Texas cave sediment hints that volcanoes caused ancient global cooling

Researchers from several Texas universities, including the University of Houston, Baylor University, and Texas A&M University have discovered some new evidence that suggests new scientific theories about why the Earth cooled globally about 13,000 years ago. The sediments obtained from a cave in Texas, have preserved geochemical signatures from ancient volcanic corruptions. The researchers say that the signatures were previously mistaken for meteorite impacts on the Earth.The team says their work shows the geochemical signature associated with the cooling event is not unique and had occurred four times between 9000 and 15,000 years ago. Scientist Alan Brandon Ph.D., a professor of geosciences at the University of Houston, says that the trigger for the cooling event didn't come from space. Brandon says that past geochemical evidence for large meteor exploding in the atmosphere instead reflects a period of major volcanic eruptions.

After a volcanic eruption, aerosols from the volcano spread into the atmosphere reflect incoming solar radiation away from Earth and could lead to a global cooling post-eruption that lasts from one to five years, depending on the size and the timescale of the eruption. Researchers say the Younger Dryas, which occurred about 13,000 years ago, disrupted a distinct warming at the end of the last Ice Age.

Scientists say that the Earth's climate could have been at a tipping point in the Younger Dryas, possibly from ice sheets discharging into the North Atlantic Ocean. Enhanced snow cover and major volcanic eruptions could have, in combination, led to intense northern hemisphere cooling. The rapid cooling phase is associated with the extinction of many species, including mammoths and mastodons. The period also coincides with the appearance of early humans of the Clovis tradition.

The researchers say that the elements in the Texas cave sediments aren't present in correct proportions for an asteroid or meteor to have hit the Earth. Rather the signature from osmium isotope analysis, and the relative proportion of elements matches data previously reported in volcanic gases.