Dour/Sour Days Ahead: What we might inadvertently be doing to our world with the mass release of Carbon Dioxide
The implications are chilling....
Bugs poisoned Earth with rotten egg gas
By Roger Highfield, Science Editor, London Telegraph
Last Updated: 6:01pm GMT 06/02/2008
Evidence that the biggest extinction of life in the Earth's history was caused by microscopic life has been found by scientists.
Some 251 million years ago, at the end of what is called the Permian period, up to 95 per cent of marine species and 85 per cent of those on land went extinct.
Few remark on how the oldest and most successful life forms on Earth - the bacteria and primitive singled-celled creatures called archaea - sailed through virtually unharmed. Now it appears that they played a starring role in the extinctions.
advertisementThis new view comes from studies of biochemicals that have been trapped inside rocks for billions of years, "molecular fossils" which mean that ancient organisms that otherwise left no trace in the fossil record can now be identified, reports New Scientist.
In 2005 Roger Summons, now at the Massachusetts Institute of Technology, teamed up with geochemist Kliti Grice of Curtin University of Technology in Perth, Western Australia. Working with cores of sedimentary rock from China and Western Australia, they identified an interesting organic chemical, a "biomarker", known as isorenieratene.
Today, the precursors of this molecule are found only in the pigments of a very specific group of microbes - the green sulphur bacteria. These peculiar microbes make a living by photosynthesis but cannot tolerate oxygen and depend on hydrogen sulphide, the "rotten egg" gas which is highly toxic to plants and animals.
The team realised that the presence of these microbes indicated an ocean environment that was shallow enough for light to penetrate and photosynthesis to occur, yet was lacking in oxygen. Instead, it was saturated with hydrogen sulphide: the seas of the late Permian were awash with poison.
The team has since found the sulphur bacteria biomarker at a dozen late-Permian sites around the world, good evidence that the hydrogen sulphide oceans were a global phenomenon.
Three years ago, Summons, Grice and others combined their biomarker evidence in an influential paper that eliminated asteroids as a suspect for the Permian extinction and pointed the finger at a mass poisoning.
A team led by geochemist Lee Kump of Pennsylvania State University in University Park suggested that so much hydrogen sulphide was produced in an ocean devoid of oxygen that it escaped into the atmosphere and poisoned plants and animals, as well as depleting the ozone layer that protects Earth from the sun's harmful UV radiation.
"Subsequent work has reduced the predicted severity of these consequences, but release of this toxic gas from the oceans still provides a compelling link between the terrestrial and marine extinctions," says Kump
The ultimate culprit was intense global warming triggered by massive emissions of greenhouse gases from one of the largest and most sustained volcanic eruptions ever known, the Siberian Traps. In the hothouse of the late Permian, temperatures at the high latitudes were barely different from those at the equator, currents ground to a halt and the oceans changed, ultimately causing a lethal build-up of hydrogen sulphide produced by bacteria.
"Warm water holds less gas (oxygen) that starts the buildup of hydrogen sulphide," explains Kump. "Further eutrophication (buildup of nutrients) intensifies the oxygen depletion and hydrogen sulphide buildup. The buildup of nutrients occurs because the warm, wet climate brings nutrients in from the land with increased river flow."
Published on Saturday, February 3, 2007 by the lndependent/UK
Global Warming: The Final Warning
Carbon Dioxide Rate is at Highest Level for 650,000 Years
by Steve Connor
Concentrations of carbon dioxide in the atmosphere are at their highest levels for at least 650,000 years and this rise began with the birth of the Industrial Revolution 250 years ago, according to the Intergovernmental Panel on Climate Change (IPCC).
This photo from the National Science Foundation shows the shear face of the massive B-15A iceberg stretches for 150 kms across McMurdo Sound after it broke off the Ross Ice Shelf in Antartica, 2001. UN scientists delivered their starkest warning yet about global warming, saying fossil fuel pollution would raise temperatures this century, worsen floods, droughts and hurricanes, melt polar sea ice and damage the climate system for a thousand years to come. (AFP/NSF-HO/File/Josh Landis)
Carbon dioxide is the principal greenhouse gas responsible for global warming and, in 2005, concentrations stood at 379 parts per million (ppm). This compares to a pre-industrial level of 278 ppm, and a range over the previous 650,000 years of between 180 and 300 ppm, the report says.
Present levels of carbon dioxide - which continue to rise inexorably each year - are unprecedented for the long period of geological history that scientists are able to analyse from gas samples trapped in the frozen bubbles of deep ice cores.
