Nature's sleeping giant

Of the millions of hectares of land that have been deforested, much of it provides little or no food production, but would provide good opportunities for cost-effective reforestation. Reforesting these lands would sequester billions of tonnes of carbon dioxide without disrupting food production. In some cases, reforestation can be inexpensive and as simple as refraining from burning marginal grazing land, allowing forests to regenerate naturally. In other cases, reforestation can require active planting of trees and then long term care as they grow, and can be a relatively expensive form of land-based sequestration.

One way to unlock this opportunity, is to create the financial incentives to plant trees – billions of them – and to create new markets for more sustainable timber and forest products. Trees deliver a remarkable range of products, including food, building materials, paper products, and fuel.

However, simply creating more markets for wood and forest products is not the answer as this could create incentives for further deforestation. Conservation of unique habitats around the world remains a critical strategy to protect standing forests. What is required is a combination of avoiding further deforestation in critical locations, reforesting on degraded lands, and encouraging more sustainable production in timber plantations and logging concessions.

Aside from the forestry sector, many other sectors can benefit from large-scale tree planting. These include:

• Water utilities and beverage companies, where planting trees can reduce sediment in water ways.
• Food companies that rely on tree crops and use raw materials from agroforestry.
• Building companies working more with sustainable timber in construction. For example, cross-laminated timber can now be made stronger even than steel. If we can displace steel usage in buildings, we can get an even bigger climate benefit.
• Cities and municipalities can plant trees to clean the air and cool the ambient temperature.
• Energy companies, cement and fertilizer producers and other large emitters of greenhouse gases could link up with the forestry sector to reduce emissions.

Can we be the first generation – since we first tilled the soil more than 10,000 years ago – to regreen the planet?

The Nature Conservancy and its partners are working to unleash the same zeal that promoted growth in the renewable energy sector to also stimulate a new wave of reforestation. 

Each year, more than 7 million hectares of forest are lost – an area larger than Sierra Leone. Avoiding most of that deforestation would prevent the release many millions of tonnes of carbon dioxide equivalent per year (GtCO2e/year).

The major challenges to preventing deforestation are political and economic. Avoiding deforestation will require establishing large-scale incentives and regulatory mechanisms to address the major sources of deforestation, such as cattle ranching in the Amazon or palm oil production in Indonesia.

Also, rural communities that depend on unsustainable forest clearing will need help in developing alternative livelihoods. Focusing on single regions will not be enough, however. When forest loss is averted in one region, it is often “transplanted” to another part of the world. To prevent deforestation, we must take an integrated, global approach.

Avoiding forest conversion is a relatively low-cost pathway that’s ready to be put into practice immediately. In the past, critics have argued that it was premature to take action given the limitations of measuring and monitoring the world’s forests. As measurement and monitoring techniques have improved, this argument is no longer a significant barrier to action. Despite some political and economic hurdles, we have the tools we need to stop deforestation now.

Natural forest management

Many of the world’s natural forests provide wood products critical to people’s lives and livelihoods. Halting all logging in forests would achieve maximum carbon sequestration, but an end to logging is neither realistic nor necessary.

Improving forest management practices allows natural forests to store more carbon while maintaining wood production for the long term. Logging should certainly be halted in some sensitive places, but the lost production can be made up by new wood production in reforested lands and plantations.

Extending harvest cycles, for example, allows trees to grow more before they’re felled, increasing the average carbon stock across a working forest. Reduced-impact logging practices like cable winching can avoid damage to unharvested trees. And competing vegetation, such as vines, can be thinned to allow trees to grow faster and bigger. Implementing such techniques can allow working forests to sequester more carbon.

Improved natural forest management practices could be applied in some form to some 1.9 billion hectares of wood-production forest worldwide, an area twice the size of the United States.

Improved plantations

Timber plantations are found across the globe, accounting for 7% of the world’s total forest area, yet more than a third of the world’s timber production. Plantations are typically managed on shortened harvest rotation lengths that optimize investment returns, rather than longer rotations that deliver broader economic and environmental benefits.

Extending harvest rotation cycles allows trees to absorb more carbon from the atmosphere, while increasing timber yields. Extending harvest cycles to increase carbon uptake in timber plantations would sequester hundreds of millions of tons of carbon dioxide equivalent per year (MtCO₂e/year).

Avoided fuelwood harvest

Around the world, 2.8 billion people burn wood or wood-based charcoal for their basic energy needs. The majority of that fuelwood is used for cooking in developing countries.

Improving cook stoves to burn more efficiently would reduce the amount of wood taken from forests, leaving more carbon in trees. Compared to open fires, modern stoves save up to 70% of fuelwood. In addition, improved cook stoves would reduce smoke inhalation, providing significant health benefits, especially for women and young children.

