Understanding past environments is key to making predictions about future changes in the Earth System that may affect humanity. Since the 1980s, environmental groups have been increasingly active in raising awareness about human-induced global warming or, more accurately, climate change. This is largely due to the continual worldwide burning of fossil fuels for energy, which releases gases into the atmosphere, warming the planet beyond its natural variability. Our notions of the impact of this warming – which includes increased storm frequency, more marked seasonal extremes and global sea level rise – are reliant on predictions made by complex global climate computer models. Global governmental strategies for mitigating these physical environmental changes are based on the results of thousands of peer-reviewed scientific articles. These studies feed information into climate models, interpret the results and are summarised every few years in the Intergovernmental Panel on Climate Change report. The study of past environments and climates is an essential part of this process. It uses the...