The Deploy Grass-Finished Beef solution involves raising cattle entirely on pasture for their full lives, as opposed to grain-finished beef, where cattle spend the final four to six months in feedlots prior to slaughter. Grass-finished beef has higher GHG emissions than grain-finished due to slower growth and forage diets, which increase enteric methane emissions per unit of beef and requires substantially more land for what is already the most resource-intensive food option available. Interest in grass-finished systems reflects efforts to reduce feed crop use, gain modest nutritional improvements, and reduce antimicrobial use. However, maintaining the current beef supply with grass-finished systems would require more cattle, far more land, and result in higher GHG emissions. Therefore, Deploy Grass-Finished Beef is “Not Recommended” as an effective climate solution.
Based on our analysis, grass-finished beef production has higher emissions of enteric methane and emissions from land use conversion than does conventional beef production, and would increase risks of biodiversity loss if scaled to meet current demand. Therefore, it is "Not Recommended" as a climate solution.
| Plausible | Could it work? | No |
|---|---|---|
| Ready | Is it ready? | Yes |
| Evidence | Are there data to evaluate it? | Yes |
| Effective | Does it consistently work? | No |
| Impact | Is it big enough to matter? | No |
| Risk | Is it risky or harmful? | ? |
| Cost | Is it cheap? | Yes |
Grass-finished beef production involves raising cattle exclusively on available pasture for their entire lives, eliminating the need for feed crops and associated resources. All cattle begin life on pasture; however, in conventional beef production, the animals spend their final four to six months in high-density feedlots, often called concentrated animal feeding operations (CAFOs). In these systems, cattle are fed high-calorie, mostly grain-based-energy feeds to gain weight quickly.The animals put on one-third to one-half of their total weight during this time, to reach slaughter weight by ~18 months. In contrast, grass-finished beef production requires ~24 to 28 months for animals to reach market weight on forage alone.
Cattle raised entirely on grazing with no other feed inputs provide only about 1% of global protein. Using broader definitions of grass-finished that allow supplementary forage increases the global beef that would qualify to roughly one-third of global production (about 2–3% of global protein). Grass-fed cattle often receive supplementary feed in pasture-based systems in places such as Brazil, Ireland, and Australia, particularly during seasonal feed shortages.
Deploying grass-finished beef is not an effective climate mitigation strategy. Grass-finished cattle eat a more fibrous diet that produces higher methane emissions per unit of energy intake, and they take longer to reach market weight, resulting in higher lifetime methane emissions per animal. One widely cited study found that forage-fed cattle produce around four times more methane per unit of digestible energy intake than those fed corn- and grain-based diets. In addition, slower weight gain and longer production time require more grazing land, which would likely increase emissions from deforestation and other land use change. Life-cycle assessments consistently show higher emissions per kilogram for grass-finished beef than for grain-finished beef. Even the most efficient grass-finished systems produce 10–25% more emissions per kilogram of protein than grain-finished U.S. beef, and three to over 40 times more than a wide range of plant and animal protein alternatives.
Interest in grass-finished beef reflects a broader effort to reduce the environmental harms of industrial livestock systems and improve land stewardship. In limited local contexts, if grass-finished and feedlot grain–finished cattle could gain weight equally, this could alleviate the need for crops destined for feedlot. A recent estimate found that, globally, 34% of crops grown on recently converted natural ecosystems went to animal feed instead of feeding people directly. While grass-finished beef has a higher total water use, it can reduce water risk by shifting from irrigated feed crops for cattle feedlots to rain-fed pastures.
From a human health standpoint, grass-finished beef may contain slightly higher omega-3 fatty acids and vitamin E, but the differences are small and unlikely to meaningfully affect health outcomes. It is often slightly leaner, which can reduce total fat and saturated fat somewhat, but beef in general remains higher in fat than most food options, which increases the risk of heart disease. Within the broader category of red meat, it is still a Group 2A probable carcinogen, according to the World Health Organization.
Another human health consideration is that grass finishing requires less antimicrobial use. Antibiotics and other antimicrobials are often used in large quantities in confined livestock systems, and cattle account for over half of antimicrobial use among cattle, chickens, and pigs. This use increased by 43% between 2010 and 2020, raising concerns about accelerating antimicrobial resistance and reducing the effectiveness of infection treatments in humans. This may be the strongest case for grass-finished beef, particularly within a global demand reduction scenario.
From an animal welfare perspective, pasture-based systems allow natural behaviors such as walking, socializing, and grazing freely. However, animals are still slaughtered at a young age (before 3 years old) relative to their natural lifespan of 20 years.
Beef production is already the largest single land use globally and the most emissions-intensive food option. Shifting to grass-finished systems would further increase this footprint. Beef is inherently protein-inefficient, requiring large amounts of feed and land. While grass-finished systems were historically the norm, the rise of grain-finishing feedlots after the 1950s modestly improved efficiency by shortening cattle lifespans and reducing per-kilogram land use. Land is a key limiting factor in any expansion of grass-finished production. In the United States, pastureland could support only approximately 27% of current beef production under grass-finished systems. Maintaining current output would require roughly 30% more cattle and 270% more land and would result in a 43% increase in associated methane emissions.
Such land expansion would pose serious biodiversity loss risks. Animal-sourced foods are the leading driver of biodiversity and habitat loss globally. Ruminant meat is disproportionately responsible, causing extinction risks ~340 times higher than grains by mass and ~100 times higher than legumes both by mass and when adjusted for protein, according to a 2025 study.
Last, many government and commercial “grass-fed” certifications are not well enforced and often include cropland-grown forage, which still results in slower weight gain, more methane emissions, and often land carbon leakage. As a result, there are concerns about greenwashing as major fast-food chains market grass-fed beef as environmentally friendly.
While there will likely continue to be an appeal to consumers to choose grass-finished beef, it does not meaningfully change the environmental reality of producing it.
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This solution involves industrially farming insects, such as crickets, mealworms, and black soldier fly larvae, to produce protein for human consumption, livestock feed, or pet food that is less resource- and emissions-intensive than meat or other high-emission foods. Insect farming as a climate solution is technically feasible, but there are limited real-world studies, and the emissions vary widely depending on location, heat and energy source, and processing. Currently, half of farmed insects end up in the pet food market, and only a few percent of total production goes to direct human consumption. In practice, it mostly replaces already low-impact plant ingredients, not high-emission animal products. Moreover, any potential climate benefits from insect farming can typically be achieved far more effectively and safely through simple shifts toward plant-rich diets. Aside from a lack of evidence of consumer acceptance, there are significant risks that invasive species could escape into local ecosystems, especially if farmed at scale. We conclude that farming insects is “Not Recommended” as an effective climate solution.
