Change In Southeast Asia Research Articles

Monitoring the effects of climate, land cover and land use changes on multi-hazards in the Gianh River watershed, Vietnam

Abstract In recent decades, global rapid urbanization has exacerbated the impacts of natural hazards due to changes in Southeast Asia’s environmental, hydrological, and socio-economic conditions. Confounding non-stationary processes of climate change and global warming and their negative impacts can make hazards more complex and severe, particularly in Vietnam. Such complexity necessitates a study that can synthesize multi-dimensional natural-human factors in disaster risk assessments. This synthesis study aims to assess and monitor climate change and land-cover/land-use change impacts on flood and landslide hazards in Vietnam’s Gianh River basin. Three Deep Neural Network (DNN) and optimization algorithms, including the Adam, Tunicate Swarm Algorithm (TSA), and Dwarf Mongoose Optimization (DMOA) were used to determine the regions with the probability of the occurrence of flood and landslide and their combination. All efficiently evaluated hazard susceptibility based on a synthesis analysis encompassing 14 natural and anthropogenic conditioning factors. Of the three, the Deep Neural Network (DNN)-DMOA model performed the best for both flood and landslide susceptibility, with area-under-curve values of 0.99 and 0.97, respectively, followed by DNN-TSA (0.97 for flood, 0.92 for landslide), and DNN-Adam (0.96 for flood, 0.89 for landslide). Although the area affected by flooding is predicted to decrease, the overall trend for total hazard-prone areas increases over 2005–2050 due to the more extensive area affected by landslides. This study develop and demonstrate a robust framework to monitor multi-hazard susceptibility, taking into account the changes in climate and land-use influence the occurrence of multiple hazards. Based on the quantitative assessment, these findings can help policymakers understand and identify confounding hazard issues to develop proactive land-management approaches in effective mitigation or adaptation strategies that are spatially and temporally appropriate.

Relative contribution of dynamic and thermodynamic components on Southeast Asia future precipitation changes from different multi-GCM ensemble members

To address the gap in understanding precipitation changes in Southeast Asia and to enhance the reliability of climate projections for the region through moisture budget analysis, this study examines the differences among six multi-model ensembles of CMIP6 simulated precipitation in term of moisture budget analysis. It investigates the relative contributions of thermodynamic and dynamic components to seasonal precipitation changes over Southeast Asia under the highest emission scenario, SSP5-8.5. The comparison between ensembles indicates that Good performance model ensembles slightly outperform the combination of all resolution and all category ensembles in reducing the biases. There is no strong evidence showing that good category ensembles outperform the combination of all model ensemble groups in simulating the spatial pattern of historical seasonal precipitation. From the perspective of moisture budget, regions receiving seasonal high rainfall intensity are mainly influenced by the moisture convergence during the monsoon seasons: northeast monsoon (December‒January‒February) and southwest monsoon (June–July–August). By the late 21st century (2081–2100), all model ensemble projections show an increase in December‒January‒February precipitation over the northern Southeast Asia and decreased June‒July‒August rainfall in the southern regions. The moisture budget analysis explained that the seasonal mean rainfall change in Southeast Asia is largely influenced by evaporation and followed by moisture flux convergence. The changes in moisture flux convergence are contributed by both the dynamic and thermodynamic components. Greater inter-model uncertainty was found in the precipitation dynamic component compared to the thermodynamic component suggesting the existence of large discrepancy between the various approaches used by GCMs in describing atmospheric dynamics. The study highlights that the Good model ensemble with middle to low resolution is able to narrow the inter-model uncertainties in terms of the moisture budget analysis compared to the combination of all Good model ensembles.

