Ornithologist Leho Luigujoe had been watching birds at the same quiet Estonian wetland near lake Vortsjärv for years when he saw a shift in the once grassy landscape.

The springy meadow that had once been a rare stronghold for the great snipe, known for its long beak and even longer love song, had vanished. In its place stood neat rows of birch and spruce trees, planted in sharp lines across the marsh. The spongy grassland of old was slowly turning into a forest. And the birds had fallen silent.

When Luigujoe set out to understand what had happened, the answer came with a twist. The trees had been planted as part of a carbon credit project  designed to help fight climate change  by offsetting fossil fuel emissions released into the atmosphere.

How carbon credits should work  

Carbon credits work like this: for every ton of CO2 emitted, a company can buy credits to support a project somewhere in the world that is removing the same amount of existing carbon. Examples include turning organic waste into biochar or using direct air capture (DAC). Such credits have price tags starting at around $100 and running to well over $1000 (about €92–€920).

A cheaper option is credits that prevent further emissions, perhaps by protecting an existing forest from logging. These tend to cost between $5–$10 per ton. 

There are two main types of carbon markets: mandatory and voluntary. The EU's Emissions Trading System (ETS), for example, is mandatory, legally capping emissions for sectors such as energy, cement, steel and aviation. It was designed to gradually reduce industrial emissions across Europe.

The voluntary sector allows interested companies to offset emissions if they want to, often for image reasons or to meet Environmental, Social and Governance (ESG) benchmarks, which can help access green finance or subsidies in some markets. 

While the EU's ETS is heavily regulated and audited, the voluntary market is more arbitrary. Worth $2 billion in 2023, according to nonprofit research platform Ecosystem Marketplace, it has few global rules and no universal enforcement. 

Siim Kuresoo from FERN, a forest policy NGO based in Brussels and the UK, says the voluntary carbon market treats woodlands like numbers in a spreadsheet. "The forest-based offsets serve as a 'get out of prison' Monopoly card for companies that are reluctant to cut their own emissions."

Nerijus Zableckis, who heads the Lithuanian NGO Foundation for Peatlands Restoration and Conservation, says the most "concerning" thing about the sector in his country "is the names of the people entering the carbon credit system." He says most are "speculators and fraudsters."

Tougher regulations needed

Jonathan Crook, a policy expert on global carbon markets with nonprofit Carbon Market Watch, says voluntary carbon markets include well-meaning actors and those exploiting weak oversight for personal gain.

"We've documented many, many cases where things are not going well," he said. "And in some cases, that is intentionally by bad actors, or what are often referred to as 'Carbon Cowboys.'

He sees an urgent need for clearer safeguards and stricter government regulations to monitor how carbon credits are used. 

"Too often, companies use credits to claim neutrality without really cutting their carbon emissions," he said. "And that is the real problem."

A 2023 meta-study published in Nature Communications found that less than 16% of carbon credits issued "constitute real emission reductions" — casting doubt over large parts of the voluntary carbon market.

Rewriting the rules: new players, old lessons

Yet not all carbon projects are flawed. In 2022, entrepreneurs in Estonia set up Arbonics as a response to the loopholes and shortcuts in the market. The idea is to support landowners who want to enter the carbon credit market by ensuring their projects meet scientifically robust standards. 

Using satellite data and environmental filters, they pre-screen each site before planting. Areas like wetlands or existing forests are ruled out entirely. Their system also flagged the lake Vortsjärv site as unsuitable. "Only high-quality projects will survive in the long run," said co-founder Kristjan Lepik.

It's not just new players changing course — some major corporate buyers are also adjusting. Few more publicly than Microsoft.

Microsoft's course correction

After facing heavy scrutiny in 2022, Microsoft admitted that many of its early carbon credit purchases were shaky. "We constructed our portfolio with a lack of perfect confidence" in how long the captured carbon would stay put and how clearly it could be measured, said the US technology company.  

In its report "Carbon Removal: Lessons from an Early Corporate Purchase,"Microsoft acknowledged it had underestimated the importance of verifying the carbon sequestering promises of the projects and added "the market lacks clear carbon-removal accounting standards," a gap it says compelled Microsoft to seek projects with more reliable, longer-lasting climate benefits.

Among other things, since at least 2021, the IT giant has been buying credits from Carbofex, a Finnish company that heats organic waste in a low-oxygen environment to make biochar. The material can store carbon in soil for centuries.

Certified by Puro.Earth, a registry that claims to vet only long-term, science-based carbon-removal projects, the credits cost $100 to $200 per ton, far more than traditional offsets — but are also more likely to deliver permanent climate benefits.

EU moves to strengthen carbon credit regulations

In early 2024, EU lawmakers approved a new framework to certify carbon removals, focusing on robust science, independent verification, and clearer definitions. They aim to weed out greenwashing and support the projects that actually store carbon — and keep it there.

Meanwhile, back in Estonia, environmental authorities have stepped in, ordering the company behind the lake Vortsjärv carbon credit scheme to remove all 120,000 saplings and restore the land to its former state. 

An open meadow will return, for the great snipe to drum its wings at dusk and dance again beneath the vast northern sky.

Edited by: Tamsin Walker

With additional reporting from Kristel Harma, Marta Frigerio and Migle Kranceviciute.

This story was produced as part of the cross-border investigation "Cashing In on Future: Carbon Credit Market's Footprint in Europe," supported by Journalismfund Europe and conducted in collaboration with Siena, Äripäev, and DW.