Tuesday, June 25, 2024

Deforestation and Reforestation

You may recall a pledge, made by world leaders at the COP26 climate summit in Glasgow in November 2021, to halt and reverse global deforestationby 2030. Among the 143 signatories were the heads of government of Australia, Brazil, Canada, Chile, France, Russia, Spain, the UK, and the US. Sadly, in most cases their fine words have yet to be met by their actions.

According to a report compiled by the World Resources Institute, tropical countries lost 11.1m hectares of tree cover in 2021, including 3.75m hectares of primary forest critical to limiting global heating and biodiversity loss, whilst the boreal forests covering much of North America, Scandinavia and Russia suffered record losses, driven by the worst wildfire season in Siberia since records began. The loss of primary rainforest, releasing the equivalent of India’s annual fossil fuel emissions, was especially marked in Brazil, where deforestation in the Amazon rainforest reached its highest level in 15 years in 2020-21. Already in 2022, record monthly levels of deforestation in the Amazon rainforest have been recorded for three of the first four months of the year. Much of the forest loss has been attributed to clearance for cattle ranching.

There are two ways to halt and reverse global deforestation: cut down fewer trees in the first place or grow a lot more of them. A study published in the journal Nature found that replacing 20% of the world’s beef consumption with microbial protein, such as Quorn, could halve the destruction of the Earth’s forests over the next three decades. Better still, 50% replacement could lead to an 82% cut in deforestation by 2050. Previous studies have shown that the protein quality of microbial ‘meat’ is equivalent to that of beef, whilst requiring 90% less land and water and producing 80% fewer greenhouse gas emissions. Although microbial protein products may not be to everyone’s liking, study leader Dr Florian Humpenöder from the Potsdam Institute for Climate Impact Research acknowledged that they “can make it easier for people to switch away from meat”. The study did not analyse the effect of plant-based alternatives to meat, but these would also be expected to significantly cut environmental impacts, as a recent review paper by Dr. Chris Bryant of the University of Bath has shown.

What about simply growing more trees: can we plant our way out of the climate crisis? An article in The Conversation by the Oxford-based ecologist Richard K Broughton warned that large scale tree planting is costly. Saplings have to be grown, transported, planted and protected with fencing and plastic tubes, producing a lot of carbon emissions and potential plastic pollution as the tubes break down into the soil. As an alternative, the author recommends natural regeneration, creating woodlands by allowing trees and shrubs to plant themselves under natural processes, citing the example of the Monks Wood Wilderness experiment in Cambridgeshire. A four-hectare arable field next to the Monks Wood National Nature Reserve was ploughed and abandoned in 1961, allowing the land to naturally regenerate, becoming what is now “a structurally complex woodland with multiple layers of tree and shrub vegetation.” Although the experiment benefited from the field lying close to an ancient woodland, the author believes that “there are many woods in the UK that could expand by allowing adjacent fields to return to nature”, eventually adding up to “a significant increase in total woodland cover.” (The UK is one of the least forested countries in Europe, with just 13% forest cover compared with an average of 38% across the European Union.)

Thus, nature can repair much of the damage that humans have done to the environment, but only if we give her the time and space to do so, and that time is rapidly running out. UK Met Office researchers predict a 48% chance that the average global temperature will rise to 1.5°C above pre-industrial levels in one of the next five years, reaching the ceiling set by the Paris climate agreement. Although the rise may prove temporary, the upward trend in global temperature is clear.

(With thanks to Nitin Mehta and Paul Freestone for two of the links below):

Sources and links:

Paul Appleby is a Fellow of the UK Vegetarian Society and a former trustee of the Society and the UK Vegan Society.  He was secretary of Oxford Vegetarians (the forerunner of OxVeg) for 25 years from 1983 to 2008.  Until he retired in 2020, Paul was a Senior Statistician at the Cancer Epidemiology Unit, University of Oxford, working mainly on long-term studies of the health of vegetarians and vegans, including the EPIC-Oxford study.


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