AFOLU’s warning

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A second sobering report from  the IPCC again provides solid scientific evidence that the climate crisis cannot be resolved if we continue along our present path. While previous assessments have focused on transportation and industry, the most recent report shows that if the way we misuse and degrade our land does not dramatically improve, there is little chance of keeping global heating within bounds, and the future climate will bring widespread global disruption and spell disaster for millions of world’s most vulnerable people.    

Human use has radically altered more than 70% of the ice-free land surface of the planet. Population growth and increases of per capita consumption of food, feed, fibre, timber and energy have caused unprecedented rates of land and freshwater use. Agriculture now accounts for about 70% of freshwater use. Soils are being decimated. Erosion from traditional forms of agriculture  is more than 100 times higher than rate at which soil is being formed. This degradation not only is destroying habitats, ecosystems and biodiversity, it is exacerbating the forces that are driving the climate crisis. Regenerative agriculture is now a global imperative.

What’s called AFOLU, meaning Agriculture, Forestry, and Other Land Use, is both a source and sink of the greenhouse gases that are driving global heating and intensifying the climate crisis.

At present, for carbon dioxide, the global sink is larger than the source. Land sequesters more than twice as much of this gas than is emitted.

Land is a net sink of carbon dioxide

But for methane and nitrogen dioxide, two other major greenhouse gases, the AFOLU sector is a serious global problem: it accounts for over 40% of global emission of methane and over 80% of emissions of nitrogen dioxide.  

Climate change creates additional and devastating stresses on land that exacerbate the risks to livelihoods, biodiversity, human health, ecosystems and, most importantly, food security.  Africa and Asia are hardest hit by desertification. Wildfires are massively destructive almost everywhere across the planet. The tropics and subtropics are the most vulnerable to declining crop yields. The rising seas coupled with more extreme weather jeopardise life and livelihoods in all cyclone-prone areas. Women, the very young, the elderly and the poor are most at risk.

Sustainable food production, improved and sustainable forest management, soil organic carbon management, ecosystem conservation, reduced deforestation and degradation, and reduced food loss and waste are all actions that collectively can ensure that land remains a carbon sink and that emissions of the other greenhouse gases are reduced.

Deforestation in Para State, Brazil

Policies that bring changes across the food system, including those that reduce food loss and waste, and influence dietary choices, foster more sustainable land-use management and enhance food security.  We are what we eat. And it’s not helping the planet.

Restoring, expanding and protecting the world’s forests is clearly a global priority.  But the report notes that some actions have immediate impact, while others take decades to deliver measurable results. Options that produce immediate impacts include the conservation of high carbon ecosystems such as peatlands, wetlands, rangelands, mangroves and forests. Afforestation, reforestation, agroforestry, soil carbon management on mineral soils, or carbon in harvested wood products do not continue to sequester carbon indefinitely. Peatlands however can continue to sequester carbon for centuries.   

A trillion trees?

About a month before the IPCC report was published a paper in Science caused a stir in the scientific community. Researchers at the Institute of Integrative Biology at ETH-Zurich argued that that the restoration of forests is one of the most effective strategies for resolving the climate crisis. Excluding existing trees and agricultural and urban areas, the scientists found that across the globe there is space for an extra 0.9 billion hectares of forest canopy cover. That’s enough land to plant close to a trillion trees. Those trees could potentially sequester and store over 200 billion tonnes of carbon—which would make a significant contribution to eventually drawing down atmospheric levels of carbon dioxide.

The authors argue that their analysis shows that “ecosystem restoration is the most effective solution at our disposal to mitigate climate change.” 

Professor Tom Crowther, who led the research at the Swiss university ETH Zurich, stressed that “This new quantitative evaluation shows restoration isn’t just one of our climate change solutions, it is overwhelmingly the top one,” He added “I thought restoration would be in the top 10, but it is overwhelmingly more powerful than all of the other climate change solutions proposed.”

But is this a feasible proposition?

First of all, planting a trillion trees can’t possibly be managed in a single year. Ethiopia recently claimed that it planted 350 million trees this year, beating India’s 250 million mark recorded in 2016. So maybe that’s about the order of magnitude a country might be able to manage.

