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Deforestation has big impact on regional temperatures, study of Brazilian Amazon shows

Deforestation has big impact on regional temperatures, study of Brazilian Amazon shows

Research highlights benefits forests bring surrounding regions in terms of cooler air and more rainfall.

Deforestation has a far greater impact on regional temperatures than previously believed, according to a new study of the Brazilian Amazon that shows agricultural businesses would be among the biggest beneficiaries of forest conservation.

The paper demonstrated Amazon deforestation causes warming at distances up to 60 miles (100km) away. The greater the forest clearance, the higher the temperature.

More recently, research at a greater scale demonstrated that the Amazon was coupled with the South American monsoon and that continued deforestation could reduce regional precipitation by 30% with dire consequences for food production.

Using satellite data and artificial intelligence, the authors found a 0.7C increase in temperature for each 10-percentage point loss of forest within a radius of 60 miles.

“We show that regional forest loss increases warming by more than a factor of four with serious consequences for the remaining Amazon forest and the people living there.”

https://www.theguardian.com/environment/2023/oct/30/deforestation-has-big-impact-on-regional-temperatures-study-of-brazilian-amazon-shows

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Scientists prove clear link between deforestation and local drop in rainfall

Scientists prove clear link between deforestation and local drop in rainfall

Very important article on the link between deforestation, evapotranspiration and rainfall:

Even at a small scale, they found an impact, but the decline became more pronounced when the affected area was greater than 50km squared (2,500 sq km). At the largest measured scale of 200km squared (40,000 sq km), the study discovered rainfall was 0.25 percentage points lower each month for every 1 percentage point loss of forest.

This can enter into a vicious cycle, as reductions in rainfall lead to further forest loss, increased fire vulnerability and weaker carbon drawdown.

One of the authors, Prof Dominick Spracklen of the University of Leeds, said 25% to 50% of the rain that fell in the Amazon came from precipitation recycling by the trees. Although the forest is sometimes described as the “lungs of the world”, it functions far more like a heart that pumps water around the region.

He said the local impact of this reduced water recycling was far more obvious, immediate and persuasive to governments and corporations in the global south than arguments about carbon sequestration, which was seen as having more benefits to industrial countries in the northern hemisphere.

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Tropical deforestation causes large reductions in observed precipitation

Tropical deforestation causes large reductions in observed precipitation

A new paper appeared »Tropical deforestation causes large reductions in observed precipitation«, indicating how (much) deforestation and precipitations in the tropics are linked:

Here we show reduced precipitation over deforested regions across the tropics. Our results arise from a pan-tropical assessment of the impacts of 2003–2017 forest loss on precipitation using satellite, station-based and reanalysis datasets. The effect of deforestation on precipitation increased at larger scales, with satellite datasets showing that forest loss caused robust reductions in precipitation at scales greater than 50 km. The greatest declines in precipitation occurred at 200 km, the largest scale we explored, for which 1 percentage point of forest loss reduced precipitation by 0.25 ± 0.1 mm per month. […] We estimate that future deforestation in the Congo will reduce local precipitation by 8–10% in 2100. Our findings provide a compelling argument for tropical forest conservation to support regional climate resilience.

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Self-amplified Amazon forest loss due to vegetation-atmosphere feedbacks

Self-amplified Amazon forest loss due to vegetation-atmosphere feedbacks

Vicious cycle of destruction in the Amazon:

Here we show that the risk of self-amplified Amazon forest loss increases nonlinearly with dry-season intensification. […] Our results suggest that the risk of self-amplified forest loss is reduced with increasing heterogeneity in the response of forest patches to reduced rainfall. […] Although our findings do not indicate that the projected rainfall changes for the end of the twenty-first century will lead to complete Amazon dieback, they suggest that frequent extreme drought events have the potential to destabilize large parts of the Amazon forest.

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Land use and land cover changes and their impacts on surface-atmosphere interactions in Brazil: A systematic review

Land use and land cover changes and their impacts on surface-atmosphere interactions in Brazil: A systematic review

Major land use and land cover changes in Brazil and their impacts on precipitation and evapotranspiration:

For the Amazon biome, decreasing dry season P and in annual ET were reported. In the Cerrado biome, decreasing P in the wet and dry seasons and decreasing dry season ET were the most common result. For the Atlantic Forest biome, increasing annual P and increasing wet season ET, likely due to reforestation, were reported.

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Amazonia´s flying rivers – no forest, no water

Amazonia´s flying rivers – no forest, no water

Interesting and informative documentary: The Amazon rainforest is not only the earth’s green lung (absorbing and storing carbon dioxide from the air and converting it to oxygen) it is also its air conditioner: intact forests suck in rain clouds from the Atlantic and evaporate water. In this way they cool the earth. Without forest, no water: if more and more forest disappears, this phenomenon of ‘flying rivers’ acting like a gigantic water pump can no longer exist. Scientists, politicians and environmental activists explain the fragile balance.

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