Before we begin, let’s set the scene.

Imagine. It is a sweltering, 100 degree day. There is not a cloud in sight, and the Sun is beating down.

You are sitting in your car waiting to pick up a passenger, and you can’t leave your vehicle. 

On this blistering summer day, would you rather: have all the windows down with gentle breezes blowing through, shade screens on the windows reflecting the Sun away, all while sitting on a moist towel in your car? Comfortable, calm, and cool. 

Or, would you rather: be sitting in a car with all the windows rolled up, on scorching black seats, and no shade screens covering your windows? Full Sun streaming. Sweat running in rivulets as the stifling heat grows exponentially. 

– – –

While the above is an overly-simplified metaphor, it attempts to illustrate how our living, interconnected Earth can keep our atmosphere and climate balanced – or not – through an experience we have probably all felt: the incredible heat-producing ability of a car parked in full sun.

What are the connections? Read on.

How Nature Cools

Let’s place this conversation in the broadest context possible: having a balanced climate means having the same level of solar energy leaving, as entering, our atmosphere – or Earth car. 

Because we’ve transformed our landscapes, waterways, and atmosphere, we are now allowing more solar energy in, creating more heat on the Earth’s surface, and trapping more heat than we are releasing back out of our atmosphere. (Think: hot car, full sun, black seats, windows up). 

The term to describe this situation – that more energy is entering our Earth system (and turning into heat) than leaving – is radiative forcing. And, there is growing recognition that radiative forcing is an equally important, if not more important, indicator to climate stability than emissions alone. 

If this is the case, how did Nature balance our energy budget previously, before we inadvertently damaged so much? Looking at an Earth Energy Budget diagram gives us helpful clues: 

Firstly, to balance our Earth’s energy budget, about 30% of the Sun’s energy should be reflected away from our atmosphere – by thick low clouds and white areas, like icy polar regions. 

In our hot car metaphor, clouds are akin to putting up a giant sun reflector in the windshield in most of the windows of our Earth car. We immediately feel a difference in temperature by reflecting the Sun’s energy back out. 

Our Earth, on average at any given time, should be mostly (70%) covered in clouds. 

Spoiler alert though: our cloud coverage on Earth is decreasing because our microbial communities in our soils, plants and oceans are decreasing, and so our Earth’s reflector shield is decreasing. (What? Yes. More on these relationships below.) 

Secondly, to balance our Earth’s energy budget, roughly a quarter of the Sun’s energy should be transported back away from the earth’s surface by the transpiration of water from diverse, green ecosystems, i.e. plants. 

When this rising water vapor condenses into low, thick clouds, the ‘latent heat’ (or energy released from vapor as it condenses back into water) has a greater chance of escaping out of the atmosphere.

Plant transpiration is like us sweating in the hot car to cool ourselves as the water evaporates off our body.  Like the spoiler alert above though: our challenge on Earth is twofold. Not only have we significantly reduced grasslands, forests and other green, living landscapes that transpire to remove the heat, but also in doing so, we have significantly reduced the volume of biological rain-nucleators that allow water vapor to condense and release that latent heat. (Again, I’m foreshadowing the below!) 

Thirdly, to balance our Earth’s energy budget, after a cool rain has washed the skies clean of particulate matter, roughly another quarter of the Sun’s energy should be re-released from the ground during clear ‘night-time re-radiation windows’. This is akin to opening the windows of our Earth car allowing the heat to escape. 

And for the final piece of this metaphor for why our Earth car is heating up, we’ve got to dig into a physics term: the Stefan-Boltzmann law. Basically, this law shows that when solar energy hits a surface, it re-radiates back in with an exponential level of heat, relative to the current temperature of the surface. 

So, when green landscapes are photosynthesising, transpiring, and cooling, this is no big deal, as the sunlight hits relatively cooler surfaces. But surface areas like bare soils, concrete, and degraded landscapes are producing ever increasing levels of exponential heat, compared to living landscapes. 

So back to our hot car scenario: originally, 100% of the inside of our Earth car was covered in a deliciously cooling moist mossy towel. But now, 75% of our Earth’s surface has been dramatically altered (drained, covered, bare soil, etc) and the re-radiating heat in our Earth car is metastasizing. 

However – and this is where things get exciting and hopeful – land stewardship can address all of this. 

Life moving water balances our Earth’s energy budget

There are several fascinating ways that Nature Cools. 

Firstly, as foreshadowed above, diverse plants and green living landscapes transpire as they eat the sunlight. (Okay, technically, scientists argue plants and phytoplankton do not ‘eat’ the Sun, but if this metaphor is good enough for Zoë Schlanger, it’s good enough for me!) 

When diverse plants transpire while they eat the sun, they effectively create heat elevators. They take the sun’s energy that could be turned into heat we feel (e.g. sensible heat), and instead use this energy to turn water into water vapor (e.g. latent heat), which rises up into the sky, transporting the Sun’s energy away from the earth’s surface. 

