Billions and counting in harm's way: Climate change and population growth

The full extent of the devastation left by Hurricane Ian as it tore through Florida remains to be determined, but its destructiveness is expected to be greater than many comparable storms because of the large amount of built infrastructure in its path.

Ian made its first U.S. landfall near Fort Myers as a Category 4 storm (where 5 is the most destructive with the highest wind speed), causing a 12-foot-high storm surge, wrecking homes and knocking out power for more than 2 million people. At the time of writing, the hurricane is believed to have claimed at least 76 lives in Florida and another four in North Carolina.

A growing target

Between 1970 and 2020, the Cape Coral-Fort Myers area grew almost seven-fold, to close to 800,000 people. Overall, Florida is the fastest growing eastern state, and from 2020 to 2021, it experienced the second largest numeric growth of all states, after Texas. Most of this growth comes from domestic migration, with people drawn from other parts of the U.S. by year-round warm weather and a lower cost of living.

More people and buildings moving into the path of hurricanes is an example of the “expanding bullseye effect,” whereby the risks and costs associated with natural disasters increase as populations grow and spread. Urban development to accommodate more people, including road construction, further increases the risk of flooding by making the ground impermeable. On top of that, hurricanes and other climate-related natural disasters are becoming more frequent and devastating under global warming.

Hazards geographer Dr. Stephen Strader told the Washington Post:

“It’s going to affect more people than ever before. We really haven’t done much to check this growth… What we are finding out is that is not sustainable.”

Disadvantaged areas worst affected

While media attention turned to Florida, hundreds of thousands of Puerto Ricans were still without reliable power after Hurricane Fiona hit the island in mid-September. Fiona arrived almost exactly five years after Hurricane Maria, an even more devastating storm with an estimated death toll of close to 3,000.

Globally, one in four people (almost two billion) are at risk of severe floods, and 89% of them live in low- to middle-income countries with limited means to protect themselves and to rebuild after disasters. A study published in 2020 found that the number of people exposed to floods increased by 34.1% between 2000 and 2015. Sea level rise and changing rainfall are expected to further increase flood risk, especially in low-lying coastal areas which have some of the fastest growing populations.

In Pakistan, more than five million people are now facing a severe food crisis after catastrophic flooding following heavy rainfall and glacier melt which killed nearly 1,700 people. Pakistan has one of the highest fertility rates in Asia, at 3.5 children per woman. Only 20% of Pakistani women of reproductive age use modern contraception, and the floods have made it even more difficult to obtain vital reproductive health care. Bangladesh is also facing a dire future—75% of the country is below sea level, and the population is growing rapidly, causing people to live in precarious settings that raise their risk of experiencing floods and landslides.

While cutting emissions to limit global climate impacts is of critical importance, research shows that sea levels will rise by at least 27cm (10.6in) due to inevitable ice melt.

Floods and flames

As some parts of the world are ravaged by excess water, others are going up in flames due to lack of it. The devastation caused by wildfires is also increasing as a result of climate change and population growth in vulnerable areas.

Towns that suffered extensive fire damage on the U.S. West Coast are now debating the logic of spending hundreds of millions on rebuilding efforts only to watch it all burn down again. Increasing wildfire smoke in the American West is now threatening to reverse decades of improvements in air quality.

A study published this year found that the fastest rate of population growth in the western states is occurring in the areas with the highest fire risk. The number of people living in high fire hazard areas grew from 1 million in 1990 to 2.6 million in 2010, the latest year with detailed population data—an increase equivalent to the current populations of San Francisco and Seattle combined. The study’s authors are unsure why so many people are moving into fire-prone areas, but they suspect lack of affordable housing is pushing people out of cities and into areas with more intact (and drought-prone) vegetation.

The only long-term fix

There is clearly a moral imperative to prevent these expanding bullseye scenarios. This can be done by limiting movement of people into disaster-prone areas through the provision of similar opportunities and lower living costs in less vulnerable areas. Many people currently located in high-risk areas will need relocation assistance.

In addition, we must work to end global population growth by ensuring everyone has the power to choose their family size. Slowing population growth by investing in family planning and girls’ education builds resilience to climate shocks and is a powerful climate change mitigation strategy.

In the face of escalating storms, floods, fires, and resource scarcity, the wealthiest countries that are largely responsible for the climate crisis must urgently ramp up international efforts to protect as many lives as possible.