The Palakkad Gap, the lowest-altitude mountain pass in the Western Ghats, serves as an important bioclimatic corridor that facilitates for biodiversity exchange. However, it is currently experiencing intensifying and unsustainable land-use transformations. Using multi-temporal Landsat imagery (Landsat 5 Thematic Mapper (TM), Landsat 7 Enhanced Thematic Mapper Plus (ETM +), and Landsat 8 Operational Land Imager/Thermal Infrared Sensor (OLI/TIRS)), this study analyses the spatiotemporal dynamics of land use/land cover (LULC), land surface temperature (LST), and land-specific carbon emissions (LCEs) across the Palakkad Gap from 1994 to 2024. Supervised classification (Maximum Likelihood) and the InVEST carbon model were employed to analyze LULC transitions, thermal landscape evolution, and carbon storage changes. Built-up areas expanded significantly by 9,101.86 ha, primarily at the expense of 7,216.54 ha of agricultural land. This land-use shift corresponded with significant thermal alterations—Medium and High LST zones increased by 57,049.18 ha and 12,927.98 ha, respectively. Carbon-rich ecosystems suffered extensive degradation with the Critical carbon category (25 tC/ha) expanding fourfold while Normal and Salubrious zones declined by > 7,000 ha. Total carbon emissions reached 555,619 tons over three decades, demonstrating urbanization’s compounded impact on regional microclimates and carbon sequestration. Land-Specific Carbon Emissions (LCEs) peaked in 2004 (1,906 × 103 tons/year) before declining marginally to 1,853 × 103 tons/year by 2024, with built-up and agricultural lands as dominant emission sources. High-emission sectors (e.g., WSW) exhibited elevated LST, while carbon sinks (e.g., NNW) showed significant LST increases (+ 4.54 °C) due to urbanization legacy effects. Regression analyses indicated a weak inverse relationship between LCEs and LST (R2 = 0.11–0.26), suggesting emissions reductions alone may not fully mitigate warming. This study presents one of the first integrated assessments of LULC, LST, and carbon emissions in the Palakkad Gap using InVEST model. It highlights the urgency of integrated land-use planning, heat mitigation strategies, and ecological zoning to protect this biodiversity hotspot. The findings provide a scientific foundation for policy making in ecologically vulnerable regions, advocating for targeted emissions control and green infrastructure to enhance climate resilience and sustainability across the Palakkad Gap and broader Western Ghats landscape. The 2034 projection highlights a strong forward trajectory of land transformation, with built-up area increasing to 15,663 ha (an additional 3,954 ha from 2024) and agricultural land declining to 95,380 ha (a reduction of 4,127 ha). Carbon storage in high-density categories contracts further, while critical low-carbon zones expand to 16,707 ha. Net land-based emissions rise to 56.6 × 103 t C per year, and mean LST reaches 31.33 °C, dominated by medium (80,786 ha) and high (17,504 ha) temperature zones. These future estimates underscore the likelihood of sustained warming and reduced carbon resilience under continued land-use pressures. Graphical Abstract This visual summary serves as a pivotal entry point into the research, offering a concise overview of the study’s core findings and methodologies in the Palakkad Gap, the lowest pass in the Western Ghats. The graphical abstract captures the integration of land use/land cover (LULC) transitions, carbon emissions, and land surface temperature (LST) dynamics from 1994 to 2024 using Landsat satellite data and the InVEST carbon model. The diagram showcases urban expansion, agricultural decline, and increasing surface temperature zones. It also highlights spatial patterns of land-specific carbon emissions, peaking in high urbanization areas. The study identifies a weak inverse correlation between carbon emissions and LST, suggesting complex climatic interactions. The visual conveys a clear message: despite emissions control, surface warming persists due to land conversion legacy effects. Through arrows, maps, and charts, the abstract efficiently guides the viewer through the research process and outcomes. It emphasizes the urgent need for integrated land-use policy, climate-resilient zoning and ecological restoration. By providing a rapid visual comprehension of the paper’s essence, the graphical abstract enhances visibility and impact, making it an effective tool for broader scientific dissemination. A simplified topographic map outlines the study area’s location and boundaries, establishing the geographical context. Sequential panels illustrate the timeline of land use/land cover (LULC) transitions from 1994 to 2024, highlighting significant landscape changes—shrinking agricultural land, expanding built-up areas, and degrading vegetation and water bodies—driven by anthropogenic activities. Carbon dynamics are depicted using red arrows for emissions from built-up and agricultural areas and green arrows for carbon sinks like vegetation and water bodies, with quantitative labels showing agricultural emissions. Despite ongoing sequestration, net carbon emissions have risen, disrupting the regional carbon balance. A bar chart shows the land surface temperature (LST) gradient shifting from Very Low (< 26 °C) to Very High (> 38 °C), underscoring increased thermal stress due to land conversion and urban heat island effects. The summary panel visually encapsulates the findings—built-up ↑, agriculture ↓, LST ↑, and carbon storage ↓—emphasizing that land-use change is intensifying climate impacts in the Palakkad Gap. The 2034 projection panel shows built-up land increasing to 15,663 ha and agricultural land declining to 95,380 ha. Critical low-carbon zones expand to 16,707 ha as higher-density carbon classes continue to shrink. Net land-based emissions rise to 56.6 × 103 t C per year. Mean land surface temperature reaches 31.33 °C, with medium and high temperature zones covering 80,786 ha and 17,504 ha. This future scenario highlights continued warming and declining carbon resilience if present land-use trends persist. Together, these elements follow a logical flow from spatial context to transformation, thermal response, emissions, and conclusions, offering a clear and impactful overview of the study’s core findings and implications.

