Jahnavi Shah

M.Sc. Candidate, Geophysics & Planetary Science

Sounds of Climate Change

Happy 2019 everyone! 

I would like to start off by setting some goals for my blog for the new year. Firstly, I will write more often than last year, hopefully an update every 1-2 weeks. And more importantly, I would like to use blog posts as an opportunity to learn and present something new every time (in addition to providing research updates, of course). So let’s get started!

Quick Research Update

Things in the research world are going well. I have started combining different data layers (optical, radar, and topography) for craters in ArcMap, and have started seeing some neat products. I have also been exploring different settings in ArcMap in order to find the most effective way to present each data layer. I am definitely feeling more comfortable working with the data and am now working towards putting little bits together (so I’m reading and re-reading the fundamentals). I have intentionally omitted image examples because I want to compile some samples and do a mini mock-crowd sourcing run in the lab (hopefully in the next few weeks). 

Sounds of Climate Change

“The underwater soundscape can be as noisy as any jungle or rainforest.” – Kate Stafford, Oceanographer 

Fish and marine mammals use sound to study their habitat, communicate with each other, and navigate. Unlike humans who tend to be very visual animals, marine mammals (such as dolphins and bowhead whales) rely on sound to “see”. Light transmits poorly underwater, whereas sound transmits very well and so signals can be heard over large distances. Let’s focus on the Arctic as an example and listen to the underwater sounds of Arctic marine life ( skip to 03:49 ): 

Although the Arctic underwater world is a rich soundscape, it has some of the lowest ambient noise levels of the world’s oceans when the ice is frozen solid. However, this is changing, mainly due to a decrease in seasonal sea ice which is a result of increased greenhouse gas emissions. A decrease in seasonal sea ice means an increase in open water season. This is causing a loss of habitat for animals such as ice seals, walrus, and polar bears. It is also changing prey availability for these marine mammals and birds as well. 

In addition to physical habitat loss, decrease in sea ice is causing a loss of acoustic habitat too. There are 3 ways in which we are able to hear the ‘sounds of climate change’ using hyrophones (underwater microphones — record ambient noise). 

Air: Wind creates waves which contributes a noise like a hiss or a static in the background. Previously, the wind didn’t make it to the water column because the ice acted as an buffer between the wind and water. However, due to climate change, there are not only more waves in the Arctic, but also an increasing number of intense storms which signficantly raise the noise levels.

Water: With less seasonal sea ice, subarctic species are moving north into the Arctic as it is a new habitat opportunity for these mammals. For example, oceanographers are hearing sounds of fin, humpback, and killer whales, further north and later in the season. This invasion of the Arctic increases competition for food, a risk of new diseases, and new sounds. 

Land: Due to an increased open water season, there is an increase in human activities in the Arctic including oil and gas exploration and extraction, commerical shipping, and tourism. These ship noises increase levels of stress hormones in whales and can disrupt feeding behaviour. As another example, dolphins reproductive rates have declined as a result of noise from dolphin-watching boats in western Australia. Increase in human activities is decreasing the acoustic space over which Arctic marine mammals can communicate.

The contribution from land (or people) is most significant because it is the only one humans can control. We can’t control the winds or migration of subarctic species to the north. Arctic marine mammals have evolved with sounds primarily from sea ice and other sea animals. These sounds are essential for their survival, but the sounds from ships are loud, alien, and are disrupting their habitat. Some solutions have been put into play to minimize disruption such as slower ships (meaning quieter ships). Additionally, we can restrict access to the Arctic in seasons and regions that are important for mating, feeding or migrating. I think it’s really important for us to recognize that our actions have consequences on different realms and is not limited to disruptions in the physical space, but also the acoustic space (in the case of Arctic marine mammals). I would recommend checking out the TEDtalks linked below. The second has some interesting figures which I was not able to include in this post.

TED talks: Kate Stafford – How human noise affects ocean habitatsPeter Tyack – The intriguing sound of marine mammals 

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