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[So far in our study of global climate change, we have examined the evidence that global climate change is taking place, and that it is induced by industry. And we looked at the scientific consensus based upon this evidence. Then we explained abrupt climate change, revealing why global warming could result in a little ice age in the North Atlantic region even as the planet overall continued to warm. We closed with a look at evidence suggesting that the global ocean conveyer, whose reversal would trigger abrupt climate change, is indeed slowing down. Now we will examine the possibility that climate change might spin out of control, threatening to extinguish the human race altogether, along with much of the life on this planet. -DAP]
The possibility of runaway global warming is not as distant a threat as we may wish. It is a threat which worries some of the greatest minds living among us today. Stephen Hawking, physicist, best selling author of A Brief History of Time, and claimant of the Cambridge University post once occupied by Sir Isaac Newton (the Lucasian Chair of Mathematics), has been quoted as saying, "I am afraid the atmosphere might get hotter and hotter until it will be like Venus with boiling sulfuric acid."1 The renowned physicist was joined by other notables such as former President Jimmy Carter, former news anchor Walter Cronkite, and former astronaut and Senator John Glenn in drafting a letter to urge President Bush to develop a plan to reduce US emissions of greenhouse gases.2 Former British Environmental Minister Michael Meacher is also worried about the survival of the human race due to global warming.3
The American Geophysical Union (AGU) released a position paper in the fall of 2003 stating that industry-induced emissions were causing carbon dioxide concentrations in the atmosphere to climb faster than at any other point in Earth's history.4 The AGU has previously been very cautious about taking any position with regard to global warming. The AGU reticence has been used by oil companies and other global warming skeptics to support their own position that global warming is some sort of environmental hoax. Among the signers of the AGU statement was John Christy, director of the University of Alabama's Earth Systems Science Center. Dr. Christy has previously been very skeptical of global warming studies, and has often been cited to support the argument that scientific understanding of global warming is flawed and uncertain. In a National Public Radio interview about the AGU consensus statement, Dr. Christy said, "It is scientifically inconceivable that after changing forests into cities, turning millions of acres into farmland, putting massive quantities of soot and dust into the atmosphere and sending quantities of greenhouse gases into the air, that the natural course of climate change hasn't been increased [sic] in the past century.'' 5
Why do so many prominent people worry about runaway global warming? The fear is that, once the atmosphere has warmed past some critical level, various feedback mechanisms will kick in and push the temperature beyond the point where the planet will become inhospitable for human life. Once these feedback mechanisms have kicked in, it is unlikely that we can do anything to intervene. And considering the current signs from the environment, accelerating industrial emissions, and the long life of greenhouse gasses in the atmosphere, some worry that it may already be too late to prevent this scenario.
Runaway Climate Change-Feedback Mechanisms
Many processes in the natural world have continuous consequences which either accelerate or retard the original process. Such consequences feed back into the process from which they arise, and so are called "feedback loops." For example, a newly-introduced predator devours the population of its chosen prey, until the food supply is so diminished that the predator can't feed its young and its own population contracts: that's negative feedback. Balance is exceeded, and the overfeeding predators give rise to an effect that drives down their own numbers.
Feedback loops occur in the social world as well; for instance, under a regressive income tax, the working poor pay plenty of tax, which tends to keep them increasingly poor and working longer hours, while the wealthy pay little or no tax, which tends to make them wealthier. That's a positive feedback loop, because the original process is exacerbated by its own effects.
Our climate system is largely a system of feedback mechanisms, both positive and negative. It is the crux of the climate change skeptics' argument that negative feedback systems will cancel out industry- induced global climate change. They suggest that excess carbon in the atmosphere will be absorbed by the oceans and will stimulate photosynthesis in land-based plants, both of which will serve to remove the excess carbon from the atmosphere and lock it safely away.
