Scientists Think They Know What Caused the Deadliest Mass Extinction in the History of the Earth

This illustration shows the percentage of marine animals that went extinct during Earth's worst extinction at the end of the Permian era by latitude, from the model (black line) and from the fossil record (blue dots).A greater percentage of marine animals survived in the tropics than at the poles. The color of the water shows the temperature change, with red being most severe warming and yellow less warming. At the top is the supercontinent Pangaea, with massive volcanic eruptions emitting carbon dioxide. The images below the line represent some of the 96 percent of marine species that died during the event. [Includes fossil drawings by Ernst Haeckel/Wikimedia; Blue crab photo by Wendy Kaveney/Flickr; Atlantic cod photo by Hans-Petter Fjeld/Wikimedia; Chambered nautilus photo by John White/CalPhotos.]Justin Penn and Curtis Deutsch/University of Washington

Humanity can have a love/hate relationship with itself, but there’s no denying that we’re the pinnacle of evolution on Earth as things stand now. But it took an awfully long time for evolution to produce beings such as we. Several times, life had to drag itself back from near annihilation.

The largest extinction setback was the Permian-Triassic extinction, also called the “Great Dying,” some 252 million years ago. Up to 96% of all marine species and 70% of terrestrial vertebrate species went extinct.

What happened?

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Climate Change is Making the Atmosphere Worse for Astronomy

Modern astronomical telescopes are extraordinarly powerful. And we keep making them more powerful. With telescopes like the Extremely Large Telescope and the Giant Magellan Telescope seeing first light in the coming years, our astronomical observing power will be greater than ever.

But a new commentary says that climate change could limit the power of our astronomical observatories.

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Did Snowball Earth Happen Because of a Sudden Drop in Sunlight?

Hundreds of millions of years ago, Earth went through two episodes of severe glaciation. These two episodes—the Sturtian and the Marinoan glaciations—occured during the Earth’s Cryogenian Period. The Cryogenian lasted from about 720 million to 635 million years ago.

The phenomenon is called “Snowball Earth” and both instances of it happened in pretty quick succession. And while a planet encased in ice and snow sounds devastating, these episodes may have paved the way for the development of complex life.

The question is, what caused the Earth to freeze over like that?

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Martian Features Were Carved by Glaciers, not Flowing Rivers

Orbiters are giving us a chance to study the surface of Mars closely, and some of the features that pop to prominence are dry river channels. There are over 10,000 of them. But a new study suggests that glaciers on ancient Mars are responsible for many of them.

According to the study, those glaciers and the water flowing under them are resonsible for carving out some of those riverbeds, rather than free-flowing rivers.

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Even If We Cut Greenhouse Gas Emissions Tomorrow, it Would Take Decades for the Earth to Start Cooling Again

Our beautiful, precious, life-supporting Earth as seen on July 6, 2015 from a distance of one million miles by a NASA scientific camera aboard the Deep Space Climate Observatory spacecraft. Credits: NASA

If—or hopefully when—we cut our Greenhouse Gas (GHG) emissions, we won’t notice much difference in the climate. The Earth’s natural systems take time to absorb carbon from the atmosphere. We may have to wait decades for the temperatures to drop.

Of course, that doesn’t mean we shouldn’t do it. It’s just that we have to temper our expectations a little.

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It Was Almost Certainly an Asteroid Impact that Wiped Out the Dinosaurs. In Fact, Volcanoes Might Have Helped Life Recover

It seems almost certain that an asteroid impact wiped out the dinosaurs. But only almost. Another competing theory won’t completely go away: the extinction-by-volcano theory.

A new study from the UK piles more evidence on the asteroid side of the debate, while adding a new volcanic twist. These researchers say that volcanic activity actually helped life recover from the asteroid strike.

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The Coast of Antarctica is Starting to Turn Green

The Antarctic Peninsula is the northernmost part of Antarctica, and has the mildest climate on the continent. In January, the warmest part of the year, the temperature averages 1 to 2 °C (34 to 36 °F). And it’s getting warmer.

Those warm temperatures allow snow algae to grow, and now scientists have used remote sensing to map those algae blooms.

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During Mass Extinction Events, Volcanoes Were Releasing About the Same Amount of CO2 as We Are Today

200 million years ago, a mass extinction event wiped out about 76% of all species on Earth—both terrestrial and marine. That event was called the end-Triassic extinction, or the Jurassic-Triassic (J-T) extinction event. At that time, the world experienced many of the same things as Earth is facing now, including a warming climate and the acidification of the oceans.

A new paper shows that pulses of volcanic eruptions were responsible, and that those pulses released the same amount of CO2 as humans are releasing today.

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