08/08/2016 What does Arctic Ocean have to do with Indian monsoons?

https://www.flickr.com/photos/kamaljith/5847957735/in/photostream/ Monsoon season in India typically lasts between June and September and is characterised by sudden heavy rainfall and flooding. Photo: K.V Kamaljith/flickr.com

The sea ice cover in the Arctic is important to more than polar bears and seals. It is also contributing to seasonal weather changes that each year affect millions of people.

Text: Maja Sojtaric

6 million NOK  by The Norwegian Research Council faktaboks-pactto study how Arctic Ocean warming affected monsoons in the past through collaboration with Indian institutions in a project called PACT.

“One of the most important objectives is to study the re-sponse of the monsoon to past episodes of global warmth and enhanced concentration of greenhouse gases. One of such periods, which has been identified for high-resolution study, is the early to middle Pliocene Epoch (3.3–3.0 million years ago). The atmospheric CO2 concentration was 400 ppm, which is more or less the same as we see today. The mean temperatures were around 3°C warmer than today”, says project leader Jochen Knies.

Analogue for current warming ocean

Pliocene Epoch is thus an analogue for our current warming ocean. It is the time in the relatively recent history of our planet when sea ice conditions in the Arctic Ocean were similar to the ones we observe now. The ice cover was also strongly reduced during this period, something that we may experience in our recentuture due to global warming.

Variability in sea ice cover can have immense implications on the Earth´s climatic exchange between the ocean, land, and atmosphere. All of the world oceans are interacting through exchange of cold and warm water, creating the weather phenomena that we experience.

One such phenomenon is monsoon, a seasonal change in atmospheric circulation and rainfall associated with the asymmetric heating of land and sea. And one of the batteries fueling that system, which most commonly is associated with South Asian countries such as India, is actually the Arctic Ocean.

Sea ice effects are not a local Arctic phenomenon

The warming of the Arctic Ocean becomes important to more than local life in the North. Monsoons are not to be trifled with: in 2013 over 10 000 people were killed in monsoon floods in India alone.

Monsoon flash flood 2013_Indian Army

June 18, 2013. Torrential rains and flash floods washed away homes and roads in north India, leaving at least 60 people dead and thousands stranded, as the annual monsoon hit the country earlier than normal. Photo: AFP/Indian Army

What if the warming of the Arctic Ocean changes the pattern and intensity of the monsoon? That is one of the questions that PACT will try to answer. The project is looking into the past to see if that happened, long before there were any humans to be harmed. Through studies of sediment cores from the Arctic and Indian oceans we will look into the geological past, trying to unveil the connection between the two when the Arctic Ocean was likely summer ice free.

“PACT project will increase quantitative estimates of the Mid-Pliocene Warmth in the Arctic Ocean by implementing innovative scientific approaches on well established Pliocene Arctic sediment sequences. This will improve our understanding of how world ocean and atmospheric circulation patterns generate and maintain Mid-Pliocene warmth through the use of a fully coupled atmosphere-ice-ocean model,” the proposal states.

“Our researchers will also participate in International Ocean Discovery Program expeditions to the Arabian Sea and Australia. We hope that samples from these expeditions will improve our understanding of large-scale teleconnections between the Arctic Ocean and Asian/Australian monsoon system, says project leader Jochen Knies.

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