Currently, photosynthesis in forests is accelerating, leading to greener, lusher forests and a higher absorption rate for carbon dioxide. However, decomposition rates in dead wood and soils are also beginning to accelerate. And as the climate warms, eventually this outgassing of decomposed carbon will overtake the accelerated photosynthesis. Worse, the Amazonian rainforests are expected to fail about mid-century. The dying rainforests would then release their store of carbon into the atmosphere. According to studies undertaken by the Met Office Hadley Centre for Climate Prediction in Great Britain, if industrial carbon emissions go unmitigated then the forests will become net contributors of carbon to the atmosphere by 2070. Stabilization of industrial emissions could possibly delay this forest dieback for another century.6
Global vegetation biomass in the 1990s (top), in the 2080s due to global climate change from unmitigated emissions (middle), and in the 2080s with emissions stabilizing CO2 at 750 ppm (bottom).
Taken from The Impacts of Climate Change on Natural Vegetation, Hadley Centre for Climate Prediction and Research
Climate change skeptics point to the oceans as an immense carbon sink, capable of absorbing all industrial carbon emissions. Indeed, the oceans hold a volume of carbon equivalent to more than 6,000 years of fossil fuel burning at current rates.7 Without the absorption of carbon by the oceans and the linked production of free oxygen by ocean phytoplankton, the Earth's atmosphere would consist almost entirely of carbon dioxide, with a little bit of nitrogen. Temperatures would hover around 600º Celsius, and atmospheric pressure would be 60 times heavier than it is currently.8
Ocean waters absorb carbon dioxide from the atmosphere, holding much of it in solution, but transforming some into carbolic acid. Phytoplankton in the upper ocean layers fix the carbon dioxide in their cells through the process of photosynthesis. These Phytoplankton form the basis of the ocean food chain. They are grazed by animal plankton and other organisms, which utilize most of the carbon as an energy source but return a small portion of it to the atmosphere through respiration. Some of this carbon ultimately settles through the ocean column in the form of cast-off tests and shells, and animal feces. During periods of global warming millions of years ago, this sediment of carbon wastes formed the source for the hydrocarbon deposits which have served to power our civilization through the past century, and which are now, ironically, resulting in industry-induced climate change.
Unfortunately, this oceanic carbon sink could very well break down in response to climate change. Warmer seawater is already saturated with carbon, so it absorbs less. Robust absorption of carbon requires a continuous cycling of colder, carbon-poor water upward from the ocean depths. If the global thermohaline conveyor were to fail (see Part II of this series), a dangerous drop in carbon absorption could result.
But the biggest threat to the oceanic carbon cycle lies in diminishing phytoplankton productivity. In the past 20 years, phytoplankton concentrations in northern oceans have decreased by as much as 30%. Scientists from NASA and the National Oceanic and Atmospheric Administration suspect that warmer temperatures and low winds are depriving the phytoplankton of nitrogen and carbon dioxide.9 A Japanese researcher at Hokkaido University has noted a sharp drop in the amount of carbon dioxide absorbed by the northern Pacific Ocean over the past 15 years. Yutaka Watanabe has stated that the amount of carbon dioxide in the ocean has dropped by 10%. 10
Another feedback mechanism which is already beginning to work against us is the retreat of ice cover, particularly from the Arctic ice cap and from Greenland. The melting ice cover will trouble us in several ways. Freshwater runoff will help to disrupt thermohaline circulation in the oceans, as discussed in the second part of this series. Melting ice cover would also raise ocean levels. As mentioned in the first part of this series, satellite studies from NASA demonstrate that the Arctic ice cap is already retreating dramatically. A report released by the German Advisory Council on Global Change states that if the world's average temperature increases by more than 2° C beyond what it was at the beginning of the Industrial Revolution, it will likely trigger the melting of the Greenland ice cap and West Antarctic ice sheet. This would raise world sea levels by as much as 30 feet, submerging major cities such as New York, London, Tokyo, Miami, Bombay, Calcutta, Sydney, and Shanghai. 11 The Hadley Centre for Climate Prediction and Research has stated that there are already sufficient Greenhouse gases to raise Greenland's average temperature by 3º C by the middle of the century.12
The retreating ice cover will decrease the Earth's albedo, as discussed in the first part of this series, reflecting less of the sun's energy and resulting in a further warming of the Earth's surface. Evaporating melt waters could also increase the water vapor content in the lower atmosphere. Water vapor is a greenhouse gas. The result of both of these effects would be a positive feedback cycle where melting ice results in a warmer climate, which in turn leads to the melting of yet more ice.