The challenges of reducing fuelwood harvest are mostly logistical. There can be cultural barriers to convincing people to change the way they cook. Switching to clean cook stoves and alternative fuels, such as gas, can have high upfront costs for homeowners. Further, distributing new technology to remote villages can be difficult. Due to these limitations, this is a comparatively high-cost pathway.

The Global Alliance for Clean Cookstoves is working to strengthen the market for clean cookstoves and fuels in Bangladesh, China, Ghana, Guatemala, India, Kenya, Nigeria and Uganda.

Forest fire management

Forest and savanna fires release large amounts of carbon into the atmosphere in a short amount of time. Better managing how and when forest and savanna burns can prevent excessive loss of carbon into the atmosphere, through:

• Prescribed fires in fire-prone systems. Some landscapes are adapted to fire disturbance. When those landscapes are not burned regularly, plant material builds up. Eventually this will result in a large catastrophic fire which produces much greater emissions than if small, intentional fires had been set periodically over time.
• Prescribed early-season burns in the savanna to avoid higher emissions from late-season burns.
• Fire control practices (such as fire breaks at forest edges) in tropical moist forests to avoid unintended fires that degrade the forest.

Conservationists must consider that prescribed fires will involve increased initial emissions in order to avoid future larger emissions. Implementing prescribed fires and fire breaks will require an initial investment of upfront capital. And because fire management is not a one-time intervention, there are reoccurring costs. Improved fire management practices will be particularly important in African savanna ecosystems and the frontier forests of the Brazilian Amazon.

Cropland nutrient management

When synthetic fertilizers are applied to croplands, excess nitrogen is released to the atmosphere or carried away by water. That nitrogen is emitted into the air in the form of nitrous oxide, a greenhouse gas 300 times more potent than carbon.

Cropland nutrient management ensures that the amount of nitrogen applied to the field does not exceed the amount that the plants can absorb. It also ensures fertilizer application is timed to avoid unnecessary runoff and reapplication.

Realizing the full potential for cropland nutrient management would require the adoption of best practices and efficient nutrient management in agricultural systems across the globe.

The main challenge is disseminating information to farmers and encouraging them to implement best practices. Another is the existence of policies designed to stimulate agricultural production, that actively subsidize the overuse of fertilizer. In such cases, policy changes will be necessary to reduce fertilizer use.

To maximize the potential of cropland nutrient management, the farmers around the world would need to adopt standards practiced in North American and Western European agriculture where appropriate. A large improvement could be realized, for example, simply by disseminating information about best practices among regions such as East Asia, where fertilizer use is unnecessarily high. More efficient use of fertilizer can reduce a farmer’s costs without reducing productivity.

In the future, further improvements could come from precision agriculture technologies and the use of alternative forms of fertilizer.

Conservation agriculture

When bare soil is exposed between crops, carbon stored in the soil is lost to the atmosphere. By planting cover crops on croplands that have an off-season fallow period, farmers can expand the length of time that photosynthesis occurs on cropland. This practice, also known as conservation agriculture, increases the amount of carbon stored in the soil, while also improving soil quality and fertility.

Cover crops aren’t suitable everywhere: some areas in the tropics are already double-cropped, and other regions may not have the right conditions to support a second crop. However, about 400 million hectares – up to 25% of the world’s cropland – could be planted with cover crops. That’s an area six times the size of Texas.

Cover crops have the potential to improve soil fertility, increase yields and retain soil moisture to mitigate the effects of drought. One of the challenges to conservation agriculture is disseminating knowledge to farmers about what type of cover crop or crop mixture to plant, when to plant, how deeply to plant and, in some cases, what new equipment might be necessary.

Already, many farming and conservation groups are actively educating farmers about the use of cover crops, but more effort will be needed to spread that knowledge to growers around the world.

Avoided grassland conversion

As populations grow and the demand for food increases, grasslands and shrub lands around the world continue to be cleared for agriculture. When natural grasslands are tilled for planting, nearly half of the carbon stored in the soil surface is lost to the atmosphere.

Globally, roughly 1.7 million hectares of natural grasslands and shrub lands per year are converted for crops or other uses – an area slightly larger than Connecticut or Kuwait. In the United States, 77% of land converted to croplands between 2008 and 2012 was from grasslands. Agriculture is also crowding into grasslands in East Africa and West Africa.

Feeding our growing population remains a significant challenge. To avoid the conversion of grasslands, we must improve management of the world’s existing croplands and continue efforts to intensify sustainable agriculture on those lands. Due to the high demand for arable land, avoided grassland conversion is a relatively high-cost pathway.

