“The Guardian and researchers from Corporate Accountability, a non-profit, transnational corporate watchdog, analysed the top 50 emission offset projects, those that have sold the most carbon credits in the global market.
“According to our criteria and classification system:
A total of 39 of the top 50 emission offset projects, or 78% of them, were categorised as likely junk or worthless due to one or more fundamental failing that undermines its promised emission cuts.
Eight others (16%) look problematic, with evidence suggesting they may have at least one fundamental failing and are potentially junk, according to the classification system applied.
The efficacy of the remaining three projects (6%) could not be determined definitively as there was insufficient public, independent information to adequately assess the quality of the credits and/or accuracy of their claimed climate benefits.
“Overall, $1.16bn (£937m) of carbon credits have been traded so far from the projects classified by the investigation as likely junk or worthless; a further $400m of credits bought and sold were potentially junk.” – keep reading
Infographic: How are carbon offsets supposed to work?
Carbon Brief have also released a detailed analysis and mapping, including carbon credits claims made by New Zealand companies:
Beneath our feet, remarkable networks of fungal filaments stretch out in all directions. These mycorrhizal fungi live in partnership with plants, offering nutrients, water and protection from pests in exchange for carbon-rich sugars.
How much bigger? These microscopic filaments take up the equivalent of more than a third (36%) of the world’s annual carbon emissions from fossil fuels – every year.
As we search for ways to slow or stop the climate crisis, we often look to familiar solutions: cutting fossil fuel use, switching to renewables and restoring forests. This research shows we need to look down too, into our soils.
This fungi-plant partnership is 400 million years old
Mycorrhizal fungi are hard to spot, but their effects are startling. They thread networks of microscopic filaments through the soil and into the roots of almost every plant on earth.
But this is no hostile takeover. They’ve been partnering with plants for more than 400 million years. The length of these complex relationships has given them a vital role in our ecosystems.
Sometimes fungi take more than they give. But often, these are relationships of mutual benefit. Through their network, the fungi transport essential nutrients and water to plants, and can even boost their resistance to pests and disease.
In return, plants pump sugars and fat made by photosynthesis in their leaves down through their roots to the fungi. These compounds are rich in carbon, taken from the atmosphere.
How do these fungi fit into the carbon cycle?
On land, the natural carbon cycle involves a delicate balance. Plants take CO₂ from the atmosphere through photosynthesis, while other organisms emit it back into the atmosphere.
Now we know the carbon transfer from plants to mycorrhizal fungi isn’t a side note – it’s a substantial part of this equation.
By analysing almost 200 datasets, the researchers estimate the world’s plants are transferring a staggering 3.58 billion tonnes of carbon per year to this underground network. That’s the same as 13.12 billion tonnes of CO₂ – more than a third of the world’s 36.3 billion tonnes of CO₂ emitted yearly by burning fossil fuels.
To be clear, fungal carbon doesn’t present a climate solution by itself. It’s a missing piece in the carbon cycle puzzle.
We still have big gaps in data from particular ecosystems and geographic regions. For instance, this study didn’t have any data of this kind from Australia or Southeast Asia – because it doesn’t yet exist.
What does this mean for the climate?
We already know mycorrhizal fungi help soils retain carbon by releasing specific chemical compounds. These compounds contain carbon and nitrogen. Once in the soil, these compounds can be used by other soil microorganisms, such as bacteria. When this happens it helps to form a highly stable soil carbon store that is more resistant to breakdown, and this store can accumulate more than four times faster in the presence of mycorrhizal fungi.
When these fungi die, they leave behind “necromass” – a complex scaffold of dead organic material which can be stored in soil, and often inside clumps of soil particles. The carbon inside these clumps can stay in the soil for close to a decade without being released back to the atmosphere.
In fact, other studies suggest this fungal necromass might contribute more to the carbon content of soil than living fungi.
But these fungi also naturally cause carbon to escape back to the atmosphere by decomposing organic matter or changing water and nutrient availability, which influences how other organisms decompose. Mycorrhizal fungi also release some carbon back into the atmosphere, though the rate this happens depends on many factors.
What does this mean for climate change? While atmospheric CO₂ concentrations keep rising, it doesn’t necessarily mean fungi are storing more of it. Recent research in an Australian woodland found higher atmospheric CO₂ did see more carbon sent below the ground. But this carbon wasn’t stored for long periods.
