Climate is not constant on Earth. Consider ice ages coming and going as an example. Parallel to ice age cycles, atmospheric carbon dioxide reduces during glacial periods and increases during warmer times, although modern fossil fuel-related carbon dioxide emission broke this natural cyclicity. With the proper proxy measurements, scientists can look into these past cycles to determine how exactly climate systems were naturally governed.
Increase in volcanic eruptions at the end of the ice age caused by melting ice caps and glacial erosion
The combination of erosion and melting ice caps led to a massive increase in volcanic activity at the end of the last ice age, according to new research.
Fossil fuel emissions could soon make it impossible for radiocarbon dating artefacts that are hundreds of years old
Carbon released by burning fossil fuels is diluting radioactive carbon-14 and artificially raising the radiocarbon 'age' of the atmosphere.
A multi-decade drought that occurred in the 2nd century has been revealed by researchers from the University of Arizona by studying tree-rings (dendrochronology).