Geologists from FAU and the University of Vigo (Spain) have proven that where fossils are found is decisive when reconstructing the planet’s climate. Taking samples from certain latitudes may blur results when determining average global temperatures. The researchers have now published the results of their investigations in the journal Geology.
Human activity in the Industrial Age is having a severe impact on the world’s climate system, on biodiversity and on the natural basis for our survival. Taking a look at the past helps us understand and evaluate these developments better.
Whilst it is true that we cannot directly measure Earth’s climate over the ages, researchers can reconstruct it, for example by investigating the chemical composition of sediments and fossils. One of the most commonly used methods involves determining oxygen isotopes in shells of fossilised marine animals. This gives an indication of how water temperatures have changed over the last 500 million years.
Analysing the climatic archive in this way has one decisive weakness, however. The rocks capable of giving information about certain periods in the Earth’s history tend to be found in only a few areas around the globe. The problem with this is that temperatures generally fall the further you move along the mid-latitudes away from the Equator towards the North or South Pole. If the location where the fossils are found is not taken into consideration, samples from different latitudes may either indicate erroneous temperature fluctuations or lead to actual changes in the climate being underestimated.
The researchers, including Dr. Kilian Eichenseer from the Chair of Palaeoenvironmental Research therefore argue that the geographical origin of individual samples ought to be taken into consideration when drawing up meaningful global temperature curves.