Thermal inertia and precipitation patterns

[trm1958]

My understanding is that ocean water takes a lot longer to heat up than air or ground surface. Also, I would expect that much if not most of precipitation comes from evaporated ocean water. And temperature determines how fast water evaporates.
So I am thinking that, as the world warms rapidly, the ground will dry faster than the oceans accelerate evaporation. Thus, on average the world will generally get more arid until the oceans "catch up" and precipitation and evaporation are back in equilibrium (and even then the climate zones will probably be in different places).
Am I right? If so, what might the timescale of this transition be? Decades? Centuries? Millennia?

[binntho]

My understanding is that ocean water takes a lot longer to heat up than air or ground surface.

You cannot compare the ground surface to the entire ocean. The "ground" that we walk on has almost no heat capacity, daily temperature fluctuation hardly reach past the surface and seasonal temperature variations reach at most half a meter or so down.

Atmospheric temperatures are mostly governed by the oceans, which makes sense when you consider that they cover 71% of the surface. The atmosphere has much less heat capacity than the oceans.

The oceans absorb 94% of incoming solar energy, with sunlight reaching several meters down. The heat capacity of the oceans is vast compared to the surface or the atmosphere, but the oceans are also deep and are even now seeking thermal balance after the last glacial. Even so, the oceans hold most of the heat increase, i.e. the added energy in the system, never mind what the thermometer says. So a logical conclusion of a warmer planet should be increased evaporation everywhere, particularly from the oceans, and increased amount of water vapor that the atmosphere can carry.

Also, I would expect that much if not most of precipitation comes from evaporated ocean water.

Certainly a lot of precipitation originates with the oceans, but land and in particlar forests generate significant amounts also (hence "rain forest").

So I am thinking that, as the world warms rapidly, the ground will dry faster than the oceans accelerate evaporation. Thus, on average the world will generally get more arid until the oceans "catch up" and precipitation and evaporation are back in equilibrium (and even then the climate zones will probably be in different places).
Am I right? If so, what might the timescale of this transition be? Decades? Centuries? Millennia?

I'm not sure if this logic holds water ... certainly the models are forecasting a wetter globe, although the distribution may change - wetter areas become wetter, and drier areas become drier. Desertification once established can be difficult to turn around.

One consequence of a warmer atmosphere is that the Hadley cells will expand north and south, pushing the desert areas with them. Northern Africa and Southern Europe will get drier - something that is already happening now, although it is difficult to tell when desertification such as is happening in the Iberian peninsula has more to do with human vegetation and soil degradation - probably a combination of the two.

Similarly, the deserts of southern Asia will shift north, and the same will probably happen with the the dry zone of desert landscape that stretches from the Gulf of Mexico to the Gulf of California.

So one should think that as the Hadley cell expands and the deserts shift north (in the northern hemisphere), vegetation cover on  the southern fringes should also move north. This seems to be happening according to some measurements, but the Sahel remains extremely dry and it is unclear if there is any improvement on the ground.

Note that these changes have nothing to do with what you ask about.

[kassy]

This is an interesting debate but more about global patterns. Maybe it would be an idea to split the thread from Toms question on and then have it moved to AGWIG Science?

A slightly simpler answer that i wrote before binntho added his post and there are a lot of interesting details and differences to discuss. But they go very much beyond the Arctic.

That model is really overly simplistic. Lets modify it slightly by stating that the oceans will always have water. The amount on land is different but higher temperatures bring more evaporation while at the same time our snowcaps are melting. These sort of things will make a lot of places more arid on a decadal scale while it also continues so it also happens on the longer scales due to a whole bunch of of other reasons.

[oren]

Moved here at Kassy's request.
Surprisingly the forum software let me move it. I was certain my privileges only applied with the Cryo section. Apparently they also apply to moving a thread to another section.

[trm1958]

I know that eventually the planet gets a lot more rain. I was thinking that much of its land area would be temporarily drier initially till the oceans "catch up".

[kassy]

And it will be drier.

As the world warms  there can be 7% more moisture in the air for every degree of warming.

