We hear a lot about climate change and more specifically climate change in the Arctic, but what do we really know?
We know from the fossil record that the climate was warmer millions of years ago. We also know that tropical-like forests were present in the Arctic around 50 million years ago. Indeed, some of the fossils are original plant pieces that had not mineralized into rock.
What about today? What is happening in the Arctic? This is an interesting question that can be examined in different ways. My colleagues and I had been looking at more recent fossils (less than 10,000 years old) to try to answer this question and we turned to microscopic fossils (diatoms).
Microscopic fossils are easy to find, are good indicators of water conditions and are abundant in lakes, pond, rivers and streams. The mud sediments at the bottom of lakes and ponds are excellent places to trap the diatom fossils. By looking at the sediments at the bottom of lakes and ponds we can look at the history of the lake or pond over long periods of time. My colleagues and I have been able to look at the history of many lakes across the Arctic that date to the last 7,000 to12,000 years.
What we have found is that much of the Arctic was warmer about 5,000 to 7,000 years ago, then more recently was quite cold. What is most interesting is that over the last 60or so years the Arctic has become much warmer. We know this because microfossil diatoms have increased dramatically in numbers and the species have changed. This indicates that the lakes and ponds are more productive, which can be linked directly to longer warmer summers in the Arctic.
Climate change is not always uniform and it is important to remember that part of the Arctic could be getting colder while other parts are getting warmer. What we do know is that the diatom fossils in lakes and ponds across the Arctic, away from human-settled areas, which can skew the temperature data, are indicating warmer summers. It is up to science and us scientists to keep trying to answer those climate questions.