Over the past decade, research has emerged suggesting that ramping up reforestation around the world could make a substantial contribution to tackling climate change.
Studies have estimated that the CO2-absorbing power of newly planted trees could add up to mitigation “potential” of 10bn tonnes (GtCO2) per year – more than the annual emissions of the US.
Achieving this would require planting trees across 678m hectares – an area twice the size of India.
But the uncertainty around those figures is large due to a range of factors, such as where sufficient trees already exist, how much climate mitigation those trees offer and where people actually want additional trees to be planted.
In our new study, published in Nature Communications, we unpack eight years of research into reducing these uncertainties.
We have quantified, for example, how the carbon-sucking power of trees changes when you let forests grow back naturally versus planting monoculture or mixed-species plantations.
We figured out how much carbon could be removed at different price points and mapped where trees – somewhat counterintuitively – actually act to warm, rather than cool, our climate.
But, as we shrank the uncertainty, we also shrank the estimate itself.
Our research provides the most precise estimate of global reforestation area to date – 195m hectares, or 71% less than earlier estimates.
Reforesting an area this size could capture 2GtCO2 per year.
Mapping reforestation opportunity
Maps of global reforestation potential have been cited in thousands of scientific publications, inspired large-scale tree-planting movements and been used by the International Panel on Climate Change (IPCC) in its flagship reports.
However, they have also been very controversial.
Critics have pointed out, for example, that these maps failed to account for natural disturbances that prevent forest growth, ignored existing trees and overlooked the people that live, steward and often depend on those lands for their wellbeing.
In our new study, we resolved to produce a map that addresses these past critiques.
We began by searching for existing maps of reforestation “opportunity”.
Our search uncovered 89 such maps, although most of those we identified are national or sub-national. Some places – such as Brazil’s Atlantic Forest – have many maps, but we found that most of the globe was only covered by a single older, more controversial map.
The map below shows where we found existing maps at the global, regional, national and sub-national levels.
Thus, we set about creating a new global map that built upon the methods of past efforts, tackled prominent critiques and incorporated newly available layers.
Our new map accounts for albedo, for example – how restoring tree cover can, in some locations, actively heat the Earth, rather than cool it, by affecting how much sunlight is absorbed or reflected.
It excludes native grasslands and other ecosystems where carpeting the land with trees would harm biodiversity and exacerbate the risk of wildfire. And it layers in additional safeguards, such as food security, to ensure that reforestation outcomes are more likely to be beneficial to people.
These constraints left us with up to 195m hectares of reforestation opportunity across the world.
A reforestation ‘menu’
Not all reforestation opportunities are created equal – different communities may want to implement reforestation for different reasons, such as restoring floodplains or re-establishing iconic ecosystems that have been lost.
So, alongside the reforestation opportunity, our map shows other factors that communities or decisionmakers may use to help them prioritise areas for reforestation.
We show, for example, where natural regeneration may be most likely to occur and where biodiversity benefits may be greatest, given proximity to existing forest. We show where reforestation opportunity exists on slopes and floodplains – and therefore is more likely to provide benefits for the local watershed. We show places where people have strong rights and secure land tenure, to avoid exacerbating social inequities.
Perhaps unsurprisingly, it is hard to find places that tick all of these complex boxes. But, it is still possible to achieve multiple objectives in one location.
In fact, our study finds that 83% of reforestation opportunities occur close to existing forest, while 81% occur in places that are expected to have low conflicts with rural livelihoods.
More than half of the opportunity that we identify also occurs in countries with explicit restoration goals – places such as Brazil’s Atlantic Forest, where we are working with local partners and communities to restore 1.2m hectares of forest. Forest restoration there contributes to national climate goals, supports sustainable economic development and connects habitat for wildlife.
Alongside the paper, we present the Global Reforestation Hub, which allows users to explore this menu of reforestation options, drill down to reforestation potential at county level and see what opportunities meet a given set of objectives.
For example, a government interested in climate mitigation and protection from floods might use the tool to find the places within their country where both goals might be achieved via reforestation.
The screenshot below shows the Global Reforestation Hub. Countries are coloured by their total reforestation opportunity, from low (white) to high (dark blue). The table shows the amount of land available for – and the CO2 mitigation potential of – reforestation given different priorities and constraints.
Smaller can be better
Reforestation remains one of the most cost-effective climate removal options, but it cannot – and should not – happen everywhere.
While there are certainly opportunities to plant and regrow trees beyond what we have mapped here, we created these maps to show where the climate mitigation opportunities – and their co-benefits – are most concentrated.
Prioritising other motivations, such as human health, habitat for specific wildlife species or local considerations, would also increase the total reforestation opportunity area. For example, our maps don’t include the potential for reforestation in dense urban areas, but trees in those areas can be highly beneficial for human health.
