Another important type of risk is environmental risk. So let me talk about this and I've thought a lot about this type of risk. So both Ethereum and Bitcoin use proof of work and we've already gone through that this is very energy intensive. And this amount of computing power is both, these protocols greatest strength because it provides unprecedented security but it's also in my opinion its greatest weakness because of the amount of carbon that it generates. So this is what proof of work is and this data is from Cambridge University. You can see that they estimate that Bitcoin is using about 79 terawatt hours per year and you can see that that is more than the country of Chile. And this is also an interesting diagram where it shows for example the amount of power that's used in different industries for example, televisions in the US is 60 terawatt hours Bitcoin is 79. So this is a lot that's used compared to these other applications. It is interesting nevertheless the people say well Bitcoins the new gold, well actually gold mining worldwide uses much more power than Bitcoin. So this is just to give you some comparison but the fact is that this is a lot of power. This issue of carbon is a general issue and we need to also put this into context that there's a lot of energy that is basically wasted. And one source that's very striking is the gas flaring and the recovery potential for that is enormous. Indeed some mining operations have actually tried to harvest some of these flares for the energy and basically this is almost nine times the amount of power that is used in Bitcoin mining. I'm talking Bitcoin of course, but Ethereum is also using the same very energy intensive mining algorithm. So we've talked about a very substantial mitigator for Ethereum and that is the move to proof of stake. So once we get a proof of stake, all of this redundant mining ends. So you've got somebody that's randomly assigned to validate and add a block and the amount of computational power that's necessary for that is trivial compared to the situation today. So in my opinion, Bitcoin is not going to shift to proof of stake, it's just very unlikely. They spent years trying to get agreement on just increasing the block size, so the shift to proof of stake is extremely unlikely. Indeed the miners, why would they vote for something like that? Because if they shift the proof of stake then it means that all of their mining software and hardware, the mining machines are actually worthless, so extremely unlikely. Ethereum will definitely move, it's a question of when not if. So I have done some calculations here in terms of the amount of carbon which I will share with you. And the calculations are rough, they assume the energy production is the same mix of source that we see in the US but the numbers are kind of striking and let me go through the spreadsheet. So again, I use the Cambridge university site and this is just for a Bitcoin and what the energy actually the use is and then I calculate the carbon use and that would be like 27 million tons. And then figure out the number of new Bitcoin that are created in 2021. The carbon for Bitcoin, the cost of a carbon offset I assume is $50 but I could change that, and then the marginal cost of the carbon offset for a new Bitcoin is over $4,000. And we can also look at this a different way, we could look at the number of blocks, the number of transactions that actually occur and we could look at the carbon cost per transaction and that carbon cost is about $12. So this is a very large numbers for this in terms of if we're thinking of making this clean, then you would want to buy a carbon offset and this is the cost. However, we need to be very careful in this analysis. So we can calculate the cost of a carbon off set for a Bitcoin but what if it's traded, do you pay it every time? I don't think so. So given that multiple people could be dealing with it, the cost actually would decrease and so trading volume needs to be taken into account. So the other issue is we've got 18 million Bitcoin out there but some of them, well actually most of them were mined in a period where it wasn't computationally that difficult to actually mine the Bitcoin, so not that much energy was being used. So most of the Bitcoin were created when the cost a carbon offset might be just a few cents. So the current ones are much more energy intensive but all of these Bitcoins are fungible, they're all the same, so how do we actually deal with that? So you need to actually do this historically and figure out when the coins were mined, what the computational power was and work out the carbon offset based upon that. So that's actually pretty complicated to do but I'm guessing and this is again just my opinion, that if you do that then the average carbon cost maybe it's $5, there's certainly not $4,000, okay? So that needs to be taken into account also. And even there you need to take the trading volume into account, okay? So again this is a complex problem, there's an investment fund out there that offers something like a Bitcoin ETF and they sell it as a clean ETF. And what they do is for every Bitcoin that you buy within that fund, the price includes what they calculate as the carbon offset and earns $55 per coin. And again there's a range here but obviously 4000 it doesn't make any sense to apply that to all of the 18 million bitcoins and you need to take the trading volume into account. So why do we care about Bitcoin? Indeed, I haven't talked that much about Bitcoin in the course. So Bitcoin is not a protocol where we can do smart contracts, we can't currently do defy on the Bitcoin Blockchain but we do care about Bitcoin because Bitcoin is the largest by market capitalization cryptocurrency. I guess by far the leader and it has been the leader, its share has decreased but nevertheless it is very large, okay? So it doesn't really fulfill the vision of Satoshi Nakamoto as a transaction mechanism but it is very effective transaction mechanism for very large transfers, okay? So it is not a transaction mechanism right now in general, it's more store of value but as I've mentioned a risky a store of value. Importantly we have talked about Bitcoin on the Ethereum Blockchain. So one thing that's very important is liquidity and collateral and we talk very specifically about Wrapped Bitcoin, so that is WBDC which is a version of Bitcoin that is active on the Ethereum Blockchain. So Bitcoin is important for decentralized finance, in my opinion, the way this is going to play out is fairly straightforward. Certain countries and China has taken steps to do this, we're going to say no, there's no mining of Bitcoin because basically the power that you're using is largely generated from coal fire plants, which are the worst plants in terms of putting carbon into the atmosphere. So the mining will move to areas that have locked clean energy and the country that I think is poised to do really well here is Iceland. And it's already a large amount of mining in Iceland, but it's got the advantage of essentially unlimited geothermal fuel for electricity that steam generated electricity that is clean. It's cheap and it makes sense given the climate is cold already, you don't need to spend on cooling mechanisms, it makes sense that there'll be a large migration of mining in the future to a country like Iceland that's got locked energy. Iceland is not the only country that's got geothermal but it is a good example of a solution here. I also think in the future that this won't be a problem because there just won't be any dirty energy, so we're in a transition right now. In the future in my vision, we've got lots of power, it's just a technology problem to harvest the sun and in the future power will be so cheap that the proof of work won't be a problem, it'll all be clean. So I see in kind of the short and medium term a migration to mining in places with blocked clean energy and then after that, all of the power will be clean and it just won't be an issue. So I believe actually some people say well, the proof of work is the downfall of Bitcoin, no, I don't think so. Bitcoin is going to be around for a long time and Bitcoin is important for decentralized finance.