Climate change and its impacts are no longer a subject for the future. Its impacts are being evidenced globally. Extreme events causing severe impact have been evidenced in the last decade in several places. In Goa, climate change has shifted from a future risk to a present-day environmental stressor. The State Action Plan for Climate Change (2023–2033) highlights that rising temperatures, erratic rainfall, and intensified land-use changes are accelerating ecological degradation and increasing socio-economic vulnerability.
The accumulation of greenhouse gases (GHGs) in the atmosphere has contributed significantly to the observed rise in global temperatures. Consistent with global trends, the state of Goa has experienced a measurable increase in mean annual temperature of more than 1°C during the period 1901–2018, with the warming occurring after 1990. According to the India Meteorological Department (2013), the rate of temperature increase in Goa exceeds the national average, with a pronounced acceleration observed since the 1970s.
Mean annual rainfall in Goa has risen by about 68%, with greater year-to-year variability since the 1970s, indicating increasingly erratic precipitation. In North Goa, rainfall increased from around 3000 mm in 1901 to nearly 5000 mm by 2015, a rise of about 66%. These shifts point to significant regional climate changes, impacting hydrology, ecosystems, and the need for adaptive planning strategies.
Long-term analyses (1901–2018) show a shift in Goa’s rainfall patterns, with declining light–moderate events and increasing extremes. Category 1 (2.5–64.4 mm) events decreased, while Category 2 (64.5–124.4 mm) rose by ~60%. Category 3 (>124.5 mm) more than doubled, indicating intensified extreme precipitation.
Category 1 and Category 2 rainfall events typically support ecological processes, groundwater recharge, and agricultural productivity. However, Category 3 events—representing very heavy to exceptionally heavy rainfall—are often associated with flooding, soil erosion, infrastructure damage, and ecological disruption. The increasing frequency of such high-intensity rainfall events is consistent with observed climate change impacts and reflects enhanced atmospheric moisture-holding capacity under warming conditions.
Goa’s flood-prone topography, rivers, and urbanization, combined with increasing extreme rainfall, heighten vulnerability to socio-economic and environmental risks.
Projected Climate Change in Goa
Climate change projections for Goa during the 21st century have been developed using high-resolution regional climate models. Future climate scenarios for temperature and precipitation have been assessed under two emission trajectories: RCP8.5 (worst-case climate scenario) and RCP4.5 (intermediate climate scenario).
Under the RCP8.5 scenario, which represents a high greenhouse gas emission pathway, atmospheric carbon dioxide (CO₂) concentrations are projected to reach approximately 940 ppm by 2100. In contrast, the RCP4.5 scenario, representing a stabilization pathway with moderate emission reductions, projects atmospheric CO₂ concentrations of approximately 538 ppm by the end of the century. These scenarios provide a framework for evaluating potential long-term climatic changes and associated impacts in the region.
Temperature projections for Goa (1901–2100) under RCP4.5 and RCP8.5 scenarios show significant warming. Compared to the 1901–1950 baseline, temperatures may rise by about 4.5°C under high emissions (RCP8.5) and around 2.5°C under moderate emissions (RCP4.5). These estimates highlight that continued greenhouse gas accumulation will drive substantial warming, while mitigation efforts can meaningfully limit the extent of future temperature increases.
The broader scientific consensus emphasizes limiting global mean temperature rise to below 1.5–2°C above pre-industrial levels to avoid severe climate impacts, a goal formalized under the Paris Agreement. However, regional projections for Goa suggest higher localized warming relative to global averages.
Model projections suggest Goa’s mean annual temperature, currently 26.8°C (1985–2015), may rise to 28.1°C by 2035 and 30.3°C by 2085. Under high-emission scenarios, rainfall could decline, while remaining relatively stable under moderate pathways. However, temperature extremes will intensify, with 40°C days becoming more frequent by 2040 and minimum temperatures rising by 3–7°C, indicating warmer nights and an overall shift toward hotter conditions.
Coastal vulnerability
Projected sea-level rise along the Indian coastline is estimated at 20–30 cm by the end of the 21st century, with a global mean rise of about 18±5 cm (relative to 1986–2005) even under the moderate-emission RCP4.5 scenario. In Goa, digital elevation model–based assessments identify Salcete, Tiswadi, and Bardez as highly vulnerable to coastal inundation. A one-meter rise in sea level could impact nearly 7% of the state’s population, threatening beaches, tourism infrastructure, and overall socio-economic stability.
A multi-hazard coastal vulnerability study by NIO evaluated shoreline change, relative sea-level trends, elevation, coastal slope, tidal range, wave height, and geomorphology. The findings show that nearly 30 km of coastline across Salcete, Bardez, and Tiswadi—particularly areas below 35 m elevation—are at high risk from sea-level rise and flooding. Shoreline erosion currently exceeds 0.6 m per year in Bardez and Salcete and 0.3 m per year in Tiswadi.
Goa’s creeks and river systems, which support rich biodiversity, are increasingly threatened by saline intrusion. Although some areas are protected by sluice gates and embankments, others remain exposed. Rising sea levels, altered hydrology, and unregulated groundwater extraction are likely to intensify saltwater ingress, elevate groundwater tables, reduce drainage capacity, and heighten flood risks, particularly in low-lying urban areas like Panaji.
(The writer is a Senior Scientist at the National Centre for Polar & Ocean Research, Ministry of Earth Sciences, Mormugao. He is an active freelance contributor on social, religious, cultural & scientific topics)