If we make the model less simple we can state that there will at least always be water that evaporates from the ocean.

For the land this depends on a whole bunch of factors. If we crank up the model with 1C global like we did this will dry out land way more. The extra warming is everywhere all the time. It will dry out all our lands more then used to happen. This happens in deserts and marginal lands and wetter places too but you notice it in the marginal places because the water disappears. We live in these places but it gets harder to do so or impossible.

Then most mid latitude glaciers will be gone in a decade or two which will also mean huge areas dry out.

Lots of areas we used to use will get to dry too use in a way we used to do.

The other side of the atmosphere holding more water is much more water coming down in a certain area in a short time. This is another problem because this can easily overload the local systems and then degrade the land.

What goes up must come down so what evaporates as water will come down but where?

If you were to play with two simple models where one is just water and it evaporates until is a saturation point and the second is soil with a much lower water content you should see the problems.

What matters is what will happen in all the areas where we live and a lot of those will get a lot worse n the next few decades. It will rain but not when you need it.
 

[SeanAU]

By JCM on @RealClimate

This thread seems to be the best fit to share this info/comment/refs

(fwiw , Hypothesis seems to be of Man-made induced Ecosystem / land use changes 'partially but significantly' driving global temp increases due to major shifts in hydrology cycles (drying) and surface albedo shifts etc vs merely a subsequent feedback of ghg increases? )

quoting:

I am a land steward who wishes to offer climate stabilizing perspectives in addition to efforts to reduce trace gas emission. In this forum my goal is to frame the concepts of hydrology and ecosystem effects in terms of interest to the climatological community.

These concepts discussed, such as minimizing hydrological and temperature extremes, are resisted for unknown reasons here – perhaps it is for computational simplification. The definitions proposed by radiation theorists and experimental computationalists have somehow now permeated into and displaced definitions and teaching of environment, climates, & change.

The human related factors proposed by those who reduce their perspective of climates to computational capability and radiometer observation appear to include: Surface albedo, aerosol, ozone, and trace gas emission. Everything else, therefore, such as real climates, real environments, and change is deemed a feedback to such effects.

Alternative themes centre around overall drying of the continents, directly by human intervention, in addition to feedback effects from trace gas, with particular rapid pace over the most recent centuries.

The observations related to highly degraded ecosystems and watersheds include, but are not limited to: hydrological extremes such as increasing flood and drought extremes, and increasing temperature extremes.

These observations of climate changes appear to be confused with the equally important notion of “global warming”. The result is that local community decision makers have minimal understanding of the local factors of risk for their residents, and they have no sense of accountability when things go wrong.

@macias has recently shared the following work by Liu & co which depicts a clear reduction oceanic moisture flows to continents in Figure 5. https://link.springer.com/article/10.1007/s00382-020-05451-8

Nobre & co. have noted that additional heat over land “can block oceanic” moisture transport. https://www.sciencedirect.com/science/article/pii/S2405844022024616

Wang & co. highlight an overall reduction of evaporative fraction over continents.
https://hess.copernicus.org/articles/25/3805/2021/

Makarieva & co. notes a hysteresis whereupon the shift to a dry regime is self-reinforcing /resistent and can therefore cause some confusion about the benefits of ecological restoration.
https://onlinelibrary.wiley.com/doi/10.1111/gcb.16644

In various works Huyrna and Pokorny highlight the far greater impacts of ecohydrology working in addition to albedo and sinks/sources of Co2.
https://www.semanticscholar.org/paper/The-role-of-water-and-vegetation-in-the-of-solar-a-Huryna-Pokorn%C3%BD/15f3d6ee13d35aaeb1867b781a19f29fec509048

The factors of reduced oceanic moisture flows over continents + reduced evaporative fraction is evidently a compounding effect. The drying continents directly by the hands of humanity with increasing temperature and hydrological extremes has far reaching consequences for changing climates. The common view here is that increasing continental “heat” should increase rising air currents and therefore promote “sea breezes” and return flows. But it seems there must be more going on.