Interlinking Land Use Change, Carbon Emissions, and Surface Temperature in the Palakkad Gap of Western Ghats: Insights for Climate Resilience and Sustainability

期刊论文
发表日期：

2026年1月29日

查看全文

Sajeesh Viswambharan,
Indu Tarur Kumaramkandath,
Richard Scaria,
Pankajakshan Pangunni,
Javaid Ahmad Tali,
Ishfaq Hussain Malik

摘要

The Palakkad Gap, the lowest-altitude mountain pass in the Western Ghats, serves as an important bioclimatic corridor that facilitates for biodiversity exchange. However, it is currently experiencing intensifying and unsustainable land-use transformations. Using multi-temporal Landsat imagery (Landsat 5 Thematic Mapper (TM), Landsat 7 Enhanced Thematic Mapper Plus (ETM +), and Landsat 8 Operational Land Imager/Thermal Infrared Sensor (OLI/TIRS)), this study analyses the spatiotemporal dynamics of land use/land cover (LULC), land surface temperature (LST), and land-specific carbon emissions (LCEs) across the Palakkad Gap from 1994 to 2024. Supervised classification (Maximum Likelihood) and the InVEST carbon model were employed to analyze LULC transitions, thermal landscape evolution, and carbon storage changes. Built-up areas expanded significantly by 9,101.86 ha, primarily at the expense of 7,216.54 ha of agricultural land. This land-use shift corresponded with significant thermal alterations—Medium and High LST zones increased by 57,049.18 ha and 12,927.98 ha, respectively. Carbon-rich ecosystems suffered extensive degradation with the Critical carbon category (25 tC/ha) expanding fourfold while Normal and Salubrious zones declined by > 7,000 ha. Total carbon emissions reached 555,619 tons over three decades, demonstrating urbanization’s compounded impact on regional microclimates and carbon sequestration. Land-Specific Carbon Emissions (LCEs) peaked in 2004 (1,906 × 10³ tons/year) before declining marginally to 1,853 × 10³ tons/year by 2024, with built-up and agricultural lands as dominant emission sources. High-emission sectors (e.g., WSW) exhibited elevated LST, while carbon sinks (e.g., NNW) showed significant LST increases (+ 4.54 °C) due to urbanization legacy effects. Regression analyses indicated a weak inverse relationship between LCEs and LST (R² = 0.11–0.26), suggesting emissions reductions alone may not fully mitigate warming. This study presents one of the first integrated assessments of LULC, LST, and carbon emissions in the Palakkad Gap using InVEST model. It highlights the urgency of integrated land-use planning, heat mitigation strategies, and ecological zoning to protect this biodiversity hotspot. The findings provide a scientific foundation for policy making in ecologically vulnerable regions, advocating for targeted emissions control and green infrastructure to enhance climate resilience and sustainability across the Palakkad Gap and broader Western Ghats landscape. The 2034 projection highlights a strong forward trajectory of land transformation, with built-up area increasing to 15,663 ha (an additional 3,954 ha from 2024) and agricultural land declining to 95,380 ha (a reduction of 4,127 ha). Carbon storage in high-density categories contracts further, while critical low-carbon zones expand to 16,707 ha. Net land-based emissions rise to 56.6 × 10³ t C per year, and mean LST reaches 31.33 °C, dominated by medium (80,786 ha) and high (17,504 ha) temperature zones. These future estimates underscore the likelihood of sustained warming and reduced carbon resilience under continued land-use pressures.

