Peat cores and climate change

Dr Marcus Vandergoes, a paleoecologist at GNS Science, explains how cores from Ōkārito Pākihi and other Westland peat bogs provide evidence for climate and environmental change over the last 135,000 years. Precise dating is important so that the speed of past climate changes can be estimated.

Transcript

DR MARCUS VANDERGOES
The peat bog areas in Franz Josef and Fox Glacier and the cores we recover from them, they’re incredibly important for studying climate change. We have a hidden record of some of those sites going back 135,000 years – they actually span a number of ice ages and a number of warm periods in between – and that’s why the Ōkārito peat bog is really important in New Zealand for containing that type of sediment sequence.

Studying pollen and insects and other plant fossils and microfossils helps us study environmental change and reconstruct environmental change. So if we get a cold climate, we might expect a certain type of beetle or pollen type that is representative of a cold climate, say alpine grassland. When we get a warm climate, we get tall trees, forests like say rimu forests you currently get on the West Coast of the South Island.

It’s important to understand what time these environmental changes occurred and also how fast they occurred, like particularly if we’re looking at say climate change, to know that the climate changed in a matter of 100 years or 3,000 years is a very important thing to understand, particularly when we’re trying to understand how fast climate may change in the future. Some of these events do take a long time to change and some of them are quite rapid, and by looking at this history in these sediments, the lakes and the peat bogs, by using dating techniques, we can understand how quickly these changes occurred.

What we’re trying to achieve is understanding how New Zealand responded to global climate change. Certain areas of the world responded in a different way, at different times, and looking at New Zealand’s climate history, we can see if it changed at the same time as say the Northern Hemisphere, North America or Australia and other parts of the world as well. And if they occurred all at the same time, we know that it’s responding to a global climate change, whereas if it occurred slightly differently – sooner, later – it could be something more local, something to do say with the Southern Ocean-driven climate change. So we can find a lot of this information out with using precision dating techniques.

Understanding the environmental changes in the past gives us very good insights into the current climate discussions that people around the world are having. We can find a lot of this information out of the past and then can use that to inform us for understanding global climate change in the future.

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