Analyzing sediments to investigate global warming that happened 56 million years ago – Eurasia Review

Alluvial and hydroclimatic changes at the boundary between Huesca and Lleida during Paleocene-Eocene climate warming are analyzed

The UPV/EHU Geology Department examined sediments dating back 56 million years in the Tremp-Graus basin (on the border between Lleida and Huesca). It can be deduced from the study that the episode of global warming at that time consisted of three phases in which the distribution of precipitation was different. Data from the study can be used to adjust mathematical models used to predict the effects of current climate change.

The main carbon emissions in the atmosphere and the oceans took place 56 million years ago; which led to intense global warming known as the Paleocene-Eocene Thermal Maximum, and is considered an ancient analogue of present-day anthropogenic warming. “Although the origin or cause of warming at that time was different, the process was very similar to today’s warming, so it is considered similar to today’s global warming. It is known that climate warmed, but other alterations than warming can occur with climate change. In particular, we wanted to analyze how the hydro-climatic conditions in terms of precipitation changed at this time,” said Aitor Payros, who obtained a doctorate in geology at the UPV/EHU.

The Department of Geology of the UPV/EHU studied the alluvial and hydroclimatic changes of the mid-latitudes recorded in the Tremp-Graus basin (on the border between Lleida and Huesca) during the Paleocene-Eocene thermal maximum, and concluded that this what happened then could somehow resemble what is already happening today in the southeast of the Iberian Peninsula. To do this, they collected historical data from the region, and discovered geographical as well as hydro-climatic similarities.

According to Aitor Payros, “we have seen that global warming changes the seasonal distribution of precipitation and that it also changes in several phases. At first, rainfall was concentrated in a few months around fall; later it became more evenly distributed throughout the year. The last phase, however, tended to be drier. According to Payros, “we cannot simply say that global warming is causing higher temperatures or worse rainfall. Things are not that simple. Changes are happening, but they are not sustained throughout the period of global warming. In global warming, there can be several phases.

Look to the past to predict the future

“We observed that at the beginning of this episode of global warming, there was an increase in seasonal contrasts with respect to precipitation. In other words, the precipitation was concentrated around the fall (with frequent thunderstorms and significant flooding) and during the remaining months there were periods of drought. And this is precisely what has happened in recent decades, and in the last century, in the south-east of the Iberian Peninsula: heavy rains are increasingly frequent around autumn and the end of summer, which was not the case 100 or 200 years ago. “said Payros.

The researcher pointed out that it is not possible to predict what will happen in the future in the south-east of the Iberian Peninsula, “but if we assume that the Earth reacts in a similar way to the same or similar phenomena , we could assume that the future annual distribution of precipitation could be more homogeneous in the southeast of the peninsula or in other regions with a similar climate”.

Payros emphasizes the potential value of studying paleoclimates: “We can see what happened millions of years ago. And if what happened is repeated again and again, that is, if the Earth always responds in the same way to certain phenomena, it can be assumed that it will continue to function in the same way in the future. . This type of research can be used to make future predictions: “When the computer or mathematical models used to predict the climate are able to reproduce the phenomena that have occurred during periods of past global warming, then they will be able to predict the changes that will occur. in the future. These computer and mathematical models may correspond to our data.

Teresa H. Sadler