MISSING CONTEXT: Greening by carbon dioxide does not mean climate change causes no harm

A claim that greening caused by carbon dioxide shows climate change does not cause harm is MISSING CONTEXT.

This post on X (formerly Twitter) claims that there is no evidence that climate change has caused any harm. It adds that increasing carbon dioxide causes a greener world, and is therefore good for the planet.

PesaCheck has detailed the harms caused by climate change on several occasions. For instance, the effects include: negative impacts on global health, economic losses particularly in poor countries, extreme or severe weather and wildfires, harm to bees and insects.

Others are impacts on crops and food production, melting sea ice and glaciers, rising sea levels and ocean acidification, more intense and frequent droughts, worsening humanitarian crises, affecting lakes, and increased flooding and heat waves.

But does greening mitigate the damages caused by climate change?

The image from the post originates from a news release by the United States National Aeronautics and Space Administration (NASA). It is based on a peer-reviewed paper published in Nature.

The paper found a greening trend from 1982 to 2009 over 25–50 per cent of global plant areas, which they ascribe largely to carbon dioxide fertilisation.

The researchers involved in the NASA paper admit that the harm caused by carbon dioxide far outweighs the benefits of greening.

“It is clear that the benefits of a greening Earth fall well short compared to the estimated negative impacts of extreme weather events (such as droughts, heat waves, and floods), sea level rise, and ocean acidification,” they wrote.

Other papers have described the greening effects and have also found that this trend is largely but not solely because of human carbon dioxide emissions (here, here, and here).

Plants use carbon dioxide for photosynthesis, the process where they absorb carbon dioxide, turn it into energy and release oxygen as well as water vapour. More carbon dioxide can be beneficial to plants and increase their growth, but it becomes toxic at very high levels.

The greening trend observed by the researchers because of climate change and carbon dioxide emissions has a variety of effects, some good and some not.

For instance, greening can mitigate global warming because more plants would absorb more carbon dioxide. But more plants can also increase albedo (where darker surfaces absorb more heat), which can increase local warming. Soil moisture and water run-off show a similar trend.

The cooling effect of greening because of more carbon dioxide only mitigates about 5 per cent of the heating it causes.

More carbon dioxide also does not affect crops equally. Potato growth is slowed by excess carbon dioxide, while rice’s nutrient content can change.

The boost in plant growth can also induce microbes in the soil to release carbon dioxide into the atmosphere, which would otherwise have stayed locked in the soil.

Carbon dioxide-induced warming also has a variety of other negative consequences on crops, such as decreasing plants’ ability to absorb carbon dioxide, affecting nitrogen fixation, altering growing seasons, and creating ideal conditions for pests.

So, while greening does have some benefits, it does not mitigate or even alleviate the vast negative consequences and harm caused by human emissions of carbon dioxide, global warming and climate change.

PesaCheck has examined a claim that greening by carbon dioxide means climate change is not harmful and finds it to be MISSING CONTEXT.