A high-resolution perspective of extreme rainfall and river flow under extreme climate change in Southeast Asia

Abstract. This article provides high-resolution information on the projected changes in annual extreme rainfall and high- and low-streamflow events over Southeast Asia under extreme climate change. The analysis was performed using the bias-corrected result of the High-Resolution Model Intercomparison Project (HighResMIP) multi-model experiment for the period 1971–2050. Eleven rainfall indices were calculated, along with streamflow simulation using the PCR-GLOBWB hydrological model. The historical period 1981–2010 and the near-future period 2021–2050 were considered for this analysis. Results indicate that, over former mainland Southeast Asia, Myanmar will face more challenges in the near future. The east coast of Myanmar will experience more extreme high-rainfall conditions, while northern Myanmar will have longer dry spells. Over the Indonesian maritime continent, Sumatra and Java will suffer from an increase in dry-spell length of up to 40 %, while the increase in extreme high rainfall will occur over Borneo and mountainous areas in Papua. Based on the streamflow analysis, the impact of climate change is more prominent in a low-flow event than in a high-flow event. The majority of rivers in the central Mekong catchment, Sumatra, Peninsular Malaysia, Borneo, and Java will experience more extreme low-flow events. More extreme dry conditions in the near future are also seen from the increasing probability of future low-flow occurrences, which reaches 101 % and 90 %, on average, over Sumatra and Java, respectively. In addition, based on our results over Java and Sumatra, we found that the changes in extreme high- and low-streamflow events are more pronounced in rivers with steep hydrographs (rivers where flash floods are easily triggered), while rivers with flat hydrographs have a higher risk in terms of the probability of low-flow change.

The Challenges and Upheavals in Governing Climate Change in Southeast Asia

The Challenges and Upheavals in Governing Climate Change in Southeast Asia

Exploring context-specific perspectives: a qualitative study on building climate resilience health-care facilities in southeast Asia

BackgroundAlthough existing literature provides various tools, frameworks, and guidelines for building health-care facilities that can withstand the impacts of climate change, there is little research focused on the practical implementation of such strategies. This gap in the research is particularly noticeable when applying these guidelines to specific geographical and environmental contexts. We focus specifically on the southeast Asia region, a region that has been identified as one of the most susceptible to the effects of a changing climate. By offering practical, region-specific recommendations, we hope to contribute to the ongoing efforts to mitigate the effects of climate change on health-care infrastructure and services. MethodsTo gain a comprehensive understanding of the specific challenges, needs, and feasible indicators for progress towards climate resilience in health-care facilities, we conducted in-depth interviews with members of the Global Green and Healthy Hospital Network in southeast Asia. Participants were selected based on a mix of facility and system parameters and were took into account various contexts, including urban and rural settings as well as low-income and high-income countries. Both private and public health systems and facilities were considered. This network comprises health-care professionals who are committed towards environmental sustainability and climate justice. FindingsFrom Oct 6 to 28, 2023, we conducted interviews with eight participants and augmented this analysis with data drawn from existing published reports. The interview findings highlighted various primary areas of focus, which encompassed disaster readiness, low-carbon strategies, and the financial aspects of climate resilience. A prevailing theme was the importance of behaviour change alongside staff training and education. The unique perspective centres around the notion of health equity and its relationship with climate change. This perspective underscores the heightened awareness of environmental, economic, and social disparities that are exacerbated by climate change in southeast Asia. Issues include resistance to change, lack of public awareness, and economic versus ecological priorities. The absence of a standardised and systematic approach to implementing climate-resilient healthcare indicates a need for flexible and adaptable regional policies. InterpretationThe findings of this study contribute to the broader understanding of how health services can be reoriented to face the realities of climate change effectively. This research outlines tangible recommendations for health services from both a process and impact points of view, and offers valuable insights for health policy makers, health-care providers, and researchers in the field. FundingHealth Care Without Harm southeast Asia.

Projections and patterns of heat-related mortality impacts from climate change in Southeast Asia

