Frequently Asked Questions
Some Basics
Who is Pure Leapfrog?
What is carbon offsetting?
In effect, carbon offsetting allows you to support environmental and social projects around the world and take responsibility for your carbon footprint by generating equivalent carbon savings elsewhere.
In practical terms, offsetting one tonne of CO2 (one carbon offset) will result in one tonne of CO2 less in the atmosphere compared to what could have been otherwise generated.
Offsetting is not a solution to climate change. To address this, we must all reduce emissions. However, well designed, managed and monitored offset projects can reduce the impact of our own emissions and help generate awareness of the need for others to do the same.
What do you charge for offsetting?
As part of covering our costs we charge a small handling fee to take account of transactional costs. Handling fee is 30p for transactions up to £10 and 50p for transactions above £10. This means that we also have a minimum offset charge of £1 to be sure these costs are covered alongside your offset purchase.
We track our transactional costs and the fees we charge and any ‘profit’ made on handling fees or minimum charges is passed to the British Airways Carbon Fund on a regular basis.
How do I access help and support
You can also email us at BACarbonZero@pureleapfrog.org
Carbon Offsetting
What types of carbon credit projects are there?
1. Renewable Energy – Including hydro, wind, and photovoltaic solar power, solar hot water and biomass power and heat production.
2. Energy Efficiency – these projects are fundamentally about using LESS energy (e.g. LED lighting or installing more efficient cooking stoves).
3. Forestry – Forestry projects can involve either afforestation (the establishment of a new forest or reforestation (rebuilding existing forests.) REDD+ (a UN standard) projects stand for Reducing Emissions from Reforestation and Forest Degradation.
4. Transport – These projects may involve switching transportation to less carbon intensive means or introducing new technologies to improve vehicle fuel efficiency.
5. Agriculture – By changing agricultural process techniques to methods which are more environmentally friendly, significant reductions in carbon emission can be achieved.
6. Water, sanitation and hygiene (WASH) – Projects which improve access to water, water treatment, improved sanitation and hygiene which contribute to climate change mitigation/adaptation can provide offsets.
7. Methane Capture – There are two types of methane projects. The first type captures and burns (flares) methane, convering it to less potent carbon dioxide and water. Alternatively, projects can capture methane and use it to produce hot water or electricity.
8. Waste management and handling – These include projects that reduce the emissions from waste or water management such as composting, biogas etc.
What makes for a high-quality carbon credit?
• Real – The offsets are tangible and measurable
• Additionality – The emissions reduction would not have occurred in the absence of the project.
• Permanence – The project delivers the claimed emissions reductions in a sustained manner over time.
• No Leakage – The emissions reduction achieved with the project does not lead to an increase in emissions elsewhere.
• Retired permanently – Following the sale of the carbon credit, it is permanently removed from the market mechanism, ensuring that the offsets
there is no double counting or double selling.
• Verifiability – A robust audit trail demonstrating the project’s goals and its delivery against those goals.
What is the price of a carbon credit? Why does it change?
The availability of credits will change depending on supply and demand factors as well.
As a charity we don’t profit from providing carbon offsetting as a service to British Airways customers. We have to cover some transaction costs when we buy, sell and retire credits but we minimise these as far as is practicable. Any surplus after we have covered these costs is used to support the British Airways Carbon Fund, supporting community based carbon reduction projects in the UK and Africa.
Can you offset with UK projects?
The reason for this lies in the Kyoto Protocol and the understanding that countries such as the UK that now have the Climate Change Act are mandated to reduce emissions through domestic efforts. As such voluntary carbon credits being generated are not seen as additional. In short, more developed countries can buy credits generated in developing or emerging markets. This could change in the future as the Paris Agreement commits many more countries to reduce emissions and we think in the future UK based offsets could be created.
What are the Sustainable Development Goals? (SDGs)
Why do the SDGs matter in carbon offsetting?
What is the difference between voluntary and mandatory carbon offset schemes?
Voluntary carbon offset markets enable organisations and individuals to offset their emissions by purchasing offsets that were created either through the Clean Development Mechanism (a UN led initiative born out of the Kyoto Protocol) or in the voluntary market. Voluntary credits help to serve micro projects that are too small to warrant the administrative burden or not covered under compliance schemes. Credits generated under these schemes are called Voluntary Emission Reductions (VERs).