Trees in cropland (or agroforestry)

There are many different agricultural practices that incorporate trees into existing cropping systems, and some form of these practices could be beneficial across a large share of cropland globally. One of the main challenges lies in communicating the benefits to farmers, and providing them with the technical support and services to encourage them to shift to a new (sometimes counterintuitive) method of farming.

Agricultural policies and incentives may need to be changed or created to promote the adoption of agroforestry systems. Many different agroforestry systems have been demonstrated to be valuable in different contexts. Three systems used increasingly in croplands include:

• Windbreaks: planting belts of trees and shrubs to protect fields and homes from wind.
• Alley cropping: planting lines of productive trees within croplands.
• Farmer-managed natural regeneration (FMNR): managed recovery of native trees within dryland agriculture systems to protect and improve soils.

Improved rice cultivation

Most of the world’s rice is grown in fields that are flooded year-round. When rice is harvested, most of the remaining plant material is left in the ponds, where it sinks to the bottom and begins to decay. Plants that decay in that low-oxygen environment generate methane, a powerful greenhouse gas.

Rice cultivation can be improved by alternately wetting and drying rice fields, or by draining flooded rice fields once during the mid-season. Such methods reduce the time that decaying plant material is submerged, thereby reducing methane emissions. Worldwide, rice is grown on around 192 million hectares (an area nearly the size of Mexico) the vast majority of it in Asia.

However, in many Asian countries, farmers lack the technical capacity to remove water from their fields during the rainy season. They also have little incentive to improve their water management practices.

In a best-case scenario, water management of rice fields can reduce methane emissions by as much as 90% compared to full flooding. And field experiments show that the practice maintains, and in some cases improves, rice yields. Further, many of the world’s rice-producing regions have water shortages, making water management an attractive option for farmers.

In some regions, improved rice cultivation will be expensive to implement. But in others, it would be a relatively low-cost effort. In locations such as India, the southern United States and parts of the Philippines, where farmers irrigate by pumping groundwater, the ability to engage in water management already exists. Doing so could save fuel costs related to operating the pumps.

In areas with the technological capacity, improved rice cultivation could be implemented immediately. In some areas, incentives such as subsidies might be necessary to improve rice production on a broader scale.

Animal management

Livestock are a significant source of greenhouse gas emissions, but improved efficiency can help to curb those emissions. Reducing the total number of livestock needed to meet the demand for meat and dairy products will reduce the amount of carbon released from cattle farming and ranching without affecting market supply. Beef is the most carbon intensive source of protein on the planet.

Over time, measures designed to encourage dietary change can be used as an emissions reduction strategy: for example, incentivizing people to switch to poultry, fish or beans as sources of protein. However, as the world population continues to grow, it safe to assume that demand for beef and dairy will remain constant in the near term even as people do make dietary changes in certain geographies.

Good animal management techniques include choosing improved livestock breeds, and promoting increased reproductive performance, lower mortality and increased weight gains.

Improved livestock management practices could be applied to a large portion of the 1.4 billion head of cattle worldwide. By implementing these animal management techniques, livestock will feed growing populations more efficiently.

Economic barriers and capital costs can make it difficult for ranchers to purchase new livestock breeds and change other existing management practices. Despite the hurdles, more efficient processes often provide economic benefit to the ranchers.

Many ranchers are already applying animal management strategies such as using breeds that gain weight rapidly or using reproductive management practices that yield high conception rates. Such techniques are available now and are ready for wider implementation.

Feed

Livestock release methane as a byproduct of digestion. Methane is approximately 34 times more potent a greenhouse gas than carbon dioxide. That released from animal digestion (known as enteric methane) is a significant source of greenhouse gas emissions around the world.

Improvements in livestock feed could be applied to a significant number of the more than one billion head of cattle around the world. Feeding animals energy-rich, easily digestible cereal grains can reduce the amount of methane that’s released.

One of the main challenges to improving livestock feed is to tailor new practices related to feed quality to local conditions. This involves issues related to feed availability and economic returns.

Legumes

Planting legumes such as alfalfa, clover, peas or beans in managed pastures provides increased forage for cattle and other livestock, while also adding carbon to the soil. Legumes are also notable for their ability to fix nitrogen in the soil, reducing the need for the addition of nitrogen fertilizer.

Compared to other grazing practices, planting legumes in pastures has a more limited geographic potential, because it only applies to planted pastures that have a relatively low abundance of legumes to start with. However, there are no major challenges to implementing more widespread planting and legumes could be planted in pastures across 72 million hectares globally, an area about twice the size of Japan. Many ranchers already over-seed their pastures with legumes to improve forage and productivity.

Optimal intensity

Intensive grazing on grasslands reduces the productivity of plants and reduces the amount of carbon stored in the soil. Optimizing the intensity of grazing reduces carbon loss to the atmosphere.