When we cut down forests or clear land, we not only disrupt life above the ground, but underground as well. We need to safeguard these hidden fungal networks which give our plants resilience – and play a key role in the carbon cycle.
As we better understand how these fungi work and what we’re doing to them, we can also develop farming methods which better preserve them and their carbon.
We can’t just sit around and wait to see what will happen next. We need positive action.
I’ve read a lot of Climate Adaptation Plans and Strategies over the past the last few years, but He Toka Tū Moana Mō Maketū (Maketū Climate Change Adaptation Plan) is hand-down the best. It’s clearly laid out, outlines the community’s priorities, and can readily serve as a template to help every community around Aoteara develop their own Climate Adaptation Plans. Most important of all:
It’s iwi led, community driven, it’s a plan that’s been decided by those who live here. – Elva Conroy, Kaitohotohu / Facilitator (Video; to listen Watch on Youtube)
In the words of the Maketu Iwi Collective, ‘we will be resilient like the anchor stone Takaparore – strong and steadfast against the elements and tides of change and uncertainty. Regardless of what happens as a result of a changing environment, we will remain standing’. – New Zealand Planning Institute, April 2023.
The recent report issued by the Intergovernmental Panel on Climate Change (IPCC) underscores the urgency of emissions reductions. For Aotearoa New Zealand, where 50% of emissions come from agriculture in the form of methane and nitrous oxide, this means the primary sector must be part of the response.
New Zealand is indeed the first country to investigate introducing a price on agricultural greenhouse gas emissions.
The most recent pricing proposals would require farmers to pay a levy on their agricultural emissions. To begin with, only 5% of emissions would be priced, with proposals to reduce the 95% free allocation gradually over time.
Much of the existing modelling shows emissions could be cut by up to 10% by reducing the intensity of production, often through lowering animal numbers and fertiliser use. This doesn’t necessarily mean lower profitability. With good pasture management, farmers may be able to reduce stocking rates and increase profits.
But Aotearoa is already one of the most efficient producers of meat and dairy products globally. If we reduce emissions here, will that not simply lead to other, less efficient countries picking up the lost production, while our farmers pay the price?
This idea is known as “carbon leakage” and is often used as an argument against any domestic policy that could result in reduced agricultural production. The issue is important as New Zealand depends heavily on agricultural exports. In 2022, of all merchandise trade, 65% were agricultural commodities.
Understanding whether carbon leakage will occur or not is a complex task. Here, we look at what evidence we have and insights from agricultural trade modelling.
New Zealand modelling
It’s difficult to know exactly what might happen in agriculture, as emissions pricing on agricultural products has not yet been used elsewhere. There is no historical evidence to draw on.
International modelling studies present a mixed picture of the likelihood of leakage: an OECD study estimated 34% of agricultural emissions would be leaked, mostly to developing countries.
Recent modelling for New Zealand examines a series of scenarios of domestic pricing on its own as well as international pricing. The results show that for the current proposal where only 5% of emissions are priced to begin with, with a 1% increase each year, New Zealand’s production of meat and dairy products could decline by 2050.
The effect on dairy producers would be a loss of returns of under 1%, while meat producers would face a 6% decline. Some of the production would be taken up by other countries, but the overall volume would be lower than in the baseline situation, where no emissions pricing existed.
This shows leakage may occur, with reductions in production of New Zealand dairy products. But global meat and dairy production by 2050 would be considerably lower than without the policy, which would have a positive overall impact on the climate.
As the proportion of emissions that are priced increases, we expect the quantity of meat and dairy produced in New Zealand to decrease. This in turn could increase the volume of leakage. –
More sustainable future diets
It is important to remember that although there is a reduction in meat and dairy production, there is likely to be an increase in the production of other types of food which doesn’t contribute so much to climate change.
A recent study shows how food consumption alone could contribute an additional degree of warming above preindustrial temperatures by 2100. This demonstrates the importance of food choices in addressing climate change.
Many of New Zealand’s trading partners are exploring and beginning to implement their own agricultural emissions-reduction goals and targets. Internationally, there is an increasing focus on the role international trade rules can play in addressing climate change, including border carbon adjustment mechanisms and environmental standards for imports.
In a similar scenario as described above, but where New Zealand’s main competitors also take action, New Zealand may actually see a small increase in production by 2050, despite the domestic pricing policy.
