Sea ice

So then the thickness of the ice multiplied by the area of the ice gives us the total volume, which is a truer picture of the status of the ice.

We can actually have a look at sea ice volume quite visually.

If I can just get this thing started, there we go.

There's a guy called Jim Pettit who produces really great graphic representations of sea ice volume variation over time.

So let's take a look at his spiral graph.

First of all we need to set up the years starting all the way back in 1979 and going all the way around to 2018.

Jim then sets 1979 as the sea ice volume benchmark so this circle represents 100% of the 1979 level.

Then he adds some concentric circles showing smaller and smaller percentages going all the way down to 0% in the middle here.

Brilliant.

Maria, we've hit pack ice.

You weren't outside, were you? We were

locked down.

Her whole thing is ice.

How did she

miss pack ice? She's what, 25? Well, you were fighting wars at what, 16? I wasn't 16.

If she's been given the

And we see that there's changes in migration patterns.

And with some of the research we've been doing, we've been able to link this to sea ice declines in their feeding grounds in the Antarctic.

And whales needing to travel much further than they used to to find the right amount of food.

And so that impacts their body condition, their energetic reserve, which means that they will need more time to recover between pregnancies and lactation periods.

That's fascinating.

And I think that might, the comment about the sea ice link is something that I want to pick up on there because I think a lot of people know when we talk about threats to the ocean and species that are in difficulty, we think of other species like the penguins, which have the same issue of having to travel further out to sea to find their usual diet.

Professor, do you want to tell us a little bit more about why a change in sea ice in the Antarctic impacts the feeding habit of a whale?

Yeah, so the whales are very dependent on Antarctic krill, much like most baleen whales that go feed in the Antarctic.

And so this is going to be higher.

So let's see, I thought I had some more El Nino ones, but I think Up going to this is sea ice extent jumping around here.

This is the Arctic ice and sea ice extent is the area, not the volume, but the area of sea ice.

And one thing you'll notice is that the red line, which is 2026, is about is the lowest during the peak time.

So during the winter time when there's maximum ice, 2026 was a minimum of all the years.

That last possibility gives an iceberg a role beyond its visible shape.

Once grounded, it can provide an anchor around which sea ice remains attached.

The colony's platform may therefore be held within a coastal arrangement of land and ice, while seawater continues moving underneath.

Farther out, much of the frozen sea consists of pack ice.

An insulating layer does not have to feel warm to work.

It only has to slow heat transfer.

The upper surface of snow-covered sea ice can become extremely cold while the water underneath remains liquid.

Those conditions can exist together because the intervening layers limit how quickly heat escapes.