Hydro is amazing when it comes to electricity generation, but for that reason it has already been developed as much as possible during the whole 20th century and there's really little room for enhancement (and when the technology progresses, it's quickly deployed).

In fact, I like to say that the only viable option to get 100% RE is to lower our energy consumption until hydro can cover the majority of our needs.

And there are so many valleys you can flood.

And dams are incredibly ecologically devastating.

There isn’t enough hydro potential on the planet to produce the amount energy we need.

It’s also worth pointing out that while hydro is renewable, it isn’t clean. Dams are ecological nightmares.

Hydro will like be part of our energy profile indefinitely. But it will never be more than a small fraction. And in the long run that fraction will get smaller as global energy demand continues to grow.

There is enormous potential for off-river pumped hydro storage, though. Geography that doesn't have much if any natural water flow can still hold vast amounts of water in enclosed areas.

Hydro is great, but limited.

IMO, most industrialized nations have already tapped hydro about as much as it can be tapped, given some constraints about wildlife habitat. But I'd be happy to be corrected -- what new hydro projects do you think we should be doing, and how much power do you think they'd provide?

It is also very hard to get buy-in for large new hydro plants. The resevoirs behind the damms cover a lot of area and people don't like their homes being under water. There are also ecological considerations like trout and salmon migration. Due to this they are actually demolishing old, low power legacy hydro plants and re-naturalizing the river.

Yup. Somehow climate change is supposed to be this planetary existential threat, but not, you know, so existential as to allow a salmon to be endangered or to risk building a nuclear plant.

Climate change isn't actually a planetary existential threat, despite all the fear mongering you hear.

https://en.wikipedia.org/wiki/Economic_impacts_of_climate_ch... and the more alarmist https://www.weforum.org/agenda/2021/06/impact-climate-change... say that the global economic impact of climate change will likely amount to about 10% of world GDP, and perhaps as much as 20%.

Those are huge, huge numbers! But to put them in perspective, it's less than the difference between living in, say, present day US vs present day UK. Big impact, but hardly planetarily existential.

And, yes, there's more to live than economics. But if life goes on normally enough that we can even not only still talk about GDP with any meaning, but even say that we are going to preserve 80% to 90% of GDP, things won't be too apocalyptic.

Keep in mind that this is 80% of a far larger pie than today, since normal economic growth will continue.

> say that the global economic impact of climate change will likely amount to about 10% of world GDP, and perhaps as much as 20%.

So maybe that's why governments don't act, relying on abstract GDP numbers. «A good chunk of the tropical era of the world is going to be uninhabitable[1]? Who cares, it's only gonna cost us 10% of GDP».

https://www.nytimes.com/2021/03/08/climate/climate-change-he...

> it's less than the difference between living in, say, present day US vs present day UK. Big impact, but hardly planetarily existential.

Like, the difference between living in Birmingham or living in the death valley?

https://www.nytimes.com/2021/06/30/world/canada/bc-canada-he...

> Climate change isn't actually a planetary existential threat, despite all the fear mongering you hear.

Well, no, the planet will not be destroyed. The issue is the lifestyle of the semi-hairless apes on the planet.

> https://en.wikipedia.org/wiki/Economic_impacts_of_climate_ch... and the more alarmist https://www.weforum.org/agenda/2021/06/impact-climate-change... say that the global economic impact of climate change will likely amount to about 10% of world GDP, and perhaps as much as 20%

No, its that it will grow to that share by 2050 (which is less than 30 years away) and keep growing.

> At a (somewhat generous) 3% baseline growth rate,

At a fairly generous 3% baseline growth rate, 2.35× current world GDP, for a projected population of 9.7 billion to todays 7.9 billion, so (pre-climate change impacts) a little under double the current GDP/capita.

Of course, the losses arent, expected to be evenly distributed among countries, regions, etc., so if you aren't a well-diversified capitalist (say you are working class) and in the wrong place or industry, you have a good chance at seeing dramatically* greater impacts.

Yes, those are big impacts. Just not existential impacts even just for humanity.

> Of course, the losses arent, expected to be evenly distributed among countries, regions, etc., so if you aren't a well-diversified capitalist (say you are working class) and in the wrong place or industry, you have a good chance at seeing dramatically* greater impacts.

Yes, averages hide a lot of variance.

Of course, this is another good reason in favour of allowing freer migration around the globe.

> Of course, this is another good reason in favour of allowing freer migration around the globe.

From the perspective of the people in places likely to see lesser adverse impacts, its a reason against freer inbound migration.

Why? For those people it's at worst a neutral argument, as getting migrants ain't bad for you (and is arguably good).

Of course, now we'd have to discuss who 'you' is. If you are talking about individual people, or about eg some statistical measure of the country or county as a whole.

See also https://openborders.info/keyhole-solutions/ which would suggest to eg just charge people to immigrate.

Dam the Gibraltar! ;-)

Totally renewable - and not just hydro, but also solar (which takes care of the water you let in)!

And yes, this has been proposed and is physically possible & it alreadyhappened for geological reasons in the past:

https://en.wikipedia.org/wiki/Atlantropa

Careful there: you might mess with the salt and mineral concentrations in the Mediterranean Sea. And, of course, there's lots of shipping through the straits of Gibraltar that you have to accommodate.

No problem withbsalinity in the most extreme varuants of this - you effectively let the whole Mediterranean Sea evapirate and only let in enough water to keep it this way, effectively making the whole scheme solar driven. That way you can also build multiple dams between island chains and get even more power, before the water eventually evaporates on the bottom most salt pan.

Also takes care of shipping. ;-) Although I guess you could build a near shore shipping channel, possibly filled with fresh water from rivers.

> No problem with salinity in the most extreme variants of this - you effectively let the whole Mediterranean Sea evaporate [...]

Well, then you still need to deal with the salt both as a onetime measure.

There's a far better option with the Qattara depression.

It has something like 100% availability throughout the day, yes.

But throughout the year capacity varies.

And, of course, there's only so many sites that can support dams. So you have to ask 100% of _what_? And is that enough?