Climate change indicators
We have all experienced changing weather conditions some time in our lives.
But these experiences are disjointly and not thought of as a part of global, climatic changes.
Scientists shows evidence of climate change through mainly these topics:-
Higher temperatures on land and in oceans
Sea level rise and flooding coastal areas
Changes in extreme weather events like cyclones
Melting of ice in the polar regions
In this chapter, we discuss the first 3 with respect to Sundarbans.
Warming Sea
Below is the data of how warm the Bay of Bengal (21.5°N, 88.5°E) has gotten in the last 165 years, measured through Sea Surface Temperature (SST).
…and it continues to rise
Based on predictions of greenhouse gas concentration trajectory (scientifically known as Representative Concentration Pathway), here is how Sundarban's future looks like.
It is predicted that by 2100, temperatures will rise by 4°C. Explore the various scenarios below and see how they will change given different climate scenarios.
Details of the Scenarios
Sea Level Rise
As the oceans warm due to an increasing global temperature, seawater expands—taking up more space in the ocean basin and causing a rise in water level. The second mechanism is the melting of ice over land, which then adds water to the ocean.
A general rule of thumb is that for every 1 inch (25.4 mm) Sea Level Rise, 100 inch of beach is lost.
When we talk about sea level rise, here is what happens to the coastline—
Bay of Bengal is rising and will continue to rise…
As measured at Sagar station, this data shows the historical as well as the predicted rise in Mean Sea Level.
The current sea level is shown in blue and predicted in dotted line purple.
If the rise is added to each year cumulatively (as shown in light blue), then the sea may rise by 1.5 metre which is an extreme amount. It is enough to drown Kolkata and the lower half of West Bengal.
Salinity levels in Sundarbans
The rising sea level has lead to saltwater intrusion into freshwater sources like river mouths and estuaries. This can be particularly problematic for a delicate ecosystem like Sundarbans.
Implications of increase in salinity:
The Sundari (Heritiera fomes) which is the dominant species of mangrove in Sundarbans has low tolerance for saline water and may die.
When saline water goes into the fields through tidal surges, agriculture suffers a lot. Safe limits for rice cultivation is 4-6 psu. Most of the farmers suffer because of this.
Here are the salinity levels as observed in the last 40 years. One can see that salinity decreases after rainfall.
Cyclones of Sundarbans
A hotspot of cyclonic activity
Sundarbans is known as the Cyclone capital of India. It is vulnerable to cyclones, especially in June-November due to warm waters, high humidity levels and its unique geography in the Bay of Bengal.
Below is the visualization of cyclonic storms or above in the last century.
The highlighted parts show cyclones in the last 15 years. The most devastating ones are shown below
How are the animals of Sundarbans faring in this changing climate?
Are there any conflicts with humans?
Made with ♥ in IDC | Alivia Chaudhuri