This study aims to investigate the impact of climate change on heat-related mortality in Southeast Asia in the future. The ensemble mean from five General Circulation Models (GCMs) including the Flexible Global Ocean-Atmosphere-Land System Model: Grid-Point Version 3 (FGOALS-g3), Max Planck Institute Earth System Model Version 1.2 (MPI-ESM1-2-LR), EC-Earth3, The Meteorological Research Institute Earth System Model Version 2.0 (MRI-ESM2-0), and Geophysical Fluid Dynamics Laboratory Earth System Model Version 4 (GFDL-ESM4) was used to project severe temperatures and heat indices in Southeast Asia under the Coupled Model Intercomparison Projects Phase 6 (CMIP6). This data was used to correlate with mortality data from the Global Burden of Disease database to quantify heat-related mortality in the region. The ensemble mean results show a reasonable level of accuracy in capturing temperature patterns in the Southeast Asian region with an R2 of 0.96, root mean square error (RMSE) of 0.84 and a standard deviation of residual (SDR) of 0.02. When compared to the baseline (1990–2019), temperature extreme indices are rising across all climatic scenarios, with a substantial increase in the SSP3–7.0 and SSP5–8.5 scenarios, ranging from 10% to 50% over the regions, with the heat index predicted to peak in the middle of the century. The two low-emission scenarios, SSP1-2.6 and SSP2-4.5, on the other hand, anticipate more moderate increases, indicating a potentially less severe impact on the region. As a result, under high-emission scenarios, there is expected to be a significant increase in heat-related mortality across Southeast Asia. The expected impact is estimated to affect between 200 and 300 people per 100,000 people from 2030 to 2079, accordingly. Our results highlight the critical need to address health-related impacts of climate change in this region.

Improving Functional Exercises Based on Experts’ Evaluation Weights for Emergency Responses

Social and economic changes in Southeast Asia have caused significant changes to Vietnam’s national emergency management structure, including expanding the role of firefighters from firefighting to rescue activities in various situations. It is essential to develop methods for designing exercises to identify and address the gaps in competencies related to the new roles assigned to Vietnamese firefighters. This study aimed to develop a quantitative method to effectively arrange exercise injects. It applies the analytic hierarchy process to determine the weights of response actions in functional exercises and uses comparison methods to establish the relationship between the weights of the action types, players’ capability targets, and disaster types. The results indicate that the action type weights change when the disaster type changes, whereas the capability weights within each action type remain constant. In this study, we developed a method to adjust the exercise structure based on response action weights and to optimize the number of injects that represent each action type. This innovative approach holds great significance in exercise design, increasing the likelihood of achieving the exercise capability targets, not only in Vietnam, but also in other countries.

ENSO may have contributed to sea level changes in the Gulf of Thailand during the Late-Holocene

The Gulf of Thailand is ideal for studying eustatic sea level fluctuations in Southeast Asia due to its shallow basin and tectonic stability. However, our understanding of how this region’s relative sea level (RSL) has fluctuated over the Holocene epoch is far from complete. In this study, we used lithostratigraphy, loss on ignition, grain size, and pollen analyses to reconstruct the environmental changes in the Sam Roi Yot wetland, which was significantly influenced by seawater intrusion, driven by fluctuations in RSL in the Gulf of Thailand. Therefore, the analyzed pollen records of the sediment core from the wetland reflected variabilities in the RSL in the Gulf of Thailand. Subsequently, we found that after a sea level highstand prior to 4000 cal y BP, the RSL gradually fell with two significant regressions at c. 2950 and 1850–1450 cal y BP before rising at 1450–1050 cal y BP and declining after that. The inconsistency between RSL reconstruction based on our results and the global sea level changes simulated by the Glacial Isostatic Adjustment (GIA) model further suggests that long–term El Niño Southern Oscillations (ENSO) variabilities may have played a significant role in sea level changes in the Gulf of Thailand over the Late-Holocene period. Thus, during extended El Niño or La Niña conditions, the sea level would have been consistently lower or higher than expected from eustatic and isostatic processes alone. Overall, this study emphasizes the importance of considering regional factors such as ENSO to understand sea level changes in Southeast Asia.

Emerging and re-emerging zoonotic viral diseases in Southeast Asia: One Health challenge.

The ongoing significant social, environmental, and economic changes in Southeast Asia (SEA) make the region highly vulnerable to the emergence and re-emergence of zoonotic viral diseases. In the last century, SEA has faced major viral outbreaks with great health and economic impact, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), arboviruses, highly pathogenic avian influenza (H5N1), and Severe Acute Respiratory Syndrome (SARS-CoV); and so far, imported cases of Middle East Respiratory Syndrome Coronavirus (MERS-CoV). Given the recent challenging experiences in addressing emerging zoonotic diseases, it is necessary to redouble efforts to effectively implement the "One Health" initiative in the region, which aims to strengthen the human-animal-plant-environment interface to better prevent, detect and respond to health threats while promoting sustainable development. This review provides an overview of important emerging and re-emerging zoonotic viral diseases in SEA, with emphasis on the main drivers behind their emergency, the epidemiological situation from January 2000 to October 2022, and the importance of One Health to promote improved intervention strategies.

