Dr. Syed Hafizur RahmanAssociate professor

Department of Environmental SciencesJahangirnagar University

Dhaka, BangladeshE-mail: hafizsr@gmail.com

16 November 2011

Impact of Himalayan Glacier Melting and Coastal Region of

Bangladesh

Presentation Outline

•Himalayan Glaciers

•Impact of Climate Change (CC) in Himalaya

•Bangladesh Profile and Coastal Region

•Impact of CC in coastal region of Bangladesh

•Impact of HGM in coastal region of Bangladesh

•Way Forward

Bangladesh

The main Himalayan range runs west to east, from the Indus river valley to the Brahmaputra river valley, forming an arc of 2,400 km (1,500 mi) long, which varies in width from 400 km (250 mi) in the western Kashmir-Xinjiang region to 150 km (93 mi) in the eastern Tibet-Arunachal Pradesh region

HIMALAYAN: THE ROOF OF THE WORLD

•The Himalayas have the largest concentration of

glaciers outside the polar region.

• Approximately 15,000 glaciers (covering an area of

33,340 sq.km), and 9000 glacial lakes throughout

Bhutan, Nepal and Pakistan, as well as selected river

basins in China and India (ICIMOD, 2007) which store

about 12,000 km3 of freshwater.

Impact of Climate Change (CC) in Himalaya

•“Himalayan glaciers are retreating more rapidly than anywhere else in the world which is up to 70 meters (230 feet) per year” (Mats Eriksson).

• resulting in an increase in the number and size of glacial lakes and a simultaneous increase in the threat of glacial lake outburst floods (GLOFs).

• “Temperature on the Tibetan Plateau is increasing by 0.3 degrees Celsius each decade that’s double the worldwide average” (Xu Jianchu)

Impact of Climate Change (CC) in Himalaya

•“If the present rate continues, the likelihood of them disappearing by the year 2035 and perhaps sooner is very high if the Earth keeps warming at the current rate” (ABC news).

•With the increased glacial melt, the trapped CO2 will be released into the atmosphere causing further environmental damage.

•The change in glacier ice or snowmelt impacts water storage and the water yield to downstream areas.

Impact of Climate Change (CC) in Himalaya

Glacier retreat in the Pho Chu sub-basin of Bhutan: The Luggye Glacier retreated by 160m per year from 1988 to 1993, resulting in a high growth rate of Lake Luggye Tso.

(ICIMOD, 2007)

Impact of Climate Change (CC) in Himalaya

Glacier retreat in the Pho Chu sub-basin of Bhutan: The Raphsthreng Glacier retreated on average 35m per year from 1984 to 1998, but from 1988 to 1993 the retreat rate was 60m per year. (ICIMOD, 2007)

Bangladesh Profile and Coastal Region

Bangladesh is one of the largest deltas in the world, formed by a dense network of the distributaries of the rivers Ganges, Brahmaputra, and the Meghna, and more than 230 major rivers and their tributaries and distributaries.

The total land area is 147, 570 sq km and consists mostly of low, flat land.

Trans-boundary rivers

Bangladesh Profile and Coastal Region

•Bangladesh has a population of 142.319 million people with an average population density of 964 inhabitants per square kilometer (2011)

•Bangladesh is predominantly agricultural, with two thirds of the population engaged in farming activities

Trans-boundary rivers

Map of the combined drainage basins of the Brahmaputra, Ganges, and Meghna

Bangladesh Profile and Coastal Region•In terms of climate,

Bangladesh is characterized by high temperatures, heavy rainfall, high humidity, and fairly marked seasonal variations. Although over half of Bangladesh is north of the Tropics, the climate is characterized as tropical for most of the year because of the effect of the Himalayan mountain chain, with a warm, almost uniformly humid climate throughout most of the year. There are three main seasons in Bangladesh:

i. A hot summer season,

ii. A hot and humid monsoon season,

iii. A cooler and drier winter.

