Please refrain from assigning intent to a simple comment.
Given the large amount of statistics and facts that you bring to the question it is clearly evident that you know more about this problem than I do. I merely wish to point out that a simple linear scaling of current consumption levels is not a convincing model for adoption of any new technology / paradigm. You had me on the facts, but lost me on the projection.
When you say something like Keyword there is => "current levels", it comes off as pessimistic and poisonously negative. It's the kind of statement that shuts down conversation rather than encourages it. Rather than inquisitive, this comes off as dismissive. I may have misread your intent, though, and if so I apologize.
I am aware that constant usage is not generally a valid assumption. I made a simplifying assumption that I believe reasonable given the sheer size of the energy store. It doesn't matter much if our usage is constant or increases a thousandfold. There's so much energy in the crust that we essentially could not use it all, and I doubt that we would use enough to cause global issues (vs local issues caused by overuse in certain areas which seems more feasible).
P.S. To be clear, I don't know much about this problem at all. My only data is from Wikipedia and its references.
I made a simplifying assumption that I believe reasonable given the sheer size of the energy store.
One of the points that TeMPOraL made above is "and again, trees were a renewable resource too, before the industrial revolution.". The point being that resources that are seemingly infinite when first used can end up being not so unlimited.
So for example, the person downthread who uses energy trends estimates a lower bound of about 1000 years (if current energy consumption trends continue, we immediately switched to only geothermal, and we used the entire heat of the earth edit: Earth's crust, not the whole earth). So now we have a range of 1,000 to 800,000 years (based on varying assumptions).
800,000 years to take up 0.001% of the total heat would be fine. 1,000 years to take up 100% of the heat would be really bad.
The 1,000 year quote is based on historical data, and 800,000 years is based on flat/zero growth. So there appears to be room for discussion, not all of which is 'fear monger'ing.
> One of the points that TeMPOraL made above is "and again, trees were a renewable resource too, before the industrial revolution.". The point being that resources that are seemingly infinite when first used can end up being not so unlimited.
It's legitimate to ask what our energy usage might grow to. It's not legitimate to dismiss potential energy sources because we cannot predict the future with perfect accuracy. We will never predict the future perfectly, or even close, and if we have a choice between killing the planet in 1000 years or killing it in 100, we'd still be better off taking the first option.
The "1000 years" comment also assumes we'll double our energy usage every 25 years. If we accept that as true then our only viable strategy is to get off this planet because it assumes that in 1000 years we will literally have extracted all energy from the core. We're doomed if this is our future.
Also, please stop mentioning the trees. This has been addressed multiple times now. The industrial revolution didn't result in trees being cut down. Quite the opposite. The large-scale adoption of fossil fuels resulted in forests rebounding worldwide as we stopped relying on timber as a fuel.
> *The 1,000 year quote is based on historical data, and 800,000 years is based on flat/zero growth. So there appears to be room for discussion, not all of which is 'fear monger'ing.
It's rather generous to say it was based on historical data. It was based on taking the log2() of our current energy usage and eyeballing an energy usage chart to produce a guess at a 25-year doubling rate. Our energy growth is no more a constant than our usage, though, so extrapolating this way is as unrealistic as assuming we'll stay at present-day usage forever.
There is certainly room for discussion. Again, though, I'll point out that a discussion should be about options and not just the worst case for geothermal exhaustion. If we found that we could replace all of our fossil fuel use with geothermal but we'd only get to extract energy for 1000 years safely, that would be a great deal, because the obvious alternative is that we literally burn every bit of fossil fuel we can extract from the Earth.
On the trees numbers, the US now actually has more forest or trees than it did at the start of the twentieth century.
The argument sometimes gets confused, since conservationists are concerned about the loss of old-growth forests, and animal habitats vs. the quantity and area of forests.
Or you can fear monger and oppose change and prefer that we burn fossil fuels indefinitely, I guess.