Messages mislead about how CO2 affects Earth

Carbon dioxide (CO2) contributes to global warming, but social media posts claim that an image showing increased vegetation over time suggests the greenhouse gas is actually good for the planet. It is misleading; the map is over five years old, research shows the “greening” trend may be coming to an end, and experts say rising temperatures may harm plants.

“Watch carefully. The effects of CO2 on the planet…,” reads a November 27, 2022 tweet from former University of Toronto professor Jordan Peterson, which has tens of thousands of interactions.

Screenshot of a tweet from December 13, 2022

Similar claims have been circulating on Twitter and TikTok.

The messages spread as scientists warned at the UN COP27 climate summit in Egypt that global emissions of CO2, one of the main drivers of climate change, had reached record highs in 2022.

Rising CO2 is associated with higher temperatures, and research suggests it could increase the risk of extreme weather events. Most scientists agree that recent climate change is due to human-induced greenhouse gas emissions.

Increased CO2 can also improve plant growth, but claiming it’s good for the planet is misleading.

Greening effect

A reverse image search reveals that the map shared online is from a 2016 study published in Nature Climate Change by an international team of scientists. They used satellite data to see how the Leaf Area Index (places on Earth with green leaves) changed from 1982 to 2015.

“Nearly half of all vegetated land is greener today, and remarkably, only 4% of land has become browner,” Pep Canadell and Yingping Wang said in an April 25, 2016, The Conversation article on study results.

The co-authors said the Earth is greener primarily because the increased concentration of CO2 in the atmosphere has a fertilizing effect, but noted that this should decrease over time as plants face to nutrient limitations in a warming world.

Canadell and Wang also stated, “It is clear that the benefits of a greener Earth far outweigh the estimated negative impacts of extreme weather events (such as droughts, heat waves and floods), rising sea ​​level and ocean acidification.”

Other experts have said rising temperatures can have negative effects on vegetation – and higher atmospheric CO2 can alter the nutritional content of crops. Other studies have shown that higher temperatures will negatively affect the yield of staple crops in the world’s diet such as wheat.

Narrow interpretation

Ranga Myneni, a professor in the Department of Earth and Environment at Boston University, also worked on the 2016 study. He told AFP in a December 13, 2022 email that focusing on a “short-term effect of improved plant growth through higher CO2 concentration misses the important point”.

“CO2 is a greenhouse gas, it causes climate change whose effects include global warming, sea ice loss, sea level rise, etc.,” Myneni said.

He added: “I have tried many times to put our results in context, but some people intend to interpret our work narrowly.”

Myneni pointed to his most recent research published in Biogeosciences in 2021, which found “a slowing greening and strengthening browning trends, particularly over the past two decades.”

He also said that carbon emissions from human activities such as the burning of fossil fuels and deforestation are responsible for increasing the concentration of CO2 in the atmosphere – a fact confirmed by the latest report from the Group d intergovernmental experts on climate change. report.

“There is NO benefit to a high concentration of CO2 in the atmosphere,” Myneni said.

AFP has verified other false and misleading climate change claims here.

Leave a Reply

Your email address will not be published. Required fields are marked *