme Events
The World Weather Attribution initiative has been instrumental in raising awareness about extreme events fueled by fossil fuels through rapid attribution studies. However, this has also led to misunderstandings about the questions attribution science can address.
Attribution science can answer questions like: Did climate change increase the frequency or intensity of this event? However, it does not determine whether climate change was the sole contributor. Not every event will have a dedicated attribution study, but existing climate science, especially trend attribution research, can still provide insights.
For hurricanes, while specific EEA studies may be unavailable, trend attribution research shows that climate change contributes to rising sea surface temperatures and sea level rise, both of which intensify hurricane impacts.
The complexity of wildfires makes them challenging to attribute to climate change directly. However, trend attribution studies indicate that climate change has significantly increased dryness, nearly doubling burned areas in North American forests from 1986 to 2015. Rapid attribution studies, like the one for the January 2025 Los Angeles wildfires, found that climate change made extreme fire weather 35% more likely.
Key Considerations for Discussing Attribution Science
1. Clarify the scope of EEA. EEA addresses how climate change impacted an event’s likelihood or intensity, not whether it was the sole cause.
2. Communicate confidence variations without undermining credibility. Confidence in attribution varies by event type. Transparency about these variations strengthens the science’s credibility.
3. Lack of an attribution study doesn’t mean no climate link. Trend attribution research can offer insights even in the absence of event-specific studies.
4. Recognize EEA as part of the broader attribution science field. EEA is one of four subfields, contributing to a comprehensive understanding of climate change impacts.
5. Attribution science is evolving. From early studies to recent breakthroughs, EEA continues to advance, expanding the questions it can address.
By effectively communicating the findings and boundaries of attribution science, we can ensure that this research continues to inform policies, decisions, and accountability efforts shaping our climate future.
Original Story at blog.ucs.org