World Soil Day on 5 December highlights the importance of soils and their role in supporting all aspects of human wellbeing. Soils are indeed very important. Well-managed soils underpin all of nature’s contributions to people as well as to all of the United Nations’ Sustainable Development Goals (SDGs).
For example, by providing food and feed, soils contribute to seven SDGs, including ending poverty and hunger, providing good health and decent work and opportunities for economic growth.
Well-managed soils provide resilience to future climate shocks, by preventing erosion and helping to avert flooding. Healthy soils hold more water than unhealthy ones. This makes them less prone to drought and able to recover more quickly from flooding.
Soils are also very important to remove carbon dioxide from the atmosphere. They hold large stocks of carbon and soils that have been depleted in carbon can also sequester carbon, helping us to tackle climate change.
Scottish peatlands
However, many soils around the world – approximately 11 million square kilometres – are in poor condition and thus contribute less to improving people’s lives and the environment.
Just in Scotland, 80% of our peatlands are degraded to some extent and we need to make big efforts to restore them.
Large areas of peatlands were drained many years ago for sheep grazing and other purposes, and that caused them to degrade. Blocking up drainage ditches can help rewet the soil and turn degraded peatlands into thriving carbon sinks and reservoirs for biodiversity.
The Scottish Government is running a programme that aims to restore peatlands, called Peatland ACTION administered through NatureScot. Landowners can apply for funding through the programme to help them restore their land.
The clock is ticking though. We will need to act quicker than we currently are, if we are to restore the vast areas of peatlands that will help Scotland reach net zero emissions by 2045.
Improving farming practices
Farmers use fertilisers to get high yields, but these are costly and cause pollution. If farmers can increase the organic matter in soil, this increases nutrient supply and less fertiliser would be needed.
Soil organic matter can be increased by putting back more organic matter into the soil and keeping it covered. Farmers already do this by applying animal manure, but using municipal compost and other sources could be additional ways of increasing organic matter in soils. We should regard organic “waste” as an important resource that can be recycled, rather than sending it to landfill.
Combining trees and agriculture in the same plot of land, known as agroforestry, could play a role here. For example, integrating trees into pasture land can help increase the organic matter in soil under the trees, while also removing greenhouse gases from the atmosphere and providing co-benefits for animal welfare and biodiversity.
These approaches are still in their early days in Scotland and could be introduced more widely.
Carbon loss
Organic matter is around 58% carbon and regularly ploughing the soil releases carbon into the atmosphere. For that reason, organic matter content tends to be higher in grasslands than in land used to grow crops and vegetables, because the latter are ploughed every year to allow new seeds to be sown.
Intensive ploughing can eventually decrease soil productivity and contributes to climate change, so less intensive ploughing should be encouraged. When a crop is removed from the field, it is really important that farmers replenish the organic matter into soils. Keeping the ground covered, for example by cover crops during the winter, is another way to get more organic matter in to the soil.
Stopping expansion
Because natural ecosystems store more soil carbon than croplands, it is important that we don’t expand agriculture into natural systems because that is when the most carbon gets lost into the atmosphere. If agriculture can be done efficiently through the methods described above, there is no need to expand the agricultural area – so maintaining productivity is also important.
Future
Looking to the future, further education and outreach about soil restoration options that are available to farmers could play an important role. Additionally, including good soil management into future farming subsidies will help to incentivise good practice.
Scotland is heading in the right direction with regard to soil health, but we need to up our efforts to restore all of our peatlands by 2050. Soils are essential to mitigate our emissions and increase resilience to extreme weather events, which will become more frequent with climate change.
If we look after our soils, we help them to help us.
Related links
Peatland restoration and potential emissions savings on agricultural land
Measuring the vulnerability of Scottish soils to a changing climate
After over-time negotiations the Glasgow Climate Pact was agreed on Saturday 13 November. But can the outcome of the two-week gathering be hailed as a success? Our directors Prof Dave Reay and Prof Pete Smith offer their take-aways from the talks, concluding that the assessment really depends which parts of the agreement – or not – you focus on.
