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Climate change is a shift in our planet’s weather and climate systems that brings about increasing average temperatures and more erratic weather events, rising seas, changes in habitats and wildlife, and a myriad of other impacts. Understanding the implications and likelihood of climate change impacts on natural and human systems in the Asia-Pacific region is important for developing strategies to safeguard the region against environmental, social and economic perturbations.

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Terrestrial Ecosystems

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  • Technology-Driven Methods for Estimation of Nature-Based Carbon Stocks in Singapore

    Khairun Nisha Binte Mohamed Ramdzan, Zu Dienle Tan, Leah Mary Lilly Denoun, H. Manjari Jayathilake, Annabel Jia Yi Lim, Yiwen Zeng, Hao Tang, and Lian Pin Koh

    Centre for Nature-based Climate Solutions, Faculty of Science, National University of Singapore

    Final Report

    Calculating forest carbon using forest inventory measurements can be laborious, mainly when conducted across an entire forest. As a result, reliance on traditional ground-based methods alone may not provide comprehensive forest information at a broad spatial scale. Instead, remote sensing technologies such as LiDAR (Light Detection and Ranging) and satellite imagery offer invaluable tools for gathering forest information, including tree heights and canopy structure, across vast landscapes. This project incorporated remote sensing technologies and field measurements to pave the way for a cost-effective means of surveying and monitoring nature-based carbon projects. It provides a preliminary estimate of carbon for different forest ecosystem types across Singapore and demonstrated the use of remote sensing technology for potential monitoring of forest aboveground carbon density (ACD). Further, the findings show that remote sensing technology can scale up field measurements and estimate spatially explicit carbon over a larger area. These carbon maps offer valuable insights into carbon sequestration potential, allowing stakeholders from diverse fields to make informed decisions on nature-based solution projects.

    Published March 2024
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  • Uncertainties in deforestation emission baseline methodologies and implications for carbon markets

    Hoong Chen Teo, Nicole Hui Li Tan, Qiming Zheng, Annabel Jia Yi Lim, Rachakonda Sreekar, Xiao Chen, Yuchuan Zhou, Tasya Vadya Sarira, Jose Don T. De Alban, Hao Tang, Daniel A. Friess & Lian Pin Koh

    Nature Communications

    Carbon credits generated through jurisdictional-scale avoided deforestation projects require accurate estimates of deforestation emission baselines, but there are serious challenges to their robustness. We assessed the variability, accuracy, and uncertainty of baselining methods by applying sensitivity and variable importance analysis on a range of typically-used methods and parameters for 2,794 jurisdictions worldwide. The median jurisdiction’s deforestation emission baseline varied by 171% (90% range: 87%-440%) of its mean, with a median forecast error of 0.778 times (90% range: 0.548-3.56) the actual deforestation rate. Moreover, variable importance analysis emphasised the strong influence of the deforestation projection approach. For the median jurisdiction, 68.0% of possible methods (90% range: 61.1%-85.6%) exceeded 15% uncertainty. Tropical and polar biomes exhibited larger uncertainties in carbon estimations. The use of sensitivity analyses, multi-model, and multi-source ensemble approaches could reduce variabilities and biases. These findings provide a roadmap for improving baseline estimations to enhance carbon market integrity and trust.

    Published December 2023
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  • Increasing contribution of urban greenery to residential real estate valuation over time

    Hoong Chen Teo, Tze Kwan Fung, Xiao Ping Song, Richard N. Belcher, Kelly Siman, Ian Z.W. Chan, Lian Pin Koh

    Sustainable Cities and Society

    Cities can experience losing greenery to urban development, while also pursuing greening efforts. However, whether and how long-term changes in land-use and policies affect ecosystem services and greenery preferences is not well-known, due to the paucity of longitudinal data. We created a novel land cover fraction map in Singapore from 1990 to 2020 using high-resolution satellite imagery, finding an overall decline in greenery area within public housing towns and evidence of greenery intensification in the remaining greenery area. Hedonic pricing analysis suggested positive and increasing marginal effects of greenery area on real estate prices; for each apartment unit this was S$39,130 ± S$15,951 (9.2% ± 3.8% of the average real estate price) during the 1990s; S$46,049 ± S$14,124 (10.9% ± 3.3%) during the 2000s; and S$50,048 ± S$17,079 (11.7% ± 4.0%) during the 2010s. An increased preference for tree cover and decreased preference for grass cover was observed, reflecting long-term changes in urban land-use and greening efforts. Our results suggest that urban greenery has become increasingly valuable to home owners and society in Singapore, occurring alongside decreasing quantity and increasing quality of urban greenery, illustrating how combining careful development with greening efforts can lead to an increase in urban ecosystem services.

