Protecting Bangladesh's biodiversity means protecting its people

Bangladesh is located in the Ganges-Brahmaputra-Meghna delta, one of the world's most ecologically active regions, with a remarkable diversity of ecosystems. Despite covering only about 148,460 sq km, the country is home to around 5,000 species of flowering plants, more than 700 species of birds, about 125 species of mammals and 260 species of freshwater fish, as well as numerous amphibians, reptiles, insects and micro-organisms.

These biological resources are not isolated pieces of nature. They form a complex ecological web that supports food security, climate regulation, livelihoods and cultural identity. But climate change is threatening this delicate relationship — not only for wildlife, but also for the millions of people who depend directly on ecosystem services.

Climate change and biodiversity are closely linked. Ecosystems influence climate conditions, while climate conditions affect ecosystems. Forests, wetlands and mangroves are nature's climate regulators, helping to absorb carbon, buffer floods, regulate the water cycle and protect communities from extreme weather events.

But changing rainfall patterns, rising temperatures, stronger cyclones, rising sea levels and saltwater intrusion are altering ecological processes.

"Most of Bangladesh is a low-lying delta, which makes it particularly susceptible. Two-thirds of Bangladesh is less than 15 feet above sea level, and the ecosystems are therefore very vulnerable to climate change."

The Sundarbans under growing pressure

One of the best-known examples of the effects of climate change on biodiversity is the Sundarbans mangrove ecosystem, the world's largest contiguous mangrove forest.

The Sundarbans covers about 10,000 sq km, of which 60% is in Bangladesh and 40% in India. It is a UNESCO World Heritage Site and a haven for iconic species such as the Royal Bengal tiger (Panthera tigris tigris), spotted deer, estuarine crocodiles, fishing cats, freshwater dolphins and hundreds of species of birds and fish.

The Sundarbans is also a biodiversity hotspot and a protective shield for coastal communities against cyclones and storm surges.

But climate change is placing unprecedented pressure on the ecosystem. Rising sea levels, increasing salinity, reduced freshwater flows and more frequent cyclonic events are affecting species distribution and mangrove regeneration.

Earlier IPCC assessments suggested that the Sundarbans could face major changes with a 45cm rise in sea level, including greater inundation and salinity stress that could lead to habitat degradation and biodiversity loss. Future scenarios have suggested that sea levels could rise by about 28cm above 2000 levels, potentially reducing the suitable habitat of the Royal Bengal tiger in the Bangladesh Sundarbans by about 96%, leaving fewer than 20 breeding individuals.

Salinity intrusion is another major threat to Bangladesh's biodiversity. Mangroves can tolerate only a limited range of salinity levels. As saltwater intrusion increases, vegetation composition changes and sensitive species face greater pressure.

The name Sundarbans is derived from the Sundari tree (Heritiera fomes), which is economically and ecologically important. The species is particularly sensitive to rising salinity, and climate-driven changes in salinity have contributed to declines in its populations. The spread of more salt-tolerant species can further alter the structure of the mangrove ecosystem and reduce ecological diversity.

Freshwater ecosystems under pressure

Freshwater ecosystems are also under significant pressure from climate change.

Bangladesh is a land of thousands of rivers, floodplains, haors and beels, which provide breeding grounds for fish and habitats for aquatic organisms. Fisheries are a major source of animal protein and play an important role in national nutrition and the livelihoods of rural communities.

Climate change affects river flows, water temperatures and pollution levels, making dry-season and flooding patterns increasingly unpredictable. Changes in breeding cycles and habitat availability threaten fish diversity, particularly species that cannot adapt rapidly to changing environmental conditions.

Another biodiversity hotspot in Bangladesh's coastal region is facing increasing climate stress. The country has a 710km coastline along the Bay of Bengal, with estuaries, mudflats, mangroves and marine habitats that support fisheries, migratory birds, crustaceans and other marine life.

Rising sea levels, coastal erosion and more intense tropical cyclones are placing these habitats under growing pressure. Sea-level rise is linked to land loss, erosion and saltwater intrusion, threatening both coastal biodiversity and human settlements.

Climate change is not the only threat

Climate change is also interacting with existing human pressures, creating what can be described as multiple environmental stressors.

Natural habitats face threats from deforestation, agricultural expansion, industrial pollution, illegal wildlife trade and urban development. These pressures can reduce the resilience of ecosystems, while climate change can intensify their effects.

Some species may not even be able to shift in response to changes in temperature or rainfall if their habitats have already been fragmented.

The destruction of ecosystems that provide natural protection can also magnify climate-related hazards.

Biodiversity loss poses a direct threat to human survival and undermines essential ecosystem services, including pollination, soil fertility, carbon storage, water purification and disaster protection.

Wetlands can store excess water and help reduce flooding. Mangroves can lessen the impact of cyclones by reducing wave energy. When these ecosystems are lost, communities become more vulnerable to climate disasters.

The relationship between people and biodiversity in Bangladesh is therefore not one of separation, but of deep interconnectedness.

Biodiversity loss is also an economic threat

The impact of biodiversity loss is serious in socio-economic terms, particularly for rural and coastal communities.

Millions of people depend on agriculture, fisheries, forest resources and other ecosystem-based livelihoods. Climate-driven changes in biodiversity could mean fewer fish, lower agricultural productivity and greater economic insecurity.

Displacement is another major threat posed by climate change in Bangladesh. Rising sea levels, flooding and ecosystem degradation could displace millions of people in the coming decades.

The country's biodiversity must therefore be considered an important part of climate adaptation and conservation strategies.

Ecosystem-based solutions such as mangrove restoration, wetland conservation and sustainable forest management can strengthen the resilience of both ecosystems and communities.

Community-based conservation is equally important because local communities possess traditional knowledge about managing natural resources. Bangladesh also needs better biodiversity monitoring, faster adoption of climate-resilient agricultural and fisheries practices, and stronger management of protected areas.

Adaptation must be built around coexistence

Bangladesh's approach to climate adaptation should be based on the concept of coexistence between people and biodiversity.

Conservation is not simply about saving individual species. It is about preserving the ecological processes that allow ecosystems and communities to survive together.

Protecting biodiversity can also contribute to climate mitigation. Healthy forests, wetlands and mangroves store significant amounts of carbon and help prevent further accumulation of greenhouse gases in the atmosphere.

The biodiversity of Bangladesh is a complex web of ecological relationships that sustains natural systems and human life. Climate change is now threatening that delicate balance through rising seas, extreme weather, higher temperatures and habitat changes.

The challenges facing the Sundarbans, freshwater ecosystems, coastal habitats and terrestrial biodiversity show that climate change is as much a social and economic issue as it is an environmental one.

Sustainable management, scientific conservation and community participation are therefore essential not only for the survival of Bangladesh's biodiversity, but also for the resilience and wellbeing of future generations.

Md Zafar Alam Bhuiyan is a Senior Research Fellow at the Centre for Climate Change and Environmental Research (C3ER), BRAC University, and a doctoral researcher in climate change at Bangladesh University of Professionals (BUP). His research focuses on biodiversity conservation, forest governance and climate resilience.

Disclaimer: The views and opinions expressed in this article are those of the author and do not necessarily reflect the opinions and views of The Business Standard.