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Comment by chrisco255 | Hacker News Reader

Is anybody trying to make the claim that more CO2 means more droughts? Because I find that to be an extraordinary claim that demands extraordinary evidence.

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There are indeed causal links which play out differently from region to region. Here is the current best wisdom on links between global change and drought:

https://nca2018.globalchange.gov/chapter/3/

It's a big topic, partly because water is a uniquely important resource. It touches everything in the Earth system. Here is a key excerpt:

"Variable precipitation and rising temperature are intensifying droughts, increasing heavy downpours, and reducing snowpack. Reduced snow-to-rain ratios are leading to significant differences between the timing of water supply and demand. Groundwater depletion is exacerbating drought risk. Surface water quality is declining as water temperature increases and more frequent high-intensity rainfall events mobilize pollutants such as sediments and nutrients."

There is zero causal linkage between CO2 and drought. In fact, rain forests have very high CO2 levels and they get tons of rain.

https://www.tandfonline.com/doi/abs/10.1080/0028825X.1994.10...

Drought is caused by variable patterns in ocean and atmospheric currents.

The reference I offered summarizes the current state of knowledge about the linkages between climate change due to globally-rising CO2, and drought.

The quote I gave tells a couple of specific links. The report itself offers plentiful analysis to back the conclusions up.

You can't just dismiss this evidence by asserting "zero causal linkage" and then referring to a single paper that is not about climate at all.

I was trying to raise another general point. It's actually not surprising, due to the centrality of water in the Earth system, that global increases in CO2 (and hence, radiative forcing) would influence the distribution of water.

That's partly why the section on water and climate is chapter 3 of the report I linked instead of chapter 12.

Could you quantify the effect of CO2 on water distribution? How about other factors, such as the Atlantic Multi-decadal Oscillation and the Pacific Decadal Oscillation? We still do not even have predictable models for these natural oceanic patterns. The quantity of H2O on this planet VASTLY outweighs the quantity of CO2. Oceans cover 70% of the Earth's surface and are deep. The marginal difference in CO2 is not enough to move ocean currents. It is a trace gas that has gone from 280 ppm to 400 ppm. The heat capacity of water is very high and far more than what a few CO2 molecules can absorb or re-emit. The oceans store massive quantities of heat and move it around in cycles that sometimes last hundreds of years. In addition, CO2 has a thinner radiative band that it can block than water vapor. And when water takes the form of clouds it can influence temperature in dramatic ways. Cosmic rays have a strong influence on global cloudiness, known as the Svensmark effect, and this influences precipitation patterns.

We are also having near record levels of snow across the Northern Hemisphere, which according to your world view, shouldn't be happening: https://globalcryospherewatch.org/state_of_cryo/snow/fmi_swe...

You seem to be arguing that, because the planetary mass of CO2 is smaller than that of water, CO2 changes cannot substantively affect water transport.

So, I’d strongly suggest you should just read the NCA, because this argument is both ridiculous and false according to known science.

Yes I am arguing that point precisely because that's what thermodynamics dictates.

Because of solar insolation, the system is not closed. In particular, we have a valve (CO2) controlling insolation and reflection. You would not argue that the effect of a Mylar sheet placed above a sunny swimming pool has to do with the mass of the Mylar.

Incidentally, it’s worth mentioning that, while I’m not an expert, I have several recent publications in hydrology, and I talk regularly with climate scientists and hydrologists about drought, including coauthors of the report I linked. The lines of argument you stated above are nonsense, I’m afraid. If you care about this subject, please do yourself the favor of reading some high-quality research summaries. It’s actually quite striking how much we do know about the Earth system.

Mylar is a non porous material. The actual greenhouse effect is caused by trapping warm air in as it is warmed from the water itself. The solar energy first enters the pool through the transparent material, warms the water, and then the warm water warms the air. The mylar traps the warm air from rising as it naturally would, where it would mix with colder air and cause another thermodynamic exchange.

CO2 does not act literally like a blanket over the earth, that's not how radiation works. If CO2 cannot retain the heat then it will be lost to space at night.

The closest thing to a true blanket effect would be clouds, although they have complex shapes and depending on where they are located in the atmosphere can have either a cooling or warming effect. They are made up of mostly liquid water and do vary according to solar activity through cosmic ray flux as shown in Svensmark's work. Link above.

Higher temperatures mean higher evaporation and thus stronger drought, even if there's same amount of rain.

No. Sorry. The minor 0.5C warming we've seen pales in comparison to the changes in temperature on even a daily basis not to mention changes in temperature throughout the atmosphere. Rain still very much occurs in the tropics. So much in fact that rainforests form there.

Rain patterns are controlled by ocean and atmospheric currents.

1) The warming is more than 0.5 degrees C.

2) The warming is global, and in addition to changes in temperature on a daily basis.

https://data.giss.nasa.gov/gistemp/graphs_v4/graph_data/Glob...

The GISS temp data has been manipulated [1]. We don't have global temperature data for the land and the sea going back to 1880. The satellite weather era began in the late 70s. Even for land based records, outside of the first world they are very sparse prior to the 1950s. The temperatures had dropped so much by the 1970s that there was an actual ice age scare. They even hired Leonard Nimoy to pitch it. [2] The GISS data set shows this as a blip and it's a sad joke.

1) https://youtu.be/spyJhgVbvVY 2) https://youtu.be/mOC7ePWCHGk

Sorry but you are simply wrong. Tony Heller (your first video) has been debunked so many times it's a wonder he still makes videos. If you want to say GISS data is manipulated, please come up with solid evidence from peer reviewed sources. Their methods have been thoroughly peer reviewed, something that cannot be said of Tony Heller.

Why did they hire Leonard Nimoy, not an actual climate scientist? The doomsday ice age scare of the 70s has been exaggerated to the point of breaking. The vast majority of scientific papers in those times showed global warming is the issue. There was some cooling starting in the 40s, mainly due to aerosol pollution of the atmosphere. This issue was tackled. Now we're left with CO2 and other greenhouse gases.

As for the temperature records, please look up how temperature proxies (tree rings, ice cores...) can be used to reconstruct global temperature. It's not like we know the temperature from 2000 years ago because the Romans had a notebook and measurement stations spanning the globe.

Higher evaporation means more clouds (somewhere) and more rain (somewhere).

Recent studies show increased snowfall in central Antarctica for instance.

It's entirely possible that global warming has lessened the severity of these droughts. One fallacy of climate alarmists is to never admit that global warming has some positive effects, no matter how few.

If in fact global warming has in effect cancelled the next ice age, that is a giant win!

It is entirely possible, except nowhere it happened in an useful way. Where there is more rain, it tends to fall in bursts, with flooding. Because moister and hotter atmosphere is more unstable, it's basic principle in the meteorology. And the problem is, our agriculture(and not just it) can't cope with that. Proposals to compromise yields to improve land's stability/water retention are met with hostility.

No, instability in climate is caused by many factors but chief among them would be high and low pressure systems colliding with each other. Moister and warmer atmosphere is not difficult to cope with. Produce grows extremely well in the tropics and not so well in Siberia.

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