Pure Leapfrog helps organisations and individuals to reduce carbon footprints by supporting communities to develop carbon reducing projects through the voluntary market. All the projects Pure Leapfrog supports reduce carbon emissions – both via the Carbon Fund and through carbon offsetting.
Who are ICROA?
ICROA is working with leading academic institutions to understand the drivers of the voluntary market, and to research and demonstrate the additional non-carbon benefits of voluntary offsetting. For example, a recent study by Gold Standard finds that for every carbon credit issued from a clean cook stove project, £219 in economic value is created. For domestic biogas projects, the average value created is £380 per credit.
About Pure Leapfrog
What is Pure Leapfrog's role?
We work with organisations who align with our mission to tackle climate change and address poverty. Our partners support communities to develop carbon reducing projects and obtain the necessary independent verification. The reason for independent verification is so that we can be sure that the reductions have actually taken place. The projects we support must demonstrate that the funding will enable the projects to either happen or scale (“additionality”).
Upon receiving your contributions, we purchase credits in the projects specified. The credits provide funding for the project.
We maintain a ‘registry’ account that ensures the credits we purchase are ‘retired’ from the market and cannot be purchased by anyone else, as is required by the International Carbon Reduction and Offsetting Alliance’s (ICROA) Code of Best Practice.
What is Pure Leapfrog’s relationship with British Airways?
We have been offering carbon offsetting to British Airways’ customers for a number of years and the carbon calculator provides a simple way for BA customers to offset their flight emissions.
How does your relationship with British Airways for offsetting work?
We have developed our approach in consultation with British Airways to ensure the website, process used, projects selected and customer receipts meet their standards.
All offset contributions are handled directly through Pure Leapfrog. British Airways is not involved in processing transactions or aquiring credits and receives no income from the offsetting process.
Why work with British Airways?
Cost & Pricing
What are handling fees?
As part of covering our costs we charge a small administration fee to take account of transactional costs (processing your transaction through banking and accounting systems). The handling fee is 30p for transactions up to £10 and 50p for transactions above £10. We track our transactional costs and the fees we charge and any ‘profit’ made on handling fees passed to the British Airways Carbon Fund on a regular basis.
Why do you charge a minimum fee?
Why might my cost per tonne/mile vary?
– The project you select – projects vary in price
– Handling fees – see FAQ about handling fees
– Emissions factors – see FAQ ‘why is it cheaper to go internationally via somewhere in Europe than direct?’
Why is it cheaper to go internationally via somewhere in Europe than direct?
This is because the emissions factors that are applied may differ. Please note the following:
- For flights between the UK and a European destination, the UK government Department for Business, Energy and Industrial Strategy (BEIS) emissions factors for short haul air travel are applied to calculate emissions. Flights originating in the EU are subject to the EU Emissions Trading Scheme and we have therefore applied a discount to ensure that your emissions are not double-counted. For more information about this please read the FAQ entitled “How do we calculate the EU ETS reductions applicable to your flight?”
- For long haul flights to/from the UK we apply the UK government Department for Business, Energy and Industrial Strategy (BEIS) emissions factors for “long haul to/from the UK”
- For long haul flights to/from other countries, we apply the UK government Department for Business, Energy and Industrial Strategy (BEIS) emissions factors called “long haul to/from non UK”
In relation to long haul flights to/from other countries, BEIS notes: “aviation factors were introduced [in 2015] where aviation factors are now being presented for international flights between non-UK destinations. This is a relatively high-level analysis and allows users to choose a different factor for air travel if flying between countries outside of the UK. The international factors included are an average of short and long-haul flights, which explains the difference between the UK factors and the international ones”.
The BEIS approach reflects the need for balance between accuracy and complexity in modelling emissions factors.
How much do the carbon credits cost?
Each project has a different price depending on technology, location, carbon standard etc.
Our Carbon Calculator
Why can't I do this when I book my flight?
How does the carbon calculator work?
Why do other calculators come up with different tonnes to be offset?
Do I offset for my child?
When I choose to offset with a mix of offset projects, how do you decide which projects?
What are carbon emissions factors?
How often is the data in the calculator updated?
• Changes to flight destinations
• New emissions factor data issued by government (BEIS generally releases new emissions factor data on an annual basis in July/August).
• Other changes to emissions regimes
Our Offsetting Projects
How do you select offset projects?
