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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.

Coverage of peer-reviewed reforestation maps published 2011-2022 (n=89) by Global Administrative Areas v 4.1 level 1 unit
Existing coverage of peer-reviewed maps of reforestation potential, all published between 2011 and 2022. The colours indicate the coverage of the map: global only (blue), global and regional (yellow), global, regional and national (teal), global, regional and sub-national (light green) and global, regional, national and sub-national (grey). Source: Fesenmyer et al. (2025)

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.

The Global Reforestation Hub homepage
The Global Reforestation Hub homepage.

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

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Climate Change

REPORT: WA Clean Energy, Jobs & Industry Plan

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Prepared by a coalition of nine Western Australian union, industry, conservation, and community organisations—including UnionsWA, the Conservation Council WA, and the Smart Energy Council—the WA Clean Energy, Jobs & Industry Plan provides a practical roadmap to transform Western Australia into a clean energy powerhouse while creating thousands of secure local jobs.

Western Australia stands at a pivotal crossroads: lead the global clean energy economy or watch investment, future industries, and secure jobs go elsewhere. The WA Clean Energy, Jobs & Industry Plan outlines a transformative blueprint to harness the state’s world-class solar and wind resources. Discover how legislated renewable targets, green iron manufacturing, and a dedicated regional training strategy can generate tens of thousands of local jobs, lower household bills, and build a resilient, net-zero future for all Western Australians.

WA needs a clear and forward-thinking plan if it is going to become a competitive renewable energy powerhouse and maintain its economic strength through the energy transition.
“Western Australians know a faster renewable energy transition will lower their household expenses and prevent harmful climate pollution. But the community also needs clear direction to ensure this transition will create jobs, lower costs and not cause undue environmental harm.
“Here, sectors representing a broad range of interests have laid the groundwork for those outcomes, clearly outlining what is needed to create a future for WA that is good for the environment, for the climate, for workers and for the economy.

Summary

  • Creating local employment.
  • Maintaining industrial competitiveness.
  • Lowering household energy costs

To realize this vision, the framework details actionable measures to follow on from the recent WA Government announcement of a 75% Renewable Energy Target by 2031 for the South West Interconnected System. This includes developing a statewide Renewable Energy Target, coordinating statewide workforce and training pipelines, strategically planning regional infrastructure to safeguard high-value biodiversity and cultural heritage, and ensuring equitable benefit-sharing through household electrification incentives and First Nations equity partnerships. Ultimately, the plan highlights that establishing clear policy and regulatory certainty will unlock lower energy bills, boost power reliability, and secure the state’s global competitiveness in emerging green commodity export markets.

Photo of wind turbines located near the sea at Albany Wind Farm in Western Australia.

Key Findings

  • Statewide Renewable Energy Target and Emissions Reduction Targets: The report calls for a statewide RET and 1.5°C aligned emission reduction targets to remove policy risk, lower capital costs, and attract clean energy investment.
  • Transformative Job Creation: Accelerating the transition offers massive employment prospects, including up to 8,800 solar and battery jobs by 2050, as well as 24,000 ongoing and 11,000 construction jobs in a commercial green iron industry.
  • Industrial Electrification & Competitiveness: Requiring large gas users to adopt binding electrification timetables and providing concessional financing will protect existing energy-intensive manufacturers from rising energy costs and impending domestic gas shortfalls.
  • Green Commodity Export Leadership: Western Australia can build new export markets in green iron, green ammonia, and offshore oil/gas decommissioning by constructing shared common-user infrastructure and setting dedicated Green Commodity Export Targets.
  • Coordinated Workforce & Training Pipeline: To address critical skill shortages the plan recommends establishing a WA Clean Energy Jobs Plan 2050, three regional training hubs, and dedicated pathways for female and under-represented apprentices.
  • Environmental Safeguards & Community Benefits: Fast-tracked development must be paired with State Planning Policies that avoid high-biodiversity and cultural heritage lands, mandate new data centres to run on additional renewable power, and deliver household electrification rebates and First Nations equity partnerships.
Workers at Keppel Prince in Portland manufacture and install wind turbines in Australia's burgeoning industry.

What you can do

WA has an opportunity to lead on sustainable, clean energy and associated industries. You can help by:

REPORT: WA Clean Energy, Jobs & Industry Plan

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Climate Change

COP17: Key outcomes agreed at the UN biodiversity conference in Yerevan

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Article Contents

Countries have completed the first “global review” of their progress towards reversing nature loss by 2030 at the COP17 biodiversity talks in Yerevan, Armenia.

The review “notes with deep concern” that, unless action is “rapidly accelerated”, the goal to reverse nature loss and meet a set of 23 targets by 2030 “will not be achieved”.

It “urges” countries to accelerate action, including by “increased ambition in addressing the gaps”.

Much of the discussions in Yerevan focused on how to raise the necessary funds to help developing countries protect nature.

Some major economies pushed to expand the range of nations that are expected to provide finance, with countries agreeing at the end of the two weeks of talks that non-donors that want to contribute can “signal interest” before COP18.

This came after developed countries failed to meet a target to significantly ramp up nature finance over the last few years.

It also came as a landmark fund agreed at COP16 in Colombia to pay communities for the genetic resources derived from nature stands nearly empty two years on.

The Yerevan talks marked the halfway point of the “Kunming-Montreal Global Biodiversity Framework” (GBF), the “Paris Agreement for nature” first made in 2022 and due to be achieved by 2030.

During the nearly 12-hour-long final plenary, countries voted for Quito, Ecuador, to host the COP18 nature talks, which will be held in 2028.

Countries managed to sign off on all the major negotiation texts, marking a stark contrast to COP16, which ran so far over time that the Colombian presidency lost “quorum”, forcing talks to resume in Rome months later. 

Below, Carbon Brief has detailed analysis of all of the key outcomes from COP17.