Climate Change Fueling Surge in Extreme Rainfall, Warns Climate Central Study

Climate Central’s recent research highlights a significant trend: severe rainstorms are becoming increasingly common across the United States. This trend is intricately linked to the broader impacts of climate change, with warmer temperatures intensifying the water cycle. As the atmosphere warms, it holds more moisture, leading to more frequent and intense precipitation events. For flood risk management professionals, these findings underscore the urgent need to adapt infrastructure and flood prevention strategies to cope with changing weather patterns.

According to Climate Central’s analysis, the frequency and intensity of extreme precipitation events have risen markedly in recent decades. The report reveals that since the 1950s, the northeastern United States has experienced a 60% increase in the heaviest rainstorms, while the Midwest has seen a 45% rise. These regions, particularly the Northeast, are projected to continue seeing significant increases in severe rainstorms. This escalation in extreme weather events is not uniform across the country, but certain areas are undeniably more affected.

Some of the greatest increases in heavy rainfall events are expected in the Northeast, Midwest, and Great Lakes regions. Cities like New York, Boston, and Chicago are likely to face more frequent and severe rainstorms, which can lead to urban flooding, overwhelmed stormwater systems, and significant economic and social disruptions. In these densely populated areas, aging infrastructure may be particularly vulnerable, necessitating extensive upgrades.

Traditional stormwater systems, often designed based on historical rainfall data, may no longer be sufficient. Enhanced modeling and mitigation techniques that incorporate future climate projections are crucial for designing resilient infrastructure. This includes expanding stormwater capacity, integrating green infrastructure solutions like permeable pavements and green roofs, and ensuring that floodplain management practices are updated to reflect new realities.

Other key findings:

• With 2°C (3.6°F) of warming, the majority (85% or 2,645) of the 3,111 total U.S. counties are likely to experience a 10% or higher increase in precipitation falling on the heaviest 1% of days.
• On average, U.S. counties are likely to experience a 17% increase in precipitation falling on the heaviest 1% of days.
• Counties likely to experience at least a 30% increase in extreme precipitation are concentrated in: Tennessee, Alabama, Georgia, Mississippi, Maine, North Carolina, and Kentucky.
• Alaska and Hawaii are likely to experience some of the highest levels of extreme precipitation intensification (43% and 30%, respectively) at 2°C (3.6°F) of global warming.
• The Southwest may experience more flash floods due to the short bursts of extreme rainfall.  

Read more about the Climate Central research, including downloadable datasets and graphics.