By Femke van Woesik & Frank van Steenbergen
Paradigms
When we talk about climate change, the discourse is very much on greenhouse gasses – CO2, CH4 – and how these emissions trap part of the solar heat and cause global warming. But is this the only driver, or are there others?
There is a credible argument that landscapes, water, moisture and vegetation – and the changes therein – are another part of the explanation.
Landscapes don’t just react to climate change, they actively shape temperature, rainfall and wind. Vegetation and water create the earth/s cooling system, active at local and regional level. The prime mover in this process are the small water cycles.
The large global water cycle is familiar: water evaporates from the ocean, travels through the air, condenses into clouds, and eventually falls back to earth as rain or snow and finds its way in many ways back to the ocean. This large global water cycle moves moisture from oceans across continents.
The small water cycles, by contrast, have received far little attention. They happen over land and are the engine behind local water recycling and temperature regulation. How do they work? If there is vegetation, solar heat is not immediately bounced back entirely but becomes ‘latent heat’. It is absorbed in the moisture and vegetation and transformed in more vegetation. Equally – besides the vegetation on the surface – in these settings there is a healthy soil life, with soil biota capturing carbon and nitrogen. This in turn improves the moisture holding capacity of the soil and its fertility – further sustaining the process of converting solar energy in . If it rains it is largely absorbed locally – in the soil, in the vegetation, in water bodies. The atmosphere above the vegetated area does not heat up much and the moisture that evaporates condenses locally – with much chances of rainfall occurring nearby. The cooling system is working and the climate is locally buffered against extremes.
Compare this with an area that is without much vegetation – either through overgrazing, deforestation, salinization or other land use changes. Now the soil is barren or sparsely vegetated. The small water cycle is broken. The barren soil act as a boiler plate, sending all solar energy back into the atmosphere as ‘sensible heat’. Air temperature rises, condensation is inhibited, and humidity either drifts away or falls in destructive bursts elsewhere. In the meantime, the soil is becoming extremely hot and compacted. No soil moisture is retained and neither does soil life develop. Whatever carbon was there in the soil withers away and enters into the air.
The contrast is striking. A degraded landscape acts like a boiling plate: soils are compacted, dry, and lifeless and the air is dry and hot. A healthy buffered vegetated landscape, by contrast, holds water in soils, recycles it through vegetation, and stabilizes local humidity. Solar energy is used for evapotranspiration (latent heat) rather than directly heating the atmospehre, buffering temperatures by several degrees and sustaining reliable rainfall. This is the first small water cycle.
In addition, there is a second small water cycle, also sometimes called the biotic pump. Here the vegetated landscapes close to the seas release moisture to the air, that then condenses into clouds. This creates a moisture vacuum in the atmosphere which pulls in the humid air from adjacent seas and transports it onward – reaching further inland, creating moist green conditions over a large stretch.
The science is clear: the mean global rainfall over land is about 720 mm per year, of which only 310 mm comes from the global water cycle while around 410 mm comes from the small water cycles (Kravčík, 2007). This means land management decisions directly affect whether and where it rains.
In fact, recent research (Staal et al., 2024) reminds us that the rainfall effects of restoration depend on where and how it is done. Forests recycle water through evapotranspiration, which can increase rainfall locally and downwind. But location matters: in wet regions forests buffer droughts and stabilize rainfall, while in drier zones poorly planned tree planting may reduce local water availability. This shows why restoring the small water cycle is not just about more trees everywhere, but about carefully designed landscapes: forests, wetlands, grasslands, and farms, that keep water in the land and atmosphere where it is most needed.
Cooling power made visible
The book Water for the Recovery of the Climate – A New Water Paradigm (Kravčík et al., 2009) illustrates the cooling power of water and vegetation with striking examples. A drop of just 1 mm/day in evaporation over Slovakia’s land area releases as much sensible heat as the entire annual output of all Slovak power plants. This shows how degraded soils that no longer retain and evaporate water unleash immense heat into the atmosphere. Moreover, a single healthy tree with a crown about ten meters wide can transpire around 400 liters of water each day, using the sun’s energy to transform that water into vapor. In doing so, this one tree cools with a power of 20–30 kilowatts: the equivalent of running more than ten air-conditioning units at once. Together, these examples make tangible what the small water cycle really means: landscapes rich in water and vegetation act as vast natural cooling systems, while degraded land turns into a giant boiling plate.