Climate Change: An Opportunity for INDOPACOM

US Indo-Pacific Command should actively plan for operations to respond to and combat climate change because it will grow US influence in the region and provide a compelling alternative to China’s influence. Combating climate change supports the primary objective of countering China, operationalizes climate change response for US commanders, and offers a less threatening means to develop partnerships. Through qualitative analysis of threats to US security, current policy analysis, and select case studies of humanitarian assistance and disaster-relief missions to operationalize climate change as a US military mission, this article will assist US military and policy practitioners in planning for climate change in Southeast Asia and future exercises in the region.

Secular trend in water discharge transport in the Lower Mekong River-delta: Effects of multiple anthropogenic stressors, rainfall, and tropical cyclones

The Mekong River is one of the world's most important continental rivers, and provides invaluable water resources for the survival and social development of nearly 70 million inhabitants of Southeast Asia. However, little work has been carried out on the multiforcing-induced hydrological behavior of the Lower Mekong River-delta (LMR) over the past 100 years. Here, the secular variations in water discharge were analyzed for seven gauging stations along the main stream of the LMR from the 1920s-2019, to identify the riverine hydrological mechanisms under different dynamic conditions. The results show that the water discharge delivered by the LMR to the delta decreased on both 50-year and centennial scales. Meanwhile, the daily water discharge of the LMR-delta has become more evenly distributed intra-annually, leading to “no flood in the flood season, no drought in the dry season” in this reach. While regional rainfall dominates the long-term variations in the water discharge in the LMR, episodic tropical cyclones can induce a gradual increase with enlarged spatial divergences in water discharge from the mountainous region to the delta by bringing heavy rainfall. Moreover, although the operation of the mega dams in the Upper Mekong Basin has significantly influenced the distribution of the downstream water discharge in the dry season, minor impacts can also be found in the wet season. The water consumption for irrigation was increased from the upstream to the downstream basin, which may contribute to the severe reduction in the downstream water discharge, even though typhoons induced much more runoff along the downstream reach. Considering future climate change in Southeast Asia with potential upward trends in anthropogenic stressors, it can be expected that the water discharge of the LMR-delta could worsen, and urgent countermeasures that address water resource management should be strongly considered by decision-makers in the affected countries of the Mekong River-delta.

Ant-plant symbioses trade-offs and its role in forest restoration projects

Ant-plant symbioses are complex between-species interactions found only in the tropical environment. Typically, in such symbioses, plants provide housing structures and food to their ant symbionts. In return, the ants protect their plants' host against herbivore attack and additional nutrients to help with plants' growth. These win-win interactions range from facultative to obligate mutualism. This proposal aims to test the three main mechanisms: (1) by-product benefits, (2) partner fidelity feedback and (3) partner choice in stabilising the ant-plant mutualism. Understanding the mechanisms are crucial as they form the foundation of the ant-plant distribution and growth, in other words - the health of the myrmecophyte (ants-loving) trees in the forest ecosystem. Hence, ant-plant symbioses are an ideal model system for investigating the effects of anthropogenic changes, such as deforestation and climate change on the outcome of ant-plant mutualistic interactions. This project attempts to identify the mechanisms regulating the mutualistic interactions and, in particular, identify the context in which such mutualistic interactions evolved and adapt to the changing environment. We hypothesise that there will be a higher diversity of obligate mutualistic ant-plant interactions in the undisturbed environment compared to degraded habitat. Furthermore, we expect there are different complexity of symbioses, involving multiple partners (ants-hemipteran insects-bacteria-fungi-plants) that deepen our understanding of how such symbioses can be stabilised. Finally, the deforestation combined with climate change in Southeast Asia will have a detrimental effect on ant-plant symbioses, causing breakdown of mutualistic partners and invasion of cheater ant species that do not confer a protective advantage to their plants' host.

