Diatom (Achnanthidium)

This diatom has been magnified by an electron microscope. Diatoms are microscopic algae found in every water body in the world, and can be used to derive information about climate conditions in the ancient past.

Paul Hamilton

© 2007, Canadian Museum of Nature. All Rights Reserved.


What was the Arctic climate like thousands of years ago? Diatoms are simple organisms that provide valuable clues about past climate. A unicellular algae that obtains energy through photosynthesis, diatoms are at the very bottom of the aquatic food chain. They are found in almost every aquatic environment and there are so many different types of diatoms that not even scientists have counted them all; a best guess is over 100,000 species. Diatoms have adapted to live in all kinds of environmental conditions, from extremely cold to extremely warm temperatures, from saltwater to fresh water, from large bodies of water to puddles. They are microscopic but sometimes stick to each other, forming clusters or colonies that grow so big they can be seen floating on top of the water. One of the most important characteristics of diatoms is their hard, outer cell wall. Composed of silica, it acts like a transparent yet very strong glasshouse. The silica cell wall is resistant to degradation, allowing diatoms to remain well-preserved in lake or ocean sediments for thousands of years. Because some diatom species thrive when it is warmer and others when it is colder, scientists can tell what t Read More

What was the Arctic climate like thousands of years ago? Diatoms are simple organisms that provide valuable clues about past climate. A unicellular algae that obtains energy through photosynthesis, diatoms are at the very bottom of the aquatic food chain. They are found in almost every aquatic environment and there are so many different types of diatoms that not even scientists have counted them all; a best guess is over 100,000 species. Diatoms have adapted to live in all kinds of environmental conditions, from extremely cold to extremely warm temperatures, from saltwater to fresh water, from large bodies of water to puddles. They are microscopic but sometimes stick to each other, forming clusters or colonies that grow so big they can be seen floating on top of the water. One of the most important characteristics of diatoms is their hard, outer cell wall. Composed of silica, it acts like a transparent yet very strong glasshouse. The silica cell wall is resistant to degradation, allowing diatoms to remain well-preserved in lake or ocean sediments for thousands of years. Because some diatom species thrive when it is warmer and others when it is colder, scientists can tell what the climate was like by which species are found in the sediment. Greater diatom abundance and diversity are also typically associated with warmer climates.


© 2007, Canadian Museum of Nature. All Rights Reserved.

Sediment cores containing diatom deposits

Paul Hamilton, a scientist with the Canadian Museum of Nature, can estimate historical climatic conditions based on the kinds of diatoms deposited in lakebed sediment. Cores are extracted by drilling down into layers of sediment; each core can represent thousands of years of deposits. Radio-carbon dating is used to determine the age of the deepest layer of sediment in the core, and then the diatoms present in each layer are identified. Because different species thrive in different environmental conditions, a picture of how the climate has changed over time in a particular location can be drawn.

Paul Hamilton

© 2007, Canadian Museum of Nature. All Rights Reserved.


Video clip of Canadian Museum of Nature scientist Paul Hamilton collecting diatom cores on Devon Island.

Canadian Museum of Nature scientist Paul Hamilton drills into the ice to collect diatom cores on Devon Island. Once they’ve located a good spot to drill down from, the team sets up a manual drill to make a hole in the ice that will allow them the lower their equipment. This step is not unlike drilling for ice fishing! It’s important to keep a firm footing when doing this! Next, a series of poles are connected (almost like tent poles) to the corer as it is slowly lowered to the bottom of the lake where it will be buried. The team then works in reverse to slowly bring up the corer from beneath the lake’s bottom all the way to the surface. The poles are carefully detached one after another in order to facilitate this task. Now for the moment of truth! All of this hard work culminates here as the core itself is slowly revealed by carefully removing the corer’s tubular casing. It is important to ensure that the core remains intact before it is measured and eventually sliced to expose its tell-tale layers.

Paul Hamilton
Fiona Currie

© 2007, Canadian Museum of Nature. All Rights Reserved.


Learning Objectives

  • Appreciate the role and contribution of science and technology in our understanding of the world.
  • Describe interactions between biotic and abiotic factors in an ecosystem.
  • Value the role and contribution of science and technology in our understanding of phenomena that are directly observable and those that are not

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