Since Friday, Hurricane Harvey has dumped more than two feet of rain in Houston and parts of the Texas Gulf Coast, triggering unprecedented flooding and causing at least five deaths. The storm, which began as a tropical storm early last week and strengthened to a full-fledged major hurricane by the time it made landfall, has already produced a one-in-500-year flood event, with the National Weather Service calling it “unknown and beyond anything experienced.”

But while the flooding was unprecedented, it was hardly unexpected. Climate scientists have been warning for years that the area of the Gulf Coast where Hurricane Harvey hit would be especially vulnerable to a major storm. A combination of a warming climate and poor city planning left Houston especially susceptible to the kind of natural disaster currently unfolding — and showed that we’re not doing nearly enough when it comes to climate adaptation, or mitigation, to avoid similar disasters in the future.

Hurricane Harvey is a natural disaster, but it’s also a political issue, one that lays bare the risks associated with denying the threat of climate change while building increasingly vulnerable cities.

As with any extreme weather event, the question is not whether climate change caused Hurricane Harvey; the question is whether climate change helped turn what would be an otherwise natural event into the kind of unprecedented disaster now unfolding. In this case, it seems clear that climate change strengthened Hurricane Harvey in two major ways: by intensifying the rainfall associated with the storm, and by creating larger and more dangerous storm surge along the coastline.


To start, the waters in the Gulf of Mexico, over which Harvey formed, were five degrees higher than average. Warmer waters both intensify wind speeds associated with the storm, and allow the air to take up more water, which will then eventually fall as rain. Second, climate change fuels sea level rise, which in turn means higher and more dangerous storm surge. In some areas, Hurricane Harvey produced a storm surge of six feet above normally dry land.

As the world warms, evaporation speeds up. So on avg there's more water vapour for a storm to sweep up & dump now, compared to 70 years ago. https://t.co/M4R9OFFZt9 — Katharine Hayhoe (@KHayhoe) August 24, 2017

Even in a world without climate change, storms like Hurricane Harvey would form — but climate scientists are clear that human-caused warming certainly makes storms more dangerous.

“The storm is a bit more intense, bigger and longer lasting than it otherwise would be,” Kevin Trenberth, a climate researcher with the National Center for Atmospheric Research, said in an email to ThinkProgress.


Response to climate change is often divided into two actions: mitigation, or taking steps to reduce the amount of climate-changing greenhouse gas emissions released into the atmosphere, and adaptation, or taking steps to adapt society to the consequences inherent in a changed climate. Harvey is an example of what happens when neither mitigation nor adaptation are implemented effectively. If anything, Houston — a low-lying city with clear vulnerability to intense precipitation events — has done the opposite. Over the last 25 years, the city has lost almost 50 percent of its wetlands to development; wetlands traditionally serve as a kind of natural flood barrier, absorbing rainfall. Instead, Houston has become an impenetrable expanse of pavement, with 30 parking spots for every one resident. According to ProPublica, the city has paved over 166,000 acres — mostly coastal prairie — in just the last decade and a half.

Houston has also prioritized development over flood-protections, constructing new developments to house the millions of new residents that have moved to the city within the last decade. According to a ProPublica/Texas Tribune investigation published in December, more than 7,000 residential buildings have been built in FEMA-designated flood plains since 2010 in Harris County, which includes Houston. And FEMA-designated floodplain maps might not even fully account for likely flooding, since they are based on historic flood potential — something that has changed now that climate change is fueling more intense downpours.

Repairing and rebuilding developments located in floodplains often comes at a cost to the taxpayer: in Houston, the U.S. Department of Housing and Urban Development subsidized at least eight low-income housing projects located within a 100-year floodplain.

Compounding Houston’s vulnerability to climate-fueled storms is the fact that the city has seen rapid expansion of its petrochemical industry in recent years. The Houston Ship Channel houses the nation’s largest refinery, and holds 30 percent of the nation’s total refining capacity, meaning that strong storms or flooding could trigger a major environmental disaster like an oil or chemical spill. To make matters worse, the people living in close proximity to the refineries are overwhelmingly poor and minority communities, throwing into stark relief the fact that the communities most vulnerable to the consequences of climate change tend to be low-income and communities of color.