We work with EcoAct and Ecosphere+ in partnership with British Airways to select projects with the highest sustainability standards and strong social, as well as environmental outcomes.
We are a not-for-profit charity so we keep all our costs to a minimum when sourcing and providing offset credits.
How do you know the projects you select are high-quality?
The above certifications are also in line with the ICROA Code of Best Practice list of quality credible standards.
How often do you purchase credits?
Do you develop offset projects?
At this time, we do not develop offset projects. Instead, we select high-quality existing projects. Our partner, EcoAct and Ecosphere+, is a carbon offset project developer and also works with other project developers.
Who are EcoAct? What are their qualifications for offsetting?
EcoAct is a co-founder of the International Carbon Reduction and Offset Alliance (see below)
In accordance with ICROA’s Code of Best Practice, all EcoAct’s carbon offsets are certified by credible third parties and certification standards and are retired within 12 months of purchase. They correspond to real, measurable, permanent, additional, independently verified and unique emissions reductions. EcoAct carry out extra screening (above and beyond certification standards) on the carbon offset projects offered to ensure that the projects customers support are robust and really deliver CO2 savings.
What monitoring and reporting do you do on projects?
When I choose to offset with a mix of offset projects, how do you decide which projects?
Who are Ecosphere+? What are their qualifications for offsetting?
Ecosphere+ is a mission-driven business that helps companies create and implement nature-based solutions that enable them to succeed in a world aligned with global climate and development goals.
Ecosphere+ sell high-quality forest carbon credits, verified to two of the most widely used and well-respected standards. Whilst going even further with their industry-leading ESG and by translating tonnes of carbon into different measurable impacts that are relevant to our customers, such as number people directly supported, number trees saved, impact on women.
Flying and Carbon Emissions
How does flying create emissions?
These total emissions are divided among passengers, taking into account the fact that passengers in business and first class have larger seat room (and therefore more weight) and increased luggage allowances.
The factors that determine the amount of emissions are:
• Arrival and departure point – this determines distance and fuel consumption
• Number of passengers
• Travel class
• Carbon emissions factors
What is CORSIA?
CORSIA, the Carbon Offsetting and Reduction Scheme for International Aviation, is the climate regulation agreed by the international UN body the International Civil Aviation Organisation. The regulation addresses the increase in total CO2 emissions from international aviation above 2020 levels so that all growth after 2020 will be carbon neutral.
CORSIA’s obligations have already started. As of 1 January 2019, all carriers are required to report their CO2 emissions on an annual basis. Airlines will be required to offset the growth in emissions from 2021 onwards, so after this date we will adjust the offset calculation to take account of these emission reductions.
What about radiative forcing?
How does the EU ETS work?
How do we calculate the EU ETS reductions applicable to your flight?
Some Basics
What is British Airways doing to address climate change?
Who is Pure Leapfrog?
Pure Leapfrog is a charity working on accelerating decarbonisation in the UK and improving resilience of local communities.
We use our expertise in carbon markets, sustainable finance and energy systems to provide innovative solutions that address both climate change and social inequalities.
We have been providing offsetting services to individuals and businesses since our inception in 2005.
What is sustainable aviation fuel (SAF)?
Sustainable aviation fuel (SAF) is an alternative to fossil-based conventional jet fuel that has significantly lower life-cycle carbon emissions. SAF is designed to meet the same strict quality standards as conventional jet fuel so that it can simply be mixed into existing aircraft and fuel infrastructure. SAF is made from renewable sustainable sources such as used cooking oil or household waste that would have gone to landfill. When the lifecycle emissions of SAF are calculated, they result in around 80-95% less CO<sub>2</sub> emissions compared to conventional jet fuel.
What is carbon offsetting?
Offsetting one tonne of CO<sub>2</sub> will result in one tonne of CO2 less in the atmosphere. Carbon offsetting enables individuals and businesses to balance their carbon emissions by paying for equivalent carbon savings made by specially designed projects around the world. Some examples of projects are renewable energy, low emissions cook stoves and energy efficiency projects in developing countries, that reduce the amount of CO2 emissions in the environment.
Offsetting is an important element on the journey to net zero emissions, providing finance to accelerate carbon savings that would not have happened without it.
What do you charge for offsetting?
As a charity, Pure Leapfrog operates on a not-for-profit basis.
