CO2 is greening and cooling the planet, not destroying it!

Plants cool the Earth through photosynthesis and shading. More CO2 means more plant life, and more plant life means more cooling!

By Paul MacRae, Climate Realists of B.C., April 21, 2026

The Intergovernmental Panel on Climate Change (IPCC) and other climate alarmist groups wish the public to believe that increases in carbon dioxide will destroy life by making Earth so hot that most life, including humans, will perish.

In fact, the opposite is true: as Figure 1 from NASA shows, more CO2 is actually greening the planet and making it more livable (in the graduated colour scale at the bottom of the image, the right end shows increased vegetation).

NASA writes: “According to a new study published in the journal Nature Climate Change, from a quarter to half of Earth’s vegetated lands have shown significant greening over the last 35 years largely due to rising levels of atmospheric carbon dioxide.” [emphasis added]¹ (It’s worth noting that NASA is no friend of climate realism!)

What? Increased carbon dioxide not destroying the Earth but actually making it greener! And how much greener? NASA says 5 per cent greener in the last 20 years, which means an area as large as the Amazon rainforest!² Who could have predicted this greening of the planet in the midst of a “global climate catastrophe”?

How CO2 cools the planet

There is another benefit to the greening effect of increased CO2 that you won’t hear from the climate alarmists: plants cool the planet, and the more plants there are, the more cooling they produce. More CO2 means more plants, so more CO2 helps cool the planet! Plants cool the planet in two ways.

First, plants capture the heat from the sun in their leaves through photosynthesis, in which light energy, carbon dioxide, and water are turned into glucose and oxygen. (Since carbon dioxide acts as a fertilizer for plants, more CO2 enhances plant growth.) This process is endothermic—that is, photosynthesis absorbs heat, which means that each time a leaf captures and converts a bit of solar energy to glucose, the planet cools just that little bit! When you include billions (trillions? gazillions?) of leaves, that’s a lot of cooling!

Second, imagine a desert. Sunlight falls on the desert ground; some of this energy is absorbed but some is sent back up through the atmosphere as long-wave radiation; it’s this long-wave radiation that, when prevented from going into space by greenhouse gases, contributes to heating the planet. So deserts, bare of vegetation as they are, help heat the planet.

Now imagine a jungle. The many plants in a jungle capture and convert sunlight into glucose and oxygen, which aids their growth, while also absorbing heat through photosynthesis. But the plants’ leaves and stems they also prevent some of the sun’s rays—perhaps most rays if the foliage is thick enough— from reaching the ground. Solar energy that doesn’t reach the ground isn’t radiated back into the atmosphere as heat.

In other words, by capturing the sun’s rays for photosynthesis, and by preventing solar radiation from reaching the ground, plants act as a cooling agent. More CO2 means more plant life, as Figure 1 shows. And since more CO2 means more plant life—as the NASA graphic shows—believe it or not, increased CO2 also contributes to planetary cooling!

This plant-aided cooling process is occurring whenever the sun is shining. So why has the planet been warmer in the past few years? There are two obvious reasons.

First, as photosynthesis does not occur at night, the (mild) greenhouse-gas warming effect of CO2 continues at night. This brings up the overnight low temperatures, which in turn extends the growing season, and also makes for less extreme temperature changes in a 24-hour cycle.  However, the warming effect of CO2 diminishes exponentially as more CO2 is added to the atmosphere, and is now approaching its point of near saturation, which means additional CO2 causes almost no additional warming. Incidentally, this saturation process means that CO2 cannot be the “thermostat” of climate, as the IPCC claims (see “Is CO2 the ‘thermostat’ of climate“).

The second reason for recent “global warming” is that other global-warming forces not related to carbon dioxide have been unusually powerful, including the Hunga Tonga undersea eruption in 2021, which increased the amount of water vapour in the atmosphere by 10 per cent or more. Referring to the Hunga Tonga eruption, the Jet Propulsion Laboratory wrote: “The sheer amount of water vapour could be enough to temporarily affect Earth’s global average temperature.”¹

Water vapour is the primary greenhouse gas, responsible for up to 90 per cent of GHG warming, so adding 10 per cent more water vapour is going to produce increased warming. As the water vapour is reabsorbed into the oceans over the years, this warming effect will diminish and we’ll see more cooling—thanks to more CO2!

Plants die if CO2 falls to 150 ppm

This global explosion of greenery due to increased CO2 should not be a surprise to farmers, and particularly greenhouse growers. Farmers know that carbon dioxide is a fertilizer for plants—indeed, CO2 is essential for plant life: at a CO2 level of 150 parts per million or lower, plants can no longer survive. For example, a site run by the Manitoba government’s Ministry of Agriculture offers this information to greenhouse growers:

At 100 ppm of CO₂ the rate of photosynthesis would be stopped completely. At 150 ppm the plants begin to respire, and photosynthesis is stopped. At this low level the plant will no longer be able to obtain CO₂ from the atmosphere and photosynthesis is restricted. The plant will eventually use all of the CO₂ present, photosynthesis will stop and the plant will die.”³

And if the plants die, then almost all forms of life, including us, will also die.

As you can see from Figure 2, also from NASA, our planet almost reached this do-or-die CO2 point about 650,000 years ago, when we were at a close-to-rock-bottom 180 ppm (white arrow on graph).

And, as NASA notes, for much of the last 800,000 years, CO2 levels averaged a low of 200 ppm, which is a bit too close to 150 ppm for comfort.