    Published September 2023
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  • Climate co-benefits of tiger conservation

    Aakash Lamba, Hoong Chen Teo, Rachakonda Sreekar, Yiwen Zeng, Luis Roman Carrasco, Lian Pin Koh

    Nature Ecology & Evolution

    Biodiversity conservation is increasingly being recognized as an important co-benefit in climate change mitigation programmes that use nature-based climate solutions. However, the climate co-benefits of biodiversity conservation interventions, such as habitat protection and restoration, remain understudied. Here we estimate the forest carbon storage co-benefits of a national policy intervention for tiger (Panthera tigris) conservation in India. We used a synthetic control approach to model avoided forest loss and associated carbon emissions reductions in protected areas that underwent enhanced protection for tiger conservation. Over a third of the analysed reserves showed significant but mixed effects, where 24% of all reserves successfully reduced the rate of deforestation and the remaining 9% reported higher-than-expected forest loss. The policy had a net positive benefit with over 5,802 hectares of averted forest loss, corresponding to avoided emissions of 1.08 ± 0.51 MtCO2 equivalent between 2007 and 2020. This translated to US$92.55 ± 43.56 million in ecosystem services from the avoided social cost of emissions and potential revenue of US$6.24 ± 2.94 million in carbon offsets. Our findings offer an approach to quantitatively track the carbon sequestration co-benefits of a species conservation strategy and thus help align the objectives of climate action and biodiversity conservation.

    Published May 2023
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  • Blue carbon science, management and policy across a tropical urban landscape

    Daniel A. Friess, Yasmine M.Gatt, Tze Kwan Fung, Danwei Huang, Valerie Kwan, Kiah Eng, Lian Pin Koh, et al.
    Landscape and Urban Planning

    The ability of vegetated coastal ecosystems to sequester high rates of “blue” carbon over millennial time scales has attracted the interest of national and international policy makers as a tool for climate change mitigation. The experiences of Singapore show that coastal ecosystems and their blue carbon stocks can be successfully managed along an urban coastline, and can help inform blue carbon science and management along other rapidly urbanizing coastlines throughout the tropics.

    Published October 2022
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  • Gains in biodiversity conservation and ecosystem services from the expansion of the planet’s protected areas

    Yiwen Zeng, Lian Pin Koh, David S. Wilcove
    Science Advances

    Protected areas safeguard biodiversity, ensure ecosystem functioning, and deliver ecosystem services to communities. However, only ~16% of the world’s land area is under some form of protection, prompting international calls to protect at least 30% by 2030. This paper models the outcomes of achieving this 30 × 30 target for terrestrial biodiversity conservation, climate change mitigation, and nutrient regulation.

    Published June 2022
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  • Future land-use competition constrains natural climate solutions

    Qiming Zheng, Kelly Siman, Yiwen Zeng, Hoong Chen Teo, Tasya Vadya Sarira,
    Rachakonda Sreekar, Lian Pin Koh
    Science of the Total Environment

    With the ongoing population growth, allocating natural areas for natural climate solutions (NCS) may compete with other socioeconomic priorities, especially urban development and food security. Our results estimate a substantial reduction, 0.3–2.8 GtCO2 yr−1 or 4–39 %, in NCS mitigation potential, of which cropland expansion for fulfilling future food demand is the primary cause. This impact is particularly severe in the tropics where NCS hold the most abundant mitigation potential. Our findings highlight immediate actions prioritized to tropical areas are important to best realize NCS and are key to developing realistic and sustainable climate policies.

