What is our assessment?

Based on our analysis, enhanced rock weathering is a promising carbon removal technique, but it is not ready for large-scale deployment. We will “Keep Watching” this potential climate solution.

What is it?

Enhanced rock weathering is a practice that removes CO₂ from the atmosphere by accelerating the natural chemical and physical breakdown, or weathering, of rocks such as basalt, olivine, or limestone. This is typically achieved by crushing the rocks into dust or sand-sized particles to increase their surface area before applying them to croplands, beaches, or directly into the ocean, the latter of which is also a form of carbon removal known as Ocean Alkalinity Enhancement. During weathering, the rock surface chemically reacts with atmospheric CO₂ that is dissolved in rain or ocean water. This reaction produces bicarbonate ions containing the carbon from the captured CO₂ and positively charged cations, such as magnesium or calcium, depending on the type of rock. For land-based enhanced rock weathering, the bicarbonate needs to be flushed out to the ocean, where it is stable and can be securely stored for thousands of years.  

Does it work?

The basic idea of enhanced rock weathering is scientifically and geologically sound. Its effectiveness in converting atmospheric CO₂ into bicarbonate has been demonstrated in laboratory and field trials for several rock types and application sites. There are currently numerous research and demonstration projects underway. More than a dozen companies are selling enhanced rock weathering-based carbon removal credits, with nearly 10,000 t of CO₂ reported to have been removed as of early 2025.

Why are we excited?

Enhanced rock weathering has several features that improve the likelihood that it can be scaled up to remove and store globally meaningful amounts of atmospheric CO₂ (i.e., >0.1 Gt CO₂/yr). Since enhanced rock weathering utilizes a natural process – mineralization – it does not need to be combined with other technologies to capture CO₂ from the air or durably store it. Moreover, it does not require external energy for the carbon capture and storage process, although it does use energy and generate emissions from the mining, crushing, transport, and deployment of the crushed rock. Suitable rock types, such as basalt, which is widely used in construction, paving, and concrete, are common and often locally available. Globally, there are large areas of land and ocean surface on which enhanced rock weathering could be deployed, including on croplands where current agricultural practices often already include regular application of soil amendments. A recent study suggested that extensive deployment of enhanced rock weathering on U.S. agricultural lands could sequester 0.16–0.30 Gt CO₂/yr by 2050. Other studies have shown that the application of crushed rock to croplands for enhanced rock weathering can improve soil pH, provide essential soil nutrients, and improve crop yields.

Why are we concerned?

There are numerous challenges for enhanced rock weathering, as well as potential risks and adverse impacts from its large-scale deployment. Numerous studies on both land- and ocean-based enhanced rock weathering have shown that the amounts of atmospheric CO₂ converted into bicarbonate are highly variable, dependent on rock type, soil type, application rates, and other variables, and are therefore difficult to accurately predict and model. This makes measurement, reporting, and verification of the amount of CO₂ captured and stored, which is essential for the carbon market, reliant on extensive and expensive field measurements and customized models. There are also concerns about the harmful impacts of heavy metals, like nickel or chromium, that can be released during weathering, as well as other ecological impacts and environmental justice concerns, particularly for crushed rock deployed on beaches or in the ocean. Finally, costs for deployment and the purchase of enhanced rock weathering-based carbon credits are relatively high (>US$200–US$500 per t CO₂ removed) and will likely remain high if verification continues to depend on large numbers of field measurements and carbon removal cannot be easily modelled. There is a general consensus in the scientific community that the current knowledge base is not sufficient to reliably or accurately quantify the CO₂ captured and stored by most land- or ocean-based enhanced rock weathering deployments.

What is our assessment?

Based on our analysis, cultivated meat is promising in its ability to reduce emissions from meat production, but the impact on a large scale remains unclear. Based on our assessment, we will “Keep Watching” this potential solution.

What is it?

Cultivated meat (also called lab-grown or cultured meat) is a cellular agriculture product that, when used to replace meat from livestock, can reduce emissions. Cultivated meat is developed through bioengineering. Its production uses sample cells from an animal, in addition to a medium that supports cell growth in a bioreactor. Energy is required to produce the ingredients for the growth medium and to run the bioreactor (e.g., for temperature control, the mixing processes, aeration).

Does it work? 

