TURNING CO2 INTO FUEL
As scientists and policymakers around the world try to combat the increasing rate of climate change, they have focused on the chief culprit: carbon dioxide.
Produced by the burning of fossil fuels in power plants and car engines, carbon dioxide continues to accumulate in the atmosphere, warming the planet. But trees and other plants do slowly capture carbon dioxide from the atmosphere, converting it to sugars that store energy.
In a new study from the U.S. Department of Energy's Argonne National Laboratory and the University of Illinois at Chicago, researchers have found a similar way to convert carbon dioxide into a usable energy source using sunlight.
One of the chief challenges of sequestering carbon dioxide is that it is relatively chemically unreactive. "On its own, it is quite difficult to convert carbon dioxide into something else," said Argonne chemist Larry Curtiss, an author of the study.
To make carbon dioxide into something that could be a usable fuel, Curtiss and his colleagues needed to find a catalyst -- a particular compound that could make carbon dioxide react more readily. When converting carbon dioxide from the atmosphere into a sugar, plants use an organic catalyst called an enzyme; the researchers used a metal compound called tungsten diselenide, which they fashioned into nanosized flakes to maximise the surface area and to expose its reactive edges.
MASS EXTINCTION ENGINEERED BY EARLY ANIMALS
Newly discovered fossil evidence from Namibia strengthens the proposition that the world's first mass extinction was caused by "ecosystem engineers" -- newly evolved biological organisms that altered the environment so radically it drove older species to extinction.
The event, known as the end-Ediacaran extinction, took place 540 million years ago. The earliest life on Earth consisted of microbes -- various types of single-celled organisms. These held sway for more than 3 billion years, when the first multicellular organisms evolved. The most successful of these were the Ediacarans, which spread around the globe about 600 million years ago. They were a largely immobile form of marine life shaped like discs and tubes, fronds and quilted mattresses.
After 60 million years, evolution gave birth to another major innovation: metazoans, the first animals. Metazoans could move spontaneously and independently at least during some point in their life cycle and sustain themselves by eating other organisms or what other organisms produce. Animals burst onto the scene in a frenzy of diversification that paleontologists have labeled the Cambrian explosion, a 25 million-year period when most of the modern animal families -- vertebrates, mollusks, arthropods, annelids, sponges and jellyfish -- came into being.