Based on our analysis, evidence suggests that insect farming offers minimal opportunities for emission reductions and more often replaces lower-emitting foods, while also facing high costs, low consumer acceptance, and several significant risks even at small industrial scales. For these reasons, insect farming is “Not Recommended” as a climate solution.
| Plausible | Could it work? | Yes |
|---|---|---|
| Ready | Is it ready? | Yes |
| Evidence | Are there data to evaluate it? | Limited |
| Effective | Does it consistently work? | No |
| Impact | Is it big enough to matter? | No |
| Risk | Is it risky or harmful? | Yes |
| Cost | Is it cheap? | No |
This potential climate solution involves industrially farming insects, such as crickets, mealworms, and black soldier fly larvae, in controlled facilities to produce protein with lower resource use and lower climate impact for human consumption, livestock feed, or pet food. Currently, two billion people worldwide have a practice of eating insects for food, but industrial insect farming is a relatively new effort, even though one trillion insects are estimated to be farmed each year, with roughly 79–84 billion insects alive on farms at any given time globally. Most farmed insects are processed into powders, flours, and oils for snack foods, pet food, or animal feed. This solution does not include industrial insect farming for the production of honey, shellac, silk, or the use of insect waste as fertilizer.
Insects convert feed efficiently, grow quickly, can eat food waste, and require far less land than livestock, especially cattle, creating possible pathways for low-resource protein. However, recent analyses show highly variable and often high life cycle emissions, 4.2–25.8 kg CO₂‑eq per kg of protein for insects as human food, with the upper end of this range approaching the lower bound for beef. The emissions intensity of insect-based livestock feeds varies from 2.8–11 kg CO₂‑eq per kg dry matter and is higher than for soybean meal (1.06–2.26 kg CO₂‑eq per kg dry matter). Insect proteins for pet food are 2–10 times more emissions-intensive than conventional pet foods that often use meat-industry by-products. Industrial farms in colder, fossil-fuel-dependent regions show especially high footprints, with one United Kingdom industrial life cycle assessment (LCA) reporting emissions nearly 10 times those of a medium-sized farm in Thailand.
Insect farming has advantages over some widely produced foods, especially beef and pork, most notably that it requires far less land and feed. On average, insects require about 2 kg of feed to produce 1 kg of body mass, which is approximately 3–5 times more efficient than cattle and comparable to chickens. Many edible insects are also high in protein and provide micronutrients like iron, zinc, and B vitamins. There is active research focused on reducing energy needs, breeding native species, and exploring the use of mixed human food waste as feed to better position insects as a potential climate solution.
Overall, insect farming today has limited climate benefits, poor substitution of high-impact foods, significant local ecosystem risks, low consumer uptake, and high costs.
Most LCAs for insect farming are based on small-scale operations rather than industrial scales. Furthermore, common assumptions in insect farming research do not align with current industry practices, including overstated use of food waste as feed and reliance on outdated climate and price projections. While insect farming could plausibly displace some high-impact foods in the future, there is no current pathway for insects to replace pig and cattle products, a prerequisite for meaningful GHG emission reductions. Substituting insects for already low-impact foods such as flour or cereal ingredients, as is currently common, increases emissions. In addition, available insect products have limited sensory or textural similarities to meat compared with plant-based alternatives. Despite more than US$1 billion invested in scaling the sector, consumer acceptance remains low, with only 5% of production going to direct human consumption and 50% to the pet food market.
Industrial insect farming also carries serious risks. Research indicates that escapes of non-native species disrupting local ecosystems are inevitable and will intensify as operations scale, potentially affecting other food production systems. Crowded, warm rearing environments can also act as disease-spreading vectors, even if insect farming’s direct zoonotic risk to humans is likely lower than that of intensive meat production. Over 80% of small insect farms supplying pet food have been found to contain parasites, with roughly a third carrying species capable of infecting humans or animals. Contamination risks persist when using mixed human food waste as insect feed due to potential pathogens and chemical residues, which regulatory frameworks are still working to assess.
Lastly, costs are a major barrier. The most comprehensive economic model to date finds that insects are unlikely to become a viable part of industrial animal feed in the near future. Insects are also not expected to reach price parity with meat before plant-based or even single-cell/fermentation-derived proteins. Claims of future cost competitiveness rely on assumptions of near-total utilization of food waste.
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Biteau, C., Bry‐Chevalier, T., Crummett, D., Loewy, K., Ryba, R., & St. Jules, M. (2025b). Have the environmental benefits of insect farming been overstated? A critical review. Biological Reviews. Link to source: https://doi.org/10.1111/brv.70076
Biteau, C., Bry-Chevalier, T., Crummett, D., Ryba, R., & St. Jules, M. (2024). Is turning food waste into insect feed an uphill climb? A review of persistent challenges. Sustainable Production and Consumption, 49, 492-501. Link to source: https://doi.org/10.1016/j.spc.2024.06.031
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Replacing fossil-fuel-powered irrigation pumps with electric pumps powered by the grid can reduce emissions in most regions of the world. Electric irrigation pumps, which can also be powered by on-site clean energy, are more efficient than fossil fuel pumps. They are already cost-competitive and widely used, and adoption is increasing. Their emissions benefits will continue to grow as irrigation expands and the emissions intensity of the electrical grid falls. However, based on current grid emissions intensity, the climate impact of using electric pumps for agricultural irrigation is not globally meaningful (<0.1 Gt CO₂‑eq/yr ). Despite its modest climate impact, our assessment finds that deploying electric irrigation pumps is “Worthwhile.”
Based on our analysis, deploying electric irrigation pumps will reduce emissions but will not provide a globally significant climate impact (>0.1 Gt CO₂‑eq/yr ), even under high adoption scenarios, until electrical grid emissions decline further. Therefore, this potential climate solution is “Worthwhile.”
| Plausible | Could it work? | Yes |
|---|---|---|
| Ready | Is it ready? | Yes |
| Evidence | Are there data to evaluate it? | Yes |
| Effective | Does it consistently work? | Yes |
| Impact | Is it big enough to matter? | No |
| Risk | Is it risky or harmful? | No |
| Cost | Is it cheap? | Yes |
This solution reduces emissions from irrigation by replacing pumps powered by natural gas, diesel, propane, or gasoline with electric pumps. Irrigation is the practice of adding water to croplands or pastures to reduce crop water stress and increase productivity. Pumps are used on some irrigated croplands to extract groundwater, transport surface water, and pressurize water for application through sprinklers or drip irrigation systems. Electric pumps have much higher motor efficiencies (~88%) than fossil fuel pumps (~21–31%), so pump switching reduces the energy required to pump the same amount of water. The extent to which emissions are reduced depends on the emissions intensity of the electrical grid mix. Electric pumps reduce emissions when the emissions intensity of the grid is below ~0.75 kg CO₂‑eq /kWh, or when they are powered by on-site solar or wind energy. In some places, additional emissions reductions can be achieved through Improving Irrigation Water Use Efficiency.
The efficiency and emissions benefits of electric pumps over fossil fuel pumps are well established. On-farm pumping emissions, currently estimated at approximately 0.2 Gt CO₂‑eq/yr, could feasibly be eliminated if all fossil fuel pumps are replaced with electric pumps and electrical grid emissions reach net-zero, or if they are powered by on-farm solar or wind energy. However, the climate impact of electric pump adoption today would be much lower, as electricity generation still produces substantial emissions. Under current conditions, replacing a diesel pump with an electric pump will reduce emissions in most, but not all, places around the world.
