NFTs and the carbon footprint dilemma
NFTs are disrupting the creative industry by providing artists with a new medium to sell their work and even make a profit with subsequent resales. Although this technique has been around for some years already, it is in 2021 when it has started flourishing driven by the new golden era for cryptocurrencies.
However, NFTs are being criticized for the carbon emissions they produce. Each transaction is estimated to produce 20 kg of CO2  and there are often multiple transactions connected to a single artwork.
Carbon emissions associated to NFTs
An individual NFT transaction does not directly increase emissions. As SuperRare points out , Ethereum's blockchain has a fixed energy consumption at a given point in time regardless on how many transactions are processed.
While this statement is technically true, there are at least two ways NFTs are indirectly pushing carbon emissions further :
- "More NFT transactions" means more money going to the miners as gas fees. As a consequence, miners acquire even more energy-consuming devices to meet the increasing demand.
- NFT traders need to buy Ethereum in the first place. This pushes the cryptocurrency price up, making mining a more profitable business and attracting more miners (and more devices).
Ethereum's network, like Bitcoin, uses the energy-extensive Proof of Work mechanism. Even though Ethereum has plans  to cut its carbon footprint by 99% by shifting to the comparatively cleaner Proof of Stake protocol, it hasn't happened yet.
To put things into perspective, Ethereum consumes just a small fraction of the energy that a single Bitcoin transaction requires .
Offsetting carbon emissions to mitigate the effects
On March 17th 2021, the crypto art gallery aimade.art decided  to start offsetting the carbon emissions it generates by planting trees in rural areas. Two weeks later, the renowned NFT marketplace Nifty announced  its plans to become carbon-negative. Although these movements could be understood as "greenwashing", they are voluntary initiatives that help mitigate the negative impact on the environment while reinforcing blockchain as an alternative distribution channel for artists. The long term solution, though, should come from the shift to Ethereum 2.0 (proof of stake) and the increasing use of renewable energy.
The open-source project cryptoart-footprint has calculated (roughly) the carbon emissions of the main NFT marketplaces. If you are an artist or a collector, you can see your estimated carbon footprint on carbon.fyi.