Question: How do you use mud to find out about climate change?

Laura Hunt answered on 19 Jun 2020:

Hi Gus, thanks so much for your question!

I study how the climate has changed going further back in time than scientists have been able to measure and record how environments are changing.
It is important that we understand how the environment has changed further back in time than humans can remember, because this helps us understand how the earth responded to warmer climates in the past.

I study lakes in Africa – over time, mud builds up in the bottom of these lakes, building an ‘archive’ of the lake’s environment over time. We can go back in time by collecting this mud as a sediment core, and looking at the mud in the laboratory. Pollen, plants, algae (tiny tiny plants!) and parts of animals collect at the bottom of the lake with the mud, and we can use this to work out what the vegetation and habitat at the lake was like hundreds of years ago. We can build long records of change at the lakes, as the sediment at the top of the core settled at the bottom of the lake recently, but the sediment at the bottom of the core can be reaaaally old (thousands and thousands of years in some cases!). We can also look at the chemical composition of the mud (this is what I am studying) to look at how the temperature and amount of water in the lakes has changed over time, as well as how much rainfall the lakes experience.

We can work out how old the sediment in the core is by measuring the radioactivity of the mud, which helps us relate our findings to those at other lakes, so we can build up a picture of how the climate has changed, and how lakes responded to change, across the whole of eastern Africa – and even the world!

I hope that makes sense! Let me know if you’d like to know anything else.
– Laura 🙂