And then there is the thawing tundra. Globally, frozen peatlands hold an estimated 550 billion tons of stored carbon.13 Dead plant matter is frozen in permafrost, slowing and even stopping the decomposition process. The slow, anaerobic decomposition which currently takes place in these frozen lands has produced a stockpile of methane which is already showing signs of escaping into the atmosphere as the tundra thaws. Methane has a shorter lifetime in the atmosphere than does carbon dioxide, but is it up to ten times as effective at trapping heat in the lower atmosphere. However, as the soils warm and the permafrost thaws, bacteria could set to work with a vengeance, decomposing plant matter at a higher rate, releasing carbon dioxide into the atmosphere instead of methane. 14
When Oceans Exhale
Each of these feedback mechanisms (and others not mentioned here) would have dire consequences for life on this planet. Taken together, they would reinforce each other and magnify the change in climate. But the gravest concern is that rising temperatures on this planet will lead to a venting of methane from the oceans. It is this possibility which is lamented in the above quotation from Stephen Hawking.
Methane is stored in the deep ocean along the continental margins, in the form of clathrates. These are massive deposits of carbonated slush, where the methane is trapped under pressure in the crystal lattices of frozen water (i.e., ice). Though the oceans hold much more methane than does the tundra, taken together they contain an estimated 2 trillion tons of methane in the form of clathrates.15
Occurrences of Natural Methane Hydrate (Clathrates) Deposits Worldwide
The release of the entire balance of these pent up gases into the atmosphere is possible, but highly improbable. Dr. Hawking's scenario of an Earth superheated to match its sister planet, Venus, is unlikely. If the seas started venting methane into the atmosphere, the chances are that the process would halt before all of the sequestered methane escaped. However, just a portion of this enormous reserve of carbon, if released into the atmosphere, could render the planet uninhabitable. And while many scientists consider the possibility very remote, every day more investigators assess this scenario, shake their heads and wonder: could we already have set such an event into motion?
It is believed that a release of methane hydrates from the oceans has happened before in the Earth's history, and it is suspected to be a factor in most of the mass extinction events of the past. The last time was 55 million years ago (fairly recent in geological terms), in an event known as the Late Paleocene Thermal Maximum (LPTM). It lasted for about 150,000 years, and raised average global temperatures by 5 to 7º C (9 to 13º F).16 Recent studies of sea floor sediment indicate that the oceans warmed in higher latitudes by 8 to 10º C, and by 4 to 5º C in tropical latitudes.17 The LPTM was probably initiated by movements of the continental plates, such as the collision of the Indian subcontinent with Eurasia which created the Himalayas. Uplifting decreased water pressure on the ocean floors, which in turn allowed a massive methane release. This release warmed the oceans sufficiently to allow further methane release and other feedback mechanisms to kick in. The polar ice caps disappeared and life on this planet experienced a mass extinction event.18
When Life Almost Disappeared-The Permian Extinction
251 million years ago, at the end of the Permian Era, life almost entirely vanished from this planet. It is the single worst mass extinction in the history of the Earth. Fully 95% of the species extant on this planet at that time were wiped out. Only a few species of plants, animals, and likely even protozoa, survived to evolve (until the next major extinction-ecologically trivial by comparison-wiped out the dinosaurs 65 million years ago).
The cause of the horrendous Permian extinction has long been a mystery, and geologists have suggested a number of possibilities, none of which quite explains the evidence. But in the last fifteen years or so, a compelling picture has emerged. Developed in response to a wealth of new paleogeological evidence from that period-evidence from petrology, geochemistry, oceanography, paleoclimatology and various other disciplines-the scenario is quickly being accepted by the scientific community. The culprit that wiped out 95% of all species and very nearly put an end to life on this planet was runaway global warming.