Analysis of Soil Bacterial Diversity from Tropical Rainforest and Oil Palm Plantation In Jambi, Indonesia by 16S rRNA-DGGE Profiles

Oil palm plantations are the most invasive land use changes in Southeast Asia. It must have affected unique natural biodiversity. This study aimed to investigate the diversity of soil bacteria based on 16S rRNA gene profiles from tropical forest and oil palm plantation in Jambi Province, Indonesia. Soil sample was taken from tropical forest and oil palm plantation from Jambi province, Indonesia. The forest site is in Bukit Duabelas National Park, and the nearby oil palm plantation is in Sarolangun District, Jambi Province, Indonesia. The diversity of bacterial communities from topsoil was studied using Denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene and common biodiversity indices. PCR amplification of 16S rRNA gene was successfully conducted primers-using 33F/ 518R primers. Phylogenetic approach was used for revealing the community shift of bacterial phyla and genera in both areas. Phylogenetic analysis showed there were 4 phyla of bacteria i.e., Firmicutes, Alphaproteobacteria, Gammaproteobacteria, and Actinobacteria, respectively. Actinobacteria was the most dominant group in both areas. The composition of soil bacterial community in the oil palm plantation, based on total number of bands 16S rRNA generated from DGGE was richer than that in the Bukit Dua Belas National Park. It was probably caused by plantation year circle more than 10 years and routine activities during the plantation management, such as applications of agricultural lime, herbicide and fertilizer.

Indigenous peoples activism on climate change in Southeast Asia: the role of regional scalar bridging organizations

Indigenous peoples in Southeast Asia have organized on issues that affect their rights at the local, national, regional and global level. This article argues that one important component of the rise of this activism is the presence of regional scalar bridging organizations that link activism across scales and support the growth of Indigenous movements by providing access to global and regional opportunities for action. In Southeast Asia, the Asian Indigenous Peoples Pact (AIPP) and Tebtebba play this role through their presence in global political arenas and their many activities with partner organizations in the region. Drawing on social movement theory, this article outlines how regional social movement organizations potentially support global activism in the Global South by scale bridging in the areas of (1) resource mobilization, (2) creation of political spaces and opportunities and (3) the diffusion of ideas. To illustrate this, the case of Indigenous peoples activism on climate change in Southeast Asia is presented through an examination of the work done in these three areas by the Asian Indigenous Peoples Pact (AIPP) and Tebtebba

Language Teacher Education, Reading, and Curriculum Change in Southeast Asia: A Laotian Perspective

This study was conducted to understand issues related to the current practice of English teacher education development in the Lao People’s Democratic Republic with a focus on reading. It recognizes that what pre-service teachers experience both prior to and during their teacher education are important and need to be understood if the goals of teacher education are to be achieved. Previous research found that pre-service teachers’ prior experiences of both reading and learning to read were mostly a matter of learning discrete language items rather than developing comprehension and critical reading, and that these experiences had shaped perceptions about how reading is taught. This study extends this understanding by investigating reading-related pedagogy on a teacher education programme. Its findings highlight a gap between an education policy that promotes communicative language teaching and classroom practice. Therefore, for the goals of policy to be realized in the language classroom, appropriate innovations are needed.

Farmers’ Adaptation Strategies to Climate Change in Southeast Asia: A Systematic Literature Review

This systematic review focuses on the relationship between the factors of adaptation strategies and the impact of climate change among farmers in Southeast Asia. Climate change, a phenomenon that occurs over many years, has affected the lives of farmers in the agricultural sector. Therefore, it is essential to analyse the factors that affect farmers’ decisions to determine their ability to adapt to climate change and maintain their livelihoods. As such, the present study examines farmers’ understanding of climate change and its impact on adaptation strategies in Southeast Asia. Approximately 15 related studies were found based on a systematic review of the repositories from Scopus and the Web of Sciences using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Hence, the paper delineates five key themes: (1) sociodemographic factors, (2) physical capital, (3) assistance, (4) information, and (5) social networking. Therefore, the results underlining the determinant factors, such as income, household members, farm size, land, number of workers, access to information, education, experiences, training, support from agencies, and social networks, influence the adaptation strategies among Southeast Asian farmers. This systematic review study emphasises information accessibility, education, training, and income as the most important factors for developing adaptation strategies for farmers to deal with climate change, rather than programme, internet usage, relatives, and the number of workers. Finally, combining the main factors can promote technological advancement for farmers who rely on agriculture as their main source of income and help farmers deal with climate variability to sustain their livelihood.

