What is Attribution Science?

Attribution science was first used to offer vital insights on long-term climate trends. Today, advances in climate modelling and statistics make it possible to provide precise quantifications of the human influence on extreme weather events, emission sources, and the resulting societal impacts.

The earliest formal attribution studies in the 1990s focused on trend attribution, detecting fossil fuel-driven climate changes in global temperature, sea level rise, and precipitation shifts. These studies laid the groundwork for broader climate assessments, with the Intergovernmental Panel on Climate Change (IPCC) progressively incorporating attribution science as an important line of evidence in its reports.

A pivotal moment in attribution science came in 2004 when Peter Stott and colleagues published the first event attribution study quantifying how much human-induced climate change increased the likelihood of a specific extreme weather event: the deadly 2003 European heatwave. This research established event attribution as a distinct subfield and led to the rapid expansion of studies examining climate change’s role in hurricanes, droughts, wildfires, and other extreme weather events. By the IPCC’s Fifth Assessment Report in 2014, event attribution was recognized as a central component of climate science.

Source attribution emerged with the groundbreaking work of Richard Heede in 2014, who traced industrial carbon emissions back to major fossil fuel producers and cement manufacturers. This work led to further studies, including a landmark 2017 paper led by UCS scientist Brenda Ekwurzel, which quantified the contributions of these entities to global temperature rise and rising sea levels, providing scientific underpinnings for climate litigation.

The newest subfield, impact attribution, seeks to quantify the direct societal and economic consequences of climate change. This research has demonstrated that human-driven warming has increased the total area burned by wildfires, increased hurricane-related damages, and contributed to rising heat-related mortality.

Central to attribution science is the use of counterfactual analysis, a form of inquiry in which scientists compare two versions of the world using a climate model: one with human-induced heat-trapping emissions, and one without. By comparing different climate scenarios, scientists can see how much human activities have changed extreme weather and long-term climate trends.

In this way, attribution science can answer critical questions about how climate change is affecting our world today. Studies show that human-caused climate change is making heatwaves hotter, downpours more intense, and wildfire weather more extreme.

By providing clear, data-driven insights into the role of climate change in extreme weather and long-term environmental shifts, attribution science has become an important tool for climate accountability, adaptation, and resilience planning.

1. Understanding our changing world: Climate change is changing the places we live, affecting our health, economies, and daily lives. Attribution science helps us understand how and why these changes are happening, as well as who is most impacted, so people and communities can make informed decisions about their futures.

2. Shaping policy and regulation: Policymakers can use attribution science to create targeted ways to deal with and adapt to climate change. Governments and regulatory bodies can use these studies to develop climate policies, allocate resources for disaster preparedness and response, and set emission reduction targets that reflect climate risks.

3. Informing climate litigation: Attribution studies that quantify the relative contributions of different companies and governments to climate change are being used increasingly in lawsuits. These studies show a clear link between emissions traced to companies and the resulting climate damage. This evidence is important for the legal arguments being made.

4. Promoting public awareness and communications: Rapid attribution studies, like those by World Weather Attribution, help the public and media understand how climate change is influencing extreme weather events and who is responsible for emissions. By delivering timely scientific analyses, attribution science informs climate reporting and strengthens public discourse on climate action.

5. Bolstering risk management and infrastructure planning: Cities, businesses, and disaster response agencies use attribution science to assess future climate risks and build resilience. By understanding how climate change affects extreme weather events, decision-makers can enhance infrastructure, improve emergency preparedness, and protect vulnerable communities.

6. Quantifying international loss and damage: The consequences of climate change are not distributed equally. They disproportionately affect vulnerable, low-income nations. Attribution science is integral to discussions on climate finance and loss and damage compensation. Countries and non-governmental organizations use attribution research to support claims for financial assistance and advocate for global policies that address climate-related harms.

UCS is at the forefront of attribution science, producing cutting-edge research and advocating for its application in climate policy and accountability. From strengthening public data, identifying critical research to inform climate litigation, and engaging scientists to take action, UCS collaborates with leading scientists, legal experts, and policymakers to advance the field and ensure that attribution research informs real-world decision-making.

Learn more about UCS’s attribution research:

• Tracing the Tides: How Major Carbon Producers Drive Sea Level Rise and Climate Injustice. This study found that due to the delay between heat-trapping emissions and the consequential impacts on ocean temperatures and ice sheets, previous emissions traced to the largest fossil fuel companies and cement manufacturers have all but guaranteed as much as 22 inches of additional sea level rise by 2300.

• The Fossil Fuels Behind Forest Fires. This study found that emissions from major fossil fuel producers contributed to 37% of the total forest area burned in western North America since 1986. This equates to nearly 19.8 million acres of forested land. The research highlights the significant impact of these emissions on the region’s wildfire activity.

• Tracing Fossil Fuel Companies’ Contribution to Climate Change and Ocean Acidification. This research linked emissions from the largest fossil fuel companies to ocean acidification, finding that more than half of the increase in global ocean acidity since pre-industrial times is attributable to emissions traced to their activities.

• The rise in global atmospheric CO2, surface temperature, and sea level from emissions traced to major carbon producers. This research quantified the industrial contributions to global surface temperature rise, finding that nearly two-thirds of total industrial emissions can be traced to 90 major carbon producers, contributing to nearly half of global mean surface temperature and nearly one-third of global sea level rise since 1980.