Tesla CEO Elon Musk’s controversial climate comments during his interview with former president Donald Trump prompted backlash on X from fellow billionaire Vinod Khosla.

Quoting an article from the Guardian, Khosla, the cofounder of Sun Microsystems and venture capital firm Khosla Ventures, ridiculed Musk, saying his climate conversation with Trump was “Infact soooo dumb, it should not be just called dumb.”

Musk shot back in a reply to Khosla’s post by insulting the Guardian and asking if Khosla had actually listened to the interview.

‘The dumbest climate conversation of all time’: experts on the Musk-Trump interview. Infact soooo dumb, it should not be just called dumb. https://t.co/YUn04KEyV6

— Vinod Khosla (@vkhosla) August 14, 2024

Khosla replied that the conversation was “dumb” and that while he expected Trump to not be as well versed on climate science, Musk skirted responsibility with his words on climate change.

“I don’t expect @realDonaldTrumpto know the nuances of various CO2 ppm levels and their consequences, and him reaching out to the person who has arguably done more for climate than anyone else is pretty sensible. You had a responsibility that I think you largely abdicated by downplaying the reality of things,” he wrote.

Khosla, who invested in DoorDash and Affirm, was referring to atmospheric carbon dioxide concentrations, measured in parts per million. The atmospheric level of the greenhouse gas carbon dioxide is crucial to environmental science and impacts the climate. Khosla confirmed that he, in fact, heard Musk’s comments in the interview. “I did listen to the climate part and yeah, I do think it was dumb,” he wrote.

For his part, Khosla is a major clean tech investor across transit, energy, and manufacturing through his venture capital firm.

During the two-hour live interview on X Monday, the electric vehicle CEO minimized the impact of climate change, saying that the worst elevated carbon dioxide levels can do is make it harder to breathe at a certain point.

“There is some risk, I think the risk is not as high as a lot of people say it is with respect to global warming, but I think if you just keep increasing the parts per million in the atmosphere long enough, eventually it actually simply gets uncomfortable to breathe,” said Musk during the interview.

After the atmosphere surpasses 1,000 parts per million of carbon dioxide, more than double the concentration now, people can get “headaches and nausea,” Musk said. Although this level of atmospheric carbon dioxide could lead to those effects, climate scientists and activists have warned that a much lower concentration of co2 could wreak havoc on the environment. Atmospheric carbon dioxide 800 parts per million or more hasn’t been seen on Earth for 50 million years, according to the National Oceanic and Atmospheric Administration. The environmental hit of surpassing 1,000 parts per million could lead to melting polar ice caps, flooding, ocean acidification, and potential biodiversity loss.

Musk also called for the U.S. economy to wean off oil and gas and transition to a sustainable energy economy “over time” because fossil fuels aren’t infinite.

“I don’t think we should vilify the oil and gas industry,” Musk told Trump. “If we were to stop using oil and gas right now, we would all be starving and the economy would collapse.

Musk added that an energy transition needs to occur, but there’s still plenty of time before an imminent climate disaster, contrary to the opinion of climate experts.

“It’s not like the house is on fire immediately, but I think it is something we need to move towards,” he said.

In April, the United Nations’ climate chief said government and business leaders have two years to take action and avoid the worst effects of climate change.