Climate Shifts On Earth Related To Volcanoes Over Past 720 Million Years

Over the last 720 million years, our planet went through phases of warming and cooling. According to a new research published in the Science journal, the phenomena are being linked to plate tectonic movements due to volcanic activity which, when combined together, have caused gradual climatic shifts on Earth over the past hundreds of millions of years.

The research, which was carried out by the Jackson School of Geosciences at the University of Texas,  concentrated on analyzing the long term shifts in the Earth's baseline climate rather than short term or human induced examples of climate change. The researchers found that volcanoes located along the continental arcs were most active during phases of warmer climatic conditions over the past 720 million years while colder climatic conditions saw them being less active. Incidentally, continental volcanic arcs, like the Andes Mountains, are created when two tectonic plates meet and the oceanic plate descends under the continental plate, which forms a subduction zone. During the process, carbon from the Earth's crust mixes with magma to release carbon dioxide into the atmosphere when volcanoes along the arc start to erupt.

As per previous studies, it was understood that carbon dioxide has an altering effect on Earth's climate; however scientists have been keener to know the reason for the natural fluctuations of the gas over the course of the planet's history. Now, the new study has linked volcanic ruptures and the related carbon dioxide emission in the atmosphere as the main reason for previous climate shifts.

In order to aid the research, the team of experts collected data from 200 previous studies and their own fieldwork to develop a large global database. The study included the analysis of sedimentary basins near long eroded former volcanic arcs and observation of uranium-lead crystallization ages of zircon, a mineral created during continental volcanic arc activity. The data was used to understand the nature of volcanic activity along the continental margins in the last 720 million years, a time frame that covered the important geologic, greenhouse and icehouse events that occurred on the planet.

On the basis of the study, the researchers found that there was proof of greenhouse conditions during phases of high zircon production and icehouse conditions when zircon production was going through a low phase. Furthermore, the cooler periods coincided with the time frame when the planet's supercontinents assembled, a period which incidentally had lesser volcanic activities. The warm periods coincided with upheaval related to continental breakup and increased volcanic activity.