Read The Attacking Ocean Online
Authors: Brian Fagan
Tags: #The Past, #Present, #and Future of Rising Sea Levels
In the long term, Bangladesh could probably develop ways of living with the unrelenting siege of flood and sea surge. Encroaching water may cause catastrophic damage and kill people, but at least the land is still there when the waters recede, even if erosion rearranges many fields.
But what will happen when rising sea levels take away the land forever? Can the country survive the attacking sea?
SUCH A DIRE prediction is no science fiction. Even the most conservative projections allow for a 10 percent increase in monsoon rainfall by 2050, as the country gets warmer and wetter. Rising temperatures in the order of about 3.5 degrees Celsius will result in greater runoff from Himalayan glaciers. Not only coastal lands but also areas in the middle of the country will be affected. The most drastic effects will result from climbing sea levels, which will encroach dramatically on the flat delta, less than five meters above modern sea level. The past century has seen a rise of about twenty centimeters, which has brought higher soil salinity levels to the near coastal zone. The coastal zone as a whole comprises just over a quarter of Bangladesh’s land surface. Nearly a quarter of the country’s population lives in this fertile zone, mainly in farming and fishing, and off shrimp farming, which is now a major international industry. The threat of even higher sea levels has come to the fore, as research on global warming has intensified.
Back in the 1980s, a sea level rise of just under 1.5 meters in a century seemed like a reasonable projection. More conservative estimates have extended the timescale to 150 years. If this 150-year forecast became reality, almost 22,000 square kilometers of densely populated coastal territory would be directly affected by seawater, and even be lost to the ocean, a development that would directly impact about 17 million people, about 15 percent of the country’s population. Given Bangladesh’s exploding population growth, this figure is probably far too conservative.
Long before sea levels actually flood the landscape, another factor is already coming into play—rising soil salinity that is turning much of the southwestern parts of the coastal zone into vast saline swamps where no vegetation grows. Coconut palms and banana groves are dying in the increasingly brackish water. According to soil scientist Golam Mohammad Panaullah, formerly of the Bangladesh Rice Research Institute, 1.5 million hectares suffered from mild salinity in 1973.
6
By 1997, a further
975,000 hectares had been affected. There is no up-to-date survey, but the affected area may now be as much as 3 million hectares. Salinity has risen by about 45 percent in some southern rivers. Saltwater seepage is now penetrating much farther inland, in places in the southwestern portion of the coast as far as 200 kilometers from the Bay of Bengal.
Rising salinity drastically affects soil fertility, to the point that agricultural production has fallen significantly in coastal lands little more than 4.5 meters above sea level.
7
This is especially true when farmers irrigate their land with slightly saline surface water during the low flood months. Every high tide deposits more salt on farmland. Rice production is seriously affected, quite apart from other crops, according to some unofficial estimates down as much as 50 percent in some areas. In the end, much stagnant saline water seeps into the groundwater, making it useless for irrigation or consumption by human or beast. Bangladesh’s total rice production may fall by 10 percent and wheat by around 30 percent by 2050.
While the sea encroaches, so river flows are also shrinking, much of it because of much greater use by exploding populations upstream, and also because of damming. The Farakka Barrage across the Ganges, in Indian territory 16.5 kilometers from the Bangladesh frontier, is designed to divert water for Kolkata and to flush out silt from its port on the Hooghly river. Water flow downstream is significantly reduced. Farakka was completed in 1975, but so far the agreements between India and Bangladesh surrounding water release have proved fragile. The reduced water flow is leading to predictable rises in soil salinity in downstream river valleys, where there is now less water to flush out the soil and deposit silt. In the coastal city of Khulna, the main power station depends on freshwater to cool its boilers. A barge goes upstream to collect freshwater for the purpose and now has to go farther and farther upriver for acceptably fresh supplies because of saline intrusion and reduced flow from upstream.
