How do we Deal with Climate Change? By Restoring the Hydrological Cycle!

I recently found out about the work of Walter Jehne and I was blown away.

Walter is a retired soil biologist from Australia who has created a new framework for dealing with climate change that combines multiple fields of science and provides a clear path for navigating the existential challenge we face.

It turns out that even an immediate cessation of all carbon emissions would not be enough to deal with the challenges presented by climate change. We need to mimic nature to restore the hydrological cycle on a planetary scale in order to cool the planet while we go about moving the excess carbon out of the ocean and the atmosphere and back into the soil – a task that will probably take humanity a few centuries.

Here is a short talk by Walter on the topic.


Here is the big picture.

According to Walter, we receive 342 Watts per square meter of incident solar radiation (ISR) each day but only 339 W/m2 leaves Earth because some of the heat re-radiated by the Earth gets trapped in our atmosphere due to the greenhouse effect. The main culprit has been identified as CO2 concentrations in the atmosphere which has been increasing due to human activities – primarily our land management practices (deforestation, industrial agriculture, desertification) and the burning of fossil fuels. As a reference point, the pre-industrial level of CO2 concentration in the atmosphere was 280 parts per million (PPM), now in excess of 400PPM

We clearly need to stop emissions of COand in fact we need to draw down carbon from the atmosphere back into the soil. But dealing with carbon alone will not do the trick. As we draw carbon down from the atmosphere into the soil, the ocean, which has acted as a massive buffer and has acidified in the process, will rebalance and release carbon back into the atmosphere. Even in the best-case scenario, it will take humanity at least a century to rebalance the three carbon pools (ocean, atmosphere and soil) to restore the 280 PPM of COin the atmosphere that we need for a stable climate.

In other words, we have to handle the increased energy in the atmosphere due to the average daily 3 W/m2 imbalance mentioned above and the resulting climate instability for more than a century.

The key to Walter’s insight is that carbon (CO2) mediates less than 5% of the total energy in the atmosphere; 95% of the total energy is governed by Earth’s hydrology!

It turns out that COconcentration of 400PPM and even 500PPM (which we are almost certain to reach before we turn this big carbon ship around) is not going to kill us – only COconcentrations in excess of 10,000 PPM are lethal to humans.

The real issues are more powerful storms, rising oceans, aridification and the effect on food production, higher temperatures and more violent weather events. To address all of the above while we go about the long drawn process of rebalancing the planetary carbon pools, we need to understand and manage the hydrological cycle.

The punchline is that we need to engage in a planetary effort to restore the carbon sponge in the soil to take advantage of the cooling effect of plants’ transpiration.

Vegetation acts as a powerful hydrological air conditioning system – each gram of water that is transpired moves up to 590 calories of heat from the ground to the upper atmosphere. Through the process of water transpiration, forests and vegetated landscapes are currently transferring 24% of the ISR (incident solar radiation) back into the upper atmosphere. Unfortunately, we humans have created 5B hectares (one hectare is 2.47 acres) of deserts by cutting down 75% of the original Earth’s forests, thereby reducing this powerful cooling effect.  The clearcutting of forests should now be considered ecocide and a crime against humanity.

Our task now is to extend the longevity of green growth to keep transpiration going and to expand plant cover.

Keeping the ground covered by vegetation at all times is important for a couple of reasons. One is to maximize the land area that can act as a natural air conditioning system through the process of pants’ transpiration. The other is to keep the ground cool since soil covered by vegetation is much cooler than bare soil.

As exposed soil is quickly warmed up by ISR it endangers the microbes in the soil responsible for soil fertility, water retention and proper soil structure. The result is often soil erosion including the creation of soil dust in the air that acts as aerosol nuclei for vapor hazes in the air. It turns out that water vapor in the atmosphere represents 60% of the greenhouse gases (GHG) while COrepresents only 20% of GHG.

We also know that every bit of solar energy that hits the soil is re-radiated out to space as infrared-long wave radiation and that part of this re-radiation is trapped by GHG in the atmosphere.  The amount of re-radiation is governed by the Stefan-Boltzmann equation (J* = σ T4) linking the amount of re-radiation to the fourth power of the temperature.

It’s clear therefore that merely dealing with CO2 concentrations in the atmosphere is  insufficient in handling the global warming effects brought about by the 3 W/m2 of energy imbalance mentioned above.

While it is imperative that we reduce CO2 emissions, a much more powerful way to handle the planetary heat imbalance is to reduce the amount of re-radiation in the first place by keeping the ground cool. We can also reduce the amount of re-radiation that gets trapped in the atmosphere by reducing hazes particles and water vapors.

Now how to reduce the water vapor and persistent hazes in the atmosphere?

The key is to condense the water vapor into high albedo clouds which can reflect up to 120 W/m2 of the ISR and more importantly can close the hydrological cycle by bringing the water back to the land as rain. To accomplish this we need to aggregate millions of water vapor particles and haze particles into a drop of rain with the help of rain nuclei.

There are only three types of rain nuclei. The first are salt particles emitted into the air mostly by the oceans’ wave activity. The second are ice crystals that form at high altitudes or at high latitudes. But by far the most important rain nuclei are hydrophilic bacteria hitching a ride to the atmosphere through plant transpiration. The rain then clears the water vapor and persistent hazes from the atmosphere allowing more of the re-radiated heat to escape into the upper atmosphere and rehydrates the landscape, recharging the soil carbon sponge that supports and extends the ground vegetation.

The bottom line is that restoring the hydrological cycle on Earth will allow us to manage the effects of global warming by restoring the carbon sponge in the soil, therefore extending the activity of plants that are not only the most powerful hydrological air conditioning system on Earth but are also the best carbon pumps available to draw carbon out of the atmosphere and back into the soil.

The effects of increasing the soil carbon sponge are greater water holding capacity (for each additional gram of carbon the soil can retain an additional 8 grams of water), more vegetation and therefore cooler ground (reducing the level of heat re-radiation), more fertile soil, and richer microbial communities in the soil providing more nutrient dense food.

If you have read this far, you must be intrigued by the work of Walter Jehne and interested in learning more. Your reward is this more extensive talk by Walter Jehne which I’m sure you’ll find fascinating.


Besides learning more about the expanded framework Walter created, you can also make sure your investments are not still part of the problem and participating in the destruction of the remaining biological capacity we need to restore the hydrological cycle necessary to avert our species extinction!

If you have not already done so, you might want to consider attending my webinar series Align Your Investment with Your Values!