Investors are showering love on nascent tech that pulls carbon dioxide from the atmosphere, but the vibes aren't so rosy everywhere in climate circles.

Driving the news: The VC firm Lowercarbon Capital just launched a $350 million fund dedicated to carbon removal startups. They're casting a wide net, co-founder Chris Sacca writes.

• His post cites tech that boosts natural absorption in minerals, talks of manipulating aquifer brines, enhancing ocean alkalinity, and growing plants that don't decompose, and other methods.
• There are also approaches "with massive potential that haven’t even been discovered yet."

Catch up fast: Sacca's unveil came 48 hours after Meta, Alphabet and other corporate giants pledged about $1 billion in removal purchases between 2022 and 2030 to help create market demand.

• That effort, led by payment tech company Stripe, is the latest of several recent investments. For instance, last week the Swiss direct air capture company Climeworks raised a fresh $650 million.
• There's public support too. Yesterday the Energy Department announced $14 million in studies for projects to fuel direct air capture (DAC) with clean energy.
• The bipartisan infrastructure law has $3.5 billion for developing U.S. DAC "hubs" to demonstrate the tech.

Why it matters: A landmark United Nations scientific report this month calls carbon dioxide removal (CDR) a "key element" for tackling global warming, though amounts vary.

• CDR includes bioenergy with CO2 capture and storage; direct air capture machines; large-scale vegetation; tech that speeds natural CO2 absorption in minerals; and other ideas.
• It can help compensate for emissions that can't be completely negated in tough-to-decarbonize industries, and also could help moderate temperatures after any "overshoot" of Paris goals.

Yes, but: The UN report and others consistently show the most important thing is cutting fossil fuel emissions by deploying clean energy — including mature sources like solar — much faster.

• Most CDR experts agree. And Sacca notes both mitigation and removal are key (and uses a delightfully evocative analogy seven paragraphs in).

Threat level: Growing focus on CDR is nonetheless worrying people including prominent climate scientist Michael Mann of Penn State.

• He'd prefer to see the money spent on speeding clean energy use. Mann told CNBC there's "no evidence" that CDR can scale in time.
• Mann tells Axios he's concerned that focus on CDR, along with ideas like unproven geoengineering, distract from the need for near-term clean energy and emissions-cutting policies.

Separately, Greenpeace USA research manager Tim Donaghy says via email, “Funding and investments must prioritize proven mitigation solutions like a rapid transition to renewable energy sources."

• He's concerned about using CDR to compensate for the temporary overshoot of the goal of limiting warming to 1.5°C above preindustrial levels.
• "Returning to 1.5°C would not undo the irreversible impacts triggered by then," he notes, a risk the UN report pointed to as well.