Electric pumps can reliably reduce emissions, are already cost-competitive and widely used, and adoption is increasing. Irrigation is a major energy user, and its energy use is increasing as irrigated areas expand. These trends are expected to continue in the coming decades as climate change exacerbates heat and water stress and agricultural production intensifies in low- and middle-income countries. Coupled with ongoing reductions in electrical grid emissions intensity, the potential climate benefits of this solution are growing.
Electric pump adoption can also be geographically targeted, as just five countries (China, India, the United States, Pakistan, and Iran) account for almost 70% of irrigation energy use. Areas with high groundwater reliance can also be targeted, as groundwater pumping accounts for 89% of irrigation energy use.
Pump switching also provides additional benefits, such as lowering long-term energy costs for farmers and reducing air pollution from on-farm fossil fuel use. Access to the electrical grid is the primary technical barrier to electric pump adoption, but small-scale solar installations can be used where grid connectivity is limited. Powering pumps with on-site solar also eliminates operational emissions, reduces the load on the electrical grid, and insulates farmers from variability in energy costs.
The climate impacts of pump switching are highly dependent on the emissions factor of the electrical grid. A large share of the potential reduction in fossil fuel pumping is located in India and China, which currently have relatively high electrical grid emissions intensities. Under the current grid mix, we estimate that pump switching in these countries will result in only modest benefits or a small increase in emissions.
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Rollason, E., Sinha, P., & Bracken, L. J. (2022). Interbasin water transfer in a changing world: A new conceptual model. Progress in Physical Geography: Earth and Environment, 46(3), 371–397. Link to source: https://doi.org/10.1177/03091333211065004
Rosa, L., Chiarelli, D. D., Sangiorgio, M., Beltran-Peña, A. A., Rulli, M. C., D’Odorico, P., & Fung, I. (2020). Potential for sustainable irrigation expansion in a 3 °C warmer climate. Proceedings of the National Academy of Sciences, 117(47), 29526–29534. Link to source: https://doi.org/10.1073/pnas.2017796117
Rosa, L., Rulli, M. C., Ali, S., Chiarelli, D. D., Dell’Angelo, J., Mueller, N. D., Scheidel, A., Siciliano, G., & D’Odorico, P. (2021). Energy implications of the 21st century agrarian transition. Nature Communications, 12(1), Article 2319. Link to source: https://doi.org/10.1038/s41467-021-22581-7
Sanders, K. T., & Webber, M. E. (2012). Evaluating the energy consumed for water use in the United States. Environmental Research Letters, 7(3), Article 034034. Link to source: https://doi.org/10.1088/1748-9326/7/3/034034
Schmitt, R. J. P., Rosa, L., & Daily, G. C. (2022). Global expansion of sustainable irrigation limited by water storage. Proceedings of the National Academy of Sciences, 119(47), Article e2214291119. Link to source: https://doi.org/10.1073/pnas.2214291119
Siddik, M. A. B., Dickson, K. E., Rising, J., Ruddell, B. L., & Marston, L. T. (2023). Interbasin water transfers in the United States and Canada. Scientific Data, 10(1), Article 1. Link to source: https://doi.org/10.1038/s41597-023-01935-4
Sowby, R. B., & Dicataldo, E. (2022). The energy footprint of U.S. irrigation: A first estimate from open data. Energy Nexus, 6, Article 100066. Link to source: https://doi.org/10.1016/j.nexus.2022.100066
Yang, Y., Jin, Z., Mueller, N. D., Driscoll, A. W., Hernandez, R. R., Grodsky, S. M., Sloat, L. L., Chester, M. V., Zhu, Y.-G., & Lobell, D. B. (2023). Sustainable irrigation and climate feedbacks. Nature Food, 4(8), Article 8. Link to source: https://doi.org/10.1038/s43016-023-00821-x
Avery Driscoll, Ph.D.
Christina Swanson, Ph.D.
Heather McDiarmid, Ph.D.
James Gerber, Ph.D.
Advanced geothermal energy is an emerging clean energy technology that harnesses the Earth’s subsurface heat to generate emissions-free baseload and dispatchable electricity and heat. Unlike traditional geothermal systems that tap naturally occurring hot water or steam reservoirs, advanced geothermal systems (AGS) use a range of technologies, including directional drilling and hydraulic fracturing, to access or create artificial geothermal reservoirs through which they circulate water or other fluids. Accessible geothermal resources suitable for AGS occur across the globe and, if technology improvements continue, advanced geothermal systems could supply around 15% of the world’s electricity by 2050. However, to progress from pilot stage to commercialization, the industry needs more demonstration projects to address high upfront costs, technical challenges, and environmental and safety concerns, and to generate greater policy support to facilitate deployment. Based on our assessment, advanced geothermal energy is a potentially high-impact climate solution that we will “Keep Watching.”
Advanced geothermal systems (AGS) are emerging as one of the most promising technologies for reliable, utility-scale, zero-carbon energy that can complement wind and solar, strengthening grid resilience, and providing heat for district heating and industrial uses. The technology, which is built on an existing base of technical and industrial expertise and capacity, is advancing rapidly through major R&D efforts, pilot projects and, just recently, small scale commercial operations. While large-scale deployment is still in its early stages and challenges remain around cost, execution, and social acceptance, we expect meaningful progress by the 2030s. For now, we will “Keep Watching” this solution.
| Plausible | Could it work? | Yes |
|---|---|---|
| Ready | Is it ready? | No |
| Evidence | Are there data to evaluate it? | Limited |
| Effective | Does it consistently work? | Yes |
| Impact | Is it big enough to matter? | Yes |
| Risk | Is it risky or harmful? | No |
| Cost | Is it cheap? | No |
Advanced geothermal systems (AGS) are a suite of renewable energy technologies that extract heat from deep within the Earth’s crust to generate electricity, provide high-temperature heat for industrial processes or district heating, and enable geothermal energy storage by storing heat underground. Unlike traditional geothermal systems that tap naturally occurring hot water or steam reservoirs, such as geysers or volcanic areas, AGS access geothermal heat by drilling into the earth, injecting and circulating water (or other fluids) through hot, dry rock formations underground, and then recovering the heated fluid or steam to generate electricity before reinjecting it back underground. Circulation of the water between the surface and the geothermal reservoir can be a in closed loop system, where the water or other fluid is contained within pipes throughout the heat exchange circulation cycle, or in an open loop, enhanced geothermal system (EGS) where the subsurface rocks are hydraulically fractured, or “fracked,” to increase permeability and allow water to flow between an injection well and a production well.