The extent of leakage therefore really depends on how other countries tackle their own emissions. Economy-wide net zero emissions targets are in place for Australia, Chile, European Union countries, the US and the UK by 2050, and for China by 2060.
New Zealand could decide to be a leader and demonstrate to the rest of the world a commitment to reducing emissions from our highest emitting sector. This may result in some leakage initially, but this would likely decline as other countries take similar action.
In a historic first for the U.S., the Food and Drug Administration has certified that Upside Foods chicken made from cell cultures is safe to eat.
Nearly two years after Singapore approved the Good Meat company’s cellular chicken for sale at select restaurants in the Asian foodtech hub, and Supermeat opened a restaurant in Israel serving cultured chicken on its menu, U.S. buyers will soon get the chance to taste a potential future of food for themselves.
California-based Upside Foods is the first company to receive a pre-market safety clearance from the U.S. Food and Drug Administration (FDA). While the pending facility for Upside Foods will need to meet U.S. Department of Agriculture (USDA) and FDA requirements, the agency said it has “no further questions at this time” about the meat’s safety.
Using muscle samples, stem cells from animals, and fats animal tissue is “cultivated” from tiny samples into large portions of meat. In Upside’s case, the startup uses chicken’s primary cells of a fertilized egg to create “The fried chicken chicken’s dream about.
Different from plant-based, companies like Upside and Wild Type offer diners the option of real meat without the requirement of animal death or the meat industry’s environmental consequences and contributions to the climate crisis. The meats also have lower risk of contamination from bacteria because they’re not slaughtered. It is still animal meat, which means the target audience isn’t the vegetarians and vegans of the world, but their carnivorous counterparts.
The United Nations estimates the meat industry accounts for nearly a fifth of our total greenhouse gas emissions, making it one of the most polluting industries in the world, especially in the US, one of the planet’s most meat-consuming countries.
According to a study published at the University of Oxford, cultivated meat could reduce greenhouse gas emissions by 96% compared to conventionally produced meat.
Additionally, switching to cultured meat can cut our water consumption between 82 and 96%, depending on the animal. It can also reduce the quantity of land dedicated to the meat industry, which is the main driver of tropical deforestation and land degradation.
This is a submission on behalf of the Environmental Defence Society (EDS) on the Government’s Discussion Document Te Tātai utu o nā tukunga: Pricing Agricultural Emissions.
The submission responds to the schedule of questions included in the discussion document, reproduced in full with permission from Gary Taylor Chief Executive, Environmental Defence Society:
Question 1:Do you think modifications are required to the proposed farm-level levy system to ensure it delivers sufficient reductions in gross emissions from the agriculture sector? Please explain.
If farmers are to balk at the proposal as indicated by recent statements from Federated Farmers and others, and widespread non-compliance follows, then implementing a processor-level system would be a practical way forward. It is alarming how some farmers are signalling an unwillingness to comply with the rule of law. The farm-level option (which has benefits in sending price signals to individual famers) may therefore not be workable at least in the short term. Processors could develop their own incentive arrangements for their suppliers and some have experience in doing that already.
Question 2:Are tradeable methane quotas an option the Government should consider further in the future? Why?
There may be benefit in seeing the levy system as a transition to a cap and trade system. This means the levy system should be designed so that such a transition could occur. The cap should be set (and reviewed from time to time) by the Climate Change Commission (Commission) at the level that achieves the reduction targets. If Ministers were to make the decisions, then there should be transparent criteria in place, and they should be advised on the appropriate level by the Commission.
Question 3: Which option do you prefer for pricing agricultural emissions by 2025 and why?
A farm-level levy system, with fertiliser in the New Zealand Emissions Trading Scheme (ETS), would give individual farmers incentives to reduce emissions and reward those doing so. However, that may be an impractical option given that some farmers seem determined to not cooperate with any system. For that reason, we favour a pragmatic approach where pricing is set at the processor level, which would help avoid non-compliance. Processors could then develop incentives that would apply to their supplier cohort. There are also questions around whether a farm-level system could be developed in time.
Prices should be set either directly by the Commission, or if by Ministers, on the advice of the Commission and subject to transparent criteria.
Fertiliser should come under the ETS which would mean all fertiliser users are captured and the price signal applies across the sector.
Question 4:Do you support the proposed approach for reporting of emissions? Why, and what improvements should be considered?
Broadly yes but further work is needed to simplify the reporting system and ensure the obligations are proportional to the need.
