Natural Pathways to Climate Mitigation
The Paris climate agreement makes clear that every country—large or small, coastal or landlocked, developing or developed—must be responsible for taking some action on climate change. Those actions will undoubtedly be different from country to country. But virtually all countries have an untapped opportunity to make land use a key part of their plans. In fact, the land sector is the only sector with the potential to switch from being a net source of carbon to a net sink.
The agreement explicitly recognizes the importance of including tropical forests, the agricultural sector and coastal restoration in the climate-solution mix. This recognition is hugely valuable, but still, our lands can do more. Of more than 180 countries that have submitted domestic climate action targets under the agreement, 100 have mentioned different natural climate solutions. However, few have set specific targets.
The full potential for climate mitigation from the land sector has been unclear, but natural climate solutions now offers that comprehensive approach.
In a recently-published study, 25 scientists tackle three questions:
- What is the maximum climate mitigation potential of natural climate solutions?
- What proportion of the maximum is a cost-effective contribution ($100 per tonne of CO2) to meeting the Paris climate targets?
- How much mitigation from natural climate solutions can be delivered at low cost ($10 per tonne)?
Overall, the numbers are big. Deploying natural climate solutions at scale could save up to more than 11 gigatonnes of CO2 carbon dioxide every year equivalent to the combined current emissions of the United States plus the European Union or to humanity’s combined emissions from burning oil globally. This saving would put a huge dent in the current emissions deficit contributing to climate change—it’s equivalent to shutting down more than 2800 coal-fired power plants. All this is alongside the existing carbon sink provided by intact ecosystems, which are already absorbing over 25% of human greenhouse gas emissions, and which we must protect from damage by human activities so that they continue to provide this indispensible service.
1 gigatonne (gt) = 1 billion tonnes = 1 petagram (pg)
A gigatonne of carbon dioxide equivalent (GtCO2eq) is a unit used by the UN climate change panel to measure the effect of a technology or process on global warming.
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The scientists have identified 20 land management strategies involving conservation, restoration, and better land management across global forests, wetlands, grasslands and agricultural lands that have the potential to mitigate over a third of the annual greenhouse gas emissions to 2030, all the while increasing the climate resilience of communities, protecting biodiversity and habitats for plants and animals, and increasing food and water security for the world’s residents.
Better still, land-based solutions are available to us now. It will take time to completely transform our energy, industrial and transportation sectors. Many natural climate solutions are ready to put into practice immediately. These natural pathways can act as a ‘biological bridge’ as we make the transition to a zero-emission economy.
It’s a tall order, but now we have a roadmap in hand. By quantifying and comparing the mitigation potential across these ecosystems, we can paint a comprehensive picture of nature’s full power.
To explore the full potential of natural mitigation, the study outlines natural pathways which include conservation, restoration, and improved management practices across all major ecosystems or biomes. These are forests, wetlands, and grassland biomes that include agricultural lands (rangelands and croplands).
The study builds from the IPCC’s assessment of Agriculture, Forestry and other Land Use (AFOLU). It includes a comprehensive set of pathways across the three major biomes, the latest synthesis of the scientific literature, and new analyses to fill gaps. These include advances for estimates of global reforestation, coastal wetland pathways, cropland management, and forestry pathways. Forest pathways offer about one-half of the lowest-cost ($10 per tonne of CO2) opportunities, while grassland and agriculture pathways account for one-quarter, and wetlands 19%.
Unlike the Earth’s atmosphere, the land benefits from storing more carbon. Carbon enriches the soil and trees provide habitat and clean air and water. Conserving, restoring and rethinking the way we manage our lands and coasts will have multiple payoffs not only for climate, but also for the plants, animals and people that call Earth home. The payoffs of improved land use include:
- Biodiversity. Conserving and restoring natural lands (and employing more sustainable forestry and agriculture management strategies) will protect native habitats for plants, animals and other organisms.
- Food security. Soil conservation and other agricultural improvements can boost productivity, helping to meet the growing demand for food without expanding the footprint of farming.
- Air and water. Terrestrial and coastal ecosystems play an important role in improving air and water quality and protecting water security. For example, restoring wetlands boosts the land’s ability to filter freshwater. Agricultural practices that improve the efficiency of fertilizer help to protect the water supply from agricultural runoff. Reducing fire-driven deforestation helps keep the air clear and breathable. Protecting forests can even help to restore natural rainfall patterns.
- Economic benefits. Often, people think of climate change mitigation and development as being at odds with one another. In reality, well-crafted development policies and programs can create growth and prosperity while also curbing emissions. Worldwide, some 2 billion people depend directly upon the land and coastal systems for sustenance. Improved farming practices improve their livelihoods, and can revitalize rural communities. Sustainable forestry can have similar benefits for individual incomes and communities.
Technology + nature = <2°C
There is no scenario under which we can continue to clear forests and degrade natural lands and still meet our climate mitigation goals, regardless of how quickly we transition to zero-carbon energy. However, if we improve land management, natural climate solutions can contribute significantly to near-term climate mitigation. Given the pace of mitigation required to keep warming below 2°C, natural climate solutions can provide 37% of the additional needed CO2 mitigation between now and 2030 and 20% between now and 2050, whilst maintaining intact ecosystems can ensure that they continue their critical existing role of absorbing 25% of emissions each year. Combined with a rapid transition to zero-carbon energy, this could enable society to meet its climate mitigation goals.
The study’s aim was to quantify the total technical potential of natural climate solutions, but within certain constraints: one, using land to continue to supply food and two, realistic cost scenarios. Scientists predict that climate change will cost society more than $100 per tonne of CO2 emitted if we do nothing. Therefore, spending up to $100 per tonne should be considered cost-effective. This proportion of the potential total is the best measure for understanding the capacity of natural climate solutions to contribute to tackling climate change. By deploying only these most cost-effective natural climate solutions, we would deliver 37% of the commitments under the Paris Agreement by 2030. The cheapest natural climate solutions (at $10 per carbon tonne) are avoided forest conversion, natural forest management, nutrient management, conservation agriculture, avoided peat impacts, avoided coastal impacts and coastal restoration.
Challenges and uncertainty
Of course, nothing is easy about tackling climate change. As with the energy transition required, there are challenges to overcome in implementing natural climate solutions at their full potential. Some areas require more research to refine our estimates of their potential for mitigating climate change. Some pathways are certain to be more cost effective than others. We also have more work to do to design the best methods of implementing natural climate solutions. We must ensure that those methods respect and protect local cultures and communities, while also improving food security for the planet’s growing population.
Yet while we must be cognizant of these challenges, we cannot afford to wait to put these 20 pathways into practice. Our recent study draws on wide-ranging research from the world’s leading scientists, and reveals the substantial role that nature can play in combatting catastrophic climate change. It’s time to move our attention beyond forests and farms to look to all of our terrestrial resources.
With thanks to:
The Nature Conservancy, Woods Hole Research Center, Ohio State University, Cary Institute of Ecosystem Studies, TerraCarbon LLC, Resources for the Future, University of Aberdeen, Cornell University, Ministry of Agriculture, Government of Brazil, Colorado State University, World Resources Institute, Commonwealth Scientific and Industrial Research Organization (CSIRO), University of Minnesota, University of Maryland, University of Florida, Wetlands International, University of Vermont. The study was generously funded by the Doris Duke Charitable Foundation.