An ice age has been blamed for the extinctions - a huge ice sheet in the southern hemisphere caused climate change and a fall in sea level, and messed with the chemistry of the oceans.
Recent scientific analysis no longer supports the idea that extinctions on Earth happen at regular, repeating intervals. Thus, the Nemesis hypothesis is no longer needed.
Some experts believe that Marine dysoxia may be responsible for major oceanic extinctions.
Originally, Nemesis was suggested as a way to explain a cycle of mass extinctions on Earth.
He cited stronger typhoons, worsening droughts, resurgence of diseases and extinctions of species as among the alarming impacts of global warming.
But now scientists claim that the regularity of the mass extinctions actually disproves the Nemesis theory because its orbit would have changed over time as it interacted with other stars.
The big concern for me is that unless we curb carbon emissions we risk mass extinctions, degrading coastal waters and encouraging outbreaks of toxic jellyfish and algae.
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