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Comment by polskibus | Hacker News Reader

Is it really a drought only in the West? How is the rest of the globe handling it? I was under the impression that rainfall has beeen at very low levels everywhere.

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It seems likely that hundred-year-long droughts are very common in California. If you've ever seen Lake Tenaya in Yosemite, you may notice some dead trees sticking out the surface... Those trees are from a drought period in the Middle Ages [1] when the lake was much lower and totally fry in some spots - enough for pines to grow. Those deadheads are about 1000 years old! Highly recommend kayaking that lake.

[1] https://tripatini.com/profiles/blogs/yosemite-s-secrets-how-...

Global warming does not mean everywhere gets hotter.

Global warming means:

Entire planet gets hotter ON AVERAGE,

Some places will get hotter, some will get drier, but some can also get wetter or colder.

In essence, warming will cause weather patterns to change. We will get a period of changing weather and then the system may stabilise with a set of new patterns that are different from current ones.

Whatever happens, it will be very costly to humanity. Our current existence, for example placement of population centers, how we live, how our houses are built, how we produce our food -- it all depends on weather patterns being the way they are now.

In particular, it is possible that Europe will get colder soon. If the Gulfstream collapses, the masses of warm water that bring heat and humidity to north Atlantic will cease. While it is not entirely clear what is going to happen, it is possible we are going to get much more arctic air and possible that European climate gets drier.

Weather always changes.

Global warming means the planet gets hotter on average.

It does not mean every place gets hotter.

That's pretty much it.

"Climate change" is kind of a dumb phrase IMO. The climate always changes. Change is inevitable. It's fine.

Unidirectional change to warmer temperatures (global warming) is probably not fine.

Australia's east coast has had insane and unrelenting rainfall all year. This is due to La Nina which causes the moisture to be directed to Australia's east coast.

https://www.abc.net.au/news/2022-07-16/nsw-queensland-sydney...

It's actually interesting I remember people talking a lot about La Nina and El Nino back in the 90's, I didn't understand a lot of it back then because I was younger but it seems like no one talks about that, or the ozone, or any of these other major weather systems, or cycles anymore. Any change in weather is lumped into "climate change" I'm not saying I'm a denier, but I am just wondering how many other weather systems happen on decade long cycles that should also be considered or investigated?

Nobody talks about ozone because global cooperation led by science and public policy fixed the hole. Come to think of it, maybe we should talk about it more.

Can you really have a global drought? It seems like all the airborne water has to land somewhere, and climate change is increasing the water content of the atmosphere.

In total, I suspect that you're right. But it doesn't help us much if the rain falls into the ocean. What we've been seeing in the pacific northwest is long dry spells with short torrential rains, both of which are devastating to crops, but it does tend to balance out to about the same amount of annual rainfall. My very weak understanding is that the more extreme weather tends to kill plants, which contributes to desertification. Hot ground makes for high pressure zones, which prevents moisture-laden air from ever getting there. So, yeah, I'm not a climate scientist and the above is mostly guesswork, but I think you really can have a global drought.

If it lands mainly in the oceans, then effectively yes. (I don't know enough to say if there's a mechanism that would do this everywhere or most places)

There is - it's the el nino / la nina ENSO cycle. I think other people are right that the rain has to go somewhere but that thing can and has caused droughts over effectively the entire populated world. There was a world drought in the 1870s that badly affected brazil, northern africa, india, and northern china.

A lot of the water in the west comes from snowpack. But there's not going to be much snow anymore, hence there'll be less water.

That doesn't follow because rain fills reservoirs the same as snow. One difference, though, is that snow releases as it melts during the spring/summer.

Snow is localised and melts into captured streams. It gets refilled because high alt + low temp preferentially causes rainfall/fog that replenishes the snowpack.

If fewer rain cloud condense on the peak then it just rains more dispersed which leads to much less efficient capture (some absorbed by the ground, some rains over ocean, evaporation is faster when you have water spread over large area so fraction of time spent in liquid form is smaller, etc).

It makes a big difference. Imagine watering your favourite plant once per month with 4 litres of water, vs watering weekly with 1 litre of water. The snowpack melt cycle allows for gradual watering of the surrounding areas. Not directly answering the question for reservoirs, but the rapid loss of snowpack and glaciers has a massive impact on the environment.