The event began in a very spectacular fashion, with a massive volcanic eruption in Siberia that spewed out a volume of 2 million cubic kilometers of basalt, which covered an area of eastern Russia 1.6 million square kilometers in extent (roughly the size of Europe).19 Volcanic activity also vented a great deal of carbon dioxide and fine ash into the atmosphere. Gases were vented in such quantity that the average global temperature increased by approximately 6º C.20 Some 161 species became extinct as a direct result of these volcanic eruptions. The extinction rate was as high as 33%. But this was just the beginning.
The temperature rise was high enough to trigger a number of positive feedback mechanisms. Most notably, there was a massive release of methane from hydrates locked into clathrates. The warming caused by the Siberian eruption was sufficient to melt the frozen gas hydrates, allowing bodies of methane to bubble up to the surface of the oceans and belch into the atmosphere. This introduction of methane then led to further warming, which in turn melted deeper methane hydrate deposits. The outgassing of methane was far in excess of the natural mechanisms which normally reduce carbon dioxide levels in the atmosphere. The planet's climate system broke down and runaway global warming continued until it reached some unknown threshold.
It is not yet known what prevented the planet from becoming a sterile twin to Venus. Scientists are just beginning to explore the question of how the atmosphere returned to a more hospitable climate. Life on this planet came so close to complete annihilation that it took 100 million years for global biodiversity to return to pre-extinction levels.21
The Permian Extinction should be widely understood as an ominous lesson in the danger of global warming. We need to pay particular attention to the temperature rise which caused these runaway feedback mechanisms to kick in: 6º C. Back in the first installment of this series on global climate change, we looked at a report from the Intergovernmental Panel on Climate Change (IPCC) which stated that the average global surface temperature will increase by between 1.4º and 5.8º C during the next century. This would compound the increase of 0.6º C that has already occurred during the past century. So, according to this report, the temperature could rise by as much as 6.4º C by the year 2100.22 And that this estimate is on the conservative side; it is possible that temperatures could increase by much more than 6.4º C.
The warning lights should be going off all over. A temperature increase of 6.4º C would put us well beyond the threshold for runaway global warming. Could mankind be gearing up to perpetrate the greatest extinction on this planet since the end of the Permian Era?
Enter the End of the Hydrocarbon Era
The first reaction of most environmental activists to the news of peak oil is to say, "Good, we need to stop using fossil fuels anyway." It seems logical that a decline in hydrocarbon production will lead to a decline in carbon dioxide emissions. And it is likely that somewhere down the line, carbon emissions will abate simply due to the scarcity of fuel. But we will not go gently into that good night.
When you learn that heating costs are going to continue increasing, and that shortages of natural gas are likely in our near future, what alternatives come to your mind for home heating? Passive solar heating? Sure, but that alone will not keep you warm on a cold winter night. Most people immediately think of wood. As heating costs go up, and as shortages put a chill on our homes, most of us are going to start burning wood (or will burn more wood, as the case may be). We will turn to biomass.
Burning biomass is undoubtedly the dirtiest source of energy. As we burn wood, corn husks or cow chips to heat our homes, we will be pumping tremendous volumes of carbon into the atmosphere. And, in all probability, it is unavoidable. There are some things we can do to reduce the amount of wood we burn and so limit our contribution to global warming. Better insulation can increase efficiency. And consider the sort of wood furnace you will be using. Traditional brick fireplaces are the least efficient way to warm a house. Metal wood stoves are better, but soapstone is the best at holding heat and radiating it outward. A small load of wood is a soapstone stove can generate heat for hours. And when you are harvesting your wood, take care not to strip the forests bare. Be selective in choosing your wood. Practice coppicing (do a Google search to find out more about this ancient method of harvesting wood).
Burning biomass will likely add to our global warming problem, but it is probable that coal burning will be far more harmful.