The long-term effects of rising salinity include drastic losses in biodiversity, degradation of fertile agricultural land, scarcities of drinkable water, decreases in freshwater fish populations, and serious threats to
long-term food security. The government is well aware of the problem, but has done relatively little to mitigate the situation. Officials point out that farmers could turn to shrimp farming by walling off their rice paddies with high earthen walls to retain saltwater from high tides. Frozen shrimp are a major export industry in Bangladesh, and there is more money in shrimp than in rice. This may be true, but it does not help poverty-stricken rice farmers, who live from harvest to harvest. Most shrimp farming is in the hands of major industrial concerns and wealthy landowners who can afford the high capital expenditure involved in land conversion and maintenance. Many farmers look out over saline puddles that were once fertile rice fields, which they now cross with bamboo bridges and where no vegetation or trees now grow.
8
In a desperate show of resistance to the new order, significant numbers of farmers refuse to sell their land to shrimp companies.
AN ESTIMATED SEVENTEEN to forty million people will be affected if current projections of the effects of sea level rise become reality.
9
Surrounded by saline swamps and useless rice paddies, what will subsistence farmers do? As we’ve seen, people who lose land to erosion and flood are generally anxious to return to their ancestral homes. If, however, the same land is gradually lost to rising salinity and the ocean, with no prospect of recovery, there remains but one option—to move away completely. The effects are somewhat akin to those experienced by small, low-lying islands like the Maldives or Tuvalu in the Central Pacific, described in
chapter 12
. In the case of Tuvalu, you are looking at somewhere around ten thousand out-migrants. Bangladesh has tens of millions of potential refugees, under circumstances in which there is effectively nowhere for people to resettle. People in the threatened areas are in quadruple jeopardy, because they have limited income sources, low resilience, and above all, little capacity for adaptation, especially when, as is the case, population growth is rapid and there is great disparity in the distribution of wealth and livelihoods.
Traditionally, people from rural villages have moved to Dhaka and other cities to seek employment. However, cities and towns are already
bursting at the seams and there are few job opportunities. Any form of wholesale migration from the countryside is unsustainable, even with massive expenditures on infrastructure and facilities for the people being resettled; there are no funds for such work. Water and sewage problems alone are already monumental. One option might be to decentralize cities and townships in such a way that migration could be organized in a planned way, but this would still not take account of overcrowding in the country generally. Given the slow nature of the environmental changes taking hold in Bangladesh, it’s likely that both internal and external migration will be voluntary and, at first, on a relatively small scale. It’s when the pressure increases decades from now that political and security problems will mount, especially in a country surrounded by neighbors with whom relations are at times tense. At issue here are each individual’s social networks, his or her cultural ability to cope with change, his or her attitudes and position in family and society and gender; all are factors that contribute to the decision to migrate or not.
Cyclones and storm surges are nothing new in human experience. What is new is the extent of damage they can cause and the enormous numbers of people affected by them, often catastrophically. In our warming world, the frequency of such disasters is likely to increase as our vulnerability to the ocean escalates. Bangladesh gives us a haunting snapshot of what lies ahead. At this early stage, when the slow-moving threat is on the horizon and its people are already suffering, we would be wise to abandon any wistful thoughts of business as usual. The impending crisis is not just a Bangladeshi problem but also one that affects us all—for it will. We should remember Article 2.1 of the United Nations covenant, which gives all a right to a “means of subsistence.” Rising sea level and their consequences threaten that right in Bangladesh and elsewhere. The defense strategy of last resort, managed resettlement not for thousands but for millions, may move to the front burner.
An arctic ocean barrier island, Alaska. Early summer, 1100 C.E. The kayak drifts slowly in the calm, ice-strewn water close offshore. If the hunter looks to his right, he can see thin plumes of smoke rising from the summer camp on the inconspicuous island. His eyes are never still as he combs the water for a seal coming up to breathe. The ice has gone out early this year, far earlier than it did in his grandfather’s day, remembered by tales told on dark winter days. His quarry surfaces by a drifting ice patch. The hunter paddles gently, then drifts as he waits, his harpoon poised for a shot. A ripple in the water, a quick shot: The wounded seal dives as the harpoon float and line mark the spot. Hours later, the kayak returns to shore, towing the carcass of its prey.
