The role of soil and water in climate change

This is part 2 in my series on climate change.

Find part 1 here: The Generational question

_________

Very broadly speaking, the surface of the planet consists of land and ocean. Water in the ocean is salt water (plus ice, which is not salty). Land consists of all kinds of different rocks, biology  and freshwater (these make up soil). The water on the land makes life for us and all other land based animals and plants possible. Seagulls can drink saltwater by the way (same with turtles, crocodiles etc.) .

Soil and Water

Soils are influenced by many factors, including which bedrock they came from, how eroded they are, which plants grow and have grown there and many many others. Nature generally tries to make sure, that the ground is covered by plants. The plants we consider weeds are especially good at that. They grow quickly and many of them have a squat physiology. This makes them perfect to quickly grow over disturbed soil and cover the ground.

Covering the soil is incredibly important because it helps to protect it from the destructive force of the raindrop. Raindrops are very powerful when they hit the surface and wash away any bare topsoil. This is called erosion.

Humans and erosion

We humans are very industrious. We do stuff. Invariably we move things around and plant plants that we want to grow and remove those that we don’t like (which is called farming). All this disturbs the soil and each disturbance endangers the topsoil. It might be flushed away by rain or a flood. In addition to that, when soil gets disturbed, the humus gets exposed to the air and starts to be degraded by microorganisms.

Humus is what makes soil brown and is a very powerful carbon sink. It also shares a common etymological root with human. Furthermore, according to the bible, Adam was the first human. Adam comes from the Hebrew Adamah “ground”. We are creatures of the soil. Earthlings.

As creatures of the earth it is our job to protect it. Unfortunately, we are not doing a very great job at it. In the USA, average annual topsoil loss due to Erosion is around 9-11 t/ha. 24 billion tons are lost globally every year. Lost usually means that it gets flushed into the ocean. The UN FAO (United Nations Food and Agriculture Organisation) estimates that there are only 60 years of harvests left globally with current practices.

By ploughing and exposing the soil we subject it to water and wind erosion and natural degradation. Studies on island nations like the Easter Islands have shown that erosion can collapse civilisations. 

So to prevent erosion we need to grow more plants and plants need water. The combination of water and plants is called blue-green infrastructure in sustainability circles. Yeah we are a creative bunch… But blue and green aren’t only a technical thing for cities, you can also make sure the country is blue and green.

Blue-green country

Our soils store and estimated 4000 billion tons of carbon. They are the secret sauce to help us against climate change. If we can change our habits of soil destruction, we can turn this ship around.
Cover cropping, no-till farming and holistic planned grazing are all tools to help store more carbon in the soil. They also help to keep it green by curbing evaporation and storing more water. The most important thing is to keep it covered at all times. This protects it from raindrops and keeps the soil where it belongs, on land.

Blue-green cities

In our cities, we need an integrated approach. We need to minimise sealed surfaces, slow down and spread out running water. Traditional urban drainage focussed on getting all water together and away as quickly as possible. This starves the land of water and is a risk factor for flooding. Spreading the water management out into the catchment helps keep the volumes manageable.

The final piece of the puzzle is to get the water back underground. Not all soil types support infiltration, but when water is in the soil it, replenishes groundwater reserves for the future and vitalises it in times of need.

To ensure our future we need to convert our farmland into sponges and our cities into green oases. We need to slow, spread and sink our rainfall. We have the technology, we only need the will. Let’s do it.

photo by Wilson44691