As oil and natural gas production go into decline in North America, the alternative we will ultimately turn to is coal-whether we like it or not. Coal is considered to be abundant in North America, and it is cheap. Despite all the talk of a hydrogen economy, the real investment will go into stepping up coal production. In fact, the production of coal-fired power plants has already been stepped up. As of February 2004, at least 100 new coal-fired electric power plants were planned to go up in more than 36 states.23 This new growth market is currently flying below radar, because once plans for a coal-burning plant are made public, they are liable to be halted by the legislative efforts of environmentalists and neighborhood coalitions.
If even half of these plants are completed, they will increase exhaust gas emissions by 120 million cubic feet per minute. All the new coal plants being proposed would add one-tenth of one percent to the world's annual carbon dioxide emissions.24 That may not seem like much, but it is certainly a move in the wrong direction. And it is only the beginning.
As the production of oil and natural gas continues to slide, we will open up our coal reserves for electricity production, heating, industrial use, and to process coal into liquid transportation fuel. In the process, we will increase our exhaust emissions, rip up vast areas of land, create immense slag dumps, and pollute our waterways and groundwater. And we will require a major upgrade in our coal transportation network-that is, trucks and trains. You can expect strong efforts from industry and politicians to turn back environmental laws regulating coal production and coal burning. It will be argued that these regulations are damaging the economy. They will point to an economy choking from a constricting energy base, and they will insist that they cannot provide the energy we so desperately need with all these legal restrictions. Power outages will act to blunt the environmental sensibilities of the public.
Perhaps the only salvation here lies in recent research (reported in FTW), that coal is likely to peak sometime around 2032, if not sooner.25 This will leave us a little less than 20 years of stepped up production before coal joins the list of has-beens. Then our carbon emissions really may begin to decrease.
But the US is not the only country likely to turn to coal. China is also eying its large reserves of coal, as is India. If the world's two most populous countries step up their coal consumption along with the US, then the decline in petroleum and natural gas production will actually be greeted with a pronounced increase in carbon emissions.
Peak oil will not be a blessing in disguise with regard to global warming. The models of global climate change developed by the IPCC and others have not taken into account the impacts of Peak Oil and the North American Natural Gas Cliff. These models are based on faulty economic projections produced by neo-classical economics-a warped discipline which is blind to resource depletion.26 If we turn to coal and biomass to make up for the decrease in oil and natural gas production, then it is likely that our actions will push the average global temperature well beyond the 6º C threshold mentioned above. The end of the oil age could very well push us into an age of runaway global warming.
Coal will not be able to support the kind of energy-intensive economy which we have built on oil and natural gas. It will be a faltering effort from a civilization in denial, intent on clinging to unsustainable ways. It will fail in the end, but in this last mad burn-off of energy resources, we may very well incur the demise of life on this planet.
1 World famous physicist Stephen Hawking says he's worried runaway global warming could destroy human life on Earth. Nando Times, 9/30/2000. Archived at http://eces.org/archive/ec/globalwarming/runaway.shtml
2 Poll: global warming is a serious problem, AP. USA Today, 4/2/2001. http://www.usatoday.com/weather/climate/2001-04-01-globalwarmingpoll.htm