The offsetting price per tonne you pay on BA Carbon Neutral includes a 10% fee which covers the following Pure Leapfrog’s costs:
- Offsetting project research
- Administration costs, including carbon registry fees, where applicable
- Third-party payment platform costs used by BA Carbon Neutral customers
- Advancing the evolving best practice in Voluntary Carbon Markets though participation in industry bodies
- A contribution towards our work on a socially-just transition to net zero.
Your payment, after the deduction of the Pure Leapfrog fee, is used to purchase the offsetting options available on BA Carbon Neutral.
In the interest of transparency, we confirm that no other mark up, by Pure Leapfrog or British Airways, is included in the offsetting price per tonne on BA Carbon Neutral.
How do I access help and support
Sustainable Aviation Fuel
Why is SAF more sustainable than fossil-based conventional jet fuel?
SAF has been shown to provide significant reductions in overall CO2 lifecycle emissions compared to fossil fuels, and for waste-derived fuels these can be more than 90%. Furthermore, SAF contains fewer impurities (such as sulphur), so it has lower air quality impacts than conventional jet fuel. Most of the SAF in production at the moment are based on waste oils and fats. British Airways is working on new supply chains using municipal waste that it hopes will be commercially available within the next 2 years.
How is my share of SAF calculated?
How do I know the SAF is allocated to me?
Will the SAF all be loaded onto my flight?
What are the sources of SAF I am purchasing?
What sustainability criteria does the SAF meet?
Am I paying for 10% of all the fuel for my flight?
Why doesn’t British Airways just buy the sustainable fuel?
What acknowledgement will I get once I have supported SAF and offsets?
Carbon Offsetting
What types of carbon credit projects are there?
1. Renewable Energy – Including hydro, wind, and photovoltaic solar power, solar hot water and biomass power and heat production.
2. Energy Efficiency – these projects are fundamentally about using LESS energy (e.g. LED lighting or installing more efficient cooking stoves).
3. Forestry – Forestry projects can involve either afforestation (the establishment of a new forest or reforestation (rebuilding existing forests.) REDD+ (a UN standard) projects stand for Reducing Emissions from Reforestation and Forest Degradation.
4. Transport – These projects may involve switching transportation to less carbon intensive means or introducing new technologies to improve vehicle fuel efficiency.
5. Agriculture – By changing agricultural process techniques to methods which are more environmentally friendly, significant reductions in carbon emission can be achieved.
6. Water, sanitation and hygiene (WASH) – Projects which improve access to water, water treatment, improved sanitation and hygiene which contribute to climate change mitigation/adaptation can provide offsets.
7. Methane Capture – There are two types of methane projects. The first type captures and burns (flares) methane, convering it to less potent carbon dioxide and water. Alternatively, projects can capture methane and use it to produce hot water or electricity.
8. Waste management and handling – These include projects that reduce the emissions from waste or water management such as composting, biogas etc.
What makes for a high-quality carbon credit?
• Real – The offsets are tangible and measurable
• Additionality – The emissions reduction would not have occurred in the absence of the project.
• Permanence – The project delivers the claimed emissions reductions in a sustained manner over time.
• No Leakage – The emissions reduction achieved with the project does not lead to an increase in emissions elsewhere.
• Retired permanently – Following the sale of the carbon credit, it is permanently removed from the market mechanism, ensuring that the offsets
there is no double counting or double selling.
• Verifiability – A robust audit trail demonstrating the project’s goals and its delivery against those goals.
What is the price of a carbon credit? Why does it change?
The price of a carbon credit depends on many factors, including supply and demand in the market and the quality, type, size, and geographical location of the project and the credit age (vintage) – but most importantly, the value that credit creates.
The availability of credits will change depending on supply and demand factors as well.
What are the Sustainable Development Goals? (SDGs)
Why do the SDGs matter in carbon offsetting?
Reducing carbon is just one component of making our world a more sustainable place. Carbon offset projects that have other social and environmental outcomes associated with them help to create a more sustainable world where those in developing countries benefit more holistically from reducing/avoiding carbon.
What is the difference between voluntary and mandatory carbon markets?
Regulated, mandatory or compliance carbon markets are regional, national or international regimes, enforced through legislation. The most comprehensive of these is the European Emissions Trading System. British Airways is a long-standing supporter of carbon trading to achieve robust carbon pricing at the least cost to customers.
