beragampengetahuan: Unforced variations: March 2024 – Beragampengetahuan

Re JCM “Cool, you might be right.” – thanks, but please note all the caveats, guesswork and hypothetical-for-the-sake-of-the-argument supposition that went into my 0.3 K figure. I actually suspect it is smaller (In particular I don’t believe exposed soil (uncovered by leaf canopy/etc.) automatically functions as ‘desert’), but I lack the background and time to go much farther with it.

Re Piotr (above) – “ 12.6% is not of “globe”, but of land without ice. So give up all crops in exchange for … 0.07K. Cool! 😉” – yes, but the ~6.8 K (ΔGMST, whole globe) figure (**calc. from Fig. 1**) is for 100% of land without ice (not whole globe) so take 12.6%/3 = 4.2% of that ΔGMST …( )

**Fig. 3d seems to show a ΔGMST of ~ 8 K.

“ because patrick got also the other part of his argument wrong:” No.… “On the other hand, both “ Irrigation and corn’s tendency to keep its stomata open“, INCREASE evaporation” Yes, we agree.

I can see why my writing left room for confusion, but try reading again with the assumption that I actually do understand such logical implications, and I think you’ll see where I was going.
But I do admit there’s a lot I don’t know – see my re JCM. And there is only so much time, and other things I want to do (work on my blog about GHE physics, … artwork, …watch more Leslie the Bird Nerd videos). I want to be upfront about this: I haven’t read much more of the study; but I chimed in partly because I suspected you misunderstood the implication/context of the ≈0.3 W/m² TOA imbalance, given the magnitude of the ΔGMST:

(PS from the wording in the quote below, I wonder if this 0.3 value is a bounding magnitude of fluctuation, or/rather than a time-average value(??)) “ After 20 years, there is <0.1 K drift in global mean surface temperatures (figure 1); the top of atmosphere (TOA) energy imbalance in these near-equilibrium simulations is near-zero (≈0.3  W m⁻²).”-Lague et. al. 2023 , 1st paragraph of section 2.1. Unless the same flux number appears elsewhere (as given or calculated from given) in a different context…

More:

I forgot to include urband/built-up land area (1 M km² ) effects, but … does that include parks, lawns, sports fields, gardens, ponds?

A significant amount of forest area loss has happened after 1950, so I expect it would/may be harder to separate this from anthro-GHE effects on the basis of timing alone (as opposed to agricultural expansion (at least for global total)).

The following is just following logic on my part, these are not things I’ve studied much:

Hypothesis: the more leaf area per unit land surface area, and the more spread-out it is vertically, the more ET (other things being =), thus more LH flux … and maybe more SH (sensible heat) flux – particularly when solar heating occurs in the leaves, so we needn’t worry about limited thermal conductivity of plants. How much heat is transported in xylem/phloem/etc.?… (in whole, I’m thinking of vegetation as acting like a heat-exchanger. On water, wind-whipped surf also helps, I’d expect)…so RH (relative humidity) will be higher.

Hypothesis: However, vegetation will reduce wind and reduce ET closer to the ground; a thick canopy can trap the humidity to some extent, reducing the ET (via high RH). (But also, vegetation can slow/intercept rain drops and spread precipitation over time at the surface and thus, along with mechanically stabilizing soil, reduce runoff.)

Hypothesis: A negative feedback should tend to reduce ET reduction due to leaf area reduction, because lower RH (and more wind exposure) should increase ET, including from soil (assuming liquid/solid H2O is available).

Hypothesis: moist bare soil will not be like ‘Desert land’. Although I believe dry (drought-baked) mud can limit permeability and thus increase runoff (?)and reduce ET from deeper soil(?). Note: snow can’t significanly runoff or seep into aquifers until it melts.

What creates the ‘Desert land’ is liquid/solid H2O going to the ocean before evaporating. Hypothesis: Runoff and drainage into groundwater is what to watch for, and then it must be noted how far they go (effect could be regional or even create microclimates, eg. dry hill, wet valley).

(Don’t waste rain!)

PS It’s my understanding that CO2, via effect on plant stomatal behavior (species-dependent, also how much of this is via evolution to new conditions vs the capacity of an individual organism to adapt?), allows plants to grow in dryer and higher places. Is this considered part of the CO2 fertilization effect?

PS JCM – earlier you mentioned a choice between wind turbines and a land hydrology project and you said the later was the better option but the former was chosen. Was the need to choose a matter of funding (which seems a bit odd because wind turbines should supply income), or did one project preclude the other ie. same land area? Would the wind turbines have a drying effect, eg. via enhanced nocturnal T due to mixing of air?