3 Human Race is Killing the Planet, Says Meacher, Brown, Paul. The Guardian, February 14th, 2003.
End of the World Nigh-It's Official, Meacher, Michael. The Guardian, February 14th, 2003. http://www.guardian.co.uk/comment/story/0,3604,895217,00.html
4 US Science Body Warns on Climate. BBC News, December 16th, 2003. http://news.bbc.co.uk/1/hi/sci/tech/3325341.stm
5 Science Group Issues Climate Change Warming, Harris Richard. National Public Radio, Morning Edition, December 17th, 2003. http://www.npr.org/features/feature.php?wfId=1551355
6 The Impacts of Climate Change on Natural Vegetation. The Met Office Hadley Centre for Climate Prediction & Research, 1999. http://www.met-office.gov.uk/research/hadleycentre/pubs/brochures/B1999/imp_nat_veg.html#tgt
7 The Ocean Carbon Cycle. The Met Office Hadley Centre for Climate Prediction & Research, 1996. http://www.met-office.gov.uk/research/hadleycentre/pubs/brochures/B1996/ocncarb.html
8 The Rain of Ocean Particles and the Earth's Carbon Cycle, Honjo, Susumu. Oceanus, December 1997. http://oceanusmag.whoi.edu/v40n2/honjo2.html
9 Phytoplankton in Northern Oceans have Declined from 1980s Levels, Chohan, Rani. Goddard Space Flight Center, August 8th, 2002. http://www.gsfc.nasa.gov/topstory/20020801plankton.html
Satellites See Big Changes since 1980s in Key Element of the Ocean's Food Chain, Steitz, David, et al. Goddard Space Flight Center, August 8th, 2002. http://www.gsfc.nasa.gov/topstory/20020801plankton2.html
10 Global Warming could Disturb Ocean's Ecosystem. ABC (Australian Broadcasting Corporation) News Online, September 3rd, 2001. http://www.abc.net.au/news/science/environment/2001/09/item20010903191131_1.htm
11 Climate Protection Strategies for the 21st Century, Kyoto and Beyond, Grabl, Hartmut, et al. German Advisory Council on Global Change, December 10th, 2003. http://www.wbgu.de/wbgu_sn2003_engl.pdf
12 Melting Greenland Ice Threatens Global Rise in Sea Levels. Met Office Hadley Centre for Climate Prediction & Research, April 7th, 2004. http://www.met-office.gov.uk/corporate/pressoffice/2004/pr20040407a.html
13 Study: Siberian Bogs Big Player in Greenhouse Gas, Owen, James. National Geographic News, January 15th, 2004. http://news.nationalgeographic.com/news/2004/01/0115_040115_siberianpeatbog.html
Scientists Fear Cycle of Global Warming, Reuters. ABCNews.com, Febraury 7th, 2001. http://abcnews.go.com/sections/scitech/DailyNews/warming_permafrost010207.html
15 New Evidence of Global Warming in Earth's Past supports Greenhouse Warming Theory, Stephens, Tim. Eurekalerts, October 23rd, 2003. http://www.eurekalert.org/pub_releases/2003-10/uoc--neo102003.php
16 Methane Explosion Warmed the Prehistoric Earth, Possible Again, Tawney, Timothy R. NASA, Goddard Space Flight Center, Dec. 10th, 2001. http://www.gsfc.nasa.gov/topstory/20011212methane
17 A Transient Rise in Tropical Sea Surface Temperature During the Paleocene-Eocene Thermal Maximum, Zachos, James C., et al. Science 28 November 2003; 302: 1551-1554.
18 Methane Gas Research Could Help Scientists Understand Global Warming, Kanipe, Jeff. Space.com, October 29th, 1999. http://www.space.com/scienceastronomy/planetearth/climate_globalwarming_991029.html
19 How to kill (almost) all life: the end-Permian extinction event, Benton, Michael J., and Twitchett, Richard J. Trends in Ecology and Evolution, Vol. 18, No. 7, July 2003. http://palaeo/gly/bris/ac/ukpublsBenton2003TREEPTr.pdf
22 Climate Change 2001, The Intergovernmental Panel on Climate Change. Cambridge University Press, 2001. http://www.grida.no/climate/ipcc_tar/
23 Resurgence in Coal Forecast by R.W. Beck. PRNewswire, June 2nd, 2004. http://biz.yahoo.com/prnews/040602/flw024_1.html
America's New Coal Rush, Clayton, Mark. The Christian Science Monitor, February 26, 2004. http://www.csmonitor.com/2004/0226/p01s04-sten.html
25 The Peak in US Coal Production, Gregson Vaux. From the Wilderness, May 27th, 2004. http://www.fromthewilderness.com/members/052504_coal_peak.html
26 Bradford Jason, personal communication.