Palaeoclimate: oxygen’s rise reduced.
A team of researchers from Rensselaer Polytechnic Institute and the University of Texas Austin has used a new technique to analyze tiny amounts of gas trapped inside million-year-old rocks from the Colorado Plateau and the Newark Basin. Their results show that oxygen levels in these rocks leapt by nearly a third in just a couple of million years, possibly setting the scene for a dinosaur expansion into the tropics of North America and elsewhere.
Chindesaurus bryansmalli. Image credit: Petrified Forest National Park. Chindesaurus was an upright carnivorous dinosaur, around 6.
Dating the rise of atmospheric oxygen. Nature. , –doi/nature Crossref, PubMed, ISI, Google Scholar.
For hundreds of millions of years, wildfires have shaped the planet. Credit: Naomi Kelly. We owe Earth as we know it to fire. For hundreds of millions of years, wildfires have shaped the planet, from the plants, animals and ecosystems around us to the air we breathe. The process and timing of the onset of fire-favoring conditions and the subsequent impacts on the atmosphere, land and oceans are areas of growing interest. And scientists are increasingly uncovering feedbacks within and between these critical earth systems, and finding that fire plays a role in many of them.
A growing body of evidence, obtained in recent years from studies of ancient charcoal, the fossil record and laboratory burn experiments, as well as from biogeochemical modeling, demonstrates that wildfires may have had a more profound impact than previously imagined. But the details are far from settled. Without more data, particularly a better understanding of the charcoal signals that fires leave behind, it remains difficult to fully resolve the history and complex impacts of ancient wildfires.
Nonetheless, recent research now points toward fire driving and sustaining key evolutionary innovations that spurred biodiversity and played a role in extinction events. Scientists also think that fire may ultimately be responsible for maintaining oxygen levels in our atmosphere within a range that supports life, including large, terrestrial organisms, such as humans.
The oldest evidence of wildfire comes from a million-year-old rhyniophytoid plant, a small leafless plant from the Silurian Period, whose charred remains were found in an English siltstone.