By this time, a rising wind is blowing from offshore. Quickly the hunter and his relatives drag the carcass ashore, carrying the kayak to safety. While the women gut, skin, and butcher the seal, the men watch the growing storm and the rising tide. Soon waves are breaking practically underfoot as the ocean cascades ever closer to the hide shelters. Once again, the summer camp is under attack. The hunters quietly prepare their large skin boats, beached on the inshore side of the barrier island, ready to move to higher ground if necessary. Within a few hours, the island is deserted and barely visible above the surf. The people have set up camp elsewhere, but know they’ll return to a place where they’ve hunted for many centuries.
Sea level changes have a long history in the North American Arctic. In about 2500 B.C.E., sea level rise around the Bering Sea slowed, forming
beaches along its coastlines. Fishing and sea mammal hunting thrived in the following centuries, as human settlement spread gradually across the far north into what is now eastern Canada. Around the northern shores of Hudson Bay and the southern Canadian Arctic archipelago, some groups settled in areas where game, fish, and sea mammals abounded. As sea levels receded owing to a combination of geological factors, the people moved their camps to stay close to the water’s edge. Sea levels declined locally from sixty meters down to four meters above modern sea level.
1
Much of local subsistence came from seal hunting from the ice edge and at winter breathing holes. The hunters would crouch for hours, waiting for the moment when the seal came up to breathe. A quick harpoon thrust, then frantic chiseling with the butt of the weapon to widen the hole in the ice, so they could drag the seal onto the ice before it carried the harpoon, and perhaps the hunter, into the water.
As far as we can discern, coastal populations along the northern shore and islands were extremely sparse, except where caribou herds abounded. After about 700 B.C.E., advances in sea mammal hunting technology, including much more effective harpoons, revolutionized coastal life throughout the Arctic. In the words of archaeologist Owen Mason, life throughout the Bering Strait region was “a welter of small villages with divided and shifting loyalties, multiple origins, and limited spans of occupation.”
2
Many communities settled on barrier islands and along low-lying estuaries, where they exploited the seasonal migrations of fish and sea mammals.
Around 1300 C.E., during the warmer centuries of the Medieval Warm Period, groups of highly mobile hunters with kayaks and larger hide boats ranged from the Bering Strait along the Arctic Ocean coast. Their watercraft enabled them to move over wider territories, following seal migration routes through narrow defiles in the ice far from their bases. Ice conditions were less severe during the warmer centuries, so they could also prey on whale migrations that moved eastward in spring, westward in fall, following ice-free leads close to shore. This may have been the time when the ancestors of modern-day Eskimo communities along the Chukchi Sea coast north of the Bering Strait used summer camps on the low barrier islands that protected much of the shore.
Their descendants still hunt on the ice and along the coast, but with a significant difference. Temporary camps have become permanent villages, at a time when global warming melts the ice ever earlier each year.
ACCORDING TO A succinct definition on the web, a barrier island is “a long, relatively narrow island running parallel to the mainland, built up by the action of waves and currents and serving to protect the coast from erosion by surf and tidal surges.”
3
Barrier islands often develop in the mouths of flooded river valleys as the sea levels rise, or at river mouths where sediment accumulates and forms a delta. Local geology, sea level changes, vegetation, and wave activity are but a few of the factors that can affect such islands. Over the past five thousand years, rising sea levels have created a plethora of barrier islands, especially in the Arctic and North Atlantic. They are rarer in the Southern Hemisphere, where sea levels have tended to be more stable. Over two thousand barrier islands are known, many of them identified from high quality satellite imagery. They most typically form along geologically stable coasts with shallow estuaries, like those along much of the eastern United States. About three quarters of the world’s barrier islands are in the Northern Hemisphere, most of them in the high-latitude Arctic, where sea levels are rising faster than anywhere else.