Question 5:Do you support the proposed approach to setting levy prices? Why, and what improvements should be considered?
Price setting cannot be the responsibility of the sector itself. It must be independent and linked to the methane reductions required. As mentioned above, EDS favours this responsibility resting with the independent Commission (analogous to the Reserve Bank on interest rates). But if set by Ministers, then there should be clear decision-making criteria, and they should receive advice from the Commission. Further, the proposed ETS discount rates for long-lived gases are too generous given the persistent delays in bringing the sector into a pricing mechanism.
Question 6:Do you support the proposed approach to revenue recycling? Why, and what improvements should be considered?
Recycling revenue into finding new abatement approaches makes sense in theory, but the problem is that over $100m of public money has gone down that route since the early 2000s, with very little to show for it. If revenue is to go into research it needs to be to entities that offer prospect of deployment of real technologies into the field. Research criteria therefore need to focus on deployment.
The answer to emissions mitigation is to reduce land use intensity. Some compensation for that might also be needed given the farming sector has simply been following the economic signals to date. There is virtue in the model of low-impact pastoral farming with indigenous forestry, and recycling could support that kind of transition.
The big gap in the policy settings, at present, is the lack of strong and effective incentives for indigenous afforestation. Revenue recycling should be used to create such incentives, given the longer term sequestration and biodiversity benefits that would follow.
Further consideration should be given to whether revenue from the levy should also be used to support farmers needing assistance with adaptation crises on the farm (such as droughts and floods).
Question 7:Do you support the proposed approach for incentive payments to encourage additional emissions reductions? Why, and what improvements should be considered?
The price signals should be robust enough to incentivise the emission reductions required. Otherwise the sector is getting disproportional assistance / subsidies from the Government over other sectors.
Question 8:Do you support the proposed approach for recognising carbon sequestration from riparian plantings and management of indigenous vegetation, both in the short and long term? Why, and what improvements should be considered?
Two approaches are required here.
The first is to create a biodiversity incentive payment to support native forest and related plantings or regeneration. The proposed interim approach will achieve that, in part, but biodiversity enhancements need to be considered in the broader context and be designed to encourage and support native forest restoration at landscape scale.
The second is to ban permanent exotic carbon forests in the ETS.
The first approach can help support related government policies such as the National Policy Statement for Indigenous Biodiversity. The second would prevent widespread monocultures with their attendant adverse landscape impacts and fire and disease risks.
Question 9:Do you support the introduction of an interim processor-level levy in 2025 if the farm-level system is not ready? If not, what alternative would you propose to ensure agricultural emissions pricing starts in 2025?
Yes. In fact we think that should be the way forward in any event.
Question 10:Do you think the proposed system for pricing agricultural emissions is equitable, both within the agriculture sector, and across other sectors, and across New Zealand generally? Why and what changes to the system would be required to make it equitable?
It is time that the sector played its part in mitigating the impacts of climate change. It has got away with too much, for too long, and continuing taxpayer subsidy and support and the proposed incremental nature of the pricing obligations continue that approach. It is inequitable for the primary sector to be relying on others which are paying their way through the ETS.
With respect to Māori landowners, there may be a case for some interim support given they appear to be disproportionately impacted by the proposal. The best way to do that is to create a special category in the ETS for native forest regeneration and establishment that gives a long-term revenue stream as good as or better than permanent exotic carbon forests.
Question 11:In principle, do you think the agricultural sector should pay for any shortfall in its emissions reductions? If so, do you think using levy revenue would be an appropriate mechanism for this?
Yes and that calculation should be made by the Commission.
Question 12:What impacts or implications do you foresee as a result of each of the Government’s proposals in the short and long term?
Unless the Government’s proposals are enacted, we see widespread planting of permanent exotic carbon forests and rural non-compliance with the law. There will be some emission reductions, but the sector will continue to hold out on meeting its fair share, as it has since 2002. The climate will continue to warm with consequent droughts, floods and sea-level rise and farmers will continue to hold out their hands for Government support when impacted.
Question 13:What steps should the Crown be taking to protect relevant iwi and Māori interests, in line with Te Tiriti o Waitangi? How should the Crown support Māori land owners, farmers and growers in a pricing system?
By changing the pricing incentives to favour permanent native forests over permanent exotic ones. Māori landowners have indicated a preference for natives but the pricing incentives are going the wrong way.