The impacts of transport from South and Southeast Asia on O<sub>3</sub> concentrations in China from 2015 to 2050

<p indent="0mm">Although the significant decrease in PM_2.5 concentrations across China in response to the Air Pollution Prevention and Control Action Plan during 2013–2017, the ozone (O₃) concentrations have increased rapidly. Previous studies have revealed that long-range transboundary transport from South Asia (SA) and Southeast Asia (SEA) greatly influences the O₃ concentrations in China; however, these studies majorly focused on biomass burning events. The impact of anthropogenic emissions from neighboring countries on China’s O₃ pollution has not been comprehensively and quantitatively investigated. In addition, the analysis of the impact of future transport from SA and SEA on O₃ concentrations in China is required. Based on (Shared Socioeconomic Pathways) SSPs, a new set of future emission inventories, this study estimated the MDA8 O₃ concentrations in China, SA, and SEA under different SSPs scenarios from 2015 to 2050 with varying anthropogenic and open burning emissions using a three-dimensional chemical transport model (GEOS-Chem). Several sensitivity experiments were simulated to quantitatively assess the impact of anthropogenic and open burning emission changes in SA and SEA on the future atmospheric O₃ concentrations in China. Transport from SA and SEA can influence MDA8 O₃ concentrations in China widely, covering the Pearl River Delta (PRD), Guangxi, Yunnan, Guizhou, Sichuan Basin (SCB), Qinghai, Tibet and parts of Xinjiang. It contributed to an increase in annual mean MDA O₃ concentrations over above regions by <sc>3.0–19.0 μg m⁻³</sc> in 2015, and led to an increase in MDA8 O₃ concentration in China by <sc>4.0 μg m⁻³.</sc> Monthly variation characteristics of the impacts of SA and SEA transport on concentrations of MDA O₃ in SCB, PRD, and YRD regions were further explored in this study. In 2015, the regional transport from SA and SEA had the highest impact on the MDA8 O₃ concentrations in SCB, increased its annual mean concentration by <sc>6.2 μg m⁻³,</sc> followed by PRD <sc>(+4.7 μg m⁻³),</sc> and YRD <sc>(+0.6 μg m⁻³).</sc> Accompanied by the strong westerly and southwesterly winds on the surface and 850 hPa near 30°N in spring, the influence of transport from SA and SEA on MDA8 O₃ concentrations was highest in SCB in March 2015 <sc>(+10.1 μg m⁻³,</sc> +7.2%), followed by April <sc>(+9.4 μg m⁻³,</sc> +6.4%). Due to the prevailing southwesterly winds at 10°–30°N on the surface and 850 hPa in summer, the contribution attained its peak in July <sc>(+14.0 μg m⁻³,</sc> +10.4%), followed by August <sc>(+9.1 μg m⁻³,</sc> +6.5%) in PRD, while it peaked in July <sc>(+2.5 μg m⁻³,</sc> +1.7%), followed by June <sc>(+1.4 μg m⁻³,</sc> +0.9%) in YRD. Based on medium and long-term perspectives (2015–2030), the impact of transport from SA and SEA on MDA8 O₃ concentrations in SCB, PRD, and YRD from 2015 to 2030 were simulated. Substantive reductions under SSP1, especially under SSP1-1.9 pathway were observed (the largest decline in SCB was <sc>−3.5 μg m⁻³</sc> (−36.5%) in April, and <sc>−3.0 μg m⁻³</sc> (−21.1%) and <sc>−1.1 μg m⁻³</sc> (−43.1%) in PRD and YRD, respectively, in July). The MDA8 O₃ concentrations in SCB, PRD, and YRD during 2015–2030 were projected to increase under SSP3-7.0 scenario (the highest increase in the SCB will be <sc>+1.5 μg m⁻³</sc> (+20.1%) in May, and <sc>+1.2 μg m⁻³</sc> (+8.5%) and <sc>0.2 μg m⁻³</sc> (+7.5%) in July, respectively, in PRD and YRD). Therefore, controlling O₃ pollution due to the transport from SA and SEA in China during 2015–2030 will be easier year by year under the SSP1-1.9 scenario, while greater efforts would be required under the SSP3-7.0 pathway. The long-term (2015–2050) trend of MDA8 O₃ concentrations in the above three regions affected by the transport from SA and SEA is similar to that of the mid-to-long term.

