Trees for COOLING and carbon sequestration

[Robert Northup]

Plant Trees for Cooling and to Protect Soil and Water

Trees can have an important local cooling effect in populated areas, where the shading from trees can reduce energy consumption in the summer. Evaporative cooling, as trees transpire water through their leaves, continues through the dry season, as trees draw deeper water even while the surface soil is dry. Tree planting is essential to combat global warming, particularly reforestation efforts where forests have been cleared. Trees regulate water quality in rivers. Rain intercepted by trees in the wet season continues supplying water to streams during the dry season. The litter layer of dead leaves on the forest floor acts like a protective sponge over the soil surface. Rain is temporarily stored in the leaf litter during the most intense storms, giving it time to infiltrate into the soil and recharge underground aquifers. One of the more serious consequences of deforestation has been the loss of tree leaf litter as soil surface protection, with consequent soil erosion, sediment-laden runoff, and inadequate infiltration to replenish aquifers. Rivers flood with muddy water when it rains, only to dry up later. Efforts to plant trees in these deforested watersheds have multiple environmental and social benefits, including direct local and global impact to mitigate some of the ravages of climate change.

[Windguy]

How about the energy. Since evaporation cools, it is really only transfering the latent energy into to water molecules as gas. What I believe is the latent heat energy is released in the upper atmosphere and therefore the infrared radiation that comes form those molecules has more chance of escaping our atmosphere into space than if the energy was radiated from the ground. So besides a localised effect, it would also contribute globally if you show the planet as a net energy system.

That is where I believe climate change is also from deforestation (as a contributor) because we are essentially reducing that effect since the worlds forests have gone from 14% to 6% since the civilisation of man.

[Robert Northup]

Absolutely, one impact of evaporative cooling at the surface is to transfer the heat, via mass flow of latent heat in water vapor, to a higher level in the atmosphere, and more likely to radiate toward space.

Factor in to that the fact that trees multiply the effective surface area for evaporative cooling by more than an order of magnitude compared to open water, multiply how many joules of energy get transferred in a given mass of water, and you can see why one impact of deforestation is a dramatic increase in local temperature. This despite the low albedo of dark green leaves that reflect little incoming radiation, versus the relatively pale deforested soil.

[Windguy]

Only one slight problem though. We can reforest where we chopped down, but we cannot reforest old nature caused deserts. The reason is because of the way the climate is on the planet. The subtropic regions across the planet are desert, and no artificial altering could change them. A big argument in a science forum with a 25yr experience meteorologist put paid to any suggestions to do so. Other guys had said to flood the interior of Australia would help increase forests and rainfall over all of Australia.

[Robert Northup]

Deforestation and the Hydrologic Cycle.

The large scale cycling of water on earth involves sea water evaporating, supplying water vapor that ultimately produces rainfall over land areas, and ultimately flowing back to the sea. The significance of forests is in the degree to which the sea breeze rain fall gets captured and recycled over the land environment, before flowing back to the sea again.
Deforested watersheds are unable to effectively capture rainfall to recharge aquifers, particularly where there is a pronounced wet and dry season. Without the forest floor to absorb it and allow infiltration, rain fall flows over land as muddy floods during the wet season, only to leave dry river beds during the dry season. The deforested watershed is a hot, dry place during the dry season. The where there is adjacent intact forest, it is measurably cooler, a LOT cooler, in addition to maintaining a flow of clean surface water all year long. Regarding the impact of deforestation and humidity, there can be no doubt that the air is much more humid where the forest is intact, with greater likelihood of cloud formation and rain fall. Deforestation has no impact on the amount of moisture entering the system with the sea breeze, but it dramatically impacts the amount of moisture recycled within the system over land as it generated by evapotranspiration, recaptured as rain fall, and regenerated again, transpired through the forest leaves. There are huge fluxes of energy involved, as well as moisture. Without the forest to capture the rainfall and transpire it through leaves, a great deal less moisture enters the atmosphere.