Planet on the Brink

The greenhouse effect:
CO2 in the atmosphere causes a greenhouse effect. The science of this is generally understood. Short wave solar radiation crosses the earth’s atmosphere, passing through the mix of gases in the air including CO2, and warms the body of the earth. The earth avoids overheating with the release of heat energy that radiates out to space. Emitted from the earth in the form of long wave radiation1 however, some of the heat fails to escape the atmosphere, trapped by the action of CO2 and other greenhouse gases, which absorb long wave radiation. The more greenhouse gases in the atmosphere, the hotter the earth becomes2.

1. A body as hot as the sun emits short wave radiation (in accordance with Wien’s Distribution Law) and short wave radiation passes right through greenhouse gases. While the colder earth releases long wave radiation the greenhouse gases absorb.

2. With no greenhouse atmosphere the earth would be almost as a cold as the moon (which is 33C colder). With an excess concentration of greenhouse gases however, not enough radiation will escape to space, and the planet will overheat. A natural result of the hydrological and carbon cycles, a limited greenhouse effect is necessary to keep us warm, but an exaggerated greenhouse effect, provoked by the burning of fossil fuels to the extent of too much carbon in the atmosphere, will cook the planet.

CO2 concentrations in the atmosphere:
Corroborating data for the greenhouse phenomenon is there in the geological record and ice core samples. During ice ages the CO2 concentration is about 200 parts-per-million (ppm), whereas in the warmer periods between ice ages, the concentration reaches around 270ppm. *The data is consistent with the theoretical understanding (see addendum below). Pre-industrial levels were around 280ppm. By 1958 concentrations were 315ppm, and by the 1990’s atmospheric CO2 levels had soared to 360ppm. Currently above 380ppm, CO2 levels are possibly higher than they’ve been for millions of years1. Unsurprisingly, recent global temperatures are outbidding the previous highs and rising2. Nineteen of the twenty warmest years on record have occurred since 1980. Of particular concern is the fact that CO2 and methane (another greenhouse gas) are implicated in several major extinction events.

1. The UK government’s chief scientific advisor, David King, suggested CO2 levels were now higher than they’ve been for 55 million years. Notably, at the Paleocene-Eocene boundary, a thermal maximum extinction event occurred. What initiated the increase in temperature (and rise in CO2 levels) is unknown, but a large amount of carbon 12 isotope appears in the geological record at this time, the signature of methane hydrate release. It’s possible as temperatures soared, methane hydrates frozen solid beneath permafrost and the seabed thawed, expelling large amounts of the greenhouse gas methane (becoming CO2 as it dissolves) into the atmosphere. This would have led to an exaggerated greenhouse effect and a much greater temperature rise. (A methane hydrate release also occurred 251 million years ago. See below, the Permian extinction) It seems however, for the entire Eocene period from 55 million to 35 million years ago, atmospheric CO2 concentrations remained high. Possibly David King was meaning levels of CO2 haven’t risen from glacial-interglacial base levels (200-270ppm) to current levels and beyond for 55 million years.

2. The indications are the increase of CO2 in the atmosphere is responsible for the temperature rise in the modern industrial era. The CO2 data for the twentieth century if input into the most reliable scientific models, with other forcings, which are small by comparison, and the temporary cooling effect of global dimming factored in, elicits a pattern that closely matches the graph of observed temperature change.

*Addendum: The data over the last 650 000 years is uncontested, and clearly shows the up-and-down swings between ice ages (glacial) and temperate (inter-glacial) climate, and depicts a perfect correlation of CO2 and temperature patterns. But the CO2 lags 400-800 years behind the temperature rise. The prevailing scientific view is small changes in the earth’s orbit initiate the warming, but is not enough to explain the magnitude of the temperature rise, which continues over 5000 years. The only viable explanation is the CO2 feedback suggested by the correlation. The initial warming releases CO2, and the CO2 magnifies the warming.
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Global dimming :
The scientific data shows a 0.6C increase in global temperatures has occurred over the last century. But the true damage CO2 has in store for the global climate has been temporarily restrained paradoxically by an effect of pollution. Tiny droplets of water condense on pollutant dust – particulates of soot, ash and sulphates. The cumulative water droplets, like a giant shimmering mirror, shield the earth from the sun’s rays. Measurements worldwide confirm that the amount of solar energy penetrating to the earth has dropped significantly compared to that of the 1950’s. Commensurate with this: pan evaporation rates (how quickly a pan of water in open air evaporates) have declined. This result is at first anomalous given that global temperatures have increased. But it is not the surrounding temperature that determines the evaporation so much as the increase in energy from the photons as sunlight hits the water in the pan. The results are conclusive: less evaporation means less sunlight coming through. Project Indoex, an international collaboration of scientists set up to measure the effects of pollution on sunlight, confirmed the effect. The skies over the Northern Maldives are overcast with polluted air descending from India, but a front of cold air from Antarctica keeps the Southern tip fresh and clear. Indoex discovered sunlight in the north was 10% less than that measured at the southern tip. The full impact of CO2 warming has been hidden by a cooling effect caused by pollution. Yet despite an average 4-8% loss of sunlight1 (from the 1950’s to the 1990’s) due to pollution, global temperatures are on the up.

