Climate Change and Flood Risks

Written by: Peter Harrison

Category: General

Published: June 8, 2023

Floods have the potential to disrupt lives, destroy property and damage ecosystems. They are also one of the most common and costliest natural hazards, with annual damages estimated to be in the billions of dollars globally.

A range of factors contribute to increased flooding risks, including climate change, population growth and urbanization. In the US, for example, the number of people at risk from a 1-in-100-year flood is projected to increase by 45 percent by 2050. Those at greatest risk are low-income households, older people and minority communities. This is because they are less likely to have access to insurance, transportation during an evacuation and cash on hand in the event of a disaster.

Local governments can take a number of steps to protect their residents and businesses from flooding, such as encouraging their citizens to visit FEMA’s Flood LA flooding risks Map Service Center to understand their community’s flood risk, and by promoting and incentivizing smart planning in local land use decisions. They can also prioritize investments in flood defenses and support state and federal efforts to fund practical solutions for reducing flood risks.

The occurrence of floods is a complex interaction of a wide range of factors, including the frequency and severity of storms, the amount of rainfall, the amount of time between storms, how fast the water rises and the speed at which it flows downstream. The impact of these factors varies across different locations. For instance, flooding from heavy downpours will increase in urban areas as the capacity of drainage systems becomes overwhelmed, whereas riverine flooding will increase in rural areas as the flow of rivers exceeds their capacities.

Climate change is expected to intensify these interactions, increasing the frequency of severe storms and their intensity. It will also result in more moisture being added to the atmosphere, which could lead to an increase in the amount of water that reaches the ground or changes in streamflow or snowmelt conditions.

This combination of factors means that the world’s 1.47 billion people currently exposed to intense flooding are more than twice as likely to experience life-threatening impacts. Around the world, most of those affected by flooding are poor and lack the resources to recover. Those who are insured and have access to financial support are more resilient in the face of flooding, but it is still very difficult for them to cover the entire cost of flood losses.