Climate Change Made Texas Floods 20% to 30% More Severe

Last Updated on: 11th July 2025, 10:39 am

The devastating floods that swept through Central Texas in early July 2025 are a human tragedy, first and foremost. Current reports have 120 dead and more than that still missing. Thousands more have lost homes, and the economic damage will likely run into the billions. This catastrophe, unfortunately, has a clear and scientifically measurable fingerprint from climate change.

While it’s tempting to perceive global warming’s influence as subtle or distant, the reality is both immediate and consequential. Climate attribution models, employing robust, peer-reviewed methods, have determined that climate change made these floods 20% to 30% more severe than they otherwise would have been.

Before examining the mechanics of this impact, it’s important to pause and acknowledge the scale of human loss. Families across Texas are grappling with enormous grief and uncertainty. Entire communities face an uncertain path to recovery. Understanding the underlying scientific drivers isn’t simply an academic exercise, it clarifies the scale of the threat we collectively face, helping ensure society’s response matches the enormity of the challenge.

Without human-caused climate change, far fewer people would have died. Far fewer people would be missing and likely dead. Far fewer people would be newly homeless. Far fewer businesses would be destroyed. Tens of millions of damages instead of billions.

How does an abstract figure like a 20% to 30% increase in flood severity manifest in reality? At its core, the flooding was driven by extraordinarily heavy rainfall. Rapid attribution studies from organizations like World Weather Attribution and Climate Central estimate that the rainfall itself was about 7% wetter due to climate change. A seemingly modest 7% increase in precipitation is surprisingly powerful.

Rainfall intensity is closely linked to air temperature through a physical principle known as the Clausius–Clapeyron relationship. This principle states clearly that warmer air can hold roughly 7% more moisture per degree Celsius of warming. Today’s global temperatures, which have increased around 2.2° F (1.2° C) since pre-industrial times, directly translate into wetter, heavier rainfall events. The recent Texas flooding event was, consequently, intensified precisely by this mechanism.

This incremental boost in rainfall quickly overwhelms the landscape. Hydrological studies consistently show that even modest increases in rainfall produce disproportionately larger impacts. A 7% increase in precipitation can translate into peak floodwater levels rising by approximately 20% to 30%. To illustrate, in Central Texas river systems, a flood event that would typically cause water levels to rise to around 9.8 feet (3 meters) can easily increase to nearly 13.1 feet (4 meters) due to the additional rainfall. This seemingly modest increment has tangible consequences. Water that previously stopped short of entering buildings instead inundates first-floor living areas, transforms passable streets into dangerous torrents, and submerges bridges that would otherwise remain clear.

The velocity of floodwaters also rises dramatically with this incremental increase. Water flow velocities are sensitive to changes in runoff volumes. A 7% rise in rainfall can lead to velocities increasing from a manageable 2.2 miles per hour (1 meter per second) to hazardous speeds of up to 4.5 to 6.7 miles per hour (2 or 3 meters per second). At these velocities, floodwaters exert significantly greater hydraulic forces, enough to erode roadbeds, undermine building foundations, and carry away vehicles.

What might previously have been slow-moving floodwaters, relatively easy to evade or manage, become fast-moving currents capable of inflicting widespread structural damage and elevating risks to human life. This exponential escalation in flood intensity, stemming directly from modest rainfall increments, underscores precisely why even small shifts in rainfall intensity due to climate change matter profoundly.

Attribution science is critical to understanding and quantifying climate change’s role in extreme events like this flood. It uses rigorous and transparent scientific methodologies, well-established over the past decade. The process begins by defining an extreme weather event clearly, gathering historical meteorological data, and then running thousands of climate model simulations under two contrasting scenarios: one reflecting current, climate-altered conditions, and another reflecting a counterfactual scenario without human-induced climate warming. Comparing these scenarios produces an estimate of how climate change affected the likelihood or intensity of the specific event.

These techniques have been extensively validated and peer-reviewed. Institutions like World Weather Attribution, Climate Central, and the Intergovernmental Panel on Climate Change consistently confirm that attribution science reliably distinguishes human-driven climate influences from natural variability. Notable examples include the attribution of the 2021 Pacific Northwest heat dome, where researchers found the event essentially impossible without climate change, the 2022 catastrophic floods in Pakistan, and Europe’s deadly 2024 floods. Each analysis contributes clear evidence of climate change’s growing fingerprints on extreme weather.

Despite its robustness, attribution science is not without limitations. It communicates probabilities and uncertainties rather than absolute certainties. Historical data limitations, especially in less-monitored regions, introduce further uncertainties. Attribution scientists acknowledge these constraints openly, yet the strength of their results consistently outweighs these uncertainties, providing a critical scientific foundation for informed policy and public response.

Unfortunately, attribution science in the United States has faced recent setbacks. The Trump administration enacted significant cuts in budgets, staffing, and resources dedicated to climate science and environmental research. Agencies critical to extreme weather and climate attribution, notably NOAA, NASA, and the National Weather Service, faced deep funding and personnel reductions. NOAA alone lost nearly a quarter of its budget and hundreds of experienced scientists and analysts, weakening its capacity to carry out rapid attribution analyses independently.

Key datasets essential to climate science have been reduced or removed from public availability. NOAA’s valuable records of billion-dollar weather disasters and climate.gov’s informational resources suffered from ideologically motivated reductions or closures. As a result, while global institutions have stepped up to ensure that the Texas floods were rapidly attributed, the weakened state of U.S. federal climate science capabilities means that crucial domestic research efforts have been compromised, undermining national preparedness and response capabilities in the face of rising climate-driven disasters.

Why does all this matter? Robust attribution science provides clarity. It allows policymakers, planners, engineers, and communities to understand precisely how climate change amplifies extreme weather. It informs policy priorities, infrastructure design, and emergency preparedness. Without strong domestic attribution capacity, the U.S. increasingly depends on external entities to fill this knowledge gap, potentially limiting the effectiveness and speed of responses to increasingly frequent and severe climate-driven events.

Of course, for the current administration that’s the point. Evidence that climate change is real, caused by us and increasingly impactful on American citizens must be suppressed in order to “drill, baby, drill.” But science is global, the attribution is clear, and the world is watching.

As we reflect on the human tragedy unfolding in Texas, it becomes clear that percentages like 20% to 30% aren’t just dry statistics. They represent very real increases in suffering, loss, and economic devastation.

Climate change isn’t a distant threat. It’s an immediate intensifier of risks, reshaping our relationship to weather and its destructive potential. Clear-eyed, objective, and transparent attribution science is essential. It helps us recognize the true costs of climate change, motivates appropriate action, and honors those affected by ensuring that their suffering prompts informed societal action. The Texas floods will likely bring some additional Americans to acceptance of the reality of climate change as something worth voting for action on, a small silver lining on the tragedy.