Our planet’s oceans are taking an enormous hit from global climate change, a daunting reality considering that oceans make up more than 70% of the Earth’s surface. The damage done to the oceans is often understated or overlooked by those living inland, but for coastal communities the changes are unavoidable and quite detrimental. Two impacts of global climate change on our oceans are especially noticeable in the Sundarbans: sea level rise and salinification.
Sea Level Rise
According to NASA, sea level is increasing at an average rate of 3.2 millimeters annually. While seemingly insignificant, this increase is occurring at an exorbitant rate, changing more in the past 6 years than in the past 30 and increasing by almost 200 millimeters (20 centimeters) since the end of the 19th century. The two primary causes of sea level rise both stem from global temperature increase: Arctic and Antarctic ice is melting and seawater is expanding as it gets warmer. When ice melts back into water, it needs someplace to go. When seawater heats up, its molecules expand, causing it to physically take up more space. For these reasons, coasts are being encroached upon by water that simply cannot go anywhere else. The protective bunds that surround Sundarbans islands are being eroded away by increasingly higher and stronger tides, causing them to crumble and allow the islands to be flooded with saltwater. Islands themselves are projected to disappear, with two already succumbing to the rising tides. The people living on these islands were forced to relocate to new areas, putting population strain on regions that were previously stable. If islanders are unable to get off the island, either because they do not want to leave their homes behind or because they do not have the means to relocate, they are left to drown along with their possessions. This depressing truth is being seen all across the globe, such as in places like Sri Lanka and Miami, Florida.
Salinification
Not only are sea levels rising, but the water itself is changing. Seawater is becoming saltier due to global warming. As temperatures increase, water is evaporated at a higher rate, leaving an increased concentration of salt in the remaining liquid water. Melting sea ice releases tons of saltwater back into the ocean currents, pulled down into sub-tropical regions like the Sundarbans. When seawater floods the Sundarbans islands, it devastates the vegetation and soil fertility in the region. Animals suffer because of a lack of drinking water, and humans who do not have the means to access freshwater are left with increasing rates of dehydration. Marine life perhaps suffers worst of all, as their habitat becomes unlivable. Human-constructed dams are exacerbating the problem by diverting fresh water from rivers such as the Ganges towards urban regions like Kolkata instead of down to the Sundarbans where it is desperately needed. The Farakka Barrage in Bangladesh is one such example of a manmade diversion that left the Sundarbans without its freshwater supply from the Ganges River.
