Climate change is the decaying cause of the Roman Empire

The decline of the Roman and Byzantine empires in the Eastern Mediterranean more than 1400 years ago may have originated from adverse climate changes.

Based on chemical traces on a piece of calcite minerals from a cave near Jerusalem, a group of US and Israeli geologists recreated the region's climate record from 200 BC to 1100 A.C. Their analysis, published in Quaternary Research, shows that dry weather from 100 BC to 700 BC , coincided with the decline of Roman rule.

Researchers, led by Professor John Valley and Ian Orland, a graduate student at Madison University-Madison, have rebuilt the climate record based on the geochemical analysis of a stalagmite from Soreg Cave, Located in the Cave Conservation Area near Jerusalem.
Orland said: 'It is like wood veins intersecting. You have a lot of concentric rings and you can analyze these rings, but instead of looking at their widths, we explore the localization component of each round '.

Using trace or oxygen isotope impurities - such as organic matter flowing into the cave by rain - in the mineral layer, Orland determines the annual precipitation in the years of stalagmites growing, from about 200 years ago. AD to AD 1100
Although cave formation is used to understand the climate, previous analyzes depend primarily on rudimentary sampling tools. The analysis uses a Wisconsin laboratory ion probe to sample spots 1/100 millimeters in size. This method produces 100 times more sharp results than previous methods. With such a high level of analysis, scientists can distinguish weather characteristics between different years and seasons.

The development circle is easily seen in the cross-section of a stalagmite from Soreg Cave near Jerusalem, Israel. Stalagmites are formed from calcite and minerals that settle down in the cave water and contain chemical traces of climate and other natural conditions. The geochemical analysis of a similar stalagmite from the same cave shows a wide-ranging weather change in the Eastern Mediterranean 1400 years ago, including dry weather lasting from 100 AD to the year 700 AD. It may be one of the reasons for the decline of the Roman Empire and Byzantine in this area. (Photo: University of Wisconsin-Madison)

Their climate analysis showed that the Eastern Mediterranean became drier from 100 AD to 700 AD, the time when the Roman and Byzantine empires faded away. Rainfall decreased sharply from about 100 to 400 AD. Valley said: 'Whether this factor undermines Byzantine is still uncertain, it is an interesting coincidence. Climate change occurs at the same time as historical changes.
The team is currently applying this technique to previous models from the same cave. Orland said: 'A remarkable period was at the end of the ice age, about 19,000 years ago - the closest time to Earth's history when the global warming was 4 to 5 degrees Celsius'.

Analysis of this fast changing period can help them better understand the changing weather when the temperature warms.

Sorey Cave - at least 185,000 years old - also offers hope in creating a long-term record of climate change to compare with records of Greenland and Antarctica.

Valley said: 'Nobody knows what happens on the continents. At the extreme, the climate may be quite different. This is a record of what happens at a very different part of the world. '

Other than Valley and Orland, other authors include Miryam Bar-Matthews and Avner Ayalon from Israel's geological survey program, Alan Matthews of Hebrew University, Jerusalem and Noriko Kita of UW-Madison.

Donors to the project include the Comer Science and Education Foundation, the National Science Foundation, the US Department of Energy, the Israel Science Foundation, Sigma Xi, and the UW-Madison Geophysics Department.