Electricity and heat production by an advanced geothermal power plant emits virtually no greenhouse gases. Analysis by the National Renewable Energy Laboratory showed that the median life cycle emissions from enhanced geothermal power plants were 32 g CO₂‑eq/kWh, just 6% of the median life cycle emissions from a natural gas power plant, with most of the emissions generated during construction rather than operation. Geothermal energy has been used for more than a century, but AGS that use the directional and horizontal drilling and hydraulic fracturing techniques developed by the oil and gas industry to access previously inaccessible underground heat resources are relatively new. To date, several small-scale and experimental AGS projects have successfully produced electricity, and in December 2025, the first commercial plant for electricity and heat production delivered electricity to the grid in Germany.
Advanced geothermal energy systems are a potentially transformative climate solution for several reasons. First, they could massively expand clean energy availability. AGS can be deployed in almost any region with hot subsurface rocks. Experts estimate the Earth’s accessible geothermal resources are staggeringly large, and that tapping just 0.1% of the heat under our feet could meet global energy needs for millennia. If technology improvements continue, advanced geothermal could supply around 15% of the world’s electricity by 2050. Second, unlike solar and wind energy, advanced geothermal power plants produce steady baseload power, dispatchable power, and even energy storage. Currently, coal and gas power plants are commonly used to provide stability and backup power to electricity grids around the world. AGS can provide the same energy benefits, complementing wind and solar energy by providing firm capacity and grid stability services to a renewable-heavy electricity grid, without the harmful climate impacts. Third, AGS plants have a relatively small land footprint and can potentially be sited near demand centers (including repurposing old fossil plant sites), improving energy security for regions with limited solar or wind resources.
Recent technological breakthroughs have improved the prospects for AGS. The application of directional drilling and hydraulic fracturing techniques has produced higher fluid flow rates and extended reservoir life. This has dramatically increased the heat extraction per well, overcoming previous limitations and boosting the energy output and economics of AGS. Industry reports show drilling rates in hot rock have increased by 300–500% in the last few years, slashing upfront costs. A recent U.S. Department of Energy report projects that the cost of next-generation geothermal projects, including AGS, will fall below that of other baseload power sources such as nuclear and natural gas with carbon capture and storage (CCS) by 2035. Other projections suggest that geothermal electricity could drop to around US$50/MWh by the 2030s, competitive with other renewables and nuclear. Finally, AGS leverage a skilled workforce and supply chain from the oil and gas sector. The necessary drilling rigs, subsurface imaging, and engineering expertise already exist, which could help scale up AGS faster than entirely new industries.
Despite its promise, AGS face several challenges that temper its near-term prospects. To bridge the gap from pilot stage to commercialization, the industry needs more demonstration projects, case studies of success, and greater public trust. This is challenging because advanced geothermal projects today have high upfront capital costs, primarily due to deep drilling and, for EGS, hydraulic stimulation expenses, as well as high operational costs. Current AGS electricity is also far more expensive than conventional renewables, often hundreds of dollars per MWh. Until these costs decline, the industry may struggle to attract the investment financing needed to scale up. Moreover, the geological uncertainty in any given project is high because limited geophysical data in many regions makes it hard to pinpoint the best spots to drill. Developers must invest in exploration with no guarantee of finding an adequate resource, so early projects carry a significant risk of cost overruns.
Safety and environmental concerns also pose challenges. In some types of geologies, enhanced geothermal systems, which use hydraulic fracturing to create the heat exchange reservoirs and circulate fluid underground, can trigger small earthquakes. Some EGS have been halted after local earthquakes caused alarm and minor damage. Because they use water and circulate hot brines, AGS could pose risks for groundwater contamination or water consumption in arid regions, although geothermal system designs that use closed-loop systems or non-potable water can avoid these problems. Finally, geothermal projects often face regulatory and logistical hurdles and lengthy permitting processes. In many countries, regulatory regimes and incentives have focused on solar, wind, and even nuclear, while geothermal energy (and especially AGS) has received comparatively little support. This means AGS developers may struggle with financing and grid access due to policy gaps or obstacles.
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Akindipe, D. F., Smith, M., Witter, E., et al. (2026). 2025 U.S. Geothermal Market Report. (Technical Report No. NLR/TP-5700-91898). National Laboratory of the Rockies. https://docs.nrel.gov/docs/fy26osti/91898.pdf
Blankenship, D., Gertler, C., Kamaludeen, M., O’Connor, M., & Porse, S. (2024). Pathways to Commercial Liftoff: Next-Generation Geothermal Power. U.S. Department of Energy. Link to source: https://cdn.catf.us/wp-content/uploads/2025/06/09154348/doe-liftoff-nextgen-geothermal.pdf
Boretti, A. (2025). Enhanced geothermal systems: Potential, challenges, and a realistic path to integration in a sustainable energy future. Next Energy, 8, Article 100332. Link to source: https://doi.org/10.1016/J.NXENER.2025.100332
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Kah, M. & Kleinberg, R. (2025, April 7). The potential contribution of enhanced geothermal systems to future power supply: Roundtable summary. Center on Global Energy Policy at Columbia Columbia University SIPA. Link to source: https://www.energypolicy.columbia.edu/publications/the-potential-contribution-of-enhanced-geothermal-systems-to-future-power-supply-roundtable-summary/
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Green roofs sequester carbon through photosynthesis and may reduce energy consumption and emissions from cooling and heating the building thanks to the added insulation and the cooling effects of plants. Carbon sequestration by vegetation on green roofs has been documented, and many reports show energy savings from cooling and heating buildings. The effectiveness varies significantly across projects due to building and roof design, plant types, and climates. Green roofs are an attractive solution because they also provide climate adaptation, human health, environmental, and economic benefits. However, their adoption is hampered by high up-front costs, lack of supportive policies, structural and climate limitations, maintenance requirements, and lack of awareness. With the limited data available today we estimate the total impact to be relatively small, but given the significant additional benefits we conclude that this solution is “Worthwhile.”
There is strong evidence that green roofs sequester carbon and may reduce building energy consumption, although emissions reduction data are limited and vary with geography, roof design, and other factors. The potential climate impact of increasing green roofs is likely too small to be globally significant (>0.1 Gt CO₂‑eq/yr ). The solution, however, is considered “Worthwhile” because it can reduce energy use in buildings and sequester carbon while helping communities adapt to climate change and benefiting human health, the environment, and building owners.
| Plausible | Could it work? | Yes |
|---|---|---|
| Ready | Is it ready? | Yes |
| Evidence | Are there data to evaluate it? | Limited |
| Effective | Does it consistently work? | Yes |
| Impact | Is it big enough to matter? | No |
| Risk | Is it risky or harmful? | No |
| Cost | Is it cheap? | Yes |
Vegetation planted on specially engineered rooftops sequesters CO₂ through photosynthesis and provides indirect cooling for buildings through evapotranspiration, reflecting heat back to the atmosphere, and shading. This cooling plus the added insulation inherent in the design can reduce the air conditioning loads of the building, particularly compared to dark rooftop surfaces, and therefore reduce emissions from the electricity used to power cooling systems. Green roofs can also reduce heating energy use and corresponding GHG emissions due to the insulation that soils and plant matter provide. Green roofs are in use in all regions of the globe, but concentrated in high-income countries.