    Published June 2022
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  • Achieving ambitious mangrove restoration targets will need a transdisciplinary and evidence-informed approach

    Daniel A. Friess, Yasmine M. Gatt, Rio Ahmad, Benjamin M. Brown, Frida Sidik, Dominic Wodehouse
    One Earth

    There are ambitious plans to restore hundreds of thousands of hectares of mangrove forests over the next 5 years to restore habitats and mitigate climate change. However, if not properly planned, such actions have the potential to fail. This paper outlines a transdisciplinary plan for mangrove restoration based on strong scientific principles.

    Published May 2022
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  • Nature-based climate solutions for expanding the global protected area network

    Rachakonda Sreekar, Yiwen Zeng, Qiming Zheng, Aakash Lamba, Hoong Chen Teo, Tasya Vadya Sarira, Lian Pin Koh
    Biological Conservation

    Protected areas (including other effective area-based conservation measures) are a cornerstone of biodiversity conservation. Many countries are increasingly committed to expanding protected area coverage to 30%, which requires an increase in global annual spending from $24b to ~$140b (between $103b and $177b). Our results point to the largely untapped potential of nature-based climate solutions to accelerate protected area expansion, thereby conserving biodiversity and mitigating climate change.

    Published May 2022
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  • Blue carbon as a natural climate solution

    Peter I. Macreadie, Micheli D. P. Costa, Trisha B. Atwood, Daniel A. Friess, Jeffrey J. Kelleway, Hilary Kennedy, Catherine E. Lovelock, Oscar Serrano, Carlos M. Duarte
    Nature Reviews Earth Environment

    Blue carbon ecosystems (BCEs) store carbon and provide co-benefits such as coastal protection and fisheries enhancement. Blue carbon sequestration has therefore been suggested as a natural climate solution. This review examines the potential for BCEs to act as carbon sinks and the opportunities to protect or restore ecosystems for this function.

    Published November 2021
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  • Economic value of illegal wildlife trade entering the USA

    Jia Hao Tow, William S. Symes, Luis Roman Carrasco
    PLoS ONE

    Illegal wildlife trade is one of the greatest threats to biodiversity. Understanding its economic value is a first step to establishing the magnitude of the problem. This paper develops a dataset of illegal wildlife trade prices and combine it with seizure data to estimate the economic value of illegal wildlife trade entering the USA.

    Published October 2021
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  • Large conservation opportunities exist in >90% of tropic-subtropic coastal habitats adjacent to cities

    Tessa Mazor, Daniel A.Friess, Peter A.Todd, Danwei Huang,  Nhung T.H.Nguyen, Megan I.Saunders, Rebecca K.Runting, Ryan J.Lowe, PaulaCartwright, James P.Gilmour, Catherine E.Lovelock
    One Earth

    Coastal areas are urbanizing rapidly, currently supporting >40% of the world's population. Yet, coastal cities are facing greater vulnerability to climate-change-related hazards, causing significant social and economic disruptions. Investing in the protection of existing coastal habitats is considered a low-cost nature-based solution with co-benefits for society and biodiversity. This study examines the global applicability of this solution across 5,096 coastal urban areas in tropical and subtropical regions.

    Published July 2021
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  • Telecoupled environmental impacts are an obstacle to meeting the sustainable development goals

    Yiwen Zeng, Rebecca K. Runting, James E. M. Watson, Luis Roman Carrasco
    Sustainable Development

    International trade is responsible for connecting human and natural systems across distant countries, and has profound implications for sustainability. In particular, telecoupling, the socioeconomic and environmental interactions between distant countries as a result of, among others, global trade, typically leaves less affluent nations bearing the largest environmental impacts. This paper takes a broad global network analysis approach to address this gap, and assess the vulnerability of the SDGs' indicators and their interactions to telecoupling across 180 countries.

    Published July 2021
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  • Nature-based engineering: a review on reducing coastal flood risk with mangroves

    Rik Gijsman, Erik M. Horstman, Daphne van der Wal, Daniel A. Friess, Andrew Swales, Kathelijne M. Wijnberg
    Frontiers in Marine Science

    Integration of mangroves in projects to reduce coastal flood risk is increasingly being recognised as a sustainable and cost-effective alternative. The implementation of mangroves in flood risk reduction, however, remains complex. This paper reviews existing evidence, monitoring techniques and modelling approaches from the viewpoint of mangrove functionality and persistence.

