VOLCANOE CLUES TO CLIMATE CHANGE

The discovery that the ocean starved of oxygen caused a mass extinction of marine species 93 million years ago may hold valuable information for solutions to modern global warming.

Underwater volcanism in rocks dating to the period known as the "anoxic event" of the late Cretaceous Period were responsible for levels of greenhouse gases in the atmosphere to drop and lurching Earth into a sudden cooling, according to researchers from the University of Alberta, Canada .

Geologists have long been puzzled by how this extraordinary event altered the chemistry of the sea and Earth's atmosphere.

The bed of the present-day Caribbean was formed by the huge lava flows, but researchers say the flows would have preceded the extinction by up to 23,000 years.

Geologist Tim Bralower of Pennsylvania State University, US, contends that the volcanoes may have spewed out metal-rich fluids that seeded the upper level of the ocean with micronutrients allowing tiny phytoplankton to gorge on the food and store carbon as they grew. When they later sank to the sea floor and decayed the ocean was stripped of oxygen.

Another theory is that the volcanoes disgorged clouds of CO2 into the atmosphere - warming the climate and halting Earth's ocean circulation system.

Figuring out the post-volcanism scenario will help scientists better understand the unknown factors of climate change.