Protecting the Rain by Klaus Mager

(Originally published on LinkIn by Klaus Mager)

When we think about rain, we often imagine it as a force beyond human control — a natural occurrence dictated by distant weather patterns. However, a closer look at the hydrological cycle reveals that we have a profound influence on local rainfall. One key process is evapotranspiration — the movement of water from the soil through plants and back into the atmosphere. Moisture in the soil is taken up by plant roots, moves through the plant, and is released through the leaves as water vapor. This vapor then rises, contributing to cloud formation and, ultimately, local rainfall.

In fact, a significant portion of rainfall is local, coming from the water that plants release through evapotranspiration. The more plants and healthy soils we have in an area, the more moisture is available to return as rain. This cycle, often underappreciated, highlights the essential role that plants, particularly in healthy ecosystems, play in maintaining not just vegetation but water availability itself.

Evapotranspiration not only cycles water, but also energy. This system works very similar to an air conditioning unit or refrigerator. At the surface, plants take up energy (heat) to transpire water into vapor in their leaves. This cools the ground. In the sky, vapor condenses as little cloud droplets, releasing the heat and sending much of it into space. When moving from under asphalt into the shade of a tree, we all have perceived the cooling effect — it is not just the shading of sunlight, but about one third of the effect is active cooling from evapotranspiration. And there are cascades of additional cooling effects from this small water cycle: clouds shade out the sunlight during the day. Especially in warm climates, vegetation-made clouds foster evening rainfall and then leave dry and clean air such that daytime heat can radiate into space at night. Evaporation can also shift the wind patterns of entire regions.

At the heart of this cycling of water and energy is soil — specifically, the capacity of soil to hold water. This capacity is directly related to the amount of organic carbon present in the soil. Healthy soils, rich in organic matter, act like sponges, storing water from rainfall and slowly releasing it to plants and into the atmosphere. For example, soils with just a 1% increase in organic carbon can hold an additional 20,000 gallons of water per acre. This natural water retention system regulates both climate and the availability of clean water, supporting life across the ecosystem.

In a healthy ecosystem, plants, microorganisms, and soils work together to maintain this balance. Soil-rich organic carbon promotes plant growth, stabilizes water cycles, and stores carbon, mitigating climate impacts. These processes underscore the beauty of natural systems — they regulate themselves and ensure the sustainable availability of resources, like water, crucial for life on Earth.