So that a system of dams that works for snow pack would need to be scaled up five x or ten x to collect all that flow in less time.

Right. Snowpack is a form of massive reservoir. Snowmelt through the course of the year allows us to constantly release water from human-made reservoirs while their levels stay the same. There is still snow in the Sierra today, and in a typical year snow stops falling in April.

Rainfall is much, much harder to capture, and the release curve is completely different; you can very quickly go from flooding to bone-dry.

Citation needed. Climate change might create mega storms — more water in the air to fall as snow

But more rain doesn't necessarily equate to more ground level water supply. Rain more easily evaporates, and can then be transported elsewhere. Snowpack historically is critical to water supplies in the West because it slowly melts and provides a steady source of water throughout the dry season. A mega storm with no way to capture the water AND prevent it from evaporating in the dry season can still provide far less water than an equivalent amount of snowpack.

There's an article in the Washington Post today:

> "The root of the problem is an ongoing, 23-year drought, the worst stretch for the region in more than a millennium. Snowpack in the mountains that feed the 1,450-mile river has been steadily diminishing as the climate warms. Ever-drier soils absorb runoff before it can reach reservoirs, and more frequent extreme heat hastens evaporation."

https://www.washingtonpost.com/climate-environment/2022/08/1...

> It seems like all the airborne water has to land somewhere

Water is kept airborne by thermal energy. As thermal energy increases, one can expect the atmosphere to on average retain more moisture globally.

At the extreme of this effect, you get something like Venus.

Hrmm, so having now read some random papers, I learned that relative humidity over land is actually decreasing due to climate change, which isn't what I expected. Guess we're screwed.

Would not a drought that is affecting large percentages of populations worldwide not be considered a 'global' drought even if it isn't everyone?

it’s a combination of drought and over use. they like to report on drought but we keep using more water each year

Just watched a DW documentary the other day on droughts and climate change, focusing on California for some time without ever mentioning agriculture. Sure, restaurants in Mendocino have to close because they can't operate bathrooms, let's mention that. Let's also mention that it takes a gallon of water to produce a single almond, that 80% of the worldwide supply is grown in California, and such insanely water-intensive farming is still doing just dandy while people elsewhere in the state are keeping track of toilet flushes.

Northeast rainfall is more-or-less at normal levels.

I believe Massachusetts is suffering critical drought: https://www.mass.gov/info-details/drought-status

Yes but you have to keep in mind that droughts are really different in the northeast. Our reservoirs are all over 90% full. We like them at 100%, but it really isn’t all that unusual to have dry spells in July and August. People are conserving water right now because it’s the right thing to do, but nobody thinks that this is going to extend too far into the fall

I've lived in Western Mass for 20+ years and this summer has been bone dry. Most of the grass in my yard is dead (which never happens) and our town (feed by wells) has had a water restriction order in place for most of the summer.

It's been bad enough I'm starting to wonder about cisterns/rain barrels to save water for the dry season.

I'm hoping this is just an isolated pattern. Two or three years ago (not quite sure) was so wet though that it took two months to stain my deck (waiting for it to dry out after powerwashing it and then waiting for the rains to stop).

Another idea I'm entertaining is a DIY well (thanks to our pretty accessible water table) for watering the lawn. It's not clear how cool the town will be with this but worth exploring. :-)

Northeast US is in a mild to mid level drought depending on where you live. Higher temps are causing more evaporation and consequently more water usage (also rising population).

Does the northeast have much of a rising population?

In the Pacific Northwest we had the rainiest spring in a long time this year. Typically the rain up here is more of a continuous drizzle, but during the spring it started raining hard and didn’t let up like it normally does. Our rivers reached the lower flood stages from too much rain.

Has been a really rainy summer in northern Missouri, USA, at least for this last half of it.

In my neck of the Midwest, we've had a dry couple of months, but generally the last few years have seen precipitation levels at or above the yearly average.

Pacific Northwest has a had a very rainy spring/summer, very cool as well.

East coast, for example, has no drought.

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