IPCC: Human land use is key driver of the climate emergency

Last October, the Intergovernmental Panel on Climate Change sent the world a firm warning. The Earth is on track for a global temperature rise of 3°C and limiting that rise to below 1.5°C, in accordance with the goals of the Paris Climate Agreement, will require immediate action. Even then, it said, there will still be climatic difficulties.

Yesterday, the IPCC released a new report, with a message of equal urgency, this time specifically focused on land use. The report emphatically states that the way we currently use land is both a major contributor to climate change and is damaging the ability of the land to sustain humanity. The major takeaway from the report is that we are caught in vicious cycle in which the climate emergency and increasing amounts of extreme weather incidents are causing the land to deteriorate, exacerbating desertification, land erosion and soil degradation. In turn, this degradation means the land is becoming less effective as a carbon sink and is contributing more greenhouse gases (GHGs) to the atmosphere.

The problem is huge and spans the globe. The report states that humans utilise more than 70 per cent of the global ice-free land surface and that this land use contributes around 23 per cent of total human-caused GHGs. Most of this arises through deforestation, habitat conversion for agriculture, and livestock emissions. In addition, excessive application of fertiliser is leading to the release of nitrous oxide into the atmosphere.

In the face of this crisis, the authors – a group of the world’s leading environmental scientists – are calling for an urgent transformation of land use, on top of efforts to reduce carbon emissions from fossil fuels.

But while the report is stark in its warnings, urgently highlighting the risk of future food security crises as our current usage of land leads to drier soils and increased wildfires, it also presents a huge menu of short- and long-term response options, directed at governments and policy makers around the world. At a press conference in Geneva to launch the report, Valerie Masson-Delmotte, co-chair of one of the IPCC’s working groups said: ‘For each sector there is potential for action, and there are different options.’

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Clik here to view.The report warns that our use of land is exacerbating climate change which contributes to extreme weather events and increased wildfires

Speaking to Geographical from Geneva, Dr Stephen Cornelius, chief advisor on climate change for the WWF, condensed the many response options contained in the report into four categories. Coming in top is the prevention of further habitat destruction. ‘We need to halt the conversion of natural ecosystems,’ he says. ‘That might be stopping deforestation or stopping conversion of grassland. You want to keep the carbon store that we already have locked in the ground.’

It’s something that most commentators agree is both the quickest and easiest step to implement. ‘Once you convert native ecosystems to cropland you lose all the carbon [stored there] into the atmosphere. If you can prevent that, it’s a quick win for the climate,’ says Pete Smith, a professor at the University of Aberdeen and a senior author on the IPCC report. ‘It’s also a quick win for preserving biodiversity, ecosystem function and, in arid areas, for preventing desertification. And, it doesn’t require additional money.’

The second response option involves restoration of natural habitats that have already been converted, be they forests, grassland or peatlands. Though it’s a longer-term option (because trees need time to grow), Cornelius emphasises that simply saving what we’ve got isn’t enough. Peatlands, a type of wetland that occurs in almost every country on Earth, are particularly key. Though it’s planting trees that often hits the headlines, peatlands are the largest natural terrestrial carbon store on Earth, storing more carbon than all other vegetation types in the world combined. ‘Tropical peatlands have huge stores of carbon, says Smith, ‘when we convert them we lose it.’

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Clik here to view.Scotland is particularly famous for is peatlands, but they can be found in most countries on Earth

The third and fourth actionable categories relate to food production methods and the way we consume and dispose of food. In regard to the former, the report repeats the cyclical nature of the problem, pointing to a ‘current global food system that is both a major driver of climate change, and increasingly vulnerable to it.’ Many agricultural methods are hugely damaging to the environment, particularly the heavy use of inorganic fertiliser, which has increased nine-fold since 1961 and which both releases GHGs and also kills many native plants. But the culprits are not just the farming practices themselves but the entire supply chain, in which manufacturing processes, packaging and transportation drive further GHG emissions.

In response, Cornelius insists that ‘you can have farming systems with lower greenhouse gas emissions. There are production systems that use less nitrogen in fertiliser for example.’ Other options vary from increasing the use of genetically modified crops, better able to withstand pests and extreme weather, to agroforestry practices in which trees or shrubs are grown among crops.