Ranchers can optimize grazing through methods such as rotational grazing (which involves local monitoring of livestock movements and grazing patterns to allow grass to recover) and bunched grazing (in which livestock are tightly concentrated in an area for a set period of time, then moved on to let the land recover).

Changing grazing management practices is an intervention that could apply to 470 million hectares of rangeland worldwide – an area about half the size of Canada. Such practices are not only beneficial for carbon storage, but also increase profits for ranchers, reduce soil erosion and improve wildlife habitat. Implementing this approach around the world will also require educating ranchers about improved practices and the economic benefits they can offer. Many ranchers are already using these practices to maximize productivity on their rangelands.

Coastal wetland restoration

Globally, coastal wetlands are found on well over 35 million hectares (an area nearly the size of the Republic of Congo) to perhaps as many as 115 million hectares. Much of those wetlands are degraded and in need of restoration. Coastal wetlands such as mangroves, tidal marshes, or seagrass beds can be restored by reducing pollution, replanting lost vegetation and/or by repairing the natural flow of water.

Efforts to restore mangroves, salt marshes and seagrasses are already underway in many parts of the world, and there are large areas, particularly of abandoned or unproductive aquaculture where restoration would yield rapid returns in both carbon and co-benefits.

Restoring wetlands can be straightforward from a technical point of view. Mangroves, for instance, are easily planted, but in many cases restoring the hydrology alone is all that is needed to allow natural recolonization. But the opportunity cost for such restoration is sometimes high where former wetlands are now developed, or used in productive aquaculture.

Re-establishing coastal wetlands can be a relatively high-cost pathway although it varies according to ecosystem and geography. For example, mangrove restoration in developing countries is low cost compared to tidal marsh restoration in the US. In future, mangrove restoration is likely to be most important in areas that have experienced high rates of loss, including South Central America and East Asia.

Seagrass restoration is largely dependent on improving on-shore watershed and nutrient management practices. Such management policies can be expensive and often take many years to implement fully.

For salt marshes, there is great restoration potential in the U.S., which contains more than 30% of the world’s salt marshes.

A common challenge comes from obscure land tenure, which has greatly hindered some efforts to determine ownership or to undertake restoration in appropriate locations relative to the tidal cycle.

Coastal wetland protection

Around the globe, many coastal wetlands are converted for agriculture, aquaculture or urban development.

The loss of healthy wetlands releases stored carbon into the atmosphere. Polluted run-off can also degrade the health of wetlands, leading to an eventual release of carbon trapped in the soil.

Avoiding coastal wetland conversion is a low-cost climate mitigation pathway. Many interventions (such as establishing protected areas, improving land tenure and enforcing land-use laws) can be put into place immediately. Preventing conversion and maintaining the health of coastal wetlands will allow these areas to continue storing and absorbing carbon from the atmosphere.

However, the rate at which salt marshes and seagrass beds are being lost is uncertain. In particular, much more work is needed to map the locations and size of seagrass beds and salt marshes globally. National level maps do exist in a lot of places but there are gaps such as parts of Africa, Asia and South America.

In the US, for example, many states have enacted laws to protect tidal marshes. In Florida, the Mangrove Trimming and Preservation Act protects mangroves on uninhabited islands that are publicly owned or on lands set aside for conservation and preservation. Similar laws could be established to protect coastal wetlands around the world.

In Southeast Asia, meanwhile, where mangrove forests are converted for aquaculture, palm oil production and rice farms, new regulations and viable economic alternatives will be necessary to curb wetland loss.

Peatland restoration

Peatlands are considered degraded when they’ve been drained or subjected to altered water flow but have not been completely converted for other land uses. In this degraded state, the carbon stored in plant material buried in peat soil is released into the atmosphere. Dried peat is also susceptible to ground fires, releasing large amounts of stored carbon in short order.

Degraded peatlands are responsible for a large portion of carbon emissions from natural systems. Peat soils can be restored, however, to prevent the further breakdown of stored plant material and to capture new plant debris from vegetation growing aboveground. The primary method of restoration involves “re-wetting,” or restoring the natural flow of water and soil saturation.

The primary challenge to peatland restoration is economic. Altering drainage patterns and local hydrogeography can be costly. Despite the economic hurdles, the technical capacity for restoring peatlands already exists and could be implemented immediately, especially in lower-cost regions. Restoration efforts will also have important benefits for biodiversity.

Peatland Protection

The biggest challenge to avoiding peatland conversion is monitoring and enforcement. Indonesia, for instance, is a hotspot of peatland conversion. But while there are regulations in place to protect peatlands, experience shows that they are frequently not enforced.