Clearing our rainfall away

February 18, 2017

Vegetation creates rain. That is one of the conclusions of a review of more than 150 scientific papers on land-clearing’s impact on rainfall, conducted by Dailan Pugh for the North East Forest Alliance (NEFA). The review, Clearing Our Rainfall Away, reveals how land-clearing affects rainfall and its impact on the climate.

“Climate change results from many human activities, one of which is land-clearing and deforestation,” Pugh said.

“The evidence is overwhelming: clearing native vegetation reduces rainfall, increases temperatures and intensifies droughts. With NSW experiencing record-breaking temperatures it's time for the governments to end the policies that are contributing to it.

"Vegetation does not just respond to rainfall. It recycles water from the soil back into the atmosphere through transpiration; creates the updrafts that facilitate condensation as the warm air rises and cools; creates pressure gradients that draw moist air in from afar; and, just to be sure, releases the atmospheric particles which are the nuclei around which raindrops form.

"The transpiration of vegetation also results in evaporative cooling whereby the surface heat is transferred to the atmosphere in water vapour. The resultant clouds also help shade and cool the surface.

"It has been estimated that since European settlement, land-clearing in eastern Australia has directly resulted in an average summer rainfall decrease of 4–12% and a warming of around 0.4–2°C.”

Evidence from around the world shows land-clearing has directly caused a significant reduction in regional rainfalls and an increase in land temperatures. The release of CO2 stored in trees has contributed about a third of the world's CO2 emissions in the past two centuries.

NEFA called on NSW Premier Gladys Berejiklian to reconsider the previous Mike Baird Government's draconian legislation that has reopened NSW's remnant native vegetation for broadscale clearing.

"Removing deep-rooted forests and woodlands has also resulted in rising water-tables and brought long-buried saline ground-waters towards the surface,” Pugh said. This has already put 7.5 million hectares of NSW's agricultural lands at risk of dryland salinity.

"It is important that Premier Berejiklian recognises that if she approves the clearing of our forests and woodlands, she is approving rainfall reductions, temperature increases and making more farmland unproductive.

“She must take action to rein in the worse aspects of Baird's climate vandalism.”

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