ENVIRONMENT

Phys.org -  Some cities have already started implementing mitigation strategies, with tree planting prominent among them. But a University of Cambridge-led study now warns that planting the wrong species or the wrong combination of trees in suboptimal locations or arrangements can limit their benefits.

The study, published in Communications Earth & Environment found that urban trees can lower pedestrian-level air temperature by up to 12°C. Its authors found that the introduction of trees reduced peak monthly temperatures to below 26°C in 83% of the cities studied, meeting the "thermal comfort threshold." The study found that urban trees generally cool cities more in hot and dry climates, and less in hot humid climates....

The study points out that cities which have more open urban layouts are more likely to feature a mix of evergreen and deciduous trees of varying sizes. This, the researchers found, tends to result in greater cooling in temperate, continental and tropical climates.

The combined use of trees in these climates generally results in 0.5°C more cooling than in cities where only deciduous or evergreen trees feature. This is because mixed trees can balance seasonal shading and sunlight, providing three-dimensional cooling at various heights.

In arid climates, however, the researchers found that evergreen species dominate and cool more effectively in the specific context of compact urban layouts such as Cairo in Egypt, or Dubai in UAE.

In general, trees cooled more effectively in open and low-rise cities in dry climates. In open urban layouts, cooling can be improved by about 0.4°C because their larger green spaces allow for more and larger tree canopies and a greater mix of tree species.

"Our study provides context-specific greening guidelines for urban planners to more effectively harness tree cooling in the face of global warming," Dr. Ronita Bardhan said.

"Our results emphasize that urban planners not only need to give cities more green spaces, they need to plant the right mix of trees in optimal positions to maximize cooling benefits."

Nice News - As you’d imagine, wetlands need plenty of water to survive — and thanks to a coalition of engineers and conservationists, a stagnant swamp in Louisiana is about to get just that. Earlier this week, state and federal authorities broke ground on the Maurepas Swamp project, which intends to revive the wetlands’ dying trees by directing water from the Mississippi River to the swamp once again.
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Previously, water was cut off to prevent flooding, leaving the swamp nutrient-deficient. The $330 million project intends to bring balance back: It will work by allowing a max of 2,000 cubic feet per second to stream out of a gated opening in a levee system, where water will proceed to flow 5.5 miles through a diversion channel to the swamp...
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Reviving the 45,000 acres of wetlands is expected to have a beneficial ripple effect on biodiversity and actually bolster flood prevention efforts — the very concern that caused the predicament in the first place. “You’re going to have a healthier ecosystem on the outside of that levee, which means you’re going to have a better buffer for storm surge and it’s going to allow the levees to be more effective,” said Amanda Moore, the senior director of the National Wildlife Federation’s Gulf Program.