SAO PAULO (Reuters) - Alphabet unit Google has agreed for the first time ever to purchase nature-based carbon removal credits from a Brazilian startup, its first engagement with carbon projects in the South American country.

Google will buy 50,000 metric tons of carbon removal credits by 2030 from Mombak, which purchases degraded land from farmers and ranchers or partners with them to replant native species in the Amazon rainforest, the firms said on Thursday.

Google, which had previously bought engineered removal credits, follows fellow U.S. tech giant Microsoft ( MSFT ), which last year inked a deal to buy up to 1.5 million credits from Mombak.

The Brazilian startup and Google did not reveal terms of the deal. In 2023, when it sold credits to McLaren Racing, Mombak priced them at an average of more than $50 per ton.

"The vote of confidence for us and this sector in general that comes from Google stepping into this is a really positive signal," Mombak's Chief Technology Officer Dan Harburg said in an interview, hoping it would trigger more deals.

The announcement comes as companies and authorities gather this month in New York for its annual Climate Week.

Earlier this week, Facebook owner Meta agreed to buy up to 3.9 million carbon offset credits from Brazilian investment bank BTG Pactual's forestry arm.

Google, Microsoft ( MSFT ), Meta and Salesforce ( CRM ) are the co-founders of the so-called Symbiosis Coalition, which pledges to contract for up to 20 million tons of nature-based carbon removal credits by 2030.

Carbon offsets allow companies to make up for greenhouse gas emissions by paying for actions to cut emissions elsewhere to meet corporate climate goals. Each credit represents a reduction of one ton of carbon dioxide emissions.

Critics of carbon offset markets, including Greenpeace, say they allow emitters to keep releasing greenhouse gases.