As climate change accelerates, cities around the world are facing growing challenges to their infrastructure, public health, and overall resilience. The District of Columbia (DC) recognized the need to update its 2015 Climate Adaptation Plan with the latest climate projections to ensure the city’s planning and decision-making processes remain scientifically robust and informed by the most current data. At Two Degrees Adapt, we were honored to assist in this critical project, providing the District with updated climate projections that would help guide operations and enhance resilience planning across various city agencies.
The original Climate Adaptation Plan, developed in 2015, served as a foundational document for DC’s resilience strategy. However, as climate science has progressed and data has improved, the city needed to incorporate the most recent projections of extreme heat, precipitation, and sea-level rise impacts. These projections are vital for helping the District understand the future risks posed by climate change, ensuring that both short-term and long-term adaptation strategies are based on the latest scientific insights.
Our approach involved using the best available public climate data and considering both high emissions (RCP8.5, the "worst-case" scenario) and lower emissions scenarios (RCP4.5, the "likely" scenario). These models allowed us to provide a comprehensive set of projections for the 2030s, 2050s, and 2080s—key timeframes that would support both immediate actions and long-term planning. This multi-timeframe approach was designed to address the needs of city agencies working on both short-term resilience strategies and longer-term adaptation goals.
Our analysis revealed a number of concerning trends, highlighting the urgency of updating DC’s resilience plans. One of the most significant projections was the rise in extreme heat. Historically, the city experiences an average of 9 days annually exceeding 95°F, but our projections suggested that by the 2030s, that number could increase to 22 to 24 days. By the 2080s, this could rise even further, with temperatures exceeding 95°F on up to 36 to 67 days per year. Such an increase in extreme heat poses substantial challenges to public health, infrastructure, and emergency response systems, necessitating immediate adaptation measures.
The accelerating rate of sea-level rise was another key finding in our projections. By 2050, we anticipate sea levels will rise by 1.1 to 1.7 feet, with projections for the 2080s ranging from 1.6 to 4.4 feet. This represents a significant increase—19 to 60% higher than the projections in the 2015 plan—and underscores the urgency of updated coastal protection strategies. Rising sea levels will exacerbate flooding risks, which the city must plan for in both infrastructure and emergency response systems.
We also identified increasing risks of extreme precipitation, particularly intense rainfall events. To address this, we recommended updating stormwater design standards beyond the current Atlas 14 specifications to account for heavier rainfall patterns. Extreme precipitation events, combined with rising sea levels, would only worsen flooding risks, making it essential to integrate both into DC’s long-term infrastructure planning.
In addition to these individual climate hazards, we also assessed the compound effects of land subsidence, a critical factor often overlooked in climate adaptation planning. Our projections suggest that the District could experience land subsidence of up to half a foot or more over the next 100 years. This, in combination with rising sea levels, would further exacerbate flooding risks, requiring more comprehensive and multifaceted adaptation strategies.
Stakeholder engagement was a core component of this project. We conducted workshops with District agencies and key stakeholders to ensure that the findings were not only understood but also applied to the city’s resilience planning. These workshops featured carefully designed data visualizations that helped communicate complex climate projections in an accessible manner. We engaged in discussions about how these projections could be incorporated into decision-making, particularly in areas such as emergency operations, infrastructure planning, and building codes. The workshops also provided an opportunity for stakeholders to reflect on the practical applications of the data and discuss how they would affect their respective programs.
Equity considerations were at the heart of our analysis. We recognized that low-income and disadvantaged communities within the District are particularly vulnerable to climate impacts. To address this, we conducted specific analyses to understand how the projected increases in extreme heat, flooding, and sea-level rise would disproportionately affect these communities. Our findings helped identify critical areas requiring targeted adaptation measures, such as improvements to public housing, emergency response systems, and stormwater management infrastructure. By integrating equity into our analysis, we ensured that the District’s climate adaptation strategies would prioritize the most vulnerable residents, safeguarding their health, safety, and well-being.
Our work in updating the District of Columbia’s Climate Adaptation Plan provides the city with the scientific foundation needed to make informed decisions about its climate future. With detailed projections of extreme heat, precipitation, sea-level rise, and land subsidence, we have equipped the city with the tools to make proactive, data-driven decisions. Our findings also highlight the importance of equitable resilience strategies, ensuring that all communities, especially those most vulnerable, are prioritized in the face of growing climate risks.
The updated climate projections we provided will play a crucial role in shaping the District’s future adaptation strategies. By addressing both current and future climate risks, the city will be better prepared to protect its residents, infrastructure, and natural resources from the growing impacts of climate change.
At Two Degrees Adapt, we are proud to have contributed to this important project, and we remain committed to helping cities like DC plan for a more resilient, sustainable future. If you’re interested in learning more about our work or exploring how we can assist your organization in updating climate adaptation strategies, please reach out. Together, we can build cities that are ready for the challenges of tomorrow.