1. The Guardian seems to have overstated the effect in one of their reports when they put the amount of sunlight loss at 20 %.

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Runaway global warming: accelerating levels of CO2:
Just as we discover that global dimming has been masking the full effects of increased CO2, the rise in CO2 concentrations is showing signs of acceleration. In previous decades CO2 has risen steadily by 1.5ppm a year. But the increase inflated to 2.08ppm in 2002 and to 2.54ppm in 2003. Dramatically increased fossil fuel emissions in China and India and no slowdown in the US, Europe, Canada, Australia, Russia and Japan, look like driving the acceleration further. With the impact of CO2 on a 30-year time lag, it is the years beyond 2030 that will reap the devastation of accelerating CO2 levels. Yet with extreme weather events more prevalent, global warming is already wreaking destruction: from the severe floods1 that besieged Central and Eastern Europe in 2002 to the savage heatwave2 the following year that killed an estimated 35 000 people. This year has witnessed the devastation of hurricane Katrina3, drought and famine in Niger, forest fires raging across Europe and an unprecedented drought afflicting the Amazon basin4. Worldwide there is manifest disruption of the seasons5. The trend of global temperatures is towards a rapidly warming world. The last ten years with the exception of 1996 have been the warmest years on record. And as cleaner technologies continue to reduce pollution that has till now contributed a cooling effect, global warming is on course to increase further.

1. In the 2002 floods, rainfall in parts of Central and Eastern Europe was the highest since records began. There has been a significant increase in more destructive heavy rainfall events across the earth’s mid-latitudes. In the UK, the percentage of rain coming from heavy rainfall events doubled over a 35 year period (from the 1960s to the mid 1990s). As temperature rises, the air’s capacity to hold water increases exponentially, leading to significantly heavier rainfall. In England and Wales, the major floods of 2000 were the worst ever recorded for a ninety-day period, the September to December rainfall total the highest since records began in 1776.

5. In the Northern Hemisphere, spring is blooming weeks earlier while the onset of autumn is increasingly delayed. In 2002, NASA satellite data showed the growing season had extended by 18 days over the period of the previous 20 years (The Guardian, September 4, 2002).

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Runaway global warming: loss of the earth’s reflective capacity:
Ice ranges the planet over are melting and at unprecedented rates – permafrost and tundra in the North, polar sea ice and glaciers worldwide. The World Glacier Monitoring Service reports 96% of glaciers surveyed – from the Himalayas to the Andes – are in retreat. In 2002, the massive Larsen B ice shelf1 on the Antarctic peninsula snapped, later fragmenting into icebergs. The following year, the Ward Hunt ice shelf, the largest in the Arctic, ruptured and began to collapse. The boundary of the thousand metre thick Kangerdlugssuaq glacier2 in Greenland is dramatically receding. While the Exit Glacier in Alaska is in rapid decline. In the Antarctic Peninsula, some 13500sq km of ice shelf has vanished in 50 years3. Arctic sea ice4 has thinned by more than 30% in thirty years. And the permafrost thaws as temperatures in Alaska significantly rise5. A natural cooling mechanism, the ice reflects sunlight; but as ice depletes, more solar energy is absorbed, which melts more ice, causing a runaway effect6.

1. Unlike a melting glacier or ice sheet, a melting ice shelf doesn’t lift sea levels because the shelf is already in the sea, but the increase of fresh water in the oceans can disrupt the system of ocean currents. (As ocean temperatures increase, sea levels do rise as a result of thermal expansion.)

