The long-term environmental impact of blockchain technology is debatable. Largely in part, because it can vary greatly depending on the way the network was established, is maintained, and will be scaled into the future.

Here are a few things to understand & consider whenever analyzing the environmental impact of any particular blockchain:

1. Consensus Mechanisms: The two most popular consensus mechanisms used in blockchains are Proof of Work (PoW) and Proof of Stake (PoS). PoW networks like Bitcoin rely on miners to solve complex mathematical equations to validate transactions, which takes considerable computational power and consumes a significant amount of energy. Then, PoS networks like Cardano rely on validators to hold a certain amount of cryptocurrency in their wallet to validate transactions, which consumes far less energy. Leading PoS blockchains to be considered fundamentally more energy-efficient than PoW blockchains. (learn more about consensus mechanisms, here.)

2. Energy Consumption: The energy consumption of a blockchain is directly proportional to the number of nodes, and the consensus mechanism used. Look for information on the blockchain's energy consumption or carbon footprint, which should be publicly available & easily accessible.

3. Renewable Energy Sources: The use of renewable energy sources in mining and validation can significantly reduce a blockchain's carbon footprint. Some blockchains have been designed to integrate with renewable energy sources, while others may have implemented or have plans to integrate renewable energy in the future. It's important to note that not all renewable energy sources are equal in terms of environmental impact. It's essential to research the type of renewable energy source used by the blockchain, so check if the blockchain is utilizing renewable energy sources, like solar, wind, natural gas, or something else to power its nodes or has any plans to do so in the future.

4. Emission Offsets: Some blockchains offset their carbon emissions by investing in carbon credits or renewable energy projects. This is done to counterbalance the environmental impact of the blockchain. Look for information on whether the blockchain has implemented any measures to offset its carbon emissions. However, it's important to note that offsetting carbon emissions is not the same as reducing them, and it's still better to opt for a blockchain that has a lower carbon footprint.

5. Design Choices: Some blockchains are designed to limit the size of blocks, which reduces the energy needed to validate transactions. Other design choices, such as reducing the number of nodes on the network, can also lower energy consumption. It is also valuable to consider the upgradability & scalability of the blockchain. A blockchain that is scalable and upgradable will be able to adopt more energy-efficient consensus mechanisms or integrate with renewable energy sources in the future. The most scalable blockchains will adapt to changing environmental concerns and remain relevant in the long term. Networks that are not fundamentally scalable or upgradable may have limited options to reduce environmental impact over time.

6. Community Involvement: The involvement of the blockchain community in the project's environmental impact is also important. Look for information on whether the blockchain project is actively working to reduce its environmental impact and if the community is involved in, or leading these efforts. A blockchain project that is transparent about its intentions with its environmental impact and actively works to reduce it can be considered more environmentally friendly than one that does not involve its community in such efforts.

It's important to remember that each blockchain has its unique environmental impact, and no blockchain is entirely environmentally friendly.

However, understanding the main factors above can help you make informed decisions when choosing to use, or create a blockchain.