Ryan: Wow! What weird looking aliens. Somebody must have hit a wrong button and sent us off to another planet!

Morgan: This sure doesn't look like my backyard.

Inukshuk: Look closer, my friends. These are indeed amazing life forms, tiny organisms called diatoms that are neither plants nor animals. Their glassy skeletons let sunlight pass right inside their bodies where chlorophyll turns it into food energy. Millions and millions of diatoms drift in every water body on earth, from jungle rivers to arctic lakes.

Ryan: So why can't we see them?

Inukshuk: All this amazing complexity is squeezed into just one cell, 50 of which could stand on the head of a pin.

Morgan & Ryan: (together) Whoah! That's small!

Inukshuk: Small but significant. Without diatoms, a lot of creatures higher up the food chain would starve since diatoms produce almost one quarter of the world's food energy.

Morgan: Do you mean we couldn't go fishing or seal hunting if it weren't for these strange little beasts?

Inukshuk: Let's just say it would be pretty slim pickings without them. Though nearly invisible, diatoms are biologically priceless. And that's not all. Diatoms are worth a lot to scientists as microscopic messengers from past climates, telling stories that go back hundreds, even thousands of years.

Ryan: You mean those...what did you call them?

Inukshuk: (slowly) Diatoms.

Ryan: Right! Those...diatoms are thousands of years old?

Inukshuk: (chuckles) In fact they don't live long at all. It's their skeletons that tell the story. Diatoms are wrapped in a sort of two-sided crystal shoebox. Each species - and there are hundreds of them - is decorated with its own fancy pattern of pinprick holes and...

Morgan: (interrupting) Wait a minute! So all these lakes in my backyard are full of floating skeletons?!

Inukshuk: Don't worry. All those skeletons fall to the bottom of the lake and get buried in the muck. Over the years, they stay beautifully preserved down there, especially in arctic lakes, and often pile up in thick layers. Changes in water temperature and ice conditions can play a huge role in determining the kinds of diatoms found in each layer. That's why they give us such excellent clues about long ago climates.

Ryan: I get it. Some diatoms like it hot. Some like it cold.

Inukshuk: Exactly. As climate changes, the kinds and numbers of diatoms change. By sampling diatoms from the lake bottom, scientists can read this story like a book.

Morgan: It must be a pretty messy book with all that muck down there!

Inukshuk: The trick is to create a sort of mud sausage then...

Ryan: (interrupts) Sounds disgusting!

Morgan: I'll stick to caribou sausage, thanks.

Inukshuk: Think of it like drilling for oil. You plunge a long steel pipe into the lake bottom then pull up a cylinder of sediments loaded with diatoms - there's your sausage! Slice this into layers, remove as much dirt as possible then voila: diatoms ready to be sorted under a microscope.

Ryan: That must be a big job. You said there were hundreds of kinds of diatoms. How many have scientists pulled out of lakes up north?

Morgan: Now that you mention it, it does look familiar...

Inukshuk: Let's see now... Meet lake DV09, a favourite sampling area for diatom researchers. They have identified 52 different species from this one lake...

Morgan: (interrupts) Lake DV09? Where the heck is that?

Inukshuk: On Devon Island. The scientists gave it that name. (knowingly) I believe I've seen your family hunting seal up there?

Morgan: Now that you mention it, it does look familiar... Why that's Tasiq Ingiusilik!

Ryan: What's that mean?

Morgan: Singing Lake. You can hear the rocks sing when the wind's right.

Ryan: No kidding?

Inukshuk: She's not kidding. I've heard it too.

Morgan: We have our own names for every lake and hill and creek we travel by.

Ryan: So Mr. Inukshuk, what kind of story did those 50 species of diatoms tell? A murder mystery? Adventure? Romance maybe?

Inukshuk: It was 52 species actually - probably twice that if they'd counted every single kind. Story? I'd call it a...detective story. By cracking the identities of diatoms in each slice of mud then tallying their numbers, the scientists were able to answer the question, "Is the climate warmer today than it was almost two hundred years ago?"

Ryan: And?...And? What did they find?

Inukshuk: A slice from around 1812 showed only a few diatoms and very little variety in species. One from about a little over a hundred years later, 1917, showed hundreds of diatoms and much more variety. A slice from 1994, just seventy-seven years later, showed a wide variety of diatoms present - not in the hundreds, not in the thousands but the hundreds of thousands. More heat means less ice, more sunlight, and more diatoms.

Ryan: So it looks like the diatom record is telling us that things are heating up.

Inukshuk: And fast. Diatom sampling sites across the Arctic tell basically the same story - that our climate has been generally warming over the past two centuries at an unusually rapid pace.

Morgan: The elders in my community will be very interested to hear about this. They've been telling the same story for years. Maybe they could compare notes with these microscopic messengers in the muck.

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