Now take in some global facts. The most recent State of the World’s Land and Water Resources Report (FAO 2022) assesses that 13% of the global earth surface is affected by human-induced land degradation. The Aridity Report assesses that 78% of the global surface has become more arid in 1990-2020 compared to the 1960-1990 period and that drylands – with more boilerplate effects – are increasing (Vincente-Serrano et al, 2024). Clearly this suggests that there is widespread damage to local water cycles and hence the earth’s cooling system: how can this not be a cause to global climate change as well?
There is an important call
Restoring the small water cycles has been by and large left out of the climate debate that has been dominated by the discussion on greenhouse gas emissions. Restoring (or preserving) these local water cycles deserves far much more attention in addressing climate change. Restoring the local water cycles can be done in many ways: watershed rehabilitation, different types of well-considered afforestation, improved regenerative agriculture that build up carbon in the soil, or improved rangeland management, whereby grazing is used to restore vegetative diversity and create healthy soils. They will restore brittle landscapes, and ensure solar heat is used for building up carbon in soils and vegetation and create well buffered local climates – that regulate temperatures and insulate against extremes.
The important implication of restoring the local small water cycles is that climate change is maybe at least partly reversible, that it can be dealt with locally and not only globally; and that it can be achieved by positive action rather than reducing consumption. All of this is different from the current CO2 emission dominated mitigation discourse.
Restoring the small water cycles is not a zero-sum game: it creates abundance, not scarcity. The benefits are real and measurable (van Woesik et al, 2023): local temperatures drop, land use becomes more stable and productive, rainfall and microclimates improve, groundwater and soil moisture are restored, erosion and nutrient loss decline, and biodiversity thrives.
Read more:
Bunyard, P. P., Collin, E., de Laet, R., Hodnett, M., & Fourman, M. (2024). Restoring the earth’s damaged temperature regulation is the fastest way out of the climate crisis. Cooling the planet with plants. International Journal of Biosensors & Bioelectronics, 9(1), 7-15. https://doi.org/10.15406/ijbsbe.2024.09.00237
FAO. 2022. The State of the World’s Land and Water Resources for Food and Agriculture – Systems at breaking point. Main report. Rome. https://doi.org/10.4060/cb9910en
Kravčík, M., Pokorný, J., Kohutiar, J., Ková, M., & Tóth, E. (2007). Water for the Recovery of the Climate – A New Water Paradigm. Krupa Print, Žilina. From: http://www.waterparadigm.org/indexen.php?web=./home/homeen.htm
Staal, A., Theeuwen, J. J. E., Wang-Erlandsson, L., Wunderling, N., & Dekker, S. C. (2024). Targeted rainfall enhancement as an objective of forestation. Global Change Biology, 30(1), e17096. https://doi.org/10.1111/gcb.17096
van Woesik, F, van Steenbergen, F, F. Sambalino, H. de Boer, , J.M. Pace Ricci, W, Bastiaanssen (2023), Managing the Local Climate: A third way to respond to climate change, Practical Action Publishing.
Vicente-Serrano, S. M., N. G. Pricope, A. Toreti, E. Morán-Tejeda, J. Spinoni, A. Ocampo-Melgar, E. Archer, A. Diedhiou, T. Mesbahzadeh, N. H. Ravindranath, R. S. Pulwarty and S. Alibakhshi (2024). The Global Threat of Drying Lands: Regional and global aridity trends and future projections. A Report of the Science-Policy Interface. United Nations Convention to Combat Desertification (UNCCD). Bonn, Germany.
Widows, R. (2016, May 8). Rehydrating the Earth: A New Paradigm For Water Management. Medium. https://medium.com/@rwidows/rehydrating-the-earth-a-new-paradigm-for-water-management-3567866671a2