There is strong evidence that green roofs sequester carbon and can reduce the energy consumption and therefore emissions from cooling and heating buildings. Carbon sequestration by vegetation on green roofs has been documented in several studies. A study in Germany found that plants absorbed 141 g carbon/m2/yr (517 g CO₂ /m2/yr) over a 5-year period. However, carbon sequestration rates are difficult to generalize due to variations in design, plant types, and climates.
Reported building energy savings from green roofs can range from negligible to 60% or more for cooling. For heating the savings can reach 45% or more, but some studies also show a roughly 10% increase in heating energy use with a green roof. The large variability in energy savings outcomes is due to differences in climate; existing insulation and other properties of buildings; green roof design, vegetation and maintenance practices; and measurement and modeling approaches. The highest energy savings potential has been calculated in dry-winter subtropical highlands for cooling and in humid subtropical climates for heating. Areas with short and mild winters are most likely to see heating energy use increase with green roofs, but these areas often have net energy savings when heating and cooling are combined, and most studies of green roofs show a reduction in heating energy use.
When combined with the carbon sequestration effect of vegetation, green roofs appear to consistently reduce GHG emissions.
Green roofs and other urban green spaces (see Increase Urban Vegetation) provide valuable climate adaptation, human health, environmental, and economic benefits. Green roofs can help cities adapt to climate change because the vegetation reduces heat exposure during extreme heat, while the soil and root systems absorb stormwater – thereby reducing runoff and flooding risks during extreme rainfall. Green roofs improve human health because vegetation filters the air and reduces noise transmission, and interactions with green spaces, including green roofs, have been shown to improve mental well-being. Green roofs can increase biodiversity and habitat and remove water pollution. They also can increase the property value of a building and prolong the longevity of the roof.
Increasing green roofs can be challenging due to high up-front cost, lack of supportive policies, structural and climate limitations, maintenance requirements, and lack of awareness. A green roof can cost three to six times more than a conventional roof, and although it can save energy for cooling and heating, the returns on investment can be lengthy and savings may not be enough to fully offset the higher costs. In addition, not all roofs can support vegetation, rooftop plants can struggle to survive in hot and dry climates, and green roofs may increase heating energy use in buildings in climates with short and mild winters. A green roof also requires maintenance such as watering, plant care, weed control, pruning, and regular inspections. Finally, a lack of awareness is a major barrier to greater adoption. We also noted a lack of measured, rather than modeled emissions reduction data and on current and potential green roof adoption globally.
Addo-Bankas, O., Wei, T., Zhao, Y., Bai, X., Núñez, A. E., & Stefanakis, A. (2024). Revisiting the concept, urban practices, current advances, and future prospects of green infrastructure. Science of The Total Environment, 954, 176473. Link to source: https://doi.org/10.1016/j.scitotenv.2024.176473
Getter, K. L., Rowe, D. B., Robertson, G. P., Cregg, B. M., & Andresen, J. A. (2009). Carbon Sequestration Potential of Extensive Green Roofs. Environmental Science & Technology, 43(19), 7564–7570. Link to source: https://doi.org/10.1021/es901539x
Green roof guide. (n.d.). Green roof maintenance tips. Green Roof Guide. Link to source: https://greenroofguide.com/green-roof-maintenance-tips/
He, Q., Tapia, F., & Reith, A. (2023). Quantifying the influence of nature-based solutions on building cooling and heating energy demand: A climate specific review. Renewable and Sustainable Energy Reviews, 186, 113660. Link to source: https://doi.org/10.1016/j.rser.2023.113660
Knight, T., Price, S., Bowler, D., Hookway, A., King, S., Konno, K., & Richter, R. L. (2021). How effective is ‘greening’ of urban areas in reducing human exposure to ground-level ozone concentrations, UV exposure and the ‘urban heat island effect’? An updated systematic review. Environmental Evidence, 10(1), 12. Link to source: https://doi.org/10.1186/s13750-021-00226-y
Konopka, J., Heusinger, J., & Weber, S. (2021). Extensive Urban Green Roof Shows Consistent Annual Net Uptake of Carbon as Documented by 5 Years of Eddy‐Covariance Flux Measurements. Journal of Geophysical Research: Biogeosciences, 126(2), e2020JG005879. Link to source: https://doi.org/10.1029/2020JG005879
Mihalakakou, G., Souliotis, M., Papadaki, M., Menounou, P., Dimopoulos, P., Kolokotsa, D., Paravantis, J. A., Tsangrassoulis, A., Panaras, G., Giannakopoulos, E., & Papaefthimiou, S. (2023). Green roofs as a nature-based solution for improving urban sustainability: Progress and perspectives. Renewable and Sustainable Energy Reviews, 180, 113306. Link to source: https://doi.org/10.1016/j.rser.2023.113306
Perivoliotis, D., Arvanitis, I., Tzavali, A., Papakostas, V., Kappou, S., Andreakos, G., Fotiadi, A., Paravantis, J. A., Souliotis, M., & Mihalakakou, G. (2023). Sustainable Urban Environment through Green Roofs: A Literature Review with Case Studies. Sustainability, 15(22), 15976. Link to source: https://doi.org/10.3390/su152215976
Shafique, M., Xue, X., & Luo, X. (2020). An overview of carbon sequestration of green roofs in urban areas. Urban Forestry & Urban Greening, 47, 126515. Link to source: https://doi.org/10.1016/j.ufug.2019.126515
Susca, T. (2019). Green roofs to reduce building energy use? A review on key structural factors of green roofs and their effects on urban climate. Building and Environment, 162, 106273. Link to source: https://doi.org/10.1016/j.buildenv.2019.106273
Tan, T., Kong, F., Yin, H., Cook, L. M., Middel, A., & Yang, S. (2023). Carbon dioxide reduction from green roofs: A comprehensive review of processes, factors, and quantitative methods. Renewable and Sustainable Energy Reviews, 182, 113412. Link to source: https://doi.org/10.1016/j.rser.2023.113412
Tiago, P., Leal, A. I., & Silva, C. M. (2024). Assessing Ecological Gains: A Review of How Arthropods, Bats and Birds Benefit from Green Roofs and Walls. Environments, 11(4), 76. Link to source: https://doi.org/10.3390/environments11040076
US Environmental Protection Agency. (2025, April 2). Using green roofs to reduce heat islands. US Environmental Protection Agency. Link to source: https://www.epa.gov/heatislands/using-green-roofs-reduce-heat-islands
Zhang, G., & He, B.-J. (2021). Towards green roof implementation: Drivers, motivations, barriers and recommendations. Urban Forestry & Urban Greening, 58, 126992. Link to source: https://doi.org/10.1016/j.ufug.2021.126992
Zhuo, Z., Ran, K., & Dong, L. (2025). Assessing the Effects of Exposure to Green Rooftop Spaces on Perceived Restorativeness: A Field Study in Xiamen, China. Buildings, 15(9), 1427. Link to source: https://doi.org/10.3390/buildings15091427
Heather McDiarmid, Ph.D.
