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New flood maps show that US damages will rise by 26% in the next 30 years alone due to climate change. The inequity is striking.

New flood maps show that US damages will rise by 26% in the next 30 years alone due to climate change. The inequity is striking.

A map of Houston showing flooding extending much farther inland.

Climate change is increasing flood risk in U.S. neighborhoods much faster than people realize. Climate change alone is expected to increase flood damage costs by 26% over the next three decades. An analysis of our flood risk maps shows.

That’s only part of the risk. Despite recent devastating floodsPeople are still building high-risk areas. When we factor in population growth, we find that the U.S. flood-loss rate will be four times greater than the climate-only effect.

Our team Develops Innovative flood risk mapsThat include climate change. It’s the data that Local risk estimates drive local risk you’re likely to see on real estate websites.

We estimated the following in our new analysis, which was published on January 31, 2022 where flood risk is rising fastest and who is in harm’s way. The results show the high costs of flooding and lay bare the inequities of who has to endure America’s crippling flood problem. They also demonstrate the importance to alter development patterns.

Climate change: What role does it play?

Flooding is the Most frequent and most expensiveThe United States is vulnerable to natural disasters and their costs are expected to rise as the climate warms. The results of decades of measurements, computer models, and basic physics prove that. Increasing precipitation and sea level rising.

As the atmosphere heats, it holds approximately 7% more moisture Each degree Celsius that the temperature rises means more moisture is available to be poured as rain, potentially increasing the risk of flooding in the inland. Warmer climates also lead to higher sea levels and storm surges due to land ice melting. Warming ocean water expands.

However, it is difficult to translate that understanding into the impact of future flooding.

A map of Houston showing flooding extending much farther inland.

A Houston map shows how flood risks will change over the next thirty years. Blue areas are today’s 100-year flood-risk zones. The same zones will be found in 2050 as the red areas.
Wing et al., 2022

Previous efforts to link climate change to flood models offered only a broad view of the threat and didn’t zoom in close enough to provide reliable measures of local risk, although they could illustrate the general direction of change. Most flood maps for local areas, such the ones produced by The Federal Emergency Management Agency, have a different problem: They’re based on historical changes rather than incorporating the risks ahead, and The government is Slow to update them.

Our maps account for flooding from rivers, rainfall and the oceans – both now and into the future – across the entire contiguous United States. They are scaled at street-by-street levels and, unlike FEMA maps. They cover floods of all sizes, from nuisance flooding which may occur every few decades to once in a millennium catastrophes.

The hazard maps show only the potential flood areas, Our new risk analysisIt combines this data with data on the U.S. buildings stock to understand what happens when floodwaters come into contact with homes and businesses. It’s the first validated analysis of climate-driven flood risk for the U.S.

The inequity of America’s flood problem

We estimate that flooding costs the nation over $32 billion annually, with a significant burden on the Northwest, Gulf Coast, and Appalachia.

When we looked at demographics, we found that today’s flood risk is predominantly concentrated in white, impoverished communities. Many of these communities are located in low-lying regions near the coasts or Appalachian Valleys that are at high risk from heavy rainfall.

But the risk is rising Rising oceans can reach further inland during storms, high tides and other extreme weather conditions.Over the next 30 year, the flood risk will fall disproportionately on communities with large African American population on the Atlantic or Gulf coasts. Both urban and rural areas in Texas, Florida, and Virginia are home to predominantly Black communities. They are expected to experience at least a 20% rise in flood risk over 30 years.

In the past, poorer communities have been more successful haven’t seen as muchInvestment in Flood adaptationOr infrastructure They are left more exposed. The new data that shows the cost of damage refutes a common belief that flood risk is more concentrated in areas with higher wealth.

A woman carries a child past an area where flood water surrounds low-rise apartment buildings.
Hurricane Florence’s storm surge and extreme rainfall flooded towns on North Carolina’s Neuse River many miles inland from the ocean in 2018.
Chip Somodevilla/Getty Images

Our findings raise policy questions about disaster recovery. Previous research has not found. These groups recover slowerMore privileged residents can lead to more inequalities. Current federal disaster aid Wealthier residents are disproportionately helped. Financial safety nets are essential to avoid financial disasters that can lead to financial stress and deeper poverty.

Flood risk is driven by population growth

Flood risk is also influenced by the increasing population.

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As urban areas expand, people are building in riskier locations, including expanding into existing floodplains – areas that were already at risk of flooding, even in a stable climate. That’s making adapting to the rising climate risks even more difficult.

A satellite image of Kansas City showing flood risk overlaid along the rivers.

A flood map of Kansas City shows the developments in the 100-year flood area.

Hurricane Harvey made this risk very clear when it sent two reservoirs bursting into neighborhoods and flooding homes. built in the reservoirs’ flood zones. It was 2017, Houston is rebuilding communitiesYou should not be in dangerous areas again.

In order to predict future flood risk, we integrated into our model projections how and where people will live. The result: Flood risk in 2050 will be four times greater than that of climate change.

On loan

These results are not alarming. We used a A middle-of the-road pathFor atmospheric greenhouse gas concentrations, one in global carbon Emissions peak in 2040And then, fall.

Importantly, a lot of this impact over three decades is Already locked Climate system. While it is essential to cut emissions now to slow the rate at which sea levels rise and reduce future flood risk, adaptation must be done to protect against the losses projected to 2050.

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These projected losses could be avoided if future developments were not concentrated in the most vulnerable areas. In previous research, we found that for a third of currently undeveloped U.S. floodplains it is cheaper to buy the land at today’s prices and preserve it for recreation and wildlife than develop it and pay for the inevitable flood damages later.

These results highlight how crucial land use and building codes are in adapting to climate change. Protecting lives and property will mean moving existing populations out of harm’s way and stopping new construction in flood-risk areas.

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