Southeast Asia island coastline changes and driving forces from 1990 to 2015

Global climate change and high-intensity human interventions have caused significant changes in island coastline. Due to the increase in sea level rise (SLR), inundation risk of islands has attracted attention in the recent past. However, high-quality data and large-scale studies on island coastline change are very few. This study aimed at investigating island changes in South East Asia (SEA) between 1990 and 2015 using an integrated workflow, including coastline extraction, analysis of changes, and discussion of driving forces based on remote sensing technology and GIS spatial analysis. More than 9000 islands were extracted. Approximately 12% of the total islands had undergone changes in coastlines, resulting in about 251 km2 decrease in area (421 islands showed increase in area while 678 islands showed a decrease in area). Coastline length increased by 821 km from 1990 to 2015. Natural coastlines decreased by 4238 km, whereas artificial coastlines increased by 5059 km. Approximately 1/3 of total coastlines changed in location (14.9% underwent deposition and 16.1% underwent retreat). The overall land-sea pattern of SEA islands presented a “west (slightly north) to east (slightly south)” distribution, with the evolutionary process of expansion patches spanning from west to east and from south to north. Human activities, material composition and landforms of the island coast played key roles in coastline changes, whereas SLR was not associated with extensive erosion of SEA islands. Our findings form a basis for integrated management of coastal zones of SEA island countries.

A multi-proxy approach to exploring Homo sapiens\u2019 arrival, environments and adaptations in Southeast Asia

The capability of Pleistocene hominins to successfully adapt to different types of tropical forested environments has long been debated. In order to investigate environmental changes in Southeast Asia during a critical period for the turnover of hominin species, we analysed palaeoenvironmental proxies from five late Middle to Late Pleistocene faunas. Human teeth discoveries have been reported at Duoi U’Oi, Vietnam (70–60 ka) and Nam Lot, Laos (86–72 ka). However, the use of palaeoproteomics allowed us to discard the latter, and, to date, no human remains older than ~ 70 ka are documented in the area. Our findings indicate that tropical rainforests were highly sensitive to climatic changes over that period, with significant fluctuations of the canopy forests. Locally, large-bodied faunas were resilient to these fluctuations until the cooling period of the Marine Isotope Stage 4 (MIS 4; 74–59 ka) that transformed the overall biotope. Then, under strong selective pressures, populations with new phenotypic characteristics emerged while some other species disappeared. We argue that this climate-driven shift offered new foraging opportunities for hominins in a novel rainforest environment and was most likely a key factor in the settlement and dispersal of our species during MIS 4 in SE Asia.

Genetic diversity and phylogenetic relationships of Malayan tapir (Tapirus indicus) populations in the Malay Peninsula based on mitochondrial DNA control region

The Malayan tapir (Tapirus indicus) is an endangered species in Southeast Asia (SEA). Over the years, there has only been a few reports on its population genetic structure and evolutionary history in SEA. In particular, while the captive Malayan tapir population in Thailand has received fairly more research in recent years, there has not been any wide-scale population genetic study in the Malay Peninsula since the last decade. In this study, we report on the genetic diversity and attempt to make inferences on the phylogeography of the Malayan tapir in the Malay Peninsula, using the mitochondrial DNA control region, including also data from previous studies. We identified 12 novel haplotypes and two distinct Malayan tapir clades with a divergence time of 14.6 million years ago (mya) in the Peninsular Malaysia (i.e. southern Malay Peninsula) samples, as opposed to only one clade found in the Thai (i.e. Thailand western border and northern Malay Peninsula) captive individuals, with an almost two-fold higher nucleotide diversity compared to the latter. The co-occurrence of the two lineages in southern Malay Peninsula suggested past historical events of population isolation, migration and admixture as a result of episodic glacial periods and paleoenvironmental changes in SEA. Only one haplotype shared between the populations of the two regions suggested further gene flow restriction at the narrow corridor of the Malay Peninsula as of present day.