Since the development of cultivated meat is still in its infancy, there is limited evidence on its emissions savings potential from large-scale production. Preliminary estimates differ by an order of magnitude, depending on the energy source used in the lab environment. Using fossil energy sources, emissions generated from the production of one kilogram of cultivated meat could reach 25 kilograms CO₂‑eq. If renewable energy is used, emissions could be about two kilograms CO₂‑eq per kilogram of cultivated meat. By comparison, producing a kilogram of beef from livestock generates 80–100 kilograms CO₂‑eq, on average. Almost half of those emissions from livestock beef are in the form of methane. Producing pig meat and poultry meat generates about 12 kilograms and 10 kilograms of CO₂‑eq, respectively. Based on these estimates, cultivated meat could substantially reduce the emissions of beef. Compared to pork and chicken, however, its emissions depend on the source of energy used during production.

Why are we excited?

The cultivated meat industry is fairly new but growing rapidly. The first cell-cultivated meat product was developed in 2013. In 2024, there were 155 companies involved in the industry, located across six continents, mostly based in the United States, Israel, the United Kingdom, and Singapore. Agriculture is responsible for about 22% of global GHG emissions, and raising livestock, especially beef, is particularly emissions-intensive. Therefore, cultivated meat has great potential to reduce related emissions as demand for meat continues to grow across the world. Cultivated meat enables the production of a large amount of meat from a single stem cell. This means that far fewer animals will be needed for meat production. Cultivated meat is also more efficient at converting feed into meat than chickens, which reduces emissions associated with feed production and demand for land.

Why are we concerned?

Concerns about cultivated meat include scalability, cost, and consumer acceptance. Because cultivated meat is still an emerging area of food science, the cost of production may be prohibitive at a large scale. Although cell culture is routinely performed in industrial and academic labs, creating the culture medium for mass-market production at competitive prices will require innovations and significant cost reductions. There are still many unknowns about the commercial potential of cultivated meat and whether consumers will accept the products. In 2024, companies began to move from research labs to larger facilities to start producing meat for consumers. There are only two countries that allow the sale of cultivated meat: Singapore and the United States. Within the United States, about one-third of adults find the concept of cultivated meat appealing, and only about 17% would be likely to purchase it, according to a poll conducted on behalf of the Good Food Institute. However, even substituting a fraction of the beef consumed in the United States with cultivated meat could have an important impact on reducing emissions. Cultivated meat is a novel food and may require consumer education and producer transparency on production methods and safeguards in order to become more widely accepted.

What is our assessment?

Based on our analysis, green hydrogen holds long-term potential in sectors that are difficult to decarbonize, particularly long-haul aviation and freight trucking. It is technologically feasible, but currently hampered by high costs, severe infrastructure gaps, and limited commercial readiness. While it is unlikely to be deployed at scale this decade, we will “Keep Watching” green hydrogen as innovation and policy evolve

What is it?

Green hydrogen is a clean, emissions-free liquid fuel produced through electrolysis powered by renewable energy that can replace fossil fuels in some transportation sectors. Unlike hydrogen from fossil fuels (gray or blue hydrogen), green hydrogen generates no CO₂ emissions during production. For transportation, green hydrogen can be used in two main ways: (1) in fuel cell electric vehicles (FCEVs) to generate electricity onboard and power electric motors, or (2) combusted in specially designed hydrogen combustion engines or turbines. For aviation, liquid hydrogen may fuel aircraft engines directly, be used to produce synthetic jet fuels, or power fuel cell airplanes. For long-haul trucking, hydrogen can replace diesel by powering fuel cell trucks, which offer long range and fast refueling.

Does it work?

Green hydrogen is being produced and used in pilot projects and select transportation initiatives globally. Hydrogen combustion engines and fuel cells are currently in use and have been shown to reduce emissions compared to fossil fuels. For aviation, aircraft manufacturers, such as Airbus, have hydrogen-powered planes in development, with test flights expected by 2030, but it could be several decades before they are put into commercial use. In heavy-duty trucking, several major automakers, including Toyota and Hyundai, have already commercialized hydrogen trucks in limited markets, such as China and Japan.

Why are we excited?