6. Mathematical models suggest a rise of less than 2C in global temperatures could trigger irreversible melting of the vast ice sheets over Antarctica and Greenland, which would lead to phenomenal sea level rises. Although scientists have predicted it would take a thousand years for the ice sheets to fully melt, Greenland is already melting around the edges, and at a rate faster than anticipated. Scientists thought Antarctic ice sheets so cold they wouldn’t begin to melt for centuries even with global warming. But there is melting now on the West Antarctic ice sheet and increased movement of ice streams.

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Runaway global warming: pressures on carbon sinks:
/ The oceans:
The earth’s ability to regulate CO2 build up is in danger of collapse. In the carbon cycle, carbonate ions dissolved in surface water are removed in the shell formation of marine organisms. When the organisms die the shells and the carbon contained fall to the ocean floor. Over time the calcium carbonate shells will end up as sediment and rock. Overburdened as too much CO2 in the atmosphere dissolves, the oceans are becoming more acidic (although they still remain slightly alkaline), endangering the survival of marine life. Atmospheric CO2 dissolving in the oceans produces carbonic acid that “strips out carbonate ions dissolved in surface waters, so there is less available for marine organisms to build calcium carbonate shells and exoskeletons”. Scientists have noted greater shell malformation and the formation of softer shells in tiny marine organisms. Marine organisms have evolved in oceans with a stable ph level of 8.2, which makes them extremely vulnerable to acidic corrosion as the ph level falls. Coral, plankton and shellfish are especially vulnerable. Ever greater CO2 in the atmosphere leads to even more acidic seas, so that less and less carbon is removed as the acidity causes shell organisms to decline. Eventually, you no longer have a carbon cycle, but carbon stagnation.

/ The Amazon rainforest:
The vast Amazon ecosystem also plays a vital role in the carbon cycle and the global climate. The trade winds from Africa drive across the Atlantic and as they flow over the warm tropical waters become laden with moisture, continuing until they reach the Amazon where the aggregate moisture falls as rain. Three quarters of the rainfall is recycled back to the atmosphere by transpiration and evaporation as water is drawn from the soil by the trees and released into the air through the leaves. (Some of this water will be received four months later as rainfall over the corn-belt of the US mid-west). A vast Amazon rainforest is necessary for the convection cycle to continue. Yet satellite images reveal 17% rainforest clearance and the decimation continues at an alarming pace. If we add in selective logging, undetected by the satellite images, estimates approach 30% forest wipeout1. Climatologists predict that if the Amazon forest were to lose more than 40% of its cover, it will tip into a process of irredeemable die back. A smaller forest is unable to sustain the convection process so that the forest receives less rain and begins to dry out. As it dries out, vegetation dies (and the forest becomes susceptible to fires), so that more of the forest disappears, which brings even less rainfall than before. In this way the forest continues to diminish until it’s completely replaced by open savanna. By the process of photosynthesis, the Amazon inhales huge amounts of CO2 and outputs 20% of the earth’s oxygen for us to breathe. If the forest were to go, the vast amount of carbon it has stored would stagnate in the atmosphere.

1. Corporations like US food giant Cargill are turning swathes of land to soya production, while large sectors are flattened to make way for cattle ranches. The soya is exported to Europe for cattle feed, or to China* to fatten pigs, poultry and fish. These profit ventures eliminate 20 000sq km every year, an area roughly the size of Belgium. Moreover scientists now estimate that selective logging, undetected by the satellite images, “where timber companies go into the forest under the canopy and take out valuable hard timber,” accounts for an additional 15 500sq km of forest chopped down each year. If this figure is consistent, instead of 17%, we now have nearer 30% forest wipeout.

*Case Study of China:
Self sufficient in food as little as 15 years ago, China is now dependent on bulk food imports. To contend with a loss of arable land as industrialisation proceeds and feed a burgeoning urban population, China is importing soya from Brazil extending the deforestation of the Amazon rainforest. The ensuing increase in carbon emissions and loss of arable land combined, coupled with the added deforestation of the Amazon rainforest (to contend with lost food production) is a global warming juggernaut, which will significantly worsen drought and desertification in China’s northern provinces. A greater loss of arable land in China will exacerbate the demand for imported soya with increased deforestation of the Amazon and further global warming the result.

