Are trees bad for the climate?

Cooling the planet

The water cycle is one of the main drivers of the greenhouse effect. I talked about this previously in my article on climate change and the generation question. Where I quoted a NASA study attributing 50% of the greenhouse effect to water vapour (25% to clouds, 20% to CO2). This is due to the absoprtion of infrared radiation by the water molecule.

The climate system is very very complex however, and the models we currently have are extremely complicated. There is a minority (like the climate scientist John Christy) who believe that carbon emissions by burning of fossil fuels aren’t as big an issue as alarmists like Al Gore can make you believe. The climate denial camp seems to have lost their mind though …

This actually happened in the US senate.

Regardless of which camp you are on, the climate is changing (human caused or not), and it’s not in a beneficial way for farming or living in the tropics. You might remember the problem with wet-bulb temperature– which kills you at 46°C and 50% humidity.

To buy us some time to make the necessary systemic changes in the way we live, work and produce, cooling the planet and our hottest areas is essential. Nature cools the environment with plants and open water (through evaporation and evapotranspiration). You notice this by walking from an urban neighbourhood into a forest or near a lake.

Having open water everywhere is unrealistic. But plants can be found almost anywhere.

The best plants for cooling while protecting the soil are perennial plants like certain grasses and trees. Trees have the added benefit of wood production, greater habitat for animals and insects and creation of shade

Trees in cities

Many cities, such as Melbourne or Vancouver with their urban forest strategies, have recognised the importance of trees in the urban realm. They provide shade and amenity to an often barren concrete wasteland.

Research in biophilia also showed benefits for physical and mental health when natural systems were present. This study mentions a few investigations showing stress-reduction, improving attention, having a positive effect on mental restoration, and coping with attention deficits, increased longevity and self-reported health to experiences of natural systems.

Also I think that there is still untapped potential for the production of tree food crops in cities. Who doesn’t love foraging for chestnuts or apricots in parks?

Trees in the country

Trees are a basic component of our experience of the countryside. Forested gullys, lonely paddock trees and tree-lined alleys occupy our farmland, wild or planted forests our forest plantations or nature parks.

In Europe it’s not that conducive to farmers to plant trees on their farm land because of disincentives related to land use and agricultural subsidies. Despite attempts at including a ‘greening’ component into the subsidies, having too many trees (of different varieties) on your land, decreases the amount farmers get paid. So hardly anyone ends up planting more trees. Farmers are also exposed to uncertainty regarding protection of those trees. They don’t know if they would ever be able to fell them again, so many opt not plant them in the first place.

The EU does have an afforestation strategy, which is working semi-well. The investment does lead to more forests getting planted, but the premiums don’t seem to be high enough to motivate a change in land-use. Trees grow too slow and yield too little from a purely economic standpoint for most landholders. This is also something I mentioned in my book review about Rowan Reid’s “Heartwood”.

Trees in Africa

In the Sahel region in Africa, lives depend on the trees and the rain and shade they bring. I recently discovered a few great initiatives, which help locals take measures into their own hands and basically “dig for rain”. By increasing rainwater retention and excluding lifestock for a while, groundwater is recharged and vegetation can come back.

The NGO Justdiggit from the Netherlands supports the farmers with money to dig half-moon shaped berms that retain runoff. The locations are chosen based on the hydrologic corridor theory in strategic locations to try and kick start the small water cycle in the region. Justdiggit as well as another NGO called Hommes et terre also use Farmer Managed Natural Regeneration (FMNR) to enable small land holders to regrow trees that have previously been grazed underground.

Farmer Managed Natural Regeneration explained.

Both of these NGOs receive money from search engines with a conscience, such as Ecosia or Zoek Groen. But FMNR spreads by word of mouth. These kinds of reforestation efforts are much more valuable than just mass-planting trees. Like Tony Rinaudo explains in the video, these projects can only have a 20% survival rate.  


I have previously talked about some of the opportunities of Agroforestry. Growing trees alongside annual crops or perennial grasses can diversify farm income and provide biodiversity and microclimate benefits.  

Are trees bad?

A legitimate counterargument could be that more tree cover decreases the Albedo effect, making the earth darker and therefore absorb more infrared radiation. But the underlying soil could actually be darker and in total, it’s just wickedly complicated and probably not that significant in regions without snow.

Also evapotranspiration increase cloud coverage and water vapour in the air, compounding the greenhouse effect, as we have learned. But the consensus among scientists seems to be regardless that deforestation is really really bad for our climate and the water cycle. And therefore our systems of agriculture. Making the soil drier, the climate more erratic and hotter, decreasing biodiversity, increasing fires and the obvious one, not storing carbon in wood.

I cannot imagine that getting more plants and trees established and thriving could be a bad thing for the planet. So to heal the water cycle, we need to get more plants growing. I am happy to help these NGOs in their mission to use sensible and effective methods to reforest the most vulnerable regions. And even if it is just by changing my search engine.
Feel free to give them some money though 🙂

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