Green hydrogen is one of the few near-zero-emission fuels with the potential to decarbonize aviation and long-haul trucking, where battery-electric solutions currently face range and weight constraints. If produced using abundant, low-cost renewables, green hydrogen could significantly cut emissions in sectors responsible for nearly 15% of global transport emissions. In aviation, hydrogen-based fuels like e-kerosene could save around five million tons of CO₂ per year in Europe by 2030. In trucking, hydrogen fuel cell vehicles are beginning to roll out but remain a niche market. Looking ahead, hydrogen has strong potential: by 2050, it could meet up to 30% of energy demand in long-haul trucking and significantly reduce aviation emissions, particularly for short- and medium-haul flights, but it will have to compete with advances in battery-electric options. Hydrogen enables fast refueling and long range, making it a strong candidate for freight and intercity applications. Additionally, investment in green hydrogen infrastructure could unlock cross-sectoral benefits, supporting decarbonization of industry, power, and potentially heating. As electrolyzer costs fall and renewable power expands, the economics and emissions profile of green hydrogen are likely to improve.

Why are we concerned?

Despite its promise, green hydrogen for transport faces significant technical, economic, and logistical hurdles. Electrolysis is energy-intensive, and green hydrogen production is still expensive (US$300–600/t CO₂ avoided for trucking and US$500–1500/t CO₂ for aviation), making it much more costly than diesel or jet fuel but comparable to sustainable aviation fuel today. It is also less energy-dense by volume than other fuels, requiring complex transportation and storage (especially for aviation, where cryogenic tanks are needed) and limiting payload capacity. In addition to producing contrails, hydrogen leakage, though not a GHG, can contribute to indirect global warming effects. There are also safety concerns related to flammability and explosiveness, and a complete overhaul of transportation and refueling infrastructure is needed for both aviation and trucking. Green hydrogen requires entirely new infrastructure for production, storage, and distribution, including refueling stations for trucks and specialized handling systems for liquid or compressed hydrogen at each airport the airplane uses. The absence of this infrastructure creates a major barrier to adoption in aviation and long-haul trucking, where fuel logistics, safety standards, and scale are critical for commercial viability. Hydrogen remains a niche fuel due to its low energy density per volume, the need for cryogenic storage in aviation, limited refueling infrastructure, and high cost. While technically viable, major deployment for aviation and trucking is still nascent. Without a clear business case or strong policy incentives, uptake will remain limited in the near term.

What is our assessment?

Based on our analysis, sustainable aviation fuel (SAF) is a promising climate mitigation solution for reducing emissions in the aviation sector, particularly for long-haul flights where few alternatives exist. However, it is not yet cost-effective and faces significant challenges to scaling production due to severe feedstock restraints, land use pressure, and the need to meet robust sustainability standards. Based on our assessment, we will “Keep Watching” this potential solution.

What is it?

Sustainable aviation fuel (SAF) is a low-carbon alternative to conventional jet fuel that reduces life-cycle greenhouse gas emissions from fuel production by using only non-petroleum feedstocks such as waste oils, agricultural residues, and municipal solid waste. It is usually produced using renewable electricity and captured CO₂. SAF is produced through chemical processes that convert these feedstocks into fuels that meet the same technical standards as fossil-based jet fuel, allowing them to be blended and used in existing aircraft engines and fueling infrastructure without modification. All SAFs approved by ASTM International, the body that sets fuel standards for aviation, are certified only for use in blends. No SAF is yet certified for 100% use in commercial aircraft (also known as “neat SAF”) for passenger flights.

Does it work?

The basic idea of sustainable aviation fuel is technologically sound and supported by decades of research into low-carbon fuel alternatives for aviation. Multiple SAF production pathways – such as hydroprocessed esters and fatty acids (HEFA), Fischer-Tropsch synthesis (FT), and alcohol-to-jet (ATJ) – have been approved by international aviation standards bodies, and several have been demonstrated at commercial scale. Real-world use of SAF is already underway: over 450,000 commercial flights have flown using SAF blends as of early 2025. SAF is currently being supplied at major airports in Europe, the United States, and Asia, with dozens of airlines integrating SAF into operations or entering offtake agreements. While current production remains limited (less than 0.5% of global jet fuel supply), government mandates, tax credits, and airline demand are driving the need for rapid scale-up. SAF is considered one of the most evidence-backed and immediately deployable climate solutions for reducing aviation emissions.

Why are we excited?