Amanda D. Smith, Ph.D.
Christina Swanson, Ph.D.
Improve Steel Production involves replacing the use of fossil fuels in making steel from iron ore with electrolytic hydrogen and clean electricity. Doing so could reduce emissions from steel production by more than 90%. Although the necessary technologies exist, adoption has been very limited, with the major barriers being the cost of clean electricity and the availability of suitable iron ore. Other strategies for reducing the emissions from steel production typically rely on bioenergy sources or carbon capture and storage (CCS), which have limited potential to reduce emissions. As demand for steel grows globally, new policies are needed to increase market demand for low-emissions steel. Given the lack of improved steel facilities and supportive policies today, we will “Keep Watching” this solution.
Based on our analysis, Improve Steel Production using H2-DRI-EAF powered by clean electricity has the potential to significantly reduce emissions. However, while the individual technologies for H2-DRI-EAF are mature and their combined use has been piloted, the process has not yet been adopted in a meaningful way. We will “Keep Watching” this solution, but it is not ready for widespread adoption.
| Plausible | Could it work? | Yes |
|---|---|---|
| Ready | Is it ready? | No |
| Evidence | Are there data to evaluate it? | Yes |
| Effective | Does it consistently work? | Yes |
| Impact | Is it big enough to matter? | Yes |
| Risk | Is it risky or harmful? | No |
| Cost | Is it cheap? | No |
Currently, making steel from iron ore relies heavily on coal and other fossil fuels to provide heat and reducing agents (chemicals that remove oxygen from iron ore). Improve Steel Production refers to using electric heat and hydrogen produced by electrolysis to reduce the iron ore (H2-DRI) and electric arc furnaces (EAF) to melt the resulting iron and alloy it with carbon to make steel. The solution also requires the electricity used in these processes to include significant renewable energy or other low-carbon generation. The output is varying grades of steel with different degrees of hardness and brittleness determined by slight variations in carbon content. This solution does not include processes that rely on bioenergy or CCS, since the emissions from burning bioenergy contribute to climate change and CCS is not an effective climate solution.
Replacing fossil fuels in steelmaking with H2-DRI-EAF that uses electrolytic hydrogen and where all electricity comes from relatively clean sources results in significantly reduced emissions. Steel made today using fossil fuels for heat and as a reducing agent results in an estimated 1.8 t CO₂‑eq /t of steel. By contrast, steel made using H2-DRI-EAF and low-carbon electricity would generate an estimated 0.12 t CO₂‑eq /t of steel and is a more energy-efficient process. EAF furnaces are already very common in steelmaking and for recycling existing steel, but are rarely combined with H2-DRI. Although H2-DRI was first used on an industrial scale in 2001, that plant was shut down for economic and political reasons, and economics remain a barrier. Finally, technologies to make industrial hydrogen from electricity are mature, but most hydrogen produced today is made from fossil fuels and is carbon-intensive. Active research is exploring other technologies that could become important for improving steel production in the future, most notably aqueous or molten oxide electrolysis, both of which use electricity to directly remove oxygen from iron ore, and can be combined with EAF to make steel.
Steelmaking is classified as a hard-to-abate industry, and H2-DRI-EAF powered by clean electricity is considered one of the best strategies for cutting emissions in this sector. The Net Zero Industry project forecasts that under an emissions-neutral steel scenario by 2050, roughly 40% of global steel production could depend on H2-DRI-EAF, with the remainder consisting of recycled steel (47%), steelmaking with CCS (11%), or technologies not yet defined (2%). The impact is potentially significant, given that steelmaking accounted for an estimated 3.7 Gt of CO₂‑eq in 2019. Improved steelmaking has the additional benefit of reducing air and land pollution, as burning coal releases fine particulate matter, heavy metals, and other pollutants. In China, steel production is the largest industrial source of air pollution. As demand for steel is expected to increase up to 30% by 2050 due to demand from India and other low- and middle-income countries, it is critical that new and existing production shift to cleaner, lower-emission technologies, and that policies supporting this shift be implemented.
While proposed low-emission steel projects have attracted significant attention from the press, many have since been canceled or put on hold. As of 2025, we could find references to only a few pilot facilities producing improved steel as we have defined it here. The entire H2-DRI-EAF process is considered to be at the large-scale prototype demonstration stage. However, contributing technologies such as electrolytic hydrogen production and EAF are more mature, and H2-DRI was first used on an industrial scale in 2001. The higher cost of making low-emission steel is a significant barrier to industrial adoption and consumer demand. Electricity accounts for nearly half the cost of producing low-emission steel from iron ore. To increase adoption, improved steel facilities need to be located in areas that can readily supply both iron ore and abundant low-carbon, low-cost electricity. In areas such as China, where the electricity grid still relies heavily on fossil fuels, transitioning to H2-DRI-EAF risks increasing emissions unless dedicated renewables are integrated into the project. To move this solution forward, new policies are needed to create an international market for low-emission steel. Meanwhile, existing steelmaking facilities typically have lifetimes of 25–40 years, which increases the likelihood of stranded assets or continued reliance on fossil fuels by 2050. Under its Sustainable Development Scenario, the International Energy Agency (IEA) projects that, by 2050, only 12% of cumulative direct emissions reductions in steelmaking will be due to electrification and the use of hydrogen (the IEA considered emissions from electricity to be indirect). Reducing demand for steel, incremental efficiency gains, and CCS are expected to make up the bulk of cumulative direct emissions reductions, according to the IEA projections.