/ Forests, mangrove and coral:
At similar rates complex rainforests are dwindling worldwide from Rwanda to Indonesia. And there are pressures on all the carbon sinks. Mangroves are being destroyed to make way for prawn farms. Soaring temperatures are bleaching the coral reefs1 in the south. The heatwave of 1998 killed more than 90% of corals on shallow Indian Ocean reefs. While in the north, cold water coral are destroyed by fishing trawlers that dredge the seas for bottom fish, turning the living sea to a sub-marine desert. With the warmer summers, tinder dry forests from Nicaragua to Portugal are readily combusting, releasing more carbon into the atmosphere as they burn. In 2003, 22m hectares of Siberian forest 1 was ravaged by fire. In the heatwave and severe drought that year plant growth in Europe dropped by 30% overall, while much of the carbon dioxide removed from the atmosphere in the preceding four years was returned to the air. Of equal concern is the degradation of topsoil. Researchers at Cranfield University examined 6 000 topsoil samples covering 25 years and discovered that the soils of England and Wales were returning carbon to the atmosphere at the rate of 4m tonnes a year.

1. The great boreal forests of Siberia, the largest in the world, have suffered a tenfold increase in fires in the last 20 years. Global warming is clearly a factor. In the heatwave of 2003, 22m hectares of forest were “enflamed, charred or scorched.” But it seems fires are also started deliberately. Timber merchants and logging companies can obtain cheap licenses to log areas of forest ravaged by fire. Regardless of the cause, the consequence is more carbon released to the atmosphere.

The conclusion seems clear: carbon sinks have a limited capacity to take up excess co2. And the pressures of intensive human activity, from destruction of mangroves to deforestation reduce that capacity further. The cyclical flow of carbon distributes the carbon between source (carbon released to the atmosphere) and sinks (carbon stored in the earth and oceans), which keeps the climate habitable. If we seriously perturb the carbon cycle by continuing to pump carbon into the atmosphere, sufficient to spur a runaway effect in the interaction of atmospheric carbon and global warming, the planet will become uninhabitable.

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Runaway global warming: loss of cloud cover:
It seems parts of the tropics are less cloudy than they were in the 1980’s. A possibility is that increasing temperatures burn off the clouds. If the findings by NASA are corroborated then global warming will reduce the earth’s cloud cover, allowing in more sunlight, further increasing temperatures.

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Runaway global warming: release of carbon dioxide from the peat bogs:
Rising levels of carbon dioxide appear to be breaking down the world’s carbon peat bogs, which releases more carbon dioxide into the atmosphere and hastens the process. As George Monbiot explained: “Research by Chris Freeman at the University of Bangor shows that the gas (CO2) stimulates bacteria which dissolves the peat. Peat bogs are more or less solid carbon. When they go into solution the carbon turns into carbon dioxide, which in turn dissolves more peat.” The Northern peat bogs hold “the equivalent of 70 years of global industrial carbon emissions.” With fossil fuel emissions continuing to rise and carbon sinks faltering, the breakdown of the peat bogs and CO2 release will only speed up. This will add to the already accelerating CO2 concentrations in the atmosphere and more rapid global warming.

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Runaway global warming: release of methane as permafrost melts:
The world’s largest frozen peat bog is melting. Extending a million square kilometres across Western Siberia, as the permafrost thaws billions of tonnes of methane, a potent greenhouse gas sunk in the frozen Siberian bog, will rise into the atmosphere. Methane is trapped within the permafrost and the deeper strata below in ice like structures known as clathrates. Scientists estimate the Siberian bog contains 70 billion tonnes of methane, which is a greenhouse gas 20 times more potent than CO2.

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Kyoto: Carbon trading and offsetting carbon emissions:
It’s a mockery of rational thinking to propose we can offset CO2 emissions by planting monoculture trees1, when at the same time we’re devastating complex ecosystems like rainforest, mangrove and coral reef. Similarly a Carbon Emissions Trading Scheme is senseless if we still end up burning all the fossil fuel reserves. The Carbon Trading scheme may (and possibly won’t) reduce the annual rate of emissions, but unless the reduction is significant and continues to drastically fall until emissions are brought hurriedly to a halt, it will do little to prevent runaway global warming. UK emissions have gone up year on year since Blair and New Labour came to govern in 1997. And companies that are the worst culprits can set their emission quotas so high that they could find themselves in carbon credit and make a profit from trading their surplus allowance without reducing their emissions at all.