Sustainable aviation fuel offers several compelling advantages that make it a potential pathway for reducing aviation emissions. By reducing emissions 60-70% per ton compared to jet fuel, SAF could potentially avoid 0.1–0.2 Gt CO₂/yr by 2050. It can also reduce contrails. SAF can be used in existing aircraft and fueling systems without requiring new infrastructure or major redesigns. This makes it one of the few ready-to-deploy solutions for long-haul and international flights, which are difficult to electrify or replace. SAF production from waste oils and residues can also deliver benefits such as reduced methane emissions from organic waste streams and improved waste management. SAF offers a potentially scalable, technically feasible route to emissions reductions in a sector with few alternatives. Growing policy support, rising carbon prices, and airline demand are accelerating development. 

Why are we concerned?

Despite its promise, sustainable aviation fuel faces significant limitations, risks, and challenges that could constrain its impact and scalability. First, supply is a critical constraint. Due to limited feedstock availability, SAF is highly unlikely to be able to meet the ambitious 2050 goals set by ICAO, ReFuelEU Aviation, and other industry organizations, associations, and governmental institutions. This means that SAF must be combined with other strategies, like demand reduction and new aircraft technologies, to achieve full decarbonization. There are also major ecological and social risks, including competition for land and feedstocks that could displace food production or degrade ecosystems, as well as unequal access to the benefits of SAF deployment. Scaling synthetic SAF (e-fuels) requires vast amounts of clean electricity, water, and CO₂ – raising concerns about resource use and trade-offs with other sectors. Another major concern is cost. Current SAF prices are substantially higher than fossil jet fuel, ranging from US$300 to over US$1,500 per t CO₂ avoided, depending on the pathway. Without strong policy support, this cost premium poses a barrier to widespread adoption. Additionally, life-cycle emissions reductions vary widely depending on the feedstock and production pathway. While some SAFs (e.g., e-fuels using renewable electricity) can achieve near-zero emissions, others, especially those using food crops or poorly regulated waste streams, may deliver modest or uncertain climate benefits. Measurement, reporting, and verification of actual emissions reductions can be complex, especially when land-use change, indirect emissions, or supply chain impacts are involved. SAF combustion still contributes to climate impacts from contrails (albeit reduced compared to jet fuel), nitrogen oxides, and soot.

What is our assessment?

Based on our analysis, the widespread use of bioplastics is challenged by their potential ecological risks and currently high costs. While bioplastics offer some environmental benefits in niche applications, their climate impact is inconsistent and hinges on feedstock type, manufacturing practices, and waste management. Therefore, we conclude that Deploy Bioplastics is a solution to “Keep Watching.”

What is it?

Bioplastics (also called biopolymers) are plastic alternatives made from renewable biological sources, such as corn, sugarcane, crop residues, or other plants, instead of fossil fuels. Bioplastics are produced by extracting sugars or starches from plants and converting them through chemical or biological processes into chemical building blocks that form the basic structure of plastics. Because plants absorb atmospheric CO₂ through photosynthesis, the carbon stored in bioplastics is considered biogenic, as it is already part of the natural carbon cycle. In contrast, petrochemical plastics are made by extracting and refining oil or natural gas, which releases new (formerly buried) carbon into the atmosphere. Bioplastics cut emissions by replacing fossil carbon feedstocks with biomass-based feedstocks. Some bioplastics are durable, non-biodegradable, chemically identical to traditional plastics (i.e., “drop-in” bioplastics), and recyclable. Others are biodegradable and can be designed to break down in compost. Emissions from bioplastics come from growing and processing biomass (which requires energy and land use), manufacturing the plastics, and managing their end-of-life waste. Bioplastics can achieve climate benefits when the emissions from production and end-of-life are kept low enough to realize the advantages of biogenic carbon.

Does it work?

The basic idea of bioplastics is scientifically and chemically sound, with their development and commercialization ongoing since the 1990s. Numerous studies support the effectiveness of bioplastics in reducing atmospheric CO₂ emissions from feedstock production and manufacturing stages compared to fossil-based plastics, particularly when made from sustainably sourced biomass under energy-efficient conditions and properly composted or recycled. However, other studies show bioplastics have inconsistent emissions reduction performance. Global adoption also remains limited, representing only about 0.5% of total plastics production (approximately 2–2.5 million tons (Mt) out of 414 Mt, according to the organization European Bioplastics). 

Why are we excited?

