“…about 8,000 years ago the [greenhouse] gas trends stopped following the trend that would have been predicted from