New research has laid bare the gulf between bitcoin and other cryptocurrencies when it comes to sustainability.

A report by Forex Suggest has put a number to the carbon cost of cryptocurrency transactions, measuring each blockchain by the number of trees that would need to be planted in order to offset the electricity consumed by them.

As you might expect, bitcoin came out ahead of the most energy-hungry network.

Forex Suggest projected that the energy costs associated with the world’s most popular cryptocurrency would contribute around 56 million tons of CO2 in 2021. According to them, offsetting this would require around 284 million trees to be planted.

Ethereum followed closely in second place. Forex Suggest estimated that the costs of maintaining the world’s second-most popular cryptocurrency would work out to be around 21.9 million tons of CO2. Offsetting this would require the planting of approximately 109 million trees. Even if that’s almost a third of that required by bitcoin, it’s still a lot of trees.

Fortunately, cryptocurrencies further down the list are not nearly so energy demanding.

Where bitcoin uses 707kWh per transaction and ethereum uses around 62kWh, bitcoin cash and litecoin use just 18kWh per transaction. These improvements in energy efficiency mean that offsetting the third and fourth most carbon-intensive cryptocurrencies is significantly more achievable.

Green cryptocurrency cardano ranked fifth when it came to projected carbon emissions.

Unlike more expensive or high-profile cryptocurrencies, cardano uses a proof-of-stake consensus mechanism. This requires much less energy than the proof-of-work mechanisms found in bitcoin and ethereum.

At a rate of 0.5479kWh per transaction, the cost of Cardano is expected to work out to around 5,288 tons of carbon dioxide for the whole of 2021. Forex Suggest said that offsetting would require 26,000 trees to be planted.

Ripple is even more energy-efficient, working out to around 0.0079kWh per transaction.

Offsetting the 3,000 or so tons of CO2 emitted by this blockchain would require an estimated 15,000 trees.

Ultimately, stellar sat at the bottom of the list here when it came to carbon emissions.

This blockchain network uses just 0.00003 kWh per transaction, racking up a projected CO2 footprint of around 37 tons of CO2 in 2021. Offsetting the energy consumed by this network would require just 183 trees to be planted.

Going forward, Forex Suggest predicted that this minimal emissions advantage would help stellar thrive in a low-carbon marketplace.

“The Stellar Consensus Protocol is so much more efficient than PoW or PoS that Stellar produced by far the least CO2 in 2020 and 2021, despite having the highest number of transactions,” the report said.

This survey of the crypto landscape comes amid increasing attention towards the controversial relationship between cryptocurrencies and carbon emissions.

Industry bodies like the Crypto Climate Accord are looking to shift the entire cryptocurrency industry towards renewable and sustainable resources by 2030.

Meanwhile, a recent report released by Apollo Capital argued that bitcoin’s shortcomings on environmental issues had been amplified by the media and sceptics.

Apollo Capital noted that, although the electricity consumption of the bitcoin mining industry uses approximately 30 per cent less than that of the gold mining industry, the two are rarely placed in conversation with one another.

“A simplistic narrative leads many to dismiss crypto as poor on the environmental, social and governance issues because of exaggerated concerns about bitcoin’s energy consumption,” the report said.

The report also made the case that the mining of cryptocurrencies often uses energy that other sectors cannot and that it sources that energy in a more efficient way – since miners are typically located closer to areas where energy is cheaply produced.

Ultimately, Apollo Capital predicted that the industry-wide push towards non-Proof-of-Work consensus mechanisms would address these sustainability issues sooner rather than later.

“PoW is a diminishing share of the crypto market and will likely fall to around 40 per cent of the overall market once ethereum 2.0 launches, probably early next year,” the report predicted.