Bioplastics, particularly biologically derived and biodegradable polymers, have functional advantages in reducing fossil fuel dependence and mitigating plastic pollution. By sourcing raw materials from renewable biomass instead of petroleum (e.g., oil, natural gas), bioplastics can lower CO₂ emissions in the production stage, especially when accounting for biogenic carbon uptake during plant cultivation. Some types of bioplastics are interchangeable with traditional plastics and can be produced with existing plastic manufacturing systems, easing the transition. Compostable plastics simplify disposal in applications where contamination with food or organic waste occurs, enabling organic recycling and returning carbon and other nutrients to soil. Biodegradable bioplastics are also advantageous for products that are often discarded and may leak into the environment. Studies show that two widely used commercial bioplastics, polylactic acid (PLA) and polyhydroxybutyrate (PHB), biodegrade 60–80% in composting conditions within 28–30 days, while cellulose-based and starch-based plastics can fully degrade in soil and marine environments in 180 days and 50 days, respectively. These functional benefits, combined with potential additional benefits, such as soil enrichment and waste stream simplification, make bioplastics appealing in specific, targeted use cases. More broadly, they can significantly contribute to emissions reduction efforts in materials production when designed for circularity and supported by infrastructure that facilitates appropriate end-of-life waste treatment. 

Why are we concerned?

Despite their promise, bioplastics have several limitations as a viable climate solution, including relatively low emissions reduction potential and possible risks and adverse impacts from their large-scale deployment. Current production is low. To reach a meaningful 20–30% marketplace share by 2040, bioplastics would need to expand manufacturing by approximately 30% per year, nearly double the current pace. This could put pressure on land and food systems, since current bioplastics rely on food-based crops for industrial-level production. This raises sustainability concerns around food security and could potentially drive unintended land-use changes such as deforestation or cropland conversion. Furthermore, the effectiveness of reducing emissions by replacing conventional plastics with bioplastics is low and inconsistent. Some bioplastics produce more life cycle emissions than conventional plastics. The likely climate impact of replacing 20–30% of traditional plastics with bioplastics is <0.1 Gt CO₂‑eq/yr. End-of-life treatment is also a major challenge. Many bioplastics are incompatible with home composting and current recycling streams, and improperly composted or landfilled biodegradable bioplastics can emit methane. Finally, bioplastics remain 2–3 times more expensive than conventional plastics.

What is our assessment?

Based on our analysis, SMRs are a plausible and potentially impactful climate solution, but they are not yet ready for widespread deployment. The core technology is credible and carries significant potential for reducing GHG emissions. However, readiness, cost certainty, and deployment evidence are still lacking. For now, we will “Keep Watching” SMRs.

What is it?

Small modular nuclear reactors (SMRs) are advanced reactors that produce low-carbon electricity by harnessing the heat from nuclear fission, an established and well-understood physical process. The innovation of SMRs lies primarily in their design. Typically smaller than traditional reactors, with a capacity of less than 300 megawatts (MW), SMRs are factory-built for enhanced quality control. This design allows them to be delivered to installation sites more quickly and potentially at a lower cost compared to conventional reactors, which typically range in capacity from about 700 MW to over 1,600 MW. While SMRs are generally considered "utility-scale" in their capacity, their smaller size makes them a viable option for smaller-scale applications, such as large micro-grids. These reactors can be assembled in a modular fashion, allowing incremental capacity additions. Additionally, some SMR designs boast enhanced safety features, including passive cooling systems that can function without external power sources, reducing the risks associated with reactor overheating or meltdowns. Currently, several countries are planning the deployment of SMRs, particularly China and the United States. Given their modular nature, several African countries, such as Ghana, are also looking toward SMRs to address their energy access deficits. Based on current plans, the International Energy Agency expects several countries to have multiple SMRs installed and operational by around 2030.

Does it work?

The physics behind SMRs is sound, and their potential as low-carbon energy sources is also scientifically valid, as they do not emit GHG emissions during operation. Several pilot SMR projects have also been launched. SMRs have yet to move beyond the demonstration phase to widespread commercial adoption. No SMR is currently deployed at the scale necessary to reduce global emissions measurably. Furthermore, independent, peer-reviewed empirical data on long-term operational performance, scalability, and cost remain sparse. While several countries, including the United States, Hungary, China, and Ghana, have announced plans or are discussing deploying SMRs within the next decade, those plans are still in the preparatory stages.

Why are we excited?