    Published July 2021
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  • A metric for spatially explicit contributions to science-based species targets

    Louise Mair, Hugh P. Possingham, Lian Pin Koh, et al.
    Nature Ecology and Evolution

    The Convention on Biological Diversity’s post-2020 Global Biodiversity Framework will probably include a goal to stabilize and restore the status of species. Its delivery would be facilitated by making the actions required to halt and reverse species loss spatially explicit. This paper developed a species threat abatement and restoration (STAR) metric that is scalable across species, threats and geographies.

    Published June 2021
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  • Global potential and limits of mangrove blue carbon for climate change mitigation

    Yiwen Zeng, Daniel A.Friess, Tasya Vadya Sarira, Kelly Siman, Lian Pin Koh
    Current Biology

    Despite the outsized role of mangrove forests in sustaining biodiversity, ecosystem function, and local livelihoods, the protection of these vital habitats through blue carbon financing has been limited. This paper quantifies the extent of this missed conservation and financial opportunity, showing that the protection of ∼20% of the world’s mangrove forests (2.6 Mha) can be funded through carbon financing.

    Published April 2021
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  • Climate-informed hydrologic modeling and policy typology to guide managed aquifer recharge

    Xiaogang He, Benjamin P. Bryant, Tara Moran, Katharine J. Mach, Zhongwang Wei, David L. Freyberg
    Science  Advances

    Harvesting floodwaters to recharge depleted groundwater aquifers can simultaneously reduce flood and drought risks and enhance groundwater sustainability. However, deployment of this multibeneficial adaptation option is fundamentally constrained by how much water is available for recharge (WAFR) at present and under future climate change. This paper develops a climate-informed and policy-relevant framework to quantify WAFR, its uncertainty, and associated policy actions.

    Published April 2021
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  • Future carbon emissions from global mangrove forest loss

    Maria F. Adame, Rod M. Connolly, Mischa P. Turschwell, Catherine E. Lovelock, Temilola Fatoyinbo, David Lagomasino, Liza A. Goldberg, Jordan Holdorf, Daniel A. Friess, Sigit D. Sasmito, Jonathan Sanderman, Michael Sievers, Christina Buelow, J. Boone Kauffman, Dale Bryan-Brown, Christopher J. Brown
    Global Change Biology

    Mangroves have among the highest carbon densities of any tropical forest. Incorporating mangroves into Nationally Determined Contributions to the Paris Agreement and their valuation on carbon markets requires predicting how the management of different land-uses can prevent future greenhouse gas emissions and increase CO2 sequestration. This paper integrates comprehensive global datasets for carbon stocks, mangrove distribution, deforestation rates, and land-use change drivers into a predictive model of mangrove carbon emissions.

    Published February 2021
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  • Carbon prospecting in tropical forests for climate change mitigation

    Lian Pin Koh, Yiwen Zeng, Tasya Vadya Sarira, Kelly Siman
    Nature Communications

    Carbon finance projects that protect tropical forests could support both nature conservation and climate change mitigation goals. Global demand for nature-based carbon credits is outpacing their supply, due partly to gaps in knowledge needed to inform and prioritize investment decisions. This paper shows that at current carbon market prices the protection of tropical forests can generate investible carbon amounting to 1.8 (±1.1) GtCO2e yr−1 globally, and financially viable carbon projects could generate return-on-investment amounting to $46.0b y−1 in net present value. However, ~80% (1.24 billion ha) of forest carbon sites would be financially unviable for failing to break even over the project lifetime. From a conservation perspective, unless carbon prices increase in the future, it is imperative to implement other conservation interventions, in addition to carbon finance, to safeguard carbon stocks and biodiversity in vulnerable forests.

    Published February 2021
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  • Global urban reforestation can be an important natural climate solution

    Hoong Chen Teo, Yiwen Zeng, Tasya Vadya Sarira, Tze Kwan Fung, Qiming Zheng, Xiao Ping Song, Kwek Yan Chong, Lian Pin Koh
    Environmental Research Letters

    The climate mitigation potential of urban nature-based solutions (NBSs) is often perceived as insignificant and thus overlooked, as cities primarily pursue NBSs for local ecosystem services. This paper modelled the global potential and limits of urban reforestation worldwide, and find that 10.9 ± 2.8 Mha of land (17.6% of all city areas) are suitable for reforestation, which would offset 82.4 ± 25.7 MtCO2e yr−1 of carbon emissions.

