The most severe period of extinction is also the time when the Earth is 'strongest'

Earth has experienced five mass extinction events, which decimated the diversity of life and devastated the planet's ecosystems. As it turned out, the deadliest extinction event on Earth in the past had another feature - it was extremely 'smelly'.

Scientists believe that volcanoes in what is now Siberia, spewed greenhouse gases and led to the most severe mass extinction event about 250 million years ago, in the late Permian. The gases cause extreme warming, leading to 95% of marine species, as well as 70% of terrestrial species, to extinction.

So far, scientists have not been able to explain exactly how the heat caused those deaths. A new study from Riverside University shows that heat speeds up microbial metabolism, creating life-threatening conditions.

The gases cause extreme warming that causes species to go extinct.

'After the oxygen in the ocean is used up to decompose organic matter, microorganisms begin to absorb the sulfates and produce hydrogen sulfide, a gas that smells like rotten eggs and is very toxic to animals. Researcher Dominik Hülse said.

If humans inhale hydrogen sulfide, they will experience a range of symptoms such as vomiting, diarrhea, insomnia, headaches, dizziness, and sneezing. With constant exposure, one can get very sick and possibly even die.

As the microorganisms and plants at the base of the ocean food chain rot, other microorganisms rapidly consume oxygen and thus the larger organisms are starved of oxygen.

Under hypoxic conditions, the microorganisms that consume the sulfate then release the toxin, producing hydrogen sulfide (H2S), forming an extreme condition known as "euxinia". Euxinia occurs when water lacks oxygen and hydrogen sulfide levels rise rapidly. Euxinic water bodies are often strongly stratified, with a thin, toxic surface layer.

Microorganisms absorb sulfates and produce hydrogen sulfide - a gas with a very toxic rotten egg odor.

Research published in the journal Nature Geoscience sheds further light on the role the oceans play in climate change, providing a glimpse into our future. With an increase in temperature, euxinic water bodies in the oceans tend to be larger. These toxic zones are easily spread and potentially toxic to marine life.

Lessons from the ancient world could be important for us to understand the processes that are challenging the modern ocean.