by Daniel Brouse and Sidd Mukherjee
August 10, 2025
Introduction: Observing a Vanishing Pool
I’ve been researching evaporation for decades, but sometimes the most telling experiments happen in my own backyard. At the start of this pool season, rainfall far exceeded evaporation. Then, for the past two months, the balance flipped: with little rain and intense heat, the pool lost about 10 inches of water solely from evaporation. This small observation mirrors what’s happening globally — a shift toward higher net water loss as temperatures climb.
The 2003 Invention: Cooling Through Evaporation
In 2003, I invented Solar Powered Climate Control: Energy Transfer Through Evaporation. The idea was simple: collect rainwater and drip it over the roof on hot days. As the water evaporated, it absorbed heat from the structure, removing massive amounts of energy from the building.
When water evaporates, it transitions from liquid to vapor, a phase change that requires a huge energy input. In our experiments, Sidd calculated:
“For every cubic foot of water that evaporated, it took 61,000 BTU with it.”
The results were remarkable: my electric bill dropped by two-thirds. Back then, I saw evaporation as a potential climate solution. Now, I see how climate change itself is supercharging evaporation — and in ways that can harm as much as help.
The Physics of Evaporation
Evaporation is among the most powerful natural cooling mechanisms on Earth. The latent heat of evaporation, L, measures the energy required to transform water into vapor without changing its temperature:
-
L = 8,094 BTU per gallon
-
1 BTU = 1,055 Joules
-
1 calorie raises the temperature of 1 gram of water by 1°C
-
Levaporation = 536 calories/gram
This means that even small amounts of evaporating water move massive amounts of energy from the surface into the atmosphere — energy that doesn’t just disappear, but fuels storms and weather extremes.
Climate Change and Evaporation’s Double-Edged Sword
Evaporation cools surfaces locally, but globally it adds more water vapor to the atmosphere. According to the Clausius-Clapeyron equation, for every 1°C increase in temperature, air can hold about 7% more water vapor. In regions of the U.S. that are experiencing +10°C seasonal anomalies, the atmosphere can now hold about 70% more water vapor than in the past.
This fuels several dangerous trends:
-
Stronger storms — The extra moisture is energy for hurricanes, atmospheric rivers, and severe thunderstorms.
-
More intense rainfall — Raindrops are becoming larger and faster, increasing their momentum (p = mv). Higher drop count per second boosts total impact force.
-
Flash flood severity — With more raindrops falling at higher velocities, momentum and destructive power increase significantly.
-
Erosion & soil degradation — Heavy rains strip away topsoil, reducing agricultural capacity.
Flow Dynamics: Scaling Forces with Climate Change
The drag equation shows that force increases with the square of velocity and is proportional to fluid density. This means:
-
Doubling wind speed quadruples its force.
-
Water is ~800× denser than air, so water flow at the same speed exerts ~800× the force of wind.
As climate change drives higher wind and water speeds, the destructive potential grows exponentially. A modest increase in velocity can translate into catastrophic increases in force — toppling trees, collapsing infrastructure, and scouring soil.
Evaporation, Drought, and the Feedback Loop
Warming oceans — particularly in the tropics — are releasing increasing amounts of water vapor into the atmosphere. Atmospheric rivers transport this moisture and energy inland, fueling more intense rainfall events.
On land, rising temperatures are accelerating evaporation from both plants and soil. By 2025, “corn sweat” had even entered weather forecasts. This term refers to the large amounts of water vapor released by corn plants through transpiration—the process by which plants draw water from their roots, move it up through the stalk, and release it into the air from tiny pores in their leaves.
A mature cornfield can release several thousand gallons of water per acre per day into the atmosphere during peak growing season. The effect is so pronounced that meteorologists now factor corn sweat into heat index forecasts for states like Iowa, Illinois, and Nebraska.
While this moisture can increase local humidity to dangerous levels for people, it’s also a sign of stress for the plants themselves. High heat and increased transpiration can sap soil moisture, reduce yields, and inflict economic losses across agricultural regions already strained by climate change.
But here’s the climate “whiplash” problem:
-
More extreme rainfall events lead to floods, soil loss, and infrastructure collapse.
-
More extreme droughts follow because warmer air strips moisture from the ground faster, especially when relative humidity remains low despite higher absolute humidity.
As soil moisture evaporates away, ecosystems degrade. Once soil structure collapses, desertification can set in — a feedback loop that is much harder to reverse than to prevent.
From My Pool to the Planet
Measuring the water loss in my swimming pool is straightforward. Measuring the net evaporation of the Earth’s soils, forests, and croplands is far more complex — but the trend is clear. Net evaporation is rising. Precipitation is becoming more extreme but also less reliable. Soil degradation is accelerating.
What began as an experiment in using evaporation to mitigate heat now reveals a stark reality: climate change is pushing evaporation into a new role as a driver of instability.
Soil Degradation and Desertification
The Rapid Acceleration of Soil Degradation and Desertification Part II
The Converging Collapse: AMOC, Jet Streams, and Deadly Wet-Bulb Temperatures
Climate Change and Deadly Humid Heat
Burning to Stay Cool: How Our Fight Against Heat Is Fueling Climate Collapse
Solar Powered Climate Control: Energy Transfer Through Evaporation
Understanding Urban Heat Islands: Causes, Data, and Climate Context
Ignite a Domino Effect: Albedo, Brown Carbon, AMOC, Permafrost, Amazon Rainforest Dieback, Sea Level Rise Pulses, Hydroclimate Whiplash, and Arctic Sea Ice