Question 14:Do you support the proposed approach for verification, compliance and enforcement? Why, and what improvements should be considered?
Question 15:Do you have any other priority issues that you would like to share on the Government’s proposals for addressing agricultural emissions?
The glaring gap is the absence of the right pricing incentives to encourage native forest restoration that would lead to a virtuous mixed land use in which native forests offset some on-farm emissions over time.
This is such a compelling press release that it’s worth reprinting in full, here:
“The Environmental Defence Society and Pure Advantage have joined forces to draft a submission on the review of the National Environmental Standards for Plantation Forestry (the Standards). The submission seeks significant tightening of the rules governing exotic forest management in Aotearoa New Zealand.
“Our submission starts with the premise that forest practices here are out of step with the rest of the developed world. There are inadequate controls over sediment, slash and soil stability and the sector needs to lift its environmental performance across all of its activities,” said EDS COO Shay Schlaepfer.
“With that in the mind, the scope of the current review, which is focused on permanent exotic carbon forests, is too narrow and we are calling on Government to undertake a fundamental reset of the regulations.“Our submission points to the following key problems with the present Standards:
It fails to effectively address adverse environmental outcomes associated with plantation forestry activities
It is unjustifiably and unlawfully permissive for such high risk activities, particularly with regard to afforestation on highly erodible land and clear fell harvesting
It fails to adequately recognise and encourage the wider and longer-term intergenerational climate resilience, biodiversity, social, cultural, and economic opportunities associated with indigenous forests
It is insufficiently aligned with national objectives and direction in relation to freshwater, coastal, and indigenous biodiversity protection and long-term carbon sequestration.
“Put in simple terms, the current Standards are failing to address significant adverse environmental effects associated withwheretrees are planted,whattrees are planted, andhowforests are managed and harvested. These effects need to be managed for both new so-called permanent carbon forests and plantation forests.
“We contend that the presumption in the current Standards that forestry activities are “permitted” is unworkable, inappropriate, and ineffective at securing environmental protection.
“We are releasing our draft submission to give some guidance to others wishing to see improvements in the way exotic forests are managed. The intention is to file the final submission on the closing date which is 18 November,” said Ms Schlaepfer.
The Environmental Defence Society has filed its submission on the Ministry for the Environment’s regulations on coastal wetlands and says that the Ministry’s approach undermines the original intent of the regulations and leaves coastal wetlands vulnerable to future degradation.
This is a classic case of maladaptation, the exact opposite to adaptation that the Government itself warned against in its National adaptation plan.
“The Resource Management (National Environmental Standards for Freshwater) Regulations 2020 (NES-F) set national direction to protect and improve wetlands and put a stop to further loss of their values”, said EDS COO Shay Schlaepfer.
“The NES-F was clearly intended to apply to both inland and coastal wetlands. The Ministry is now proposing a policy U-turn and wants to exclude coastal wetlands from the regulations.
“This approach is totally unjustified. Coastal wetlands are capable of being mapped so there is no reason why they should not be included. The NES-F is a rules framework that integrates national policy relating to wetlands and provides a consistent approach to wetland management across all domains.
“Removing coastal wetlands from the NES-F will leave a gap in their management and protection at the national level and leave too much discretion with regional councils.
“The Ministry also seeks to exempt certain activities from the consenting pathways set out in the NES-F. These activities have the potential to adversely affect coastal wetlands and should be subject to the regulations.
“Wetlands are one of the country’s most valuable ecosystems. They have undergone extensive loss with over 90% of them destroyed since human occupation. Many of those that remain are in a severely degraded state. The Ministry’s proposed approach will only serve to further continue this decline.
“This cannot be allowed to occur and we urge the Ministry to think again,” Ms Schlaepfer concluded.
The global carbon budget tells us how much more carbon we can emit or ‘spend’ before we risk temperatures passing 1.5°C. On the current trajectory, we have about 316 Gigatonnes left before we run out around May 2029. This is why there is such an urgent push to reduce emissions by 2030.
“Permafrost emissions are really hard to capture in global models, so even in the [new climate models] being used to project climate in the future and the behaviour of the planet and the global climate system, these emissions are not included…climate modellers don’t want to include it; permafrost modellers really think they should.” – Video (top) State of the Cryosphere Report, COP26
Fig. 1: Estimated permafrost changes 2003-2017. Images: International Cryosphere Climate Initiative at COP26. See the video at the top of this page for the full presentation.