We need all these trees in the ground by at least 2050. So if we spread the trillion trees over a 30 year period from 2020 to 2050, that makes the task a bit easier—although not by much. Globally, the tree planting campaign would need to plant a total of about 33 billion trees each year for 30 years.

Which countries have the greatest land areas available for these trees?  According to the work conducted at the ETH in Zurich, more than half of the restoration potential can be found in just six countries: Russia, USA, Canada, Australia, Brazil and China. But this has to be a global effort.  Just like the 2015 Paris Agreement that set out each country’s Nationally Determined Contribution to reducing global emissions of greenhouse gases, an international agreement to plant a trillion trees is only going to get close to reality if all countries sign up for what is going to be an unprecedented global challenge. 

One way to look at problems that require a globally coordinated effort shared by all countries is to allocate responsibility on a per capita basis. For example, dividing the annual target by a global population of close to 8 billion, we can get to a ballpark figure that every person on the planet needs to plant about four trees a year for 30 years. That sounds a bit easier, until we scale up again to the national level. For the USA, the national target would be to plant 1.42 billion trees a year. For Canada, with only about a tenth of the US population, the target would be to plant 161 million trees annually.  Both countries have enough space for these additional trees. But other countries, such as China and India, both major emitters of greenhouse gases, do not. There is not enough land available to plant all the trees apportioned per capita.

Setting a country’s quota on a per capita basis and taking into account the available space, the countries with the largest quotas are shown in the table.

Countries with the greatest tree planting potential

The per capita cap and land constraints mean that the program will not get to one trillion trees. Over 30 years the total comes to less than 400 billion. But that’s still a lot of trees with the potential to sequester significant amounts of carbon. Moreover, if the global program really gains traction there is no reason to stop in 2050. 

Four countries have lots of available land over and above their per capita allocation: Russia, USA, Canada, and Australia.  Will they offer to pick up the slack?  Canada should take a leadership role in this global challenge.  

But there’s a catch. Wildfires are increasingly devastating forests around the world. Canada’s forests are now thought to be a net source of carbon emissions due to the numerous and widespread wildfires that occur every year. Hotter temperatures increase the frequency of lightning that ignites fires in forests which are tinderbox dry from heatwaves and drought. If millions of trees are to be planted, it will be essential to select regions where wildfires are infrequent now and unlikely in the future.

It makes little sense to plant millions of trees in Canada while in Brazil the government is busy ripping them out of the ground.  Germany has shut down funding for forest and biodiversity projects in Brazil to try and pressure President Bolsonaro to stop clear-cutting the Amazon rainforest. Canada should follow suit and consider even tougher measures.         

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Emissions from Canada’s forests are discussed here: //www.cbc.ca/news/canada/calgary/canada-forests-carbon-sink-or-source-1.5011490. The graphic is from an excellent World Resources Institute (WRI) article and can be accessed here: //www.wri.org/blog/2019/08/7-things-know-about-ipcc-special-report-land-and-climate. Germany’s response to Brazil’s deforestation is discussed here: //www.dw.com/en/no-need-for-german-amazon-aid-brazils-bolsonaro/a-49988862 .

Ethiopia’s ambitious tree planting program is highlighted here: //www.climatechangenews.com/2019/07/31/ethiopia-bids-plant-four-billion-trees-green-push/. The quotes from Thomas Crowther at ETH are from the Guardian article: //www.theguardian.com/environment/2019/jul/04/planting-billions-trees-best-tackle-climate-crisis-scientists-canopy-emissions.

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Martin Bush

Martin Bush graduated from the University of Sheffield with a PhD in chemical engineering and fuel technology. He has spent the last 30 years leading natural resources management, renewable energy, and climate change adaptation and mitigation projects in Africa and the Caribbean. He lives in Markham, Ontario, Canada. He can be contacted at climatezone.central@gmail.com. He is the author of a new book: Climate change and renewable energy--How to end the climate crisis. Published by Palgrave-Macmillan in October 2019.

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