Graphical Abstract

This visual summary serves as a pivotal entry point into the research, offering a concise overview of the study’s core findings and methodologies in the Palakkad Gap, the lowest pass in the Western Ghats. The graphical abstract captures the integration of land use/land cover (LULC) transitions, carbon emissions, and land surface temperature (LST) dynamics from 1994 to 2024 using Landsat satellite data and the InVEST carbon model. The diagram showcases urban expansion, agricultural decline, and increasing surface temperature zones. It also highlights spatial patterns of land-specific carbon emissions, peaking in high urbanization areas. The study identifies a weak inverse correlation between carbon emissions and LST, suggesting complex climatic interactions. The visual conveys a clear message: despite emissions control, surface warming persists due to land conversion legacy effects. Through arrows, maps, and charts, the abstract efficiently guides the viewer through the research process and outcomes. It emphasizes the urgent need for integrated land-use policy, climate-resilient zoning and ecological restoration. By providing a rapid visual comprehension of the paper’s essence, the graphical abstract enhances visibility and impact, making it an effective tool for broader scientific dissemination. A simplified topographic map outlines the study area’s location and boundaries, establishing the geographical context. Sequential panels illustrate the timeline of land use/land cover (LULC) transitions from 1994 to 2024, highlighting significant landscape changes—shrinking agricultural land, expanding built-up areas, and degrading vegetation and water bodies—driven by anthropogenic activities. Carbon dynamics are depicted using red arrows for emissions from built-up and agricultural areas and green arrows for carbon sinks like vegetation and water bodies, with quantitative labels showing agricultural emissions. Despite ongoing sequestration, net carbon emissions have risen, disrupting the regional carbon balance. A bar chart shows the land surface temperature (LST) gradient shifting from Very Low (< 26 °C) to Very High (> 38 °C), underscoring increased thermal stress due to land conversion and urban heat island effects. The summary panel visually encapsulates the findings—built-up ↑, agriculture ↓, LST ↑, and carbon storage ↓—emphasizing that land-use change is intensifying climate impacts in the Palakkad Gap. The 2034 projection panel shows built-up land increasing to 15,663 ha and agricultural land declining to 95,380 ha. Critical low-carbon zones expand to 16,707 ha as higher-density carbon classes continue to shrink. Net land-based emissions rise to 56.6 × 10³ t C per year. Mean land surface temperature reaches 31.33 °C, with medium and high temperature zones covering 80,786 ha and 17,504 ha. This future scenario highlights continued warming and declining carbon resilience if present land-use trends persist. Together, these elements follow a logical flow from spatial context to transformation, thermal response, emissions, and conclusions, offering a clear and impactful overview of the study’s core findings and implications.