Geoengineering

Here’s low-tech tool to reverse climate change.

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Have you heard of geo-engineering? People hope to use cutting-edge technologies to solve the problem of climate change.

For example, they could throw microparticles of silica into the atmosphere to bounce back the heat, or send special satellites to space to stop the sunlight. They could compress carbon into blocks and store it deep, deep underground, or make massive mirrors to reflect the Earth’s heat away.

These are all great ideas of humankind, but they are very expensive to put in place and not yet ready to be safely used. Today, I want to introduce to you a low-tech, safe and cheap tool we already have in our hands.

We don’t talk about them much, but that’s because we usually take them for granted. They’ve been doing their job for as long as we can remember, and more besides. In fact, if such a solution were man-made and invented today, it would be called a marvel of engineering and hailed widely across the world.

I’m talking about trees.

Botanically speaking, a tree is a special type of plant with a key structural component: wood.

Wood is made of big chains of carbon atoms, which form molecules like cellulose and lignin. Cellulose is the most abundant molecule in the living world; all plants have at least a bit of it. Lignin is different.

A strong, tough, molecule with high resistance, lignin is something that non-wooden plants do not have. Only trees have lignin and, therefore, wood. It’s so resistant that, when placed in a medium with no oxygen and slightly acid, any piece of wood can be preserved for thousands of years.

Try engineering that manually and see where you get!

As a tree grows and enlarges its trunk, its dead cells will get  “sclerified” — turned into a protective tissue of thick cell walls, with lignin mixed in to make the dead cells stronger. In fact, a tree is mostly a mass of dead cells. Only a very small portion of a tree cells are alive: those at the surface of the trunk under the bark.

Unlike other, non-wood, plants, a tree can stand straight without bowing to the wind. As it grows high the tree can capture more light, and enjoy sunbathing to grow even bigger.

Trees are  a key component of an ecosystem. And not just that: when you add a tree where there was none before, it completely changes the environment.

The tree sucks water from the deep layers of the soil, sending down its long roots and feeling for thirst-quenching water. Then the roots, now up to thirty metres deep, draw upon that water and bring it up for other plants to drink.

A tree is a light umbrella, which shades other plants under its branches. It’s also a windbreaker protecting other plants from storms.

A tree alone can create a complete “micro climate”, which other plants and animals can comfortably live in. No matter what happens outside, the conditions within the tree’s canopy will remain more or less the same. It helps newcomer plants get settled and take hold by protecting them with its tall and large wooden body. In a dry place, a tree can gather a large community of plants under its shade.

The stable conditions created by forests is what allowed the creation of diverse wildlife: it’s one reason why biodiversity hotspots are mostly located in tropical forests today.

And forests are the next important feature — because trees, like everyone else, work better when they aren’t working alone.

Forests are a group of trees of different species and ages. It is important to have a diversity of structure, since trees can complement each other and enhance the functions of the ecosystem.

Because trees sweat a lot of water during the day, forests are responsible for creating clouds and rain. This is why there are rainforests, a place where trees sweat so much that they create rain, which enables forests to grow, which brings even more trees and keeps the whole cycle going round.

The good part about trees is, once they’re set up in a place, they carry on and spread by themselves. Unless something hinders their progress, the forest workshop will always keep spreading.

Under the shadow of the forest, there is no wind and only a low, dim light. The temperature under the branches stays constant throughout the day. These constant physical conditions allow animals and small plants to thrive, and to not worry about external disturbances.

One feature of forests is the huge amount of wood — and therefore carbon — that it can store. In addition to carbon stored in the trunk and branches, the roots and soil store a significant amount of carbon too. The soil full of dead organic matter is another large pool of carbon.

As long as the soil stays wet and slightly acidic, the organic matter will not rot but just stay there for ages.

Storing carbon in trees is important to halt the current global increase in temperature — but the climate is not just about temperature.

Climate is a complex system, made of various regulated cycles where forests play a key role. Take water, for example: before it rains, the water has to get from one place to another, travelling in wind currents and forming long rivers in the sky.

The large amount of water vapour emitted by forests contributes to the global water cycle; it influences the  rain and the humidity of the air. Trees covering the ground also absorb and reflect sunlight, controlling the amount of heat Earth gets from the sun in much the same way as those mirrors.

Instead of setting up more trees, people have a tendency to cut the forest down. They want to extend agricultural areas, or build large infrastructure like roads or dams.

But once the forest ecosystem is cut open, everything gets disrupted. Microclimate regulation stops. Conditions stop being so stable. Forest wildlife is exposed to external disturbances.

The temperature increases, the wind blows, and the ground dries out. Trees are usually removed, sold as timber or burnt on the spot. Once the vegetation has disappeared and the soil is exposed to weather, the organic matter rots quickly and releases its heating carbon. The rain washes away soil nutrients and transports the organic matter away.

After a decade, the soil becomes sterile and nothing can grow any more. The deforested area then  becomes a desert, where no plants can grow because of the lack of nutrients in the soil.

So, what do we do now?

The first important step is to maintain our current forests; to make sure they don’t  lose the carbon stored in the soil and in the old, sometimes thousand-year-old, trees. Another step is to stop land desertification, and try reforest the areas where vegetation has been lost.

Without forests, there is no protection against the weather and others climatic disturbances. Without forests, millions of species will have no places to live. Without forests millions of people won’t have a place a stay.

Without forests, Earth will be a mess and humankind won’t be here anymore to see it.

Protecting and planting forests is not only about the trees and the carbon they store, but rather about the whole ecosystem and its free environmental services that we enjoy every day.

And don’t forget: if this was a man-made solution rather than a natural one, we’d be paying through our noses for it.

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