[kassy]

fwiw , Hypothesis seems to be of Man-made induced Ecosystem / land use changes 'partially but significantly' driving global temp increases due to major shifts in hydrology cycles (drying) and surface albedo shifts etc vs merely a subsequent feedback of ghg increases?

It is a simple take on things.

These concepts discussed, such as minimizing hydrological and temperature extremes, are resisted for unknown reasons here

Not sure where on RC it comes from, variations i guess? He hints at some earlier discussion which we do not really care about.

The hydrological extremes are controlled by the temperature extremes and those are going up as long as we keep dumping these amounts of CO2 into the atmosphere. This effect is way bigger then anything we can do on land which people might have been telling him but to repeat myself we really don´t care about discussions from other places.

Of course we should preserve what nature we have and improve landscapes where we can (concrete out, plants in etc) but we are not doing it, or doing too little. But even if we did that to the max we could achieve it would be small compared to the effect of the needed CO2 cuts.

[SeanAU]

HI. Alright then. So you don't discuss this, have a thread anywhere, about LUC or regional rainfall changes or regeneration or aridity etc.

Well is there a thread/s where the research papers mentioned might be relevant, of interest to someone? I can't see anything myself yet, but I could repost them to a better location if there is one. 

thx

[kassy]

The papers are fine here. If more get added or the discussion goes deeper into them we can change the thread title later.

[morganism]

think this might go here...

Greenhouse Gas Supplement Increases Warming And Alters Circulation Patterns On Earth and Earth-like Exoplanets

delved into the effects of greenhouse gas supplements on temperate terrestrial exoplanets and Earth. Their findings demonstrate a parallel relationship between CO2 supplement and intensified warming in non-irradiated regions, impacting global circulation patterns.

Analyzing ExoCAM and CMIP6 model simulations, the research team discovered that the addition of CO2 leads to heightened warming in areas shielded from direct sunlight, i.e., the night side and polar regions. These localized temperature changes can bring about significant alterations in global circulation. Employing a dynamical systems framework, the researchers gained additional insights into the vertical dynamics of the atmospheres.

The study also reveals that introducing a greater supplement of CO2 into the atmosphere enhances temporal stability near the surface but decreases stability at low pressures. Surprisingly, this observation holds true for both Earth and TRAPPIST-1e, despite their distinct climate states. Dr. Assaf Hochman, from the Hebrew University of Jerusalem, emphasized the importance of comprehending the intricate connections between greenhouse gases and climate dynamics on both Earth and potentially habitable exoplanets."

https://astrobiology.com/2023/07/greenhouse-gas-supplement-increases-warming-and-alters-circulation-patterns-on-earth-and-earth-like-exoplanets.html


Analogous response of temperate terrestrial exoplanets and Earth’s climate dynamics to greenhouse gas supplement

https://www.nature.com/articles/s41598-023-38026-8

Abstract

Humanity is close to characterizing the atmospheres of rocky exoplanets due to the advent of JWST. These astronomical observations motivate us to understand exoplanetary atmospheres to constrain habitability. We study the influence greenhouse gas supplement has on the atmosphere of TRAPPIST-1e, an Earth-like exoplanet, and Earth itself by analyzing ExoCAM and CMIP6 model simulations. We find an analogous relationship between CO2 supplement and amplified warming at non-irradiated regions (night side and polar)—such spatial heterogeneity results in significant global circulation changes. A dynamical systems framework provides additional insight into the vertical dynamics of the atmospheres. Indeed, we demonstrate that adding CO2 increases temporal stability near the surface and decreases stability at low pressures. Although Earth and TRAPPIST-1e take entirely different climate states, they share the relative response between climate dynamics and greenhouse gas supplements."

[kassy]

Actually it does not mention precipitation but it´s too funny.

Analyzing ExoCAM and CMIP6 model simulations, the research team discovered that the addition of CO2 leads to heightened warming in areas shielded from direct sunlight, i.e., the night side and polar regions.

So they modelled things to find out something which you can know from basic CO2 knowledge...