Let me take you 12,000 years back. The continents have almost moved to their current day positions and thick sheets of ice cover Antarctica, Greenland, Europe and parts of North America and Asia. We are witnessing the end of Pleistocene Epoch, the Last Ice Age. Earth’s orientation in the orbit around the sun has caused an increase in solar radiation reaching us. The woolly mammoths, the saber-toothed tigers and the giant bears are on the brink of extinction, mostly due to this natural climate change but also due to human over-hunting. Chunks of ice are melting at unprecedented rates of 50m per day, equating to more than 10km per year! The magnanimous Antarctic ice shelves that had protected the ice sheets from melting away into the ocean for millions of years, are now drifting apart as the air temperatures continue to go up. As a result of this, the rise in sea level has accelerated – 82 feet rise in a 500 year period.
We are now on our journey to the 21st century. The global carbon dioxide levels kept increasing at almost a stable rate until industrialization in the late 18th century when carbon dioxide release rocketed and we overheated the earth’s atmosphere. Britain has colonized a number of natural resource rich countries and cleared forests for the purpose of cultivation. Electric, automobile, textile, agriculture and many more industries have been set up, making industrialization an overwhelming revolution. So, exploitation of resources continued, to make human lives easier. Global warming has started showing visible effects in the poles, with Arctic responding more than Antarctica. Scientists believe that the vast Southern Ocean surrounding the Antarctic has a buffering in preventing ice shelves from retreating at a fast rate. People have begun to realize that economic development would promote climate crisis in the future.
Fast forward to the present day. There is a lot of hubbub and active discussion on climate change. Climate activists and scientists are pressurizing world leaders and industrialists to make quick and effective amendments to human lifestyle to prevent further exploitation of natural resources. A number of research activities focus on finding sustainable energy alternatives to minimize our dependence on fossil fuels. Let’s check what the situation is in Antarctica. The fastest rate of retreating grounding lines- the zones where grounded ice sheets have lost stability and begun to float- are only about 1.6 km per year today, 10 times lesser than the retreating rate towards the end of Pleistocene. Does this mean anthropogenic activities have not contributed as much to sea level rise as projected? No, definitely not. It means that global warming might set a new upper limit to the retreating rates of ice sheets in the future, significantly higher than the rates 12,000 years ago. In how many years this upper limit will be reached? We simply do not know.
What does the future look like? Ice shelves are like stoppers for ice sheet meltdown. Faster retreating rates of ice shelves speed up glacier meltdown by a factor of 8, which in turn contribute to sea level rise. The future looks uncertain and worrisome. If retreat rates become similar to that estimated at the end of Ice Age, we could lose 138 gigaton of ice per year! There is enough ice left on Antarctica to raise sea level by about 200 feet if it all melted. In case carbon dioxide emissions continue to increase, by 2100 we will see a 3 feet rise in sea level. These projected figures imply an impending danger for the 680 million people living in coastal areas around the world. By 2050, people in low lying areas might lose their homes as entire cities sink under seas.
Further reading:
1) Antarctic ice sheets capable of much faster melting than we thought. https://edition.cnn.com/2020/05/28/world/antarctic-ice-sheet-retreat-intl-scli-scn-climate/index.html
2) Antarctic Ocean Reveals New Signs of Rapid Melt of Ancient Ice, Clues About Future Sea Level Rise https://insideclimatenews.org/news/28052020/antarctic-ocean-ice-melt-climate-change
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