# **1. Introduction**

Climate change is impacting every region on Earth at an unprecedented scale, with overwhelming scientific evidence documenting its accelerating effects (IPCC, 2023). A key consequence of climate change is the rising sea level, which has increased substantially since 1900. NASA reports that the current rise in global sea levels surpasses historical rates over at least the past 3,000 years. In the past century alone, sea level rose by approximately 0.15 to 0.25 meters (6–10 inches), with nearly half of this increase occurring since 1993. The pace of this rise has also quickened: from 2006 to 2018, the rate reached 3.7 mm per year, compared to 1.9 mm per year between 1971 and 2006, and 1.3 mm per year from 1901 to 1971.<sup>1</sup> Even with stabilized greenhouse gas emissions, it is virtually certain that sea levels will continue to rise beyond 2100. Conservative projections suggest that sea levels could rise by 1 meter by the end of the century. Recent data on deglaciation rates in Greenland and Antarctica, coupled with uncertainties around the dynamics of outlet glaciers, indicate that rapid breakups of the Greenland and West Antarctic ice sheets could result in an even more dramatic rise, potentially reaching 3 to 5 meters.

Sea-level rise exerts multifaceted impacts on coastal regions, including permanent inundation, cycloneinduced flooding, accelerated erosion, wetland loss, and the salinization of soil and water resources. While extensive research has highlighted land loss due to permanent flooding as a key risk (for example, see Blankespoor, Dasgupta and Laplante 2014; Dasgupta et al. 2009), salinization remains an underexplored yet critical consequence of rising seas. Regions such as the Nile Delta, Mekong Delta, and GangesBrahmaputra Delta are already experiencing significant salinity intrusion. For instance, in the Arab Republic of Egypt, 30%–40% of soils in the Nile Delta are adversely affected by salt, while seawater intrusion in the Mekong Delta poses serious threats to agriculture. The rising salinity is driving shifts in the composition of flora and fauna, favoring saline-tolerant species in low-lying coastal areas worldwide. These ecological changes have far-reaching implications for resource availability, market prices, and the food and nutrition security of coastal populations, particularly for those with limited resources and adaptive capacity. Addressing these vulnerabilities necessitates proactive adaptation planning to foster resilience in these increasingly fragile ecosystems. This paper examines a critical aspect of this poverty-environment nexus by analyzing the impact of increased salinity on fishing in coastal waters, with a focus on the southwest coastal region of Bangladesh.

The southwest coastal region of Bangladesh was selected as the study area as this area is among the poorest regions in the country and faces compounding challenges from climate change, including increased flooding, storm surges, and rising salinity (Dasgupta et al., 2021a,b; 2018; 2017; 2016a,b; 2015a,b; 2014; Steele et al. 2017). Poor households in this region are particularly vulnerable due to their reliance on fragile local ecosystems for livelihoods and the constraints imposed by poverty on their mobility.

Extensive research has documented that coastal fisheries play a vital role in sustaining the livelihoods and nutritional needs of the region’s poor households (World Bank, 2000; Alam and Thomson, 2001; Thilsted, 2010; Fernandes et al., 2015). However, these fisheries are increasingly threatened by climate-induced salinity changes resulting from sea-level rise and altered riverine flows (Dasgupta et al., 2016a; Gain, Uddin, and Sana, 2008). Local fish species, which vary in salinity tolerance, are adapting their ranges in response to shifting salinity patterns (Dasgupta et al., 2017). Such changes in the spatial and temporal

> 1 <u>htps://sealevel.nasa.gov/understanding-sea-level/by-the-numbers/</u>

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