Plants and trees, the lowest occupants of our food chain, serve as the base of the pillar of life on Earth. We mainly depend on them for our food. But, although not apparent, vegetation also plays a big role in regulating the Earth’s climate. The major processes through which this regulation takes place are atmospheric regulation of CO2 through photosynthesis, regulation of atmospheric moisture over land through evapotranspiration and regulation of energy absorbed from the sun through albedo (of course there are other modes of regulation as well). But I have always wondered at what spatial scales does this regulation become substantial enough to cause a detectable modification to the climate?
My PhD research focussed on the dependence of this vegetation-atmosphere coupling on the spatial scale of vegetation cover. I chose for my investigation the tropical rainforests of Amazonia. There is substantial evidence from previous research showing that this massive rainforest, which is almost the size of the contiguous United States of America, plays a major role in deciding the climate of northern South America. This is expected, given the huge size of the rainforest. What is not apparent however is if deforestation activities in the Amazon, which effect almost 20% of this forest now, can affect its regional climate? I addressed this question in my PhD finding that at present-day scales of deforestation (swaths of a few hundreds of kilometers across), the regional clouds and precipitation have modified in response to forest clearing. Specifically, deforestation has lead to a redistribution of precipitation over the deforested areas with downwind and upwind regions receiving ~25% more and less precipitation respectively as compared to the full deforested area