In the first two decades of the 21st century, the threat of flooding convinced more than 7 million people to avoid risky areas or abandon places that were risky, according to a paper Monday in the journal Nature Communications and research by the risk analysis organization First Street Foundation.

Climate change is making bad hurricanes more intense and increasing the amount of rain that storms dump on the Midwest. And in the coming decades, researchers say millions more people will decide it is too much to live with and leave.

First Street found that climate change is creating winners and losers at the neighborhood and block level.

Behind these findings is very detailed data about flood risk, population trends and the reasons people move, allowing researchers to isolate the impact of flooding even though local economic conditions and other factors motivate families to pick up and live somewhere else. They analyzed population changes in very small areas, down to the census block.

Some blocks have grown fast and would have grown even faster if flooding wasn’t a problem, according to First Street. Expanding but flood-prone places could have grown nearly 25% more — attracting about 4.1 million more people — if that risk were lower. Researchers also identified areas where flood risk is driving or worsening population decline, which they called “climate abandonment areas.” About 3.2 million people left these neighborhoods because of flood risk over a two-decade span.