Also feeding into this issue are human consumption habits. Current diets are a prime driver of land clearance and the food sector contributes up to 75 per cent of deforestation worldwide. What’s more, the report states that since 1961, the supply of global per capita food calories has increased by one third, with the consumption of vegetable oils and meat more than doubling.

Though the report doesn’t dictate the ideal diet, it notes that: ‘Balanced diets, featuring plant-based foods, such as those based on coarse grains, legumes, fruits and vegetables, nuts and seeds, and animal-sourced food produced in resilient, sustainable and low-GHG emission systems, present major opportunities for adaptation and mitigation while generating significant co-benefits in terms of human health.’

Encouraging people to change diets certainly isn’t easy and, as the report acknowledges, technical, financial and cultural factors all influence the potential for transition. Nevertheless, despite these challenges, many commentators see this as an area with dramatic potential. ‘Trees take time to grow and so the cheapest and best options are our own behaviours: diet and food waste,’ says Piers Forster, a professor of climate physics at the University of Leeds. ‘There are cultural sensitivities here, but they are easy wins.’

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Clik here to view.The report notes that changes in diet, including eating less meat, would contribute to lowering emissions

Ultimately, only a synergistic combination of these responses will be enough to transform land use to the extent required. ‘I would say we need a portfolio of measures that work together,’ says Smith, ‘For example, if we reduced our overconsumption of livestock products, particularly in developing countries, that actually frees land. Over ten times more land is used to produce one kilogram of meat than is needed to produce one kilogram of vegetable protein. So by making changes in demand we can free some of the pressure on the land which then allows us to use it for other things.’

In a similar vein, a key message to come out of the report is that many GHG-saving measures also come with a range of co-benefits, including economic benefits for farmers. ‘There are a surprising number of win-wins,’ says Smith, adding that many of the responses listed in the report both reduce emissions but also combat desertification and land degradation, and enhance food security. ‘That would be the key thing for policy makers to take away from this. There’s a whole bunch of uncaptured potential.’

Improving soil quality is a good example of this. Better soil can both sequester more carbon and prevent further soil degradation, making land more fertile and potentially more profitable. It’s something that’s also a priority for the IPCC. According to the report, soil is being lost more than 100 times faster than it is being formed in ploughed areas.

Lynn Scarlett, vice-president for public policy at The Nature Conservancy (and a former US deputy secretary of the interior under president George W Bush), points to soil quality as a vital but so far under-emphasised issue. ‘In some respects, we need to build on areas where there’s already been focus, for example, avoiding deforestation,’ she says. ‘But I think there are new areas of focus as well that are implied by the report. The soil sequesters a lot of carbon but we’ve seen through changes in agricultural practices the loss of organic matters in soils.’ She explains that methods to reverse this trend include reducing the use of chemicals and implementing ‘no till’ policies, which involve leaving the natural residue of the harvesting process in the ground rather than ploughing up the field.

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Clik here to view.Use of inorganic fertiliser is pinpointed in the report as a practice with deleterious effects on the climate

What’s strikingly evident from the report is both the scale of the problem and the plethora of potential responses. It’s equal parts doom and opportunity. Some of these opportunities are already in development. Professor Forster says that the UK’s Department for Environment, Food and Rural Affairs is already doing a lot of good work on land conversion. He points to the Committee on Climate Change’s net zero report, published in May, which stated that turning agriculture from a source of emissions to a sink would cost around £2bn a year, adding that ‘farmers and the National Farmers Union, with their 2040 net zero target, have an appetite to do this.’ What’s needed, he says is ‘the right incentives and guidance.’

But whether such policies will be rolled out at the global scale and speed required is less certain. Lack of data and bi-partisan cooperation pose difficulties and, according to Forster, ‘land ownership and the rights of those living and working on it are the major obstacle to urgent action.’ As a result, much better cooperation and organisation are required at all levels, he says.

The authors of the report are well aware of these challenges. Their hope is that the findings will at least highlight land use as a key priority going forward. ‘We normally focus on the energy industry and on fossil fuels,’ says Cornelius. ‘And certainly, you don’t want to take your eyes off that, because that's the primary driver of climate change. But a big chunk, a quarter or so, comes from land, and we need to focus on all of it.’

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