Welcome agreements
COP26 saw notable successes in terms of agreement on the ‘rule book’ that underpins the Paris Agreement. Through the so-called ‘Paris Rule Book’, covering issues such as the transparency and consistency of reporting, common time frames and, crucially, carbon trading, COP26 delivered some major successes. For all the justified chagrin that mitigation commitments by individual nations still don’t equate to sufficient global action, having a robust ‘Paris Rule Book’ that actually allows assessment of success (and failure) down to national and sub-national scales is crucial. Agreement on transparency, such as how and when emissions, finance and adaptation actions in each country are reported, was therefore a major win for the Glasgow COP – as ever, ‘You can’t manage what you don’t measure’.
Likewise, agreement on how emissions reductions can be traded at national and sub-national levels was a big step forward in terms of opening up financial flows for projects, and (mostly) dealing with gaping double-counting loopholes. These loopholes, such as selling credits to someone else while still claiming the same reductions yourself, could have badly undermined many of the commitments made before and during COP26.
Other notable steps forward included the pledge by more than 100 national leaders to stop deforestation and begin restoring the world’s forests by 2030, and the Global Methane Pledge which aims to limit methane emissions by 30% compared with 2020 levels.
That India has set a net zero by 2070 and the agreement to support South Africa to transition away from coal are both very welcome developments. The latter may be expanded to other developing countries shortly. There is also the new US-China cooperation on climate change which in the next few years may help deliver important short term actions.
The Glasgow Climate Pact
The Glasgow Climate Pact – the final cover text for COP26 – was itself a step forward in terms of areas such as:
- ramped up finance for adaptation, a push for increased national commitments in 2022;
- agreement that countries must come back every year with updates on their ambition;
- overt acknowledgement (though no mechanism to address it) of the ‘loss & damage’ already occurring, and which will occur in the future; and
- the widely reported ‘phase down’ of coal.
The emphasis on ‘just transition’ is to be found several times in the COP26 outcomes and was brought into a stark light by the commitment of the US and others to support the transition away from coal in South Africa. Internationally, safeguarding against negative impacts arising from the Paris Climate Goals – such as risks to livelihoods in high carbon industries – will become an ever-more pressing issue.
Addressing this globally, through so-called ‘Response Measures’ like international finance, is important, but even more important is the domestic response and the embedding of just transition principles into national targets and actions. Ultimately, it is a make-or-break issue for the sustainability of national and sub-national efforts on climate change, and is therefore fundamental to the Paris Climate Goals as a whole.
Nowhere near enough
However, the progress made was nowhere near enough, and ultimately COP26 fell well short of delivering the national commitments that would together limit warming globally to 1.5°C.
It is inexcusable that the $100 billion per year promised by rich nations to poorer countries in 2009 has not yet been delivered, and will not be until 2023.
Likewise, while it is good news that China has a target of net zero by 2060, it is disappointing that the country didn’t announce any new ambition at COP26.
Australia’s ambition on climate action, meanwhile, is simply woeful.
Delivering in Scotland
Closer to home we see the same picture of notable successes and significant shortcomings:
The launch of the Beyond Oil and Gas Alliance (led by Denmark and Costa Rica) is a big step forward, but it is disappointing that neither Scotland nor the UK have signed up. We have to stop burning fossil fuels as quickly as possible. Global governments subsidising fossil fuel production and consumption to the tune of $420 billion per year makes absolutely no sense, and firmly moves us in the wrong directly. Scotland, and other oil producers, should be investing in ensuring a just transition away for oil and gas – providing new opportunities and retraining of workers in the industry to enable them to contribute to the net-zero transition.
However, it is worth celebrating that Scotland is ahead of the global curve when it comes to grappling with exactly this challenge of a just transition.
