Thank you Ugo, great summary. I would like to add that the cooling capacity of the forests are by design highest around the equator where much more solar energy comes in than in for instance the boreal forest areas, where the forest design is more geared towards maximizing photosynthesis in a short summer.
As far as I understand, the forest mechanism of “Air Cooling” (lowering the temperature over a huge area) works during the growing season of trees. In the northern hemisphere it is summer. The most solar radiation comes, the air temperature is highest - and it is during this season that forests transpirate, form clouds, additionally attract moisture from the oceans into the continents ("Biotic pump"), which leads to heavy summer precipitation, feeds rivers, etc. Apparently, in the equator zone, or 0-15 degrees South latitude - where the forests of the Amazon, Congo and Indonesia are located, the same “seasonal” peaks occur: when the temperature is highest, then “forest cooling” works.
"Most models predict major damage to forests in the next century if current climate trajectories are not ameliorated. Debate still remains as to the magnitude of stabilizing forces, such as tree acclimation and positive CO2-associated effects on water use, but most observational data suggest that forest decline is well under way." and "Other long-lived, sessile organisms such as corals appear to be poorly equipped to survive rapid changes, which raises questions about the vulnerability of contemporary forests to future climate change. The emerging view that, similar to corals, tree species have rather inflexible damage thresholds, particularly in terms of water stress, is especially concerning."
Whatever the contribution of forests for a cooler planet it may soon be gone.
Hi Ugo, as I understand it, the formation of water vapour doesn't release heat to space, rather the heat energy is transformed to another type of energy (latent heat) as it suspends the water. When that vapour condenses, the energy is released again as heat energy. hence the temperature moderating effect of water in the environment. But it's probably safe to say that many forms of water vapour do reflect heat to space due to increased albedo.
Your discussion of transpiration in trees is not consistent with our considerable understanding of the mechanisms involved. You repeatedly refer to “pumping” of water in the leaves and from the roots. This is not at all what happens. You also say that trees cannot thermoregulate. This is not true. You may want to consult a modern plant physiology text.
We need to revegetate much of the planet while stopping ongoing deforestation. BUT, we need to listen to the science on how to do this rather than planting monocultures of species and planting in the wrong places. My latest post discusses this.
Thank you Ugo, great summary. I would like to add that the cooling capacity of the forests are by design highest around the equator where much more solar energy comes in than in for instance the boreal forest areas, where the forest design is more geared towards maximizing photosynthesis in a short summer.
As far as I understand, the forest mechanism of “Air Cooling” (lowering the temperature over a huge area) works during the growing season of trees. In the northern hemisphere it is summer. The most solar radiation comes, the air temperature is highest - and it is during this season that forests transpirate, form clouds, additionally attract moisture from the oceans into the continents ("Biotic pump"), which leads to heavy summer precipitation, feeds rivers, etc. Apparently, in the equator zone, or 0-15 degrees South latitude - where the forests of the Amazon, Congo and Indonesia are located, the same “seasonal” peaks occur: when the temperature is highest, then “forest cooling” works.
Adding to my pessimism is this: https://www.science.org/doi/10.1126/science.aat7631 which says:
"Most models predict major damage to forests in the next century if current climate trajectories are not ameliorated. Debate still remains as to the magnitude of stabilizing forces, such as tree acclimation and positive CO2-associated effects on water use, but most observational data suggest that forest decline is well under way." and "Other long-lived, sessile organisms such as corals appear to be poorly equipped to survive rapid changes, which raises questions about the vulnerability of contemporary forests to future climate change. The emerging view that, similar to corals, tree species have rather inflexible damage thresholds, particularly in terms of water stress, is especially concerning."
Whatever the contribution of forests for a cooler planet it may soon be gone.
Hi Ugo, as I understand it, the formation of water vapour doesn't release heat to space, rather the heat energy is transformed to another type of energy (latent heat) as it suspends the water. When that vapour condenses, the energy is released again as heat energy. hence the temperature moderating effect of water in the environment. But it's probably safe to say that many forms of water vapour do reflect heat to space due to increased albedo.
Your discussion of transpiration in trees is not consistent with our considerable understanding of the mechanisms involved. You repeatedly refer to “pumping” of water in the leaves and from the roots. This is not at all what happens. You also say that trees cannot thermoregulate. This is not true. You may want to consult a modern plant physiology text.
We need to revegetate much of the planet while stopping ongoing deforestation. BUT, we need to listen to the science on how to do this rather than planting monocultures of species and planting in the wrong places. My latest post discusses this.
Thank You, Ugo. I'll include this on my blog.