1. As Carbon Trade Watch reveal it is impossible to guarantee that offset projects lead to genuine reductions in carbon dioxide. There is no way to accurately measure the carbon ‘sink’ performance of offset projects. Almost certainly there is overestimation of the ‘sink’ performance of monoculture trees. For who is to say that the ecosystems (grasslands etc) they replace wouldn’t have performed equally as well or better. Anyway, over the longer term the trees may actually release the carbon they’ve previously stored. In some cases monoculture tree plantations may actually be doing more harm than good. According to Carbon Trade Watch, “Monoculture trees… planted on carbon-rich peat bogs – (are) emitting more carbon dioxide than they ‘sink’.”

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Cataclysmic scenario: release of methane hydrates from the ocean bed:
If the planet heats up by 6C, it will trigger a cataclysmic event that will make extinct the human species1. Methane hydrates, concentrated methane gas locked solid by ice crystals (clathrates) in the seabed, will be released as sea temperatures rise. Experiments show it only takes a 5-6C increase in temperature to unlock the methane. A small amount of methane hydrate expels a large amount of gas. And there are great reservoirs of methane hydrates all along the coastal regions, where dead organic matter has accumulated, the equivalent of 20 times the known reserves of natural gas. A greenhouse gas 20 times more potent than CO2, methane in the atmosphere will precipitate ever greater warming. If the methane oxidises and dissolves as CO2, it will poison the oceans completely.

We know this has happened before in the earth’s biography. There’s a fair amount of certainty about the events that led to the Permian extinction. First the Siberian traps2 (volcanic eruptions) released CO2 into the atmosphere causing a greenhouse effect. As the temperature increased, there were gradual extinctions. When the seas warmed sufficiently, the ice crystals locking methane gas solid in the seabed thawed, unleashing enormous quantities of gas into the oceans3. This killed most of the marine life and led to further global warming, raising temperatures another 5C, which did for most of the life on land4.

1. Scientists predict another 2C temperature rise will make runaway global warming unstoppable. The threshold may be lower than is commonly recognised. If we continue burning fossil fuels at high levels for much longer a 2C rise surely becomes inevitable. Remember the effects of CO2 are on a 30 year time lag and CO2 levels are accelerating. Ice ranges are melting at an alarming rate. If the peat bogs go, that’s it. Much of the evidence indicates: we may be on the brink now.

4. It took 40 000 years for the initial greenhouse phase to lift the temperatures by around 5C. Another 10 000 years, for the marine extinction phase and a final 30 000 years for the second land extinction phase as the temperatures soared another 5C. In total 80 000 years elapsed as the temperatures rose by 10C and killed 90-95% of life on earth. These time scales shouldn’t lead to complacency. On the contrary, temperature rises that spanned 80 000 years in the Permian, could be induced by us in 150 years (counting from 1945), driven by the round the clock burning of fossil fuels on a global scale. Our extinction phase will release the same stores of carbon as the Permian plus the fossil fuel emissions and in a much shorter time frame. It could stagnate forever the carbon cycle and bring an end to life on earth.

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Summary:

Increased CO2 and greenhouse warming:
• CO2 absorbs radiation in the atmosphere, heating up the planet
• Build up of CO2 in the atmosphere is accelerating
• Fossil fuel emissions continue apace and unabated
• There are signs the carbon sinks are faltering.
• The carbon peat bogs are beginning to dissolve, which will release large amounts of CO2

Loss of cooling capacity:
• As pollution is tackled, more sunlight will penetrate to the earth and speed up warming
• The loss of reflective cover as ice ranges melt will spur increased warming
• The loss of cloud cover as rising temperatures burn off the clouds allows more sunlight through, adding further heat to the earth.

Is the interaction of these systems enough to lift temperatures by 6C? If the answer is yes, the ice crystals that lock in superconcentrated methane gas will thaw and it is the end for the human species. The planet Venus has a CO2 concentrated atmosphere with average surface temperatures of 470C. Here between the transits of Venus will humanity awaken in time to the threat and make the transition necessary turning from the edge of the abyss and towards enlightenment. What is at stake is our survival as a species.

Original version first published September 2005 on www.taysidethink.net