Our study prioritised mapping opportunities for climate change mitigation – and we were deliberately conservative, erring on the side of caution when determining which places to include.
The result is a map that shows the places where reforestation offers both the greatest climate benefits and the fewest downsides for both people and nature.
During a year when the UN climate COP will be hosted in the most iconic forest of all, our study is less a critique of the pre-existing numbers and more an effort to create the most precise and pragmatic maps of reforestation potential. This can help ensure that we get the reforestation part of the climate equation right.
The post Guest post: Why the global area for regrowing trees is 71% smaller than thought appeared first on Carbon Brief.
Guest post: Why the global area for regrowing trees is 71% smaller than thought
A report from Greenpeace Australia Pacific and Springmount Advisory reveals the untapped green economic opportunity for Western Australia in a declining Asian gas market, which also offers a genuine solution for decarbonisation in Asia.
Is Western Australia clinging to a fading gas industry while a thriving green future passes it by? As major Asian trading partners rapidly pivot away from volatile gas imports toward cheap solar and battery storage, this report exposes a high-stakes choice: risk becoming stranded in an oversupplied fossil fuel market, or harness WA’s unmatched sun and wind to lead the global clean energy transition.
Summary
From Gas to Green: Building Western Australia’s Future State reveals that Western Australia (WA) faces a critical juncture as falling Asian gas demand, geopolitical gas supply volatility and accelerating renewable energy deployment undermine the long-term economic viability of gas exports. By harnessing its world-class wind and solar resources, the report demonstrates that WA can execute an orderly phase-out of gas and pioneer a green commodity export economy that could generate $987 billion in economic value by 2060, create 24,000 ongoing jobs, and drive a 9.6% reduction in global greenhouse gas emissions.
Key Findings
- Gas demand is falling in Asia – WA can no longer rely on gas exports: Gas demand in core Asian markets fell in 2025 and is projected to continue to decline in 2026. Legislated energy plans in Japan, South Korea, and China now prioritise renewables and nuclear over gas.
- Asia is increasing renewables, importing gas just gets in the way: Evidence from markets like Thailand suggests that gas imports are increasingly crowding out cheaper renewable energy investments and battery storage rather than displacing coal, locking in more emissions over time.
- Green commodities offer a real solution to decarbonise Asia – this is a major win for WA: With world-class renewables, WA can lead Australia’s green commodity exports, which by 2060 could be worth almost a trillion dollars ($987 billion) and support a genuine 9.6% reduction in global emissions.
Recommendations to WA government
Recommendation 1: Plan an orderly gas phase-out aligned with a trading partner pivot plan
Implement a managed, orderly phase-out of gas exports aligned with trading partners’ decarbonisation pathways, rather than waiting for demand to collapse, by:
- Developing and implementing a staged phase-out of gas facilities aligned with feedstock supply expiry or typical end of facility lifespans.
- Committing to no new gas development for gas expansion, including Browse and Kimberley fields.
- Developing new, reciprocal trade relationships with existing gas trade partners, structured to progressively replace gas exports with green commodities – integrated with recommendation 2.
Recommendation 2: Develop an integrated green commodity export strategy, positioning WA as a global green iron manufacturing hub
Establish an integrated green commodity export strategy that immediately prioritises green iron development, positioning WA as a global green iron manufacturing hub, by:
- Committing to green commodity export targets to give industry and investors a clear demand signal.
- Prioritising green iron as the lead sector within the broader green commodity strategy, given WA’s iron ore endowment and first-mover potential.
Recommendation 3: Reject false solutions such as carbon dumping (CCS) and blue hydrogen
Reject carbon dumping (also described as carbon capture and storage, or CCS) and blue hydrogen as viable decarbonisation technologies, and prioritise green hydrogen and proven renewables for clean energy and fuel production by:
- Excluding blue hydrogen projects (and CCS-dependent projects) from all government support programs.
- Requiring existing hydrogen-based production (including ammonia, methanol, synthetic fuels) to have clear, near-term transition timelines to switch to green hydrogen production.
What you can do
Together, we can push for a prosperous green future.
You can help by:
- Sending an email to Environment Minister Murray Watt and Prime Minister Anthony Albanese, calling on them to reject Browse.
- Sharing this story to help more Australians understand what’s at stake.
- Encouraging your friends and family to take action.
REPORT: “From Gas to Green” Building Western Australia’s Future State
Cleaner cooking projects in the UN carbon market will have to set aside a share of their credits to insure against the risk that the trees they save are lost to fire, drought or logging, after the market’s regulator rejected calls to exempt the sector.