Voluntary carbon offset markets enable organisations and individuals to offset their emissions by purchasing offsets that were created either through the Clean Development Mechanism (a UN led initiative born out of the Kyoto Protocol) or in the voluntary market. Voluntary credits help to serve micro projects that are too small to warrant the administrative burden or not covered under mandatory compliance schemes. Credits generated under these schemes are called Voluntary Emission Reductions (VERs).
Pure Leapfrog helps organisations and individuals to reduce their carbon footprints by supporting communities to develop carbon reducing projects through the voluntary market. All the projects Pure Leapfrog supports reduce emissions or remove carbon from the atmosphere.
What is the ICROA?
We adhere to the International Carbon Reduction and Offsetting Alliance’s (ICROA) Code of Best Practice.
ICROA is working with leading academic institutions to understand the drivers of the voluntary market, and to research and demonstrate the additional non-carbon benefits of voluntary offsetting. For example, a recent study by Gold Standard finds that for every carbon credit issued from a clean cook stove project, £219 in economic value is created. For domestic biogas projects, the average value created is £380 per credit.
About Pure Leapfrog
What is Pure Leapfrog's role?
We have been supporting people and organisations to reduce their carbon footprint by providing carbon offsets since our creation in 2005.
We work with organisations that align with our mission to tackle climate change and address poverty. Our partners support communities to develop carbon reducing projects and obtain the necessary independent verification. The reason for independent verification is so that we can be sure that the reductions have actually taken place.
Upon receiving your contributions, we purchase an equal mix of credits in the projects described on the website. The credits provide funding for these projects.
We ensure the credits we purchase are ‘retired’ from the market and cannot be purchased by anyone else. This is to ensure the emissions reductions are attributed only to you and as is required by the International Carbon Reduction and Offsetting Alliance’s (ICROA) Code of Best Practice.
What is Pure Leapfrog’s relationship with British Airways?
Pure Leapfrog has been working with British Airways since 2011 and it manages the British Airways Carbon Fund. The fund, which is created from customer donations at the point of booking, has been used to support carbon lowering projects in the UK and Africa. More about the BA Carbon Fund can be found here.
Pure Leapfrog has also been offering carbon offsetting to British Airways’ customers for a number of years and our carbon calculator provides a simple way for BA customers to make their flight carbon neutral.
Since January 2020, Pure Leapfrog has also assisted British Airways in making all its flights within the UK carbon neutral using carbon offsetting.
How does your relationship with British Airways for offsetting work?
British Airways customers are given the opportunity to offset their flight using the service provided by Pure Leapfrog.
We have developed our approach in consultation with British Airways to ensure the service, processes used, projects selected and customer experience meet their standards.
All offset contributions are handled directly through Pure Leapfrog. Given the high demand in the voluntary carbon market, British Airways has procured carbon credits in the projects available on BA Carbon Neutral to secure their supply, but it receives no income from the offsetting process.
Why work with British Airways?
We believe that all parts of our economy and energy system need decarbonising. This includes transport, which includes air travel. We work with partners who make a clear and demonstrable commitment to understanding their own impact and then take steps to address it. This describes British Airways.
Air travel provides an essential part of our transport system, providing economic benefits through commerce and tourism to all parts of the world, including parts of the developing world that rely heavily on tourism for economic security.
This is why we work with British Airways to provide them with a way that their customers can use to mitigate their impact by making their flight carbon neutral.
Cost & Pricing
Why do you charge a minimum fee?
Why might my cost per tonne/mile vary?
Cost per tonne and cost per mile may vary depending on:
- The project you select – projects vary in price, as described above
- Emissions factors – see FAQ about emission factors
How much do the carbon credits cost?
The carbon credits we are offering vary in price from approximately £8.00-£11.00 per tonne.
Each project has a different price depending on technology, location, carbon standard etc.
Can I cancel my carbon credit purchase?
Once you have completed the carbon credit purchase, no refund can be made if you change your mind or in case of cancellation, rebooking or cancellation of the flight that you have offset.
Can I cancel my SAF and offset purchase?
Once you have completed the purchase, no refund can be made if you change your mind or in case of cancellation, rebooking or cancellation of the flight that you have made carbon neutral.
Our Carbon Calculator
How does the carbon calculator work?
We combine the data that you enter with data from the airline to calculate your emissions. If your flight is within Europe, we adjust the emissions calculation to reflect the emissions already reduced by British Airways’ participation in regulatory systems including the UK and EU Emissions Trading Systems so that we aren’t double counting these emissions.