Curiously, NASA offers this graph as proof that we are experiencing too much CO2 these days. This is puzzling. You’d think we’d want to get as far above the 150 ppm mark as possible, and that current CO2 levels of 430 ppm aren’t too high but too low! And you’d think environmentalist would happy about CO2 plant-enrichment since it produces more of their favourite colour (green), but they’re not. There’s just no pleasing climate alarmists.

How CO2 benefits plants

Not only does more CO2 produce more plant growth, but these plants are also more drought-resistant. Here’s how the process works.

Plants have tiny openings on the bottom of their leaves called stomata. Plants need CO2 to grow their stems and leaves, and the stomata open up to trap carbon molecules from the atmosphere. At the same time, whenever the stomata open, the plant loses moisture, which can be a problem in drier regions. So it’s a balancing act for the plant: CO2 or moisture?

When CO2 levels are low and carbon molecules are not plentiful in the air, plants need to leave the stomata open longer to get the carbon they need, which means they lose more moisture. But as CO2 levels increase (take a bow, humanity!) there are more carbon molecules flying around and it’s easier for plant stomata to scoop them up. That means enhanced plant growth.

Also, with higher levels of carbon dioxide, the stomata don’t have to stay open as long to get the carbon molecules the plant needs and the plant loses less water, which means plants become more drought-resistant. That’s why the Earth is greening as humans add carbon dioxide to the atmosphere, especially in the semi-arid regions.⁴

Even the anti-carbon IPCC agrees that more CO2 equals more greening. In its sixth report (2021) it writes:

Increasing atmospheric CO2 concentration enhances leaf photosynthesis and drives a partial closure of leaf stomata, leading to higher water-use efficiency at the leaf canopy and ecosystem scales.⁵

Growers add CO2 to greenhouses

Here’s a fact that may shock climate alarmists: Greenhouse growers actually add CO2 to their greenhouses to reach levels of 1,000 ppm or more! That’s over twice the current level and well into doomsday territory for climate alarmists. Who knew?

Here’s what an Ontario government website for greenhouse farmers has to say about enhanced (but, for alarmists, “catastrophic”) CO2 levels:

CO2 increases productivity through improved plant growth and vigour. Some ways in which productivity is increased by CO2 include earlier flowering, higher fruit yields, reduced bud abortion in roses, improved stem strength and flower size. Growers should regard CO2 as a nutrient.

For the majority of greenhouse crops, net photosynthesis increases as CO2 levels increase from 340 to 1,000 ppm. Most crops show that for any given level of photosynthetically active radiation (PAR), increasing the CO2 level to 1,000 ppm will increase the photosynthesis by about 50% over ambient CO2 levels. [emphasis added]⁶

Pretty good for a trace gas that is, for Australian ultra-alarmist Tim Flannery, “choking the atmosphere,” that is “global warming pollution” for Al Gore, and just plain “pollutant” for the U.S. Environmental Protection Agency (EPA), until President Donald Trump called a stop to it.⁷

On the negative side, alarmists point out that these enhanced super-plants might not be quite as nutritious (have slightly less protein and nitrogen) as their less-developed cousins.⁸ Much more food, but it might be slightly less nutritious. For climate alarmists, there’s always a worm in the apple….

Overall, the CO2 that humans are adding to the atmosphere is greening and cooling the planet, not endangering it or life. Currently, CO2 levels of 400 ppm are low compared to levels in the geological past, which have sometimes been in the thousands of parts per million (see Figure 3). In fact, for optimum plant health and growth (which means optimum conditions for all life), the planet needs more CO2, not less.

This post is an edited excerpt from Chapter 8 of Paul MacRae’s book Through the Looking Glass: A Citizen’s Guide to Climate Science, available at Amazon and ebook sites.

Notes

1. NASA, “Carbon dioxide fertilization greening Earth, study finds.” April 26, 2016. [↩]
2. Magnus Aschan, NASA, “The Earth is greener now than it was 20 years ago.” March 5, 2021. [↩]
3. Ministry of Agriculture, Government of Manitoba, “Greenhouse CO2 supplement.” [↩]
4. Physicist Freeman Dyson describes the process in his essay “The Greenhouse Effect: An Alternative View,” in his book From Eros to Gaia, London, Penguin Books, 1993. It is online as a chapter of the anthology Eyewitness to Science. [↩]
5. IPCC, Climate Change 2021: The Physical Science Basis. Chapter 5, Cross-Chapter Box 5.1, p. 697. Available online. Earlier reports have noted that additional CO2 can increase plant growth by up to 33 per cent. See IPCC 2001, Chapter 3, Section 3.2.2.4, p. 195. [↩]
6. “Supplemental carbon dioxide in greenhouses.” Ontario Government. Dec., 2002. [↩]
7. For details, see Wikipedia, “Regulation of greenhouse gases under the Clean Air Act.” Basically, perhaps because it hasn’t taken complete leave of reason, the EPA doesn’t call carbon dioxide a “pollutant” directly; instead, it got the courts to agree that CO2 fell under its Clean Air Act, which is aimed at “pollutants.” [↩]
8. Cell Press, “Increasing levels of CO2 results in less nutritious crops.” Science Daily, March 27, 2023. [↩]

1. Jet Propulsion Laboratory, “Tonga Eruption Blasted Unprecedented Amount of Water Into Stratosphere.” Aug. 2, 2022.[↩]