11/14/2014 2:40:05 PM

Interview with a Sea Ice Scientist!

By Kt Miller

I have had six great weeks in Churchill, Manitoba, watching and talking about polar bears almost every day. Who wouldn't want this job? One of the neatest things for me has been watching the change from fall colors and bare tundra to a white, snow-covered landscape. Even cooler, the sea ice is just starting to form!

While I am getting more and more knowledgeable about polar bears, I really need to bone up on my sea ice knowledge. Data show that sea ice in this region is changing and that the polar bears are responding negatively to these changes. Imagine how happy I was when I found out that Dr. Jen Kay, climate scientist at the University of Colorado, would be joining us on Buggy One this week! Here are some of my questions to her and her very enlightening answers. 

1. Are there different types of sea ice?

There is annual and multi-year sea ice. The High Arctic has multi-year ice, which grows on top of itself year after year. We are seeing more of this multiyear ice melting and turning into annual sea ice.

Annual sea ice melts completely every year and regrows during the winter, like in Hudson Bay. 

2. Wow! So are there differences in thickness in these types of sea ice?

Multi-year sea ice lasts many years and grows by thermal gradients, making it pretty thick! Annual sea ice can get 1-1.5 meters thick in the span of one year, but sea ice that grows on top of itself over multiple years will be more robust and could get up to 6 meters thick!

Sea ice in many areas is getting thinner, making it more vulnerable. Thin sea ice is very mobile and gets blown around by the wind easily. Because it is so mobile, it might stack up to give lots of ice cover, or it might blow around a lot to give less cover, depending on the wind. This mobile sea ice could affect polar bears in that it makes it harder for them to track mates, find seals, and move where they want to go. The sea ice acts like a treadmill!

3. So changes in sea ice movement can impact polar bears. Are there changes in the sea ice in Hudson Bay, where we are now? 

Yes! The sea ice in this region is simply not around for as long as it used to be. This means that polar bears don't have as long to hunt, don't get as many calories, and spend more time on land not eating. As a result, the western Hudson Bay has declined in number, have gotten smaller, and now produce fewer cubs. 

4. How do we know that humans are part of the problem? What we can do to save sea ice and help polar bears?

Climate models show that there is no way that we could see the warming that we are seeing without increasing greenhouse gases in the atmosphere. Natural variability, which would cause both increases and decreases in sea ice, cannot account for what we have observed over the last 30 years. We know that these greenhouse gases come from human activities, which means that if we change our activities, we can save sea ice!

If humans reduce our greenhouse gases by driving less, turning down our thermostats, reusing materials, and voting for people in power who care about our environment, sea ice will come back and the polar bears will have their home.

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