Lying on the floodplains of the mighty Ganges, Brahmaputra and Meghna rivers Bangladesh is a rich, fertile land. These giant river systems meet in the centre of the country and flow together into the Bay of Bengal which, at over 1600km wide, is the largest delta system in the world.
Rising Sea Level
Bangladesh is often cited as one of the countries that will be most affected by rising sea levels from human induced climate change and with good reason. Two thirds of the country lies less than 5m above of sea level. With vast regions to the south much less than a 1m above sea level. The Intergovernmental Panel on Climate Change (IPCC) 2007 report claimed that just 1m rise in sea level could directly expose nearly 14 million people and result in potentially 20% land loss! Although it is unlikely that the actual figures will be so high, the numbers are worrying large.
Most of the country receives on average more than 2.5m of rainfall a year, 80% of which falls in about 4 months during the peak monsoon season. Contrast that with the UK, which in 2012 had an annual rainfall of less than 1.3m. Combine this with poor flood defences and you have large annual floods. The flood waters bring nutrient rich clays and silts from the high Himalayas and deposit them on the river floodplains during these events. These rich soils produce vast harvests of rice and other crops. Not surprising then that agriculture is the most common livelihood.
However floods, once welcomed by farmers and their families are now harbingers of disaster. Human induced climate change has resulted in more erratic monsoonal weather patterns with often larger the normal volumes of water being delivered in shorter time intervals. The resulting floods have had devastating effects on the Bangladeshi people. In 2012 three large floods hit the country in swift succession between the months of July and September directly affecting more than 5 million people. These are now a common annual occurrence.
Bangladesh is also annually subject to devastating tropical cyclones, tidal bores and tornadoes. Some of the worst natural disasters in recorded history were results of cyclonic storms in the Bengal region. Among them, the 1970 Bhola cyclone which claimed over 500,000 lives! Worryingly new research into the effects of human induced climate change has shown that large cyclonic storms will become a more common occurrence in the years and decades to come.
The foothills of great Himalayan mountain belt has historically been the location of many large earthquakes. Earthquakes in the continents tend to be more infrequent compared to regions such as Japan and California. However this makes them more unpredictable and often unexpected. But when one does occur it can result in significant ground shaking. The 1897 magnitude 8.1 and 1950 magnitude 8.7 Assam earthquakes were two of the biggest to hit the region in recent times.
Bangladesh has a population of over 160 million and among the highest population density of any country in the world. With the majority of the country built on river floodplains combined with widespread corruption and ignorance a large earthquake could quite possibly result in the greatest natural calamity to have ever hit the country!
So what can we as earth scientists do?
Bangladesh needs to increase its resilience if its people are to survive the multitude of natural hazards they face. Earth scientists are well placed to understand the risks involved from these hazards and can play a key role in all aspects of building a resilient infrastructure.
Climate science research is ongoing and needs to continue to better understand the affect human induced climate is having and will have on the annual monsoon. This knowledge then needs to be translated into rainfall variation and flooding potentials. The socio-economic issues of a rising sea level can be addressed by the sustainability community. How can we feed millions of people displaced as a direct result of climate change? How can we provide clean drinking water in flood prone regions? The hydrogeologists and geochemists can help find sustainable clean, arsenic free water sources for drinking and farming during the non-monsoon season. The seismologists and earthquake scientists can better assess the seismic risk; produce more accurate hazard maps and importantly identify the active faults within the region.
These are to name but a few of the ways earth scientists can get involved. I believe it is our moral duty to translate the practical aspects of our science into real benefits for people. Only then can we ever hope of helping these people.