The requirement is part of a new rulebook that the Paris Agreement carbon market regulator – the Article 6.4 Supervisory Body – approved last Friday for programmes that aim to cut emissions by distributing new and cleaner cookstoves in regions that still burn wood or charcoal for cooking.
These are the UN mechanism’s first rulebooks for cookstoves, one of the carbon market’s most popular credit types and also one of its most criticised for overstating climate benefits.
They consist of two methodologies: one for programmes that aim to cut greenhouse gas emissions by distributing more efficient cookstoves that burn less wood or charcoal, and a separate methodology for projects shifting households to lower-emissions cookers running on electricity or liquid petroleum gas (LPG).
Mkhuthazi Steleki, the South African chair of the Supervisory Body, said “this decision gives cleaner cooking projects a new pathway under the UN carbon market, with clear rules to ensure that each credit represents a real and credible emission reduction”.
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Exemption push rejected
More efficient cookstove projects earn credits based on the amount of carbon they save by preserving trees that would have otherwise been cut down and burned for fuel. But if those trees later burn in a wildfire or are logged, the carbon stored would be released anyway, erasing the climate benefits of the credits.
Several carbon credit developers, conservation NGOs and the UN Environment Programme (UNEP) disputed that cookstove projects face this risk, in what critics described as a “coordinated lobbying campaign”.
They argued that, unlike forest protection schemes, this type of credit represents a “flow” of avoided emissions rather than a “stock” of stored carbon that can be released. They also warned that requiring a buffer would impose disproportionate costs and undermine the financial viability of these activities.
But the UN carbon market regulator was not persuaded by the argument. It decided that projects would have to protect against this reversal risk by handing over a percentage of credits to a so-called “buffer pool” instead of selling them.
‘New paradigm’
The amount of credits to be given up is calculated by applying different methods for natural risks, like wildfires, droughts or hurricanes, and human-caused ones, such as logging or land clearing.
For natural risks, project developers will need to apply local risk values derived from new modelling published by a group of independent scientists.
Campaigners have broadly welcomed the decision. Federica Dossi, an expert at Brussels-based advocacy group Carbon Market Watch, said it sets a new paradigm for calculating reversal risk based on empirical data. “This approach is grounded in science and we hope to see this now being adopted by other carbon crediting mechanisms in the voluntary market,” she added.
Backers claim this method is more rigorous than current practice in the voluntary carbon market, which largely relies on expert guesswork.
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Pushback over science
As Climate Home News previously revealed, the same industry and NGO groups that sought an exemption from the “buffer pool”, along with some corporate buyers, criticised the use of a study backed by the UN carbon market’s experts that recommended the new risk assessment approach.
The groups pushed for more flexible rules that would have allowed natural risk values drawn from other sources, including national databases, or from the project developers themselves.
While the Supervisory Body rejected this approach, it gave project developers and countries the option to propose alternative values that would first need to be vetted by the mechanism’s expert panel and then approved by the regulator.
A carbon market expert told Climate Home News that, while it is too early to say how this provision will be used, they expect requests will have to be backed up with solid scientific evidence, lowering the risk of unfounded claims.
Policy discounts questioned
To guard against human-caused risks, projects will need to apply a flat 20% value set by the Supervisory Body, at the bottom of the 20-45% range recommended by its technical experts ahead of last week’s meeting.
That value can be further reduced by up to two-thirds if the host country has an emission-reduction plan covering forests, a long-term climate strategy and a framework for the UN’s REDD+ forest protection scheme.
Injy Johnstone, senior research fellow at the Munich-based Max Planck Institute, said that, while these are important governance measures, their existence does not necessarily demonstrate that the underlying risk of forest carbon loss has been reduced.
“It is important to distinguish between evidence of actual risk reduction and assumptions about the effectiveness of policy commitments,” she added.
Moving target
A UN source told Climate Home News that, under the approved formula, improved cookstove projects must set aside at least 9% of credits linked to saved wood if they operate in the lowest-risk areas and the host country can claim all available discounts. The share of credits rises significantly in regions with high natural risk values, such as Guyana, Sri Lanka and Timor Leste, or that do not have REDD+ programmes.
These factors could change in the future as the Supervisory Body asked its technical experts to recommend revisiting the risk values “should credible new evidence arise”.
Climate change is likely to make forest destruction events, such as wildfires or hurricanes, more frequent and more severe in certain regions. Meanwhile, national policies on forest protection can shift significantly depending on government changes.
Johnstone said the UN carbon market needs periodic reassessment to respond to new evidence showing that previously assumed levels of risk were too low.
“The integrity of credits is not guaranteed simply because a reversal risk tool exists,” she added. “The real test will be whether the mechanism provides equivalent atmospheric protection over time, rather than simply introducing another layer of accounting requirements”.
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UN carbon market forces cookstove projects to protect against forest loss