Is tree planting effective against climate change

There are different schools of thought on whether tree planting can reverse global warming. Some think it is just what we need to stop climate change once and for all, but others are not so optimistic. Before examining all the different opinions on the climate-saving power of trees, let’s see how carbon sequestration works.

The process of photosynthesis through which plants increase their biomass requires carbon dioxide, amongst other things. CO2 is responsible for 33% to 60% of plant growth. So for plants to survive, they need carbon dioxide, and there is an excess amount in the atmosphere already. So forests absorb and store carbon, and they also help our lands store it as well. In tropical forests, 50% of CO2 is stored in plant biomass, and the other half is in the soil.

Trees all over the world help to maintain the CO2 balance of the planet. Not only do forests absorb CO2, but they also release it too. When we burn trees, cut them down, or they die and decay, the carbon escapes into the atmosphere. 

Over the past four decades, forests have sequestered one-quarter of the CO2 emissions caused by humans. Scientists believe that they can do an even better job. The forests in the EU have an estimated 9.8 billion tons of carbon stored in their biomass. This means that the yearly carbon emissions of the EU are only about one-seventh of the amount already stored in the forests. Therefore, the forests in the EU are seen as a viable method of reducing global warming.

Scientific evidence shows that forests, both old-growth and managed, sequester up to 6 tons of carbon per hectare. Research theorizes that replanting trees on 2 billion hectares of degraded land can wipe out the yearly increase of atmospheric CO2. 

Using trees to reduce global warming is not as straightforward as it may sound. This is because forests could also become carbon sources. Fires, pest outbreaks, and storms cause a massive return of carbon to the atmosphere.

For instance, Canada's managed forests have done a great job as carbon sinks until recently. In the past decades, however, the forests were carbon sources at some points. This happened because of tree insect outbreaks, forest fires, and land use.

Another study advises that the tropics are the best place to plant trees2. Trees grow faster in these areas and therefore absorb CO2 faster. The study suggests that planting trees in snowy areas could become problematic. This is because the trees can create a warming effect, which is the issue we are trying to avoid in the first place.

In temperate climates like much of Europe and some parts of the US, planting trees may have no significant effect on global warming. The study concludes that planting trees to solve global warming is not the worldwide solution presented by enthusiasts.

Professor Beverly Law of Oregon state university disagrees with the idea that more trees will do damage to the icy regions of the planet. In her opinion, the polar regions are warming at a much faster rate than the rest of the earth.

It is not correct to assume that the snow cover will remain intact without trees despite the earth’s rising temperature. It is most likely that the snow will melt in the coming decades anyway. In that situation, trees will not create an albedo effect. 

Then again, Nadine Unger, a professor at the University of Exeter, UK, warns against tree planting. She states trees could form the greenhouse gas methane or ozone through a chemical reaction as the chief reason.

In her 2014 study, she calculates that deforestation from 1850 to the 2000s has created a cooling effect that slightly offsets the warming of greenhouse gas emissions. Her article “to save the planet, don't plant trees” was published in the New York Times. However, Professor Dominick Spracklen, who has studied the effects of aerosols, says such reactions are insignificant. And have a very minute impact on the climate of the earth.

Warming temperatures could also cause increased heterot