However, the IPCC points to a potentially more sinister development: the rate of increase of carbon dioxide in the atmosphere is beginning to accelerate. Between 1960 and 2005 the average rate at which carbon dioxide concentrations increased was 1.4 ppm per year. But when the figures are analysed more closely, it becomes apparent that there has been a recent rise in this rate of increase to 1.9 ppm per year between 1995 and 2005.
It is too early to explain this accelerating increase but one fear is that it may indicate a change in the way the Earth is responding to global warming. In other words, climate feedbacks that accelerate the rate of change may have kicked in.
The IPPC's report points out that, as the planet gets warmer, the natural ability of the land and the oceans to absorb carbon dioxide from the atmosphere begins to get weaker.
It is estimated that about half of all the man-made emissions of carbon dioxide have been taken out of the air and absorbed by natural carbon "sinks" on the land and in the sea. Many computer models of the climate predict that as the Earth continues to get warmer, these sinks will become less able to absorb carbon dioxide from the atmosphere.
This means that more carbon dioxide will be left in the air to exacerbate the greenhouse effect, so leading to further temperature rises and more global warming, which in turn will make the natural carbon sinks of the Earth even less efficient.
As the IPCC's summary says: "Warming tends to reduce land and ocean uptake of atmospheric carbon dioxide, increasing the fraction of anthropogenic [man-made] emissions that remain in the atmosphere."
This is just one of several "positive feedbacks" that could quickly accelerate the rate of global warming over the coming century. One isa warmer world is causing more evaporation from the oceans and a rise in water vapour - a powerful greenhouse gas - in the lower atmosphere. Another is sea ice and snow cover is shrinking at the poles and on mountains, leading to a further increase in local temperatures.
Global warming: the final warning
According to yesterday's UN report, the world will be a much hotter place by 2100. This will be the impact ...
+2.4°C: Coral reefs almost extinct
In North America, a new dust-bowl brings deserts to life in the high plains states, centred on Nebraska, but also wipes out agriculture and
cattle ranching as sand dunes appear across five US states, from Texas in the south to Montana in the north.
Rising sea levels accelerate as the Greenland ice sheet tips into irreversible melt, submerging atoll nations and low-lying deltas. In Peru, disappearing Andean glaciers mean 10 million people face water shortages. Warming seas wipe out the Great Barrier Reef and make coral reefs virtually extinct throughout the tropics. Worldwide, a third of all species on the planet face extinction
+3.4°C: Rainforest turns to desert
The Amazonian rainforest burns in a firestorm of catastrophic ferocity, covering South America with ash and smoke. Once the smoke clears, the interior of Brazil has become desert, and huge amounts of extra carbon have entered the atmosphere, further boosting global warming. The entire Arctic ice-cap disappears in the summer months, leaving the North Pole ice-free for the first time in 3 million years. Polar bears, walruses and ringed seals all go extinct. Water supplies run short in California as the Sierra Nevada snowpack melts away. Tens of millions are displaced as the Kalahari desert expands across southern Africa
+4.4°C: Melting ice caps displace millions
Rapidly-rising temperatures in the Arctic put Siberian permafrost in the melt zone, releasing vast quantities of methane and CO2. Global temperatures keep on rising rapidly in consequence. Melting ice-caps and sea level rises displace more than 100 million people, particularly in Bangladesh, the Nile Delta and Shanghai. Heatwaves and drought make much of the sub-tropics uninhabitable: large-scale migration even takes place within Europe, where deserts are growing in southern Spain, Italy and Greece. More than half of wild species are wiped out, in the worst mass extinction since the end of the dinosaurs. Agriculture collapses in Australia
+5.4°C: Sea levels rise by five metres
The West Antarctic ice sheet breaks up, eventually adding another five metres to global sea levels. If these temperatures are sustained, the entire planet will become ice-free, and sea levels will be 70 metres higher than today. South Asian society collapses due to the disappearance of glaciers in the Himalayas, drying up the Indus river, while in east India and Bangladesh, monsoon floods threaten millions. Super-El Niños spark global weather chaos. Most of humanity begins to seek refuge away from higher temperatures closer to the poles. Tens of millions of refugees force their way into Scandanavia and the British Isles. World food supplies run out
+6.4°C: Most of life is exterminated
Warming seas lead to the possible release of methane hydrates trapped in sub-oceanic sediments: methane fireballs tear across the sky, causing further warming. The oceans lose their oxygen and turn stagnant, releasing poisonous hydrogen sulphide gas and destroying the ozone layer. Deserts extend almost to the Arctic. "Hypercanes" (hurricanes of unimaginable ferocity) circumnavigate the globe, causing flash floods which strip the land of soil. Humanity reduced to a few survivors eking out a living in polar refuges. Most of life on Earth has been snuffed out, as temperatures rise higher than for hundreds of millions of years.
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