(Huq and Ayers, 2008)

Coastal Region of BangladeshThe physical geography of Bangladesh is varied and has an area characterized by two distinctive features: a broad deltaic plain subject to frequent flooding, and a small hilly region crossed by swiftly flowing rivers

The country is sloping gently from the north to the south, meeting the Bay of Bengal at the southern end

According to the coastal zone policy (CZP, 2005) of the Government of Bangladesh, 19 districts out of 64 are in the coastal zone covering a total of 147 sub districts (upazillas) of the country

On the south is a highly irregular deltaic coastline of about 580 kilometers, fissured by many rivers and streams flowing into the Bay of Bengal

… this is the part of the country most threatened from any changes in climate system and in turn any of the changes in the water balances of the river due to the melting of the Himalayan glaciers

About 1,106 km3 of water crosses the borders of Bangladesh annually:

Total Rivers: 808Transboundary Rivers: 58

COASTAL ZONES

The coastal zone covers 47,201 square kilometer land area, which is 32 percent of total landmass of the country (Islam, 2004)

Water area covers 370.4 km (200 nautical miles) from the coastline (UNCLOS, 1982; Article 57), estuaries and the internal river water

This zone is divided into three parts:Eastern coastal zone Central coastal zone Western coastal zone

Impact of CC in coastal region of Bangladesh•Coastal areas in Bangladesh are on the ‘front line’ of climate change, directly affected by storm surges, drainage congestion, and sea level rise.

• Most of Bangladesh is less than ten meters above sea level, with almost ten per cent of the country below 1 meter, making it extremely vulnerable to increasing high tides.

• With sea levels expected to rise by an average of two to three mm per year during the first part of this century, the effects on the coastal areas will be severe, and include erosion, coastal land subsistence, siltation of river estuaries, reduced sedimentation, water logging, and saltwater intrusion.

Sea Level Rise

0 cm SLR

32 cm SLR

88 cm SLR

World Bank (2000) has estimated that by the year 2030 and 2050 at least 30 and 50 cm sea level will rise respectively

Impact of CC in coastal region of Bangladesh

•The coastal area of Bangladesh and the Bay of Bengal are located at the tip of the northern Indian Ocean, which is frequently hit by severe cyclonic storms, generating long tidal waves that are aggravated by the shallow bay.

•Although Bangladesh now has good early warning systems and cyclone shelters have been constructed along much of the coast, infrastructure and livelihoods are still threatened and severely affected, hampering further development of the coastal areas.

•30 districts were damaged by cyclone Sidr for example, with the 11 districts closest to the coast damaged most severely.

Cyclone and Storm Surge

IPCC (2007) concludes that a 5-10% increase in intensity (wind-speed) would contribute to enhanced storm surges and coastal flooding

Impact of HGM in coastal region of Bangladesh

•If climate change does alter the rainfall pattern in the Himalayas, the impacts could be felt in the downstream countries-that is, India and Bangladesh.

•By and large, dry-season flow in the major Himalayan rivers in a given year results from the monsoon rainfall of the previous year.

•Catchments in Nepal supply about 70% of the dry-season flow of the Ganges River, and tributaries of the Brahmaputra River originating in Bhutan supply about 15% of the total annual flow of that river.

Impact of HGM in coastal region of Bangladesh

•If climate change disrupts these resources and alters mountain hydrological regimes, the effects will be felt not only in the mountain core of Tropical Asia but also downstream, in countries that depend on this water resource.

•The extent of flooding is exacerbated by the sediment loads brought by the three major Himalayan rivers, coupled with a negligible flow gradient, which increases congestion.

Way Forward

•Although uncertainties about the rate and magnitude of climate change and potential impacts prevail, but there is no question that climate change is gradually and powerfully changing the ecological and socioeconomic landscape, particularly in relation to water

•Implementation of international and national initiatives and policy to build community resilience

•In transboundary water sharing issues, Joint watershed management concept would be a sustainable approach to reduce climate change vulnerabilities and its impacts on common water resources

Thank you for Patience Hearing