Fact Check: Do Rising CO2 Levels Actually Benefit Life and Pose No Climate Risk?

A recent post on X by Peter Clack claims that increasing carbon dioxide levels are overwhelmingly advantageous for life on Earth and that concerns about climate change are unwarranted. The post points to global greening, rising crop yields, and declining famine deaths as proof that higher CO2 is good for the planet and humanity. While some claims are based on genuine scientific observations, the conclusions drawn are misleading. Climate scientists say the post cherry-picks data on plant growth while ignoring well-established evidence on warming, sea level rise, food system risks, and ecosystem stress linked to increasing greenhouse gases.

X Post:

We should be managing adaptation and energy abundance not waging war on a rare gas that makes our planet a green paradise. Higher CO₂ is a net benefit to life on Earth. It will not destroy the climate. It will not drive us away from our coastal wonderlands. The Earth is greening… pic.twitter.com/qvYrCdZWkm

— Peter Clack (@PeterDClack) December 26, 2025

Claim 1: Higher CO2 is a net benefit for life and does not harm the climate or coastlines

Fact: False. Carbon dioxide is essential for photosynthesis, but it is also the main driver of modern global warming. Rising CO2 traps heat in the atmosphere, leading to higher global temperatures impacting weather patterns, glaciers, oceans, and ecosystems. Scientific reports show that the rapid increase in CO2 since the Industrial Revolution is warming the planet.

This warming is directly linked to rising sea levels caused by melting ice sheets and the expansion of warmer oceans. Coastal flooding, erosion, and saltwater intrusion are already affecting communities worldwide. Presenting CO2 as harmless or entirely beneficial ignores these observed and measured impacts.

Claim 2: The Earth is greening mainly because of rising CO2

Fact: Misleading. Satellite observations since the early 1980s do show an increase in global leaf area. Elevated CO2 helps plants by enabling them to use water more efficiently and grow faster under certain conditions. This effect is real and well recognised in scientific literature.

However, A Study lead by researchers from Peking University, Beijing, China emphasise that CO2 is only one of several factors. Expanded irrigation, fertiliser use, land management changes, and reforestation efforts have been major contributors to greening trends. Viewing CO2 as the main cause oversimplifies a much more complex situation.

Claim 3: The biggest greening gains in India and China mainly result from CO2 fertilisation

Fact: False. India and China do stand out in global greening maps, but studies show this is largely due to human land use choices. Large-scale tree-planting programs, intensive agriculture, expanded irrigation, and heavy fertiliser use have transformed landscapes in both countries. While CO2 fertilisation adds to plant growth, it doesn’t explain the scale or locations of greening. Attributing these changes mainly to rising CO2 ignores the role of policy-driven land management and farming practices.

Researchers also note that greening patterns in India and China closely track areas of cropland expansion and state-led afforestation rather than natural vegetation responding to atmospheric change. China has implemented massive ecological restoration programs since the late 1970s, like the Three-North Shelterbelt Program and Grain for Green, to combat severe soil erosion and desertification, while in India, intensified irrigation and fertiliser use boosted vegetation cover through the Green Revolution. These patterns reflect policy choices and land management, rather than a passive response to rising CO2 levels alone.

Claim 4: Rising CO2 is largely responsible for increased crop yields and less famine

Fact: False and misleading. Crop yields worldwide have grown greatly since the 1960s, mainly due to improved crop varieties, fertilisers, machinery, irrigation, and pest control. These advancements underpin modern agriculture and food production. The reduction in famine deaths is also thanks to economic progress, improved governance, better food storage, and emergency systems. Climate change driven by rising CO2 is increasingly seen as a risk to food security, especially through heat stress, drought, and extreme weather.

Claim 5: Science supports a CO2 “sweet spot” of 600 to 1000 parts per million

Fact: False. There’s no scientific consensus that CO2 levels of 600 to 1000 ppm are ideal for life. Such levels are associated with much higher global temperatures and significant climate changes. Research links these high concentrations to ocean acidification, coral reef loss, biodiversity decline, and long-term sea level rise. Major scientific bodies warn that allowing CO2 to reach these levels would pose serious risks to ecosystems and human societies.

Past periods of Earth’s history with similarly high CO2 levels experienced very different climates from those supporting modern civilisation. These conditions developed over long geological timescales, allowing ecosystems to adapt gradually. Today’s rapid CO2 rise is much faster, raising concerns about how natural systems and humans can cope with such rapid change.

Claim 6: CO2 fertilisation guarantees large and continual increases in plant growth

Fact: Misleading. Plants often grow faster when exposed to higher CO2 in labs and short-term field trials. However, this response has limits. Over time, growth becomes constrained by water availability, soil nutrients, heat stress, and pests. In many areas, warming linked to rising CO2 already reduces productivity during heatwaves and droughts. The idea that plant growth will keep rising steadily with CO2 doesn’t match real-world observations.

Claim 7: Greenhouse CO2 enrichment proves higher atmospheric CO2 is beneficial

Fact: Misleading. Commercial greenhouses increase CO2 levels to boost yields, but under tightly controlled conditions. Temperature, water, nutrients, and pests are carefully managed. Natural ecosystems and open-field farming don’t have these controls. Applying greenhouse results to the entire planet ignores the climate stresses crops and ecosystems face outside controlled environments.

Claim 8: Net-zero policies would stop a global greening miracle

Fact: False. Net zero doesn’t mean removing CO2 from the atmosphere enough to halt photosynthesis. It aims to balance emissions with removals to stabilise CO2 levels. Under net zero plans, plant growth continues while risks of extreme heat, drought, and sea level rise are lowered. Climate policies are designed to limit damage from unchecked warming, not to stop plant growth.

Peter Clack’s post mixes real scientific ideas with exaggerated conclusions. While CO2 fertilisation and global greening are real, they don’t negate the broad risks linked to rising greenhouse gases. Portraying higher CO2 as overwhelmingly good while dismissing climate impacts gives an incomplete, misleading picture. Scientific evidence shows stabilising emissions is key to protecting ecosystems, food security, and communities in the future.

References:

https://www.sciencedirect.com/science/article/pii/S1018364723001556

https://science.nasa.gov/climate-change/evidence

https://e360.yale.edu/features/greening-drylands-carbon-dioxide-climate-change

https://www.nature.com/articles/nclimate3004

https://pmc.ncbi.nlm.nih.gov/articles/PMC6376198

http://sdgs.un.org/partnerships/three-north-shelterbelt-program

https://www.fao.org/4/ae537e/ae537e0j.htm

https://www.sciencedirect.com/science/article/pii/S2212096322000808

https://pmc.ncbi.nlm.nih.gov/articles/PMC9003137/#:~:text=Should%20this%20influence%20then%20be,with%20consequences%20for%20crop%20production.

https://climate.mit.edu/ask-mit/dont-plants-do-better-environments-very-high-co2

https://netzeroclimate.org/what-is-net-zero-2/#:~:text=Net%20zero%20refers%20to%20a%20state%20in,Agreement%20underlines%20the%20need%20for%20net%20zero.

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