At this point, humans have burned enough fossil fuels, deforested enough land, and generally altered the climate to bake in significant warming to the planet, potentially as much as 1.3°C (2.3°F). That means that in the future, storms like Harvey — or Matthew, or Sandy, or Katrina — will become stronger, whipping up bigger storm surges and dumping more rain onto cities. The costs associated with those storms will continue to grow in terms of lives lost and property damaged. Houston, for instance, has already seen a doubling in the number downpours of at least 10 inches over the last 30 years.


If cities like Houston continue to prioritize rampant development over resiliency, then those costs will only continue to rise. Some experts have predicted that the cost of Harvey in the Houston metro-area alone could top $325 billion in residential value, an astronomically high number, particularly considering the fact that Houston’s annual gross domestic product is $471 billion.

Adaptation and resiliency measures could certainly lessen the price tag associated with major natural disasters — but as climate-fueled extreme weather events become stronger and more frequent, continuously chasing adaptation is likely to become an expensive zero-sum game. Without taking steps to mitigate greenhouse gas emissions, costs of adapting to climate change could rise to between $280 and $500 billion per year, according to the United Nations Environment Program. Stronger storms also have a direct impact on economic inequality: one study found that for every major disaster, poverty rates in the area hardest hit tend to increase by one percentage point, meaning that in the wake of disasters, it’s the poorest residents that get left behind.

Since a certain amount of global warming, and thus warming-fueled storms, are inevitable in the future, spending money on adaptation is necessary. But it’s also crucial to spend money on mitigation strategies aimed at preventing even more greenhouse gas emissions from entering the atmosphere, thus fueling stronger storms that would, eventually, cost more in both lives and damages.

Mitigation is a long-term investment in not having to evacuate or rebuild major cities, or regions, in the wake of natural disasters. Mitigation isn’t free; it costs money to install renewable energy, to invest in technology for things like carbon capture and storage, and to essentially give up the profits inherent in extracting climate-warming fossil fuels. But studies suggest that the cost of mitigation can be offset by the public health savings (from reduced pollution-related illnesses like asthma, for instance) and from the savings associated with reduced damages from climate-related disasters.

Under the Trump administration, however, the federal government isn’t taking steps to prioritize adaptation or mitigation. Just weeks before Harvey hit, Trump rescinded Obama-era federal guidance requiring projects built with federal money to be constructed to withstand stronger floods — projects like freeways, bridges, hospitals, and schools. The guidance was specifically crafted to account for the likelihood of more frequent extreme climate-fueled flood events, and was widely supported by groups across the political spectrum. Trump is also proposing deep cuts to FEMA and the Coast Guard, two federal agencies that serve crucial roles in responding to natural disasters.

When it comes to mitigation, the Trump administration is nearly 180-degrees from where climate scientists say the world should be headed to avoid the worst consequences of climate change. The administration has time and again shown deference to fossil fuels like coal, oil, and gas, and has paused or rescinded nearly every federal policy aimed at reducing greenhouse gas emissions, from the Interior Department’s methane rule to the EPA’s Clean Power Plan. Trump has also expressed his intention to fully withdraw the United States from the Paris climate agreement, and has said that he will not send any more money to international climate funds, meaning that he will not help developing countries pay for better mitigation or adaptation strategies.

On Sunday, longtime Trump friend and Milwaukee County Sheriff David Clarke — whose book Trump promoted on Twitter over the weekend during the storm — criticized the “deranged liberal left” for “politicizing Tropical Storm Harvey to use against” Trump. But a storm like Harvey — or any disaster for that matter — is inherently political, a result of the policies like unchecked development, subsidization of flood plain construction, and climate denial that, combined, make extreme weather events even more dangerous. The smart thing to do isn’t to pretend that disasters like Harvey don’t have political underpinnings; the smart thing would be to take a look at the policies that helped make Harvey a costly and deadly disaster, and make better choices in the future.