The world’s plants don’t need more CO2

Plants on Earth have flourished for hundreds of millions of years, yet President Donald Trump’s pick to lead his new climate team insists that they need more carbon dioxide to thrive.

Princeton physicist and carbon dioxide-advocate William Happer has been selected to head the brand new Presidential Committee on Climate Security, reports The Washington Post. The atomic scientist — who achieved recognition for his work on atomic collisions and telescope optics, not climate science — maintains that the planet’s atmosphere needs significantly more CO2, the potent greenhouse gas that U.S. government scientists — and a bevy of independent scientists — have repeatedly underscored is stoking accelerating climate change.

Because plants use carbon dioxide to live, Happer has said “more CO2 is actually a benefit to the Earth,” asserted that Earth is experiencing a “CO2 famine,” and concluded that “If plants could vote, they would vote for coal.”

Earth and plant scientists, however, find Happer’s insistence that the plant kingdom would benefit from increased carbon dioxide wrong-headed and lacking evidence, at best. For reference, Earth’s CO2 concentrations have skyrocketed in the last century, and are now at their highest levels in at least 800,000 years — though other measurements show CO2 levels are higher than they’ve been in 15 million years. 

“The idea that increased CO2 is universally beneficial [to plants] is very misguided,” Jill Anderson, an evolutionary ecologist specializing in plant populations at the University of Georgia, said in an interview. 

“It’s a silly argument,” added Britton Stephens, a senior scientist in the Earth Observing Laboratory at the National Center for Atmospheric Research, in an interview. 

Both independent academic institutions and government agencies around disparate parts of the globe have concluded more carbon dioxide will “bring many negative impacts” to plant environments, Stephens emphasized. “If someone is going to claim it’s good, it’s incumbent upon them to show evidence.”

Reached by email, Happer said he would like to chat about the benefits of carbon dioxide in the future, but such requests must now be sent through (and vetted) by the National Security Council (NSC). The NSC responded by saying that “At the moment, a discussion on this topic is not possible.

If someone, like Happer, were to ignore uncomfortable realities like drought-ravaged crops, some of the deadliest wildfires on record, and the evaporating Colorado River, they could argue that some plants — but not all plants — could see growth benefits from amassing carbon dioxide concentrations.  

“If we were to hold other environmental factors completely constant, some plants would do well, some plants would do worse, and some would outcompete other plants,” said Anderson. 

But this is a reality that doesn’t exist. 

“We know that CO2 isn’t increasing in isolation,” said Anderson. Eighteen of the last 19 years have been the warmest on record. Both wild plants and crops are experiencing increased flooding, heat waves, and pestilence.

“CO2 does “fertilize” plants and by itself causes plants to grow faster, but unchecked CO2 release into the atmosphere will lead to reduced yields and the consequences could be catastrophic,” Thomas Sharkey, a plant biochemist at Michigan State University, said over email. 

Sharkey noted that pollen production — which is necessary for making seeds — is sensitive to even small increases in the average temperature.  

“The negatives far outweigh the positives,” added Stephens. 

As might be evident to anyone alive on the planet, plants flourish today and have flourished for hundreds of millions of years, so Happer’s suggestion that the planet’s vegetation is in need of more carbon dioxide is bizarre. 

“Obviously plants were doing just fine historically,” said Anderson. “There’s no indication plants are increasing their performance and doing better now than historically.”

A NASA graph showing skyrocketing CO2 levels.

A recent NASA study found that Earth’s overall greening over the last two decades — which is to say the increase in area covered by green leaves — is largely due to major tree planting programs and agricultural expansion in China and India. And some new regions of the planet are greening as the planet warms, like vast swaths of the northern tundra. But globally, the jury’s still out on whether increased carbon dioxide is having a measurable influence on plant growth. 

“This is not a huge signal that everyone can see,” said Stephens. 

There are extremely conspicuous climate signals, however, that everyone can see. One of the most widely-predicted consequences of a warming climate, stoked by historically-high carbon dioxide emissions, is increased fire weather. The California town of Paradise fell victim to profoundly dried-out vegetation and hot temperatures this past November. The forests had been turned to tinder, waiting to burn.

Is more CO2 really good for plants?

“Tell that to the trees in Paradise, California,” said Stephens.