Oceanography

Antarctica and Greenland are home to Earth’s only two ice sheets. It has been observed that the Greenland Ice Sheet (GrIS) is melting at a much faster pace than before. As per researchers, the GrIS has been losing mass for several decades due to both increased surface meltwater runoff and ablation of marine-terminating outlet glaciers via calving and submarine melting, termed ice discharge.

Reasons for this shrinkage include:

• During the summer months, increasing air temperatures heat the glacier’s surface, creating pools of meltwater. These pools leak through the ice and flow from the glacier into rivers below the surface.
  • As the meltwater flows into the sea, it encounters the warmer salty water at the bottom of the fjord. Glacial meltwater does not contain salt, so it is less dense than saltwater and thus rises as a plume.
  • The plume drags the warmer ocean water into contact with the glacier’s base. The warm water then rubs up against the bottom of the glacier, causing even more of the glacier to melt.
  • This often leads to calving – ice cracking and breaking off into large ice chunks (icebergs) – at the front end, or terminus of the glacier. This whole process creates a feedback loop thus aggravating things further.
  • The amount of undercutting depends on the depth of the fjord, the warmth of the ocean water, and the amount of meltwater flowing out from beneath the glacier.
• It is observed that global warming is having an intense impact on the Arctic. It is warming more rapidly than other regions, for example, while Earth’s average temperature has increased by one degree Fahrenheit over the past century, air temperature in Greenland has increased by about seven degrees Fahrenheit since 1991. Because warming is more rapid in the Arctic, the impact is much more pronounced.

The consequences of this phenomenon are:

• Rise in sea level: Melting glaciers add to the rising sea. levels, which in turn, increase coastal erosion turn, in and elevate storm surges as warm air and increased ocean temperatures create more frequent and intense coastal storms like hurricanes and typhoons.
• Impact on the weather pattern: As the ice melts, darker patches of the ocean start to emerge, eliminating the effect that previously cooled the poles, creating warmer air temperatures and in turn disrupting normal patterns of ocean circulation. Research shows the polar vortex is appearing outside of the Arctic more frequently because of changes to the jet stream, caused by a combination of warming air and ocean temperatures in the Arctic and the tropics.
• Impact on humans and wildlife: As sea ice and glaciers melt and oceans warm, ocean currents will continue to disrupt weather patterns worldwide.
  • Industries that thrive on vibrant fisheries will be affected as warmer waters change where and when fish spawn.
  • Coastal communities will continue to face issues as flooding becomes more frequent and storms become more intense.
  • In the Arctic, as sea ice melts, wildlife like walrus are losing their home and polar bears are spending more time on land, causing higher rates of conflict between people and bears.

How much and how quickly the Greenland Ice Sheet melts in the future will largely determine the ocean level rise in the future. If emissions continue to rise, the current rate of melting on the Greenland Ice Sheet is expected to double by the end of the century. Alarmingly, if all the ice on Greenland melted, it would raise global sea levels by 20 feet. Thus, adequate measures need to be taken in this regard.