Presently, emissions from permafrost are about the same as Japan’s; around 1.15 Gigatonnes. Not accounting for these emissions is like knowing that someone is withdrawing money from your bank account, but ignoring it. As temperatures continue to rise, more permafrost melts, so there’s even less available to ‘spend’. To compound the problem, the Arctic is warming as much as four times faster than the rest of the planet.
“Suppose we do reach net zero emissions by 2050, permafrost is going to continue emitting for at least a couple of centuries. So, in addition to the negative emissions that are in the models to keep temperature below 1.5°C, we also have to have negative emissions to offset permafrost. And we’re going to have to continue doing that for a couple of hundred years until the permafrost stabilises,” – Op cit.
The science is unequivocal. The 12-minute video above succinctly outlines this complex issue. The figures at the bottom of this page are eye-watering…and that’s just from processing meat and dairy.
“From production to transportation packaging use and waste management, based on the most detailed meta analysis of life cycle assessments to date, on average it takes 71kg of CO2 to produce 1kg of beef. For lamb, it’s about 40kg; pigs 12kg; and poultry 10kg.
“Some 26% of greenhouse gasses comes from agriculture. By far the largest share is methane and nitrous oxide from cattle. Methane alone has already caused caused around 24-40% of human-made warming.
“The destruction of forests for farmland not only releases the CO2 that was bound in the flora, it sets free carbon that was stored in the soil and destroys its ability to store it in the future. This aspect accounts for much of the range of emissions in beef.”
This loss continues in Aotearoa (13,000 hectares lost in the past 5 years alone). Then there’s the nitrogen and phosphates added to farms that ends up in waterways, which results in, amongst other things, algae blooms that emit methane when they die:
“Between 1991 and 2019, estimates from sales data of nitrogen applied to land in fertiliser increased from 62,000 to 452,000 tonnes (just over a sixfold increase, 629 percent).
“Since our last update of this indicator in April 2019, there was a 5.4 percent increase from 2015 to 2019 in nitrogen applied from fertiliser. In this period, urease inhibitor use increased 48 percent.” – Statistics NZ
And then there’s the palm oil imported to feed our ‘grass fed’ cows:
“A new Greenpeace International report has found evidence of systematic violations by the Indonesian Government regarding plantation and forest release permits in the Papua region. The report also finds that clearing forest for palm plantations in the Papua area could release huge amounts of carbon into the atmosphere, undoing previous climate action.
“New Zealand is the world’s biggest importer of palm kernel expeller–a product of the palm industry used as supplementary feed for New Zealand’s 6.5 million dairy cows.
“In 2018, a Greenpeace investigation found that Fonterra’s key supplier of PKE, Wilmar International, has been linked with the mass destruction of rainforest in Papua, Indonesia. In 2020, Fonterra handed over its half of PKE-importing business Agrifeeds to business partnerWilmar International.
“Greenpeace Aotearoa campaigner Amanda Larsson says the dairy industry’s continued use of PKE is one of myriad ways that intensive dairying is fuelling the climate crisis.
“Right now, dairying is New Zealand’s biggest climate polluter. We’ve got methane from 6.5 million cows, nitrous oxide from cows and synthetic nitrogen fertiliser, and carbon from the coal used to process milk,” says Larsson.” – Greenpeace April, 2021
Finally, there’s the carbon cost of processing all that meat and dairy. Remember, this is in addtion to the methane, nitrous oxide and CO2 emissions from growing this meat on farms. Fonterra is the worst carbon polluter in the country, emitting a staggering 16.3 million tonnes of eCO2 in 2020 alone. Silver Fern farms emitted 8.3 million tonnes(Table 9 below: from the New Zealand Government EPA report ‘ETS Participant Emissions‘, October 2021, pages 27-30).
So yes, meat and dairy really is that bad for the climate.
Some greenhouse gases are many times more powerful than others when it comes to warming the atmosphere. This is called their global warming potential (GWP). Three of these gases, carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) are the main concern.
Some greenhouse gases stay in the atmosphere longer than others, so time is also included in the equation. Over 100 years, the GWP of methane (CH4) is 25 times that of CO2, so it’s written as 25CO2-e. The GWP of nitrous oxide (N2O) over the same time period is 298 so it’s written as 298CO2-e in New Zealand.
When emissions are added together, the term eCO2 is used.