Why do other calculators come up with different tonnes to be offset?
Our calculator uses average historical British Airways data from the most recent full year. If your flight is within Europe, we adjust the emissions calculation to reflect the emissions already reduced by British Airways’ participation in regulatory systems including the UK and EU Emissions Trading Systems so that we aren’t double counting these emissions.
Other calculators may use factors that are specific to a particular airline, or standard government factors. Other reasons for differences include the extent to which data is split by cabin class and whether non-CO2 effects are included. Given that the relative scale of non-CO2 impact is uncertain and subject to ongoing research, we are using a radiative forcing index of 1. This will be reviewed when further information becomes available.
Do I offset for my child?
This is up to you. Offsets are based on the number of passengers using a seat on the aircraft. If your child is old enough to sit on their own in a seat, then you can offset for them. If they are a baby in arms, then no offset is needed.
What are emissions factors?
Why can't I do this when I book my flight?
How often is the data in the calculator updated?
The data in the calculator is updated regularly based on:
- Annual emissions factor data provided by British Airways
- Changes to emissions regimes
Our Offsetting Projects
How do you select offset projects?
Pure Leapfrog works in partnership with British Airways to select projects with the highest sustainability standards and strong social, as well as environmental outcomes.
The projects, sourced in line with Pure Leapfrog’s ethos of maximising benefits to local communities, come from project developers who have substantial carbon market experience and a long track record of successful issuance of credits.
Background information on the project developers of Mai Ndombe REDD+ and Toyola cookstoves, respectively, follows:
Wildlife Works, established in 1997, is a conservation business, committed to bringing marketplace initiatives into the fight to protect the planet’s threatened forests and the magnificent species that call them home. Wildlife Works develops and manages REDD+ projects around the world and helps forest communities and Global South governments to protect their forests and wildlife by providing a sustainable and transformative development path via the REDD+ model. Visit https://www.wildlifeworks.com/ to learn more.
Toyola Energy was set up in 2006 in Ghana to supply improved cookstoves to low-income households. It is a social enterprise using locally-developed technology combined with a proprietary financing model that allows users to pay for the stoves from cash saved on fuel using a “Toyola Money Box”. Toyola Energy has been expanding in the West African sub-region, establishing its own production and training centres.
How do you know the projects you select are high-quality?
The above certifications are also in line with the ICROA Code of Best Practice list of quality credible standards.
How often do you purchase credits?
We purchase and retire offset credits periodically, depending on volumes.
Do you develop offset projects?
At this time, we do not develop offset projects. Instead, we select high-quality existing projects from experienced project developers who have track record in issuing carbon credits.
What monitoring and reporting do you do on projects?
Projects are audited by an independent third party over a specified period and a verification report is then issued which confirms the number of credits the project can issue.
Flying and Carbon Emissions
How does flying create emissions?
Aircraft engines burn fuel in order to transport passengers from one place to another. This process creates CO2 and other emissions.
These total emissions are divided among passengers, taking into account the fact that passengers in business and first class have larger seat room and increased luggage allowances.
The factors that determine the emissions for a journey are:
• Arrival and departure point – this determines distance and fuel consumption
• Number of passengers
• Travel class
• Carbon emission factor – this determines the CO2 equivalent per kilometre
How does emissions trading work?
How do we calculate the emissions trading reductions applicable to your flight?
What is CORSIA?
CORSIA, the Carbon Offsetting and Reduction Scheme for International Aviation, is the climate regulation agreed by the international UN body the International Civil Aviation Organisation. The regulation addresses the increase in total CO2 emissions from international aviation above 2019 levels so that all growth between participating countries above that level in future will be offset.
CORSIA’s obligations have already started. As of 1 January 2019, all carriers are required to report their CO2 emissions on an annual basis. Airlines are required to offset growth emissions from 2021 onwards, so from 2021 we will adjust the offset calculation to take account of emission reductions required by CORSIA.
What about radiative forcing?
In addition to greenhouse gas emissions including CO2, aircraft also cause non-CO2 climate effects such as condensation trails. Research into these effects and the appropriate metrics to characterise them continues. Radiative forcing is a metric or measurement basis that aims to combine the CO2 and non-CO2 climate effects. Given that the relative scale of impact is uncertain and subject to ongoing research, we are using a radiative forcing index of 1. This will be reviewed when further information becomes available.