For Scotland, like all nations, the full implications of COP26 will play out in the coming months and years. Our domestic climate targets, actions and progress continue to receive a huge amount of attention from other countries, states, cities and institutions – sharing our successes, as well as our failures, in the transition to net zero represents a vital leadership role for Scotland internationally.
So, was COP26 in Glasgow a success? Yes, if you regard a major steps forward on a basket of key climate issues as success. However, if you were looking for the giant leap forward required to limit warming to 1.5°C, then it has to be a resounding no.
Watch Dave Reay’s evidence to the Scottish Parliament on COP26 outcomes
Prof Pete Smith is CXC Director, Science
This blog was first published by CarbonBrief
Since the global-warming limits of “well below 2C” and 1.5C above pre-industrial levels were enshrined in the Paris Agreement in 2015, there has been a flurry of new research assessing what the impacts of climate change could look like under each limit.
For biodiversity, the benefits of holding warming to 1.5C rather than 2C are clear. At 2C, for example, models project that 23% of the world’s plants could lose more than half of their range of suitable climate. This drops to 7-13% under 1.5C.
But there is another side to how climate change could affect biodiversity – through the land management decisions we take as part of efforts to reduce greenhouse gas (GHG) levels in the atmosphere.
Given that agriculture and forestry together are responsible for 24% (pdf) of global GHG emissions, we know that the land is going to be important for meeting either the 2C or 1.5C goals.
Not least because, as we pursue efforts to reach a 1.5C limit, it becomes increasingly likely that we will need to ramp up how much CO2 the land surface absorbs from the atmosphere. This means applying “negative emissions” techniques that often need substantial land and water when deployed at scale.
So, what does the latest research suggest are the biggest risks to biodiversity?
Land use
In a paper published by the Royal Society earlier this year, my colleagues and I reviewed the existing research on the options for land-based mitigation and their implications for biodiversity.
There are two main ways to use the land to help tackle climate change: reduce the emissions from land use – including farming and forestry – and enhance the amount of CO2 the land surface takes up from the atmosphere.
The former includes options such as reducing deforestation, restoring degraded land and changing the way the land is managed. In farming, for example, management changes could mean altering the rotation of crops, optimising fertiliser and water use (particularly for rice for the latter), improving tillage and residue management, and reducing grazing intensity.
By and large, these can be achieved without intensifying land management. They broadly have benefits for plant and animal life and are consistent with biodiversity protection.
The latter includes negative emissions techniques – also known as CO2 removal – such as afforestation and reforestation, restoration of peatlands, wetlands and coastal ecosystems, soil carbon sequestration, addition of biochar to soils, enhanced mineral weathering, and bioenergy with carbon capture and storage (BECCS).
These techniques vary in their cost, readiness, technological complexity and ease of deployment at scale.
Deforestation in the Gran Chaco near Mariscal Estigarribia, Paraguay. Credit: Michael Edwards / Alamy Stock Photo.All of these options could have scale-dependent implications for biodiversity. In other words, deploying any of these approaches on a large enough scale to make a dent in global CO2 emissions may well have knock-on impacts for the plants and creatures that share the land.
Some options – such as BECCS and afforestation/reforestation – have a large land footprint and, when implemented, prevent the land from being used for other purposes. Others – such as biochar, soil carbon sequestration and enhanced weathering – require land, but allow continued use for its current purpose.
To a large extent, biodiversity impacts are likely to depend how a negative emissions technology is deployed. With BECCS, for example, although some bioenergy crops can provide biodiversity benefits when grown on former cropland, very large-scale cultivation of bioenergy can result in biodiversity loss.
Similarly, with afforestation/reforestation, the species of trees and where they are planted will govern the impact on the wider ecosystem. Planting a diverse mix of trees on degraded former cropland would likely improve biodiversity, for example.
Overall, our analysis suggests that many negative emissions options could be largely positive in terms on biodiversity, or at worst neutral. Whereas some, such as BECCS, will almost certainly lead to biodiversity conflicts, if implemented at a very large scale.
