Mr. Rogers knows the arguments: The last time venture capitalists invested heavily in environmentally focused technology during the so-called clean-tech boom of the 2000s, they lost a lot of money. Getting one of these companies off the ground can be expensive, as investors learned a decade ago. But he is not swayed by their caution.

“Sitting on your pile of money while the oceans are rising may not help you stay dry,” he said.

It is common wisdom in the tech industry that it is much easier to raise money for a software company than it is for a start-up that wants to work in biotechnology or energy. The current wave of internet-focused start-ups going public, and reaping billions of dollars for investors, has hardened the bias against so-called hard technology.

Total funding for clean-tech start-ups fell during most of the past decade, according to data from the research firm Pitchbook. In 2018, $6.6 billion was invested in clean tech, about 15 percent of what went to software start-ups. Carbon-removal start-ups got a tiny sliver of that.

The lack of investment in carbon-focused start-ups poses a particularly existential problem. Two major scientific organizations said last fall that even if greenhouse-gas emissions were reduced significantly, stopping drastic global warming would require technological breakthroughs that allowed for the removal of billions of tons of carbon dioxide already in the atmosphere.