And essential to this story is that fungi in healthy soils, bacteria in healthy landscapes, and phytoplankton in oceans and living waters, all add their bits of life which hitch a ride into the atmosphere with water vapor and wind currents.

These microscopic bits have a crucial, essential, irreplaceable job. They are what’s called ‘cloud condensation nuclei’, or ‘biological ice nucleators, or ‘bio-nucleators’. 

They help water vapor condense into thick, sun-reflecting clouds, at ‘very warm’ temperatures – i.e. lower levels in the atmosphere. This also means that rain forms and falls closer to where it transpired. 

And, as mentioned above, when the water vapor condenses into clouds, this released ‘latent heat’ has a greater chance of escaping out of the atmosphere.

– – – 

So, when Climate Land Leaders steward landscapes towards more life above and below ground, their regeneration efforts cool our climate, and help balance our energy budget in several important ways: 

• Fungi-fuelled soils, plant transpiration, and phytoplankton in waterscapes foster bio-precipitation, which means local, cooling rain more often. And, these healthy landscapes effectively capture and store this rain in the soil (like keeping our seats moist and mossy on our Earth car).
• Rain-cleared night-time reradiation windows allow trapped heat to more freely escape out of our atmosphere (like opening our Earth car windows).
• Diverse plants transpire heat from the Earth’s surface (like us perspiring in our Earth car).
• Plants shade everybody, from soil organisms to mammals to songbirds. And, bacteria on plants, and fungi in soils increase the frequency of thick, sun-reflecting clouds (like putting up solar reflectors in our Earth car).
• Restoring any degraded, heat-generating, landscapes and waterways to places that cool via the above processes (changing our Earth seats from black leather to moist, mossy surfaces).

As often repeated by Walter Jehne, hydrology governs 95% of the Earth’s heat dynamics, and three processes are most significant: transpiration, clouds reflection and nightly re-radiation windows. By supporting diverse life below and above ground, we can help regenerate these governing processes.

So, what happened during the Nature Cools project?

There are many observations to contextualise how land stewardship helps Nature Cool.  We could observe many dimensions and relationships of water and energy flows, plants, soils, microbes, animals and waterscapes. 

Amidst this complexity, we prioritized two observations to illustrate how land stewardship helps #NatureCool: water infiltration and temperature. 

With four participating Climate Land Leaders in Illinois and Wisconsin – across sites with differing histories and stewardship approaches – we asked:

• How long will it take for one inch of water to infiltrate into the soil in dry and wet conditions? (USDA, 2008; Soilmentor, 2026), and
• What are the temperature differences of: air at shoulder height, soil surface, and soil subsurface on a hot summer day?

Why water infiltration?

As our first soil observation, timed water infiltration illustrates the ability of soil to absorb and effectively capture rainwater. 

As the saying goes, it’s not the volume of rain, but the landscapes’ ability to harvest and store each drop in order to better: 

• support diverse soil organisms, such as rain-nucleating fungi and bacteria; 
• help plant life into drought longer, and out of drought faster; 
• ensure plants are cooling through transpiration and transporting cloud nucleating bacteria. 

In other words, holding water in the soil is fundamental for plant health, climate balancing and precipitation (Figure 2).

A fast infiltration can indicate stable soil aggregates and structure, around which water can percolate down. (In some cases, fast infiltration might indicate sandy soils and the need to build organic matter.) 

A slow infiltration rate can indicate compacted or poor soil structure, with unstable aggregates blocking water from percolating downwards. Instead water runs off, taking topsoil and nutrients with it.

How to do a water infiltration 

A simple water infiltration observation involves a 6-inch diameter tube (either PVC, metal drain, or even an old Folger’s coffee tin), 900 mL of water, perhaps a rubber mallet (depending on your soil type) and a timer. 

Pick a site representative of the pasture, push or mallet the tube 3 inches down (being careful to push the tube evenly across its diameter), and pour in one inch of water (which equates to around 450ml of water). 

Record the time it takes for the first pour to disappear into the soils, and then time it takes for a second pour to infiltrate, and compare how the soil absorbs water when both dry and when more saturated. 

If time permits, you can also observe water infiltration in three to four different places in the same pasture, to account for diversity in soils and soil life occurring even in the same paddock.  

Soilmentor and the USDA provide helpful guidance on making your tube, and the methodology.  

Why temperature?

Our second soil observation was temperature of air, ground surface and below ground across diverse landscapes and management practices. 

Diverse living landscapes produce more latent heat (e.g. energy stored in rising water vapor), while dry, microbial-poor dirt produces more sensible heat (e.g. heat we can feel) (Figure 3). 

So, measuring temperature can illustrate the difference in sensible heat, depending on how easily the landscape absorbs energy and whether the Sun’s energy is being reflected, shaded or removed as latent heat (Figure 2). 

In other words, is the landscape cooling or heat-generating (Figure 3)?