SMRs have several features that make them appealing as a potential climate solution. If scaled appropriately, they could displace fossil-fuel-based power generation and reduce carbon emissions significantly. Projected deployment scenarios by the Nuclear Energy Agency suggest that by 2050, the global SMR market could reach 375 gigawatts of installed capacity, avoiding up to 15 Gt of cumulative CO₂ emissions. Their smaller size and modular nature reduce financial risk, making them potentially more accessible to developing countries or smaller utilities. They are also flexible in siting and can complement variable renewable energy sources like solar and wind by providing reliable baseload or backup power. Additionally, SMRs could help decarbonize hard-to-electrify sectors like process heat in industry or remote energy systems. These attributes have prompted excitement among proponents who see SMRs as a scalable, flexible, and resilient solution for emissions-free power. 

Why are we concerned?

Despite their promise, SMRs face several challenges that limit their readiness for large-scale deployment. Safety remains a concern – not necessarily because of design flaws, but because any nuclear reactor carries inherent risks. Waste disposal and the potential for proliferation of nuclear materials remain persistent issues. Regulatory hurdles are also significant, as existing frameworks are often geared toward conventional reactors and may slow the licensing of newer designs. The cost of SMRs is another outstanding question. Recent analyses by Wood Mackenzie suggest that SMRs could cost US$6,000 to US$8,000 per kilowatt of capacity, which is well above the costs of utility-scale solar (US$1,448) or onshore wind (US$2,098). Deployment timelines also pose a challenge. Given the urgency of climate action, technologies that cannot be deployed at scale within the next 10–15 years may offer limited near-term benefits. A recent study by the Institute for Energy Economics and Financial Analysis opines that SMRs are still too costly, too time-consuming to construct, and too risky to significantly impact the transition away from fossil fuels in the next decade. While peer-reviewed academic studies have been conducted, a comprehensive, independent evaluation of large-scale deployment remains absent.

What is our assessment?

Based on our analysis, nuclear fusion is a promising alternative form of electricity generation, but it is still at a theoretical stage and will not be ready for large-scale deployment within the next 10–15 years, when it could have the most impact on meeting global climate targets. We will “Keep Watching” this potential climate solution.

What is it?

Nuclear fusion is the process by which two individual elements are fused together into a single larger element using high pressure and temperature; this reaction releases large amounts of energy. This is the same reaction that happens in stars such as the Sun. The energy from the fusion reaction can then be harnessed to produce electricity without emitting any GHG emissions. Nuclear fusion power plants are best suited for centralized, large-scale generation (between 500 MW and 1.2 GW of electricity output).

Does it work?

Nuclear fusion experiments have been carried out that prove the scientific principle is sound. However, only in recent years have experiments succeeded in producing more energy than was needed to initiate and sustain the fusion reaction. There have been no nuclear fusion power plants built to date, and it is unlikely that nuclear fusion–powered electricity generation will be ready for deployment before 2050.

Why are we excited?

Nuclear fusion energy offers several advantages as a solution to climate change, including high power density, the ability to deliver “firm” power (i.e., power that can be relied upon to meet demand when needed), and no greenhouse gas emissions. In addition, the most commonly used fuel for nuclear fusion – hydrogen – is readily accessible, there is no risk of a nuclear meltdown, and the process produces relatively little nuclear waste, meaning the risk of nuclear proliferation is almost nonexistent. Some research suggests that nuclear fusion could provide up to 15% of total electricity production either by replacing existing centralized power plants (e.g., oil and gas, coal, nuclear fission) that have reached end-of-life or to satisfy growing demand for electricity as access and electrification increase.

Why are we concerned?

Nuclear fusion is not considered remotely close to being ready to deploy as a climate solution. It faces many technical challenges, including uncertainties related to fusion reactor design and optimal fuel types. The costs for nuclear fusion–produced electricity are highly uncertain and are expected to grow compared to existing estimates. Current estimates for nuclear fusion energy costs exceed US$150/MWh, nearly double the 2020 price per MWh for other energy sources. There are also large uncertainties about the policy environment for nuclear fusion plants, which could hinder both development and deployment. Currently, projections suggest that nuclear fusion reactors could be introduced between 2050 and 2060. This means that even under optimistic conditions, nuclear fusion is unlikely to make a significant contribution to meeting 2050 emissions reduction targets.