Planetary boundaries
Around the same time that our paper was accepted by the Royal Society for publication, two important papers were published – both in Nature Climate Change – which furthered our understanding of how negative emissions options might influence biodiversity.
The first, by Dr Vera Heck of the Potsdam Institute for Climate Impact Research (PIK) and colleagues, provided an in-depth analysis of how BECCS might contribute to CO2 removal, as well as the risks to planetary boundaries associated with widespread implementation of BECCS in different regions.
The risks to planetary boundaries considered in the study were freshwater use, biogeochemical cycling (using nitrogen use as an indicator), land system change (using percentage forest loss as an indicator), and biosphere integrity (using biodiversity “intactness” as an indicator).
Native tree planting in Cranberry Clough, Howden Moors. Peak District National Park, Derbyshire, UK. Credit: Nature Picture Library / Alamy Stock Photo.
The authors found that, when running model simulations that use BECCS to meet the 1.5C or 2C limit while prioritising the protection of freshwater biodiversity, global biodiversity intactness declined by 25-35%.
In addition, this risk varied between regions. While implementation of BECCS in some regions – such as Europe, New Zealand, part of Australia – presented a relatively low risk to planetary boundaries, others – including central, east and west Africa, and Madagascar – were at risk under all scenarios. Other regions – most of Latin America and the Caribbean, parts of North America, China and East Asia and the Himalayas – were classed as “high-risk” when biodiversity was not prioritised.
My main takeaway from the Heck study was that, given the risks, perhaps we should park BECCS and pursue other land-based negative emissions options instead – particularly those proposed as “natural climate solutions”, such as reforestation and habitat restoration.
That was until I read the second paper, by Dr Michael Obersteiner of the International Institute for Applied Systems Analysis (IIASA) and colleagues.
Obersteiner’s study looked at different ways of “spending” our dwindling carbon budget– the amount of CO2 that we can still emit without exceeding either the 1.5C or the 2C limit. Their findings got me thinking again about whether or not we need to use BECCS sooner rather than later.
The research looked at a range of different benchmarks including carbon budget overshoot, the amount of CO2 that would need to be captured from 2080 onwards, and natural land lost. They then compared a number of scenarios of timing of negative emissions deployment.
The results were striking: waiting to apply negative emissions late in the 21st century had the worst outcomes across all scenarios examined. This was because it led to a significant overshoot of the carbon budget – and, hence, missing the warming limits they were aiming for.
Natural land lost (a surrogate for biodiversity impact) was 26-33%, depending on peak emission date, whereas their “rapid decarbonisation”, “no overshoot” and “minimise greenhouse gas removal” scenarios had much lower impacts on natural land lost.
These findings suggested that very early deployment of negative emissions at scale is necessary to avoid overshoot – and with direct air capture not yet available at scale, the authors conclude that early deployment of BECCS is necessary.
Learn by doing
After reading the Heck study, I thought we could, perhaps, kick BECCS into the long grass, and deploy it later – perhaps after 2050 – depending on how much mitigation had been achieved.
The Illinois Industrial Carbon Capture and Storage plant captures CO2 from Archer Daniel Midland’s Decatur corn processing facility and stores it almost a mile and a half underground. Credit: Archer Daniel Midland.
But following the Obersteiner paper, I now think we might need to bite the bullet and implement BECCS earlier.
This means we need demonstration projects. They need to be in regions where risks to planetary boundaries are deemed to be low, so that we can test the efficacy of BECCS and monitor and assess the environmental impacts. We learn best by doing.
In this emerging and fast-paced field of research, new studies on land-based negative emissions have the potential to reshape our thinking on the best way forward. In part, this is what makes working in this field so interesting at the moment.
New studies such as those described here are starting to provide the information we need to assess the potential impacts of different mitigation strategies on biodiversity – helping us to target observations and experimentation to get a better handle on the real impacts.