Courtesy National Center for Ecological Analysis and SynthesisOne of the great extinctions in Earth history occurred 252 million years ago when about 95 percent of all marine species went extinct. The cause or causes of the Great Dying have long been a subject of much scientific interest.
Now careful analyses of fossils by scientists at Stanford and the University of California, Santa Crux offer evidence that marine animals throughout the ocean died from a combination of factors – a lack of dissolved oxygen, increased ocean acidity and higher water temperatures. What happened to so dramatically stress marine life everywhere?
Geochemical and fossil evidence points to a dramatic rise in the concentration of carbon dioxide in the atmosphere, which in caused a rapid warming of the planet and resulted in large amounts of carbon dioxide dissolving into the ocean and reacting with water to produce carbonic acid, increasing ocean acidity. The top candidate for all this carbon dioxide? – huge volcanic eruptions over thousands of years in what is now northern Russia.
Why should the Great Dying be of more than just academic interest? Humans currently release far more carbon dioxide into the atmosphere than volcanoes and we are releasing carbon dioxide into the atmosphere at a rate that greatly exceeds that believed to have occurred 252 million years ago. The future of Earth’s oceans will be determined by human decision making, either by default or by design. What do we want our future ocean to be?
Courtesy Wikipedia CommonsSkeptics of human-induced climate change have long pointed to a lag between an increase in temperature and a rise in atmospheric carbon dioxide at the end of the last Ice Age as suggesting that carbon dioxide is an effect of rising temperatures, not a cause. This lag, however, was based on evidence from only one place on Earth - ice core records from Antarctica.
A much more extensive study of paleo-temperature records from 80 sites around the world just published in Nature reveals that global temperature increases followed rises in the carbon dioxide concentration in the atmosphere. Carbon dioxide is a heat-trapping gas that can drive climate change. This study greatly substantiates climate scientists who point out that the enormous quantities of carbon dioxide that human activities are putting into the atmosphere will result in dramatic changes in global climate if they are not curtailed.
Courtesy NASAThe March 30 issue Science summarized an article in a recent issue of Geophysical Research Letters with significant implications for human welfare.
Many climatologists have expected that extreme weather events will increase in frequency and intensity as human activities continue to increase the concentration of heat-trapping gases in the atmosphere. But how in particular could global warming exacerbate extreme weather?
A couple of processes have been identified that are impacting North America. First, the increasing melting of Arctic sea ice in summer means that a tremendous amount of solar energy that in the past was reflected back into space instead is absorbed by the ocean, which in turn warms the overlying atmosphere. Second, snow cover is melting earlier across much of North America and so more solar energy goes into drying out soils. These two processes – Arctic sea ice loss and the heating up and drying out of the interior of the continent – interact to slow the passage of weather systems from west to east across the continent, thereby strengthening their impacts.
Scientists are beginning to figure out how global warming can end up impacting our daily weather.
Courtesy CECAR - Climate and Ecosystems Change Adaptation R (adapted by Mark Ryan)Several months back there was a lot of hoopla revolving around the so-called "Climategate" scandal. Climate scientists' emails were hacked, posted online and taken out of context as they were disseminated around the internet and through the news channels. Some researchers were charged with manipulating climate data to bolster their own point of view, and indignant investigations were launched against them. As the story fermented in the media, the blogosphere, and political circles, it grew into an over-inflated bag of hot-air. But, eventually, the truth prevailed, and those accused were exonerated by the facts. Michael Mann, a climate change researcher at Pennsylvania State University, was one of key figures in the "scandal", and has written (both here and in a new book) about his experience dealing with the kind of smear campaign that was hurled his way. He terms it the "scientization" of politics. It's involves some of same anti-science tactics used by the tobacco industry and creationists: mainly to cast doubt on the facts, and fabricate controversy where there is none.
I stole that title directly from Gizmodo. This animation is gorgeous and does bear a striking resemblance to Van Gogh's Starry Nights. I could watch the currents move for hours.
From the NASA website "This visualization shows ocean surface currents around the world during the period from June 2005 through December 2007. The visualization does not include a narration or annotations; the goal was to use ocean flow data to create a simple, visceral experience."
Well done, folks. Well done.
Animators: Greg Shirah (NASA/GSFC) (Lead) & Horace Mitchell (NASA/GSFC)
Video Editor: Victoria Weeks (HTSI)
Scientists: Hong Zhang (UCLA) & Dimitris Menemenlis (NASA/JPL CalTech)
Check out this insightful TED Talk on "How simple ideas lead to scientific discoveries" given by Adam Savage, host of television's Mythbusters. The simple method he describes that was used to first calculate the speed of light is pretty inspiring.
This kind of thing has been around for a long time but I always find it fun and enlightening. Click and play
Wondering where all the snow is? Is this normal? This short video from NASA Goddard will answer some of your questions.