Paleo-ecosystems and climate – University of Copenhagen

Paleo-ecosystems and climate

Plants and animals that were part of the ecosystems that existed in Greenland and Antarctica before the ice sheets covered the Earth can be traced in the basal ice when the right conditions are present. The right conditions are an environment where the temperatures are cold at the bottom and there is no melting. Such a frozen and dry environment provides good conditions for preservation and ensures that the chemical decomposition processes take place slowly.

We can now detect the short DNA fragments from terrestrial ecosystems that existed before the ice was formed, where the cells and DNA of former organisms are degraded, bound to soil particles and quickly frozen.

By propagating the DNA and comparing it with modern species, it is possible to describe the ecosystem that existed just before the climate changed.

Greenland today has a variety of arctic ecosystems that are
representative of the current interglacial period we are in.
Limited  information is available about what kind of ecosystems
were present in previous interglacials.

By choosing DNA fragments that virtually all plants contain, it is possible to compare them in a database with known species and thus get an overview over past biodiversity. Researchers can, for example, conclude that the climate was cold before the ice came if the plants appear to be typical of a tundra ecosystem. On the other hand, if the plants represent an ecosystem with boreal and temperate species, it indicates a warmer climate and that climate change was abrupt.

Past biodiversity adds to our understanding of how interglacial and glacial periods succeed each other. And it provides new insights into how climate change happened the last time we had a warm period in Greenland, when the ice sheet was either completely gone or greatly reduced.

- Reconstruction of past ecosystems and climate using fossil DNA
- Preserved fossil DNA in the ice
- Fossil DNA's potential and limitations
- Combining biodiversity and climate parameters