    Published February 2021
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  • The value of China’s ban on wildlife trade and consumption

    Lian Pin Koh, Yuhan Li, Janice Ser Huay Lee
    Nature Sustainability

    China’s decision to ban the trade and consumption of terrestrial wild animals, while controversial, is a viable response to the COVID-19 pandemic. The ban has implications that extend beyond safeguarding human health to also help combat illegal wildlife trade and protect threatened species.

    Published January 2021
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  • Conservation cost-effectiveness: a review of the evidence base

    Thomas Pienkowski, Carly Cook, Megha Verma, Luis Roman Carrasco
    Conservation Science and Practice

    Prioritizing conservation interventions based on their cost-effectiveness may enhance global conservation impact. To do this prioritization, conservation decision-makers need evidence of what works where and how much it costs. Yet, the size, representativeness, and strength of the cost-effectiveness evidence base are unknown. This paper reviews conservation cost-effectiveness studies, exploring the representation of different types of conservation interventions, habitats and locations, and the methods used.

    Published January 2021
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  • Artificial light at night advances spring phenology in the United States

    Qiming Zheng, Hoong Chen Teo, Lian Pin Koh
    Remote Sensing

    Plant phenology is closely related to light availability as diurnal and seasonal cycles are essential environmental cues for organizing bio-ecological processes. The natural cycles of light, however, have been dramatically disrupted by artificial light at night (ALAN) due to recent urbanization. The influence on plant phenology of ALAN and its spatial variation remain largely unknown. By analyzing satellite data on ALAN intensity across the United States, this paper showed that ALAN tended to advance the start date of the growing season (SOS), although the overall response of SOS to ALAN was relatively weak compared with other potential factors.

    Published January 2021
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  • The environmental impacts of palm oil in context

    Erik Meijaard, Thomas M. Brooks, Janice Ser Huay Lee, Lian Pin Koh et al.
    Nature Plants

    Delivering the Sustainable Development Goals (SDGs) requires balancing demands on land between agriculture (SDG 2) and biodiversity (SDG 15). The production of vegetable oils and, in particular, palm oil, illustrates these competing demands and trade-offs. This Review highlights that although substantial gaps remain in our understanding of the relationship between the environmental, socio-cultural and economic impacts of oil palm, and the scope, stringency and effectiveness of initiatives to address these, there has been little research into the impacts and trade-offs of other vegetable oil crops.

    Published December 2020
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  • Economic and social constraints on reforestation for climate mitigation in Southeast Asia

    Yiwen Zeng, Tasya Vadya Sarira, L. Roman Carrasco, Kwek Yan Chong, Daniel A. Friess, Janice Ser Huay Lee, Pierre Taillardat, Thomas A. Worthington, Yuchen Zhang, Lian Pin Koh
    Nature Climate Change

    As climate change continues to threaten human and natural systems, the search for cost-effective and practical mitigation solutions is gaining momentum. Reforestation has recently been identified as a promising nature-based climate solution. Yet there are context-dependent biophysical, financial, land-use and operational constraints to reforestation that demand careful consideration. This paper shows that 121 million ha of presently degraded land in Southeast Asia, a region noted for its significant reforestation potential, are biophysically suitable for reforestation.

    Published August 2020
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  • Protecting irrecoverable carbon in Earth’s ecosystems

    Allie Goldstein, Will R. Turner, Seth A. Spawn, Lian Pin Koh et al.
    Nature Climate Change

    Avoiding catastrophic climate change requires rapid decarbonization and improved ecosystem stewardship. To achieve the latter, ecosystems should be prioritized by responsiveness to direct, localized action and the magnitude and recoverability of their carbon stores. This paper shows that a range of ecosystems contain ‘irrecoverable carbon’ that is vulnerable to release upon land use conversion and, once lost, is not recoverable on timescales relevant to avoiding dangerous climate impacts.

    Published March 2020
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