An international group of scientists published a study where they studied the process of climate change in the seas. Accurate estimates of the temperature of ancient oceans are important because they provide insight into the climatic picture of the past. The work was published in the journal Geophysical Research Letters.
Climate models provide scenarios of what the world might look like in the future. And paleoclimate studies (the study of the climate of the past) provide an idea of how the world looked in the past. If the models mimic the past well enough, scientists will be able to get the most realistic results.
By understanding how latitudinal temperature gradients have changed over the course of Earth’s history and under different climates, we can better predict what will happen in the future.
Emily Judd, researcher in the Department of Earth and Environmental Sciences
To determine ancient temperatures, geologists study chemical or biological footprints that record temperatures from sedimentary deposits preserved on the seabed or on continents.
Due to the reuse of ancient seabed in the Earth’s mantle, there is a so-called shelf life, which determines how long this data can be preserved. Thus, the most ancient temperature indicators come from sediments that have accumulated on the outskirts of continents or in shallow inland seas, where records can last much longer.
Data from shallow, partially enclosed seas (eg the Mediterranean and Baltic Seas) show that sea surface temperatures are higher than those of the open ocean.
As a result, the main conclusion of the article: the average temperature in the Paleozoic era (~ 540–250 million years ago) was unrealistically high.
According to Judd, the paleoclimatic community has made significant progress in understanding the ancient climate over the past few decades. New, faster, and cheaper analytical methods, as well as an increase in the number of expeditions that extract cores of oceanic sediments, have led to an array of information about the climate of ancient seas.
Despite these advances, there are still significant discrepancies between temperature estimates from different locations within the same time interval and / or between temperatures.