Bataille, C., Stiebert, S., Li, F. (2021). Global facility level net-zero steel pathways. Net Zero Steel. Link to source: https://netzeroindustry.org/wp-content/uploads/pdf/net_zero_steel_report.pdf
Devlin, A., Kossen, J., Goldie-Jones, H., & Yang, A. (2023). Global green hydrogen-based steel opportunities surrounding high quality renewable energy and iron ore deposits. Nature Communications, 14(1), 2578. Link to source: https://doi.org/10.1038/s41467-023-38123-2
Hubner Australia. (n.d.). Green steel manufacturing: Processes and comparisons. Hubner Australia. Link to source: https://hubner.au/green-steel-manufacturing/
IEA. (2020). Iron and steel technology roadmap. Link to source: https://iea.blob.core.windows.net/assets/eb0c8ec1-3665-4959-97d0-187ceca189a8/Iron_and_Steel_Technology_Roadmap.pdf
Kueppers, M., Hall, W., Levi, P., Simon, R., & Vass, T. (2023, July 11). Steel. IEA. Link to source: https://www.iea.org/energy-system/industry/steel
Lang, S., Kopf, M., & Valery, R. (2021, November 18). Cicored fine ore direct reduction—A proven process to decarbonize steelmaking. Metso. Link to source: https://www.metso.com/insights/blog/mining-and-metals/circored-fine-ore-direct-reduction-a-proven-process-to-decarbonize-steelmaking/
Leadit. (2025, May). Green steel tracker. Leadit Leadership Group for Industry Transition. Link to source: https://www.industrytransition.org/green-steel-tracker/
McKinsey & Company. (2024). Green-steel hubs: A pathway to decarbonize the steel industry. McKinsey & Company. Link to source: https://www.mckinsey.com/industries/metals-and-mining/our-insights/green-steel-hubs-a-pathway-to-decarbonize-the-steel-industry#/
Milne, R. (2025, October 13). Flagship green steel start-up in funding crisis as Europe’s low-carbon ambitions falter. Financial Times. Link to source: https://www.ft.com/content/ac619c2d-9c7a-4208-baa5-6c648d10cacc
Net Zero Industry. (n.d.). Net zero steel pathways. Net Zero Industry. Link to source: https://netzeroindustry.org/net-zero-parhways /
Russell, C. (2025, May 29). Green steel is distant and expensive, but teal steel is coming. Reuters. Link to source: https://www.reuters.com/markets/commodities/green-steel-is-distant-expensive-teal-steel-is-coming-russell-2025-05-29/
Ryan, N. A., Miller, S. A., Skerlos, S. J., & Cooper, D. R. (2020). Reducing CO2 emissions from U.S. steel consumption by 70% by 2050. Environmental Science & Technology, 54(22). Link to source: https://doi.org/10.1021/acs.est.0c04321
Wrede, I. (2025, July 19). ArcelorMittal’s pullout plunges German green steel in doubt. DW. Link to source: https://www.dw.com/en/arcelormittals-pullout-plunges-german-green-steel-in-doubt/a-73303680
Zhang, J., Shen, H., Chen, Y., Meng, J., Li, J., He, J., Guo, P., Dai, R., Zhang, Y., Xu, R., Wang, J., Zheng, S., Lei, T., Shen, G., Wang, C., Ye, J., Zhu, L., Sun, H. Z., Fu, T.-M., … Tao, S. (2023). Iron and Steel Industry Emissions: A Global Analysis of Trends and Drivers. Environmental Science & Technology, 57(43), 16477–16488. Link to source: https://doi.org/10.1021/acs.est.3c05474
Improving district heating for industry involves using low-carbon alternatives, such as electric boilers, heat pumps, and waste heat from other industries, to provide heat to industries for their operations. Currently, most district heating for industry relies heavily on fossil fuels to generate heat. Low-carbon alternatives have the potential to make a significant dent in the global emissions from industry, but such projects are also challenging to implement due to their scale and complexity, and there is currently a lack of publicly available data that would allow for a deeper analysis. Based on our assessment, we will “Keep Watching” this potential solution.
Based on our analysis, improving district heating for industry by integrating low-carbon heat sources has the potential to significantly reduce the use of fossil fuels and the emissions they generate. However, the lack of data, combined with the complexity of such projects and the growing interest in alternative decarbonization pathways, makes this a potential solution to “Keep Watching.”
| Plausible | Could it work? | Yes |
|---|---|---|
| Ready | Is it ready? | Yes |
| Evidence | Are there data to evaluate it? | No |
| Effective | Does it consistently work? | Yes |
| Impact | Is it big enough to matter? | Yes |
| Risk | Is it risky or harmful? | No |
| Cost | Is it cheap? | No |
District heating systems consist of a network of underground pipes that distribute heat to a large number of buildings, including industrial buildings. In the industrial sector, district heating is used by light industries and for processes such as drying, paper making, food processing, as well as space heating and even heat-driven chillers for refrigeration. Industry is well-suited to district heating because it typically has steady and predictable heat demand throughout the year. Current district heating systems rely heavily on coal and natural gas for heat generation, often as part of combined heat and power generation. Low-carbon alternatives for district heating can include electric heat pumps, solar thermal, deep geothermal, and even waste heat from other industries.
Shifting district heating for industry from conventional heat sources to low-carbon heat sources will significantly reduce emissions. Our analysis for district heating use by commercial and residential buildings shows that significant emissions can be avoided by shifting to electric boilers, heat pumps, and the use of waste heat (see Improve District Heating: Buildings). Similar outcomes are likely possible for industrial district heating use, and emissions reductions will increase as more renewables are integrated into the electricity systems used to power electric boilers and heat pumps.
District heating for industry currently produces significant emissions. According to the International Energy Agency (IEA), district heating for all applications accounted for 4% of global emissions in 2022, and roughly 40% of the heat energy from district heating was delivered to industry. China is a major adopter of district heating for industries, with the combustion of coal supplying much of that heat. The shift to renewable heat sources is likely to increase because both China and the EU have policies targeting the adoption of renewables in district heating. Because district heating systems serve multiple buildings, a single project to replace fossil fuels with renewables can have a large impact. Such projects also have the benefit of reducing local air pollution.
Although simple on paper, replacing fossil fuel systems with lower-carbon alternatives in district heating systems can be an extended undertaking involving many stakeholders and years of planning. Some low-carbon options may not be suitable for industrial processes that require higher temperatures than those needed for space heating. There is also a significant lack of publicly available data about how industry currently uses district heating and the opportunities and challenges involved in shifting to renewables. In the meantime, industrial heat pumps with higher temperature outputs (100–200°C) are increasingly available and could become a low-carbon competitor to the use of a conventional district heating system.
Bellevrat, E., & West, K. (2018). Clean and efficient heat for industry. IEA. Link to source: https://www.iea.org/commentaries/clean-and-efficient-heat-for-industry
Difs, K., Danestig, M., & Trygg, L. (2009). Increased use of district heating in industrial processes – Impacts on heat load duration. Applied Energy, 86(11), 2327–2334. Link to source: https://doi.org/10.1016/j.apenergy.2009.03.011
European Commission. (2022). Implementing the repower EU action plan: Investment needs, hydrogen accelerator and achieving the bio-methane targets. Link to source: https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:52022SC0230
Gouy, A., Mooney, E., & Voswinkel, F. (2023). Light Industry. IEA. Link to source: https://www.iea.org/energy-system/industry/light-industry
IEA. (2025). District heating. Link to source: https://www.iea.org/energy-system/buildings/district-heating#programmes
IRENA, IEA, & REN21. (2020). Renewable energy policies in a time of transition: Heating and cooling. Link to source: https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2020/Nov/IRENA_IEA_REN21_Policies_Heating_Cooling_2020.pdf
Lake, A., Rezaie, B., & Beyerlein, S. (2017). Review of district heating and cooling systems for a sustainable future. Renewable and Sustainable Energy Reviews, 67, 417–425. Link to source: https://doi.org/10.1016/j.rser.2016.09.061
Werner, S. (2017). International review of district heating and cooling. Energy, 137, 617–631. Link to source: https://doi.org/10.1016/j.energy.2017.04.045
Improving fishing vessel efficiency cuts CO₂ emissions in wild capture fisheries by lowering fuel use through vessel, gear, or operational modifications. Advantages include the long-term cost savings from fuel use reductions, the ability to implement many of these improvements without reducing fishing effort, and the potential additional benefits for air quality and marine ecosystems. Disadvantages include its limited climate impact due to the sector’s overall small contribution to global GHG emissions and the possibly high up-front costs associated with vessel or gear upgrades. We conclude that, despite its modest emissions impact, Improve Fishing Vessel Efficiency is “Worthwhile,” with likely ecosystem and economic benefits.
Based on our analysis, we find that fishing vessel efficiency improvements are ready to deploy and feasible, but probably have limited climate impact because the wild capture fisheries sector contributes a relatively small share of global GHG emissions. These improvements will likely provide long-term cost savings and added benefits for ecosystems and air quality. We conclude this climate solution is “Worthwhile.”
| Plausible | Could it work? | Yes |
|---|---|---|
| Ready | Is it ready? | Yes |
| Evidence | Are there data to evaluate it? | Yes |
| Effective | Does it consistently work? | Yes |
| Impact | Is it big enough to matter? | No |
| Risk | Is it risky or harmful? | No |
| Cost | Is it cheap? | ? |
Improving fishing vessel efficiency reduces CO₂ emissions by using gear, vessel, or operational changes that lower fuel use in wild capture fisheries. Vessel upgrades include propulsion-related changes, such as installation of more efficient engines, and non-propulsion-related alterations, such as modified bows and hulls that reduce drag. Changing to low-fuel-use gear to catch fish, when and where possible, can also reduce CO₂ emissions. Operational changes, such as speed reductions or route optimization, can likewise lead to more efficient fuel use.
Vessel efficiency improvements are expected to deliver substantial fuel savings. An estimated 60–90% of emissions in wild capture fisheries, which emit roughly 0.18 Gt CO₂‑eq/yr in total, likely result from fuel consumption. Speed reductions alone can reduce fuel use by up to 30%. Vessel modifications could provide fuel savings of up to 20% in small fishing vessels, which comprise roughly 86% of all motorized fishing vessels globally. Upgrading engines and other propulsion-related equipment can reduce fuel use by up to 30%. Gear switching, when viable, can also be highly effective at improving fuel use efficiency, particularly if the target species are typically caught using methods such as trawling, which has a high carbon footprint.
The average emissions per metric ton of landed fish in wild capture fisheries have grown by over 20% since 1990, highlighting the need for efficiency improvements. Many of these improvements can be implemented without sacrificing fishing effort or opportunities, and some operational changes, such as reducing vessel speed, can be done without any new equipment. All changes reduce fuel use, saving fishers money over time and likely resulting in fewer emissions of harmful air pollutants, such as sulfur oxides and black carbon. Some upgrades could deliver additional benefits to air quality and ocean ecosystems. Cleaner engines can further reduce air pollution through more complete combustion of fuel, and gear changes could benefit seafloor ecosystems, which can be damaged from bottom fishing practices, such as trawling and dredging. Additionally, some fishing gear has high bycatch rates, and switching to gear that allows for more exclusive capture of target species can reduce waste.
Even with widespread adoption, efficiency improvements that reduce fuel use are unlikely to have a major climate impact. Efficiency improvements could also inadvertently encourage increases in fishing effort, which would increase fuel use and offset emissions cuts. Initial costs to upgrade can be highly variable, but might be high in some cases and therefore not feasible for some fishers. Gear switching can result in lower fish catches, as some methods might not be as efficient. Some operational changes, such as reducing speeds, could lead to fishers arriving at fishing grounds late.
Althaus, F., Williams, A., Schlacher, T. A., Kloser, R. J., Green, M. A., Barker, B. A., ... & Schlacher-Hoenlinger, M. A. (2009). Impacts of bottom trawling on deep-coral ecosystems of seamounts are long-lasting. Marine Ecology Progress Series, 397, 279–294. Link to source: https://doi.org/10.3354/meps08248
Bastardie, F., Hornborg, S., Ziegler, F., Gislason, H., & Eigaard, O. R. (2022). Reducing the fuel use intensity of fisheries: through efficient fishing techniques and recovered fish stocks. Frontiers in Marine Science, 9, 817335. Link to source: https://doi.org/10.3389/fmars.2022.817335
Bastardie, F., Feary, D. A., Kell, L., Brunel, T. P. A., Metz, S., Döring, R., ... & van Hoof, L. J. W. (2022). Climate change and the Common Fisheries Policy: adaptation and building resilience to the effects of climate change on fisheries and reducing emissions of greenhouse gases from fishing. European Commission. Link to source: https://doi.org/10.2926/155626
Gilman, E., Perez Roda, A., Huntington, T., Kennelly, S. J., Suuronen, P., Chaloupka, M., & Medley, P. A. H. (2020). Benchmarking global fisheries discards. Scientific Reports, 10(1), 14017. Link to source: https://doi.org/10.1038/s41598-020-71021-x
Gulbrandsen, O. (2012). Fuel savings for small fishing vessels. Food and Agriculture Organization of the United Nations. Link to source: https://www.fao.org/4/i2461e/i2461e.pdf
Gray, C. A., & Kennelly, S. J. (2018). Bycatches of endangered, threatened and protected species in marine fisheries. Reviews in Fish Biology and Fisheries, 28(3), 521–541. Link to source: https://doi.org/10.1007/s11160-018-9520-7
Food and Agriculture Organization of the United Nations. (2018). The state of world fisheries and aquaculture. Food and Agriculture Organization of the United Nations. Link to source: https://openknowledge.fao.org/handle/20.500.14283/i9540en
Food and Agriculture Organization of the United Nations. (2018). Impacts of climate change on fisheries and aquaculture. United Nations’ Food and Agriculture Organization, 12(4), 628-635. Link to source: https://fao.org/3/i9705en/i9705en.pdf
Food and Agriculture Organization of the United Nations. (2024). The State of World Fisheries and Aquaculture 2024 – Blue Transformation in action. Food and Agriculture Organization of the United Nations. Link to source: https://openknowledge.fao.org/handle/20.500.14283/cd0683en
Hilborn, R., Amoroso, R., Collie, J., Hiddink, J. G., Kaiser, M. J., Mazor, T., ... & Suuronen, P. (2023). Evaluating the sustainability and environmental impacts of trawling compared to other food production systems. ICES Journal of Marine Science, 80(6), 1567–1579. Link to source: https://doi.org/10.1093/icesjms/fsad115
Parker, R. W., Blanchard, J. L., Gardner, C., Green, B. S., Hartmann, K., Tyedmers, P. H., & Watson, R. A. (2018). Fuel use and greenhouse gas emissions of world fisheries. Nature Climate Change, 8(4), 333–337. Link to source: https://doi.org/10.1038/s41558-018-0117-x
United Nations Global Compact and World Wildlife Fund. (2022). Setting science-based targets in the seafood sector: Best practices to date. Link to source: https://unglobalcompact.org/library/6050
United Nations Conference on Trade and Development (UNCTAD). (2024). Energy Transition of Fishing Fleets: Opportunities and Challenges for Developing Countries (UNCTAD/DITC/TED/2023/5). Geneva: UNCTAD. Link to source: https://unctad.org/system/files/official-document/ditcted2023d5_en.pdf
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