So, I’m sure all of you guys have had a drink with ice cubes in at some point, and it’s probably pretty obvious to you that the ice in your glass melts much quicker if your drink is warmer! This everyday, seemingly obvious effect, is what I study – but on a much larger scale. All around the world, and particularly at the poles, there are glaciers which enter the ocean. That effect that you see in your glass of Coke happens to glaciers which are more than one and a half times the height of the Empire State Building and three times the length of New York’s Central Park!
But, if it’s as obvious as the ice in your drink, why study it? Well there are a few more effects going on at “ocean terminating” glaciers – combined with the fact that it is much easier to see what is happening in your glass than what is happening in ocean water more than 500m deep! In addition to the temperature of the ocean, we also have complicated circulation patterns caused by water that is released from the glacier way below the ocean’s surface. This constantly mixes water at the ice front, and leads to faster melting – you can see this effect as well, by swirling your glass of Coke around and you’ll see that the ice melts faster than if you just let it stand still. For glaciers, this is such a complicated process that I use a computer model to reproduce what is happening and allow it to be more thoroughly investigated.
But why do we need to study this? Well, it looks like the melt rates at the front of these glaciers can have a huge impact on how quickly the glacier loses ice – and since these glaciers drain the Greenland and Antarctic Ice Sheets, there is a lot of ice to lose! Also, consider that this ice goes straight into the ocean, directly impacting global sea levels. It’s really important that we understand how sea levels might be affected by melting ice, so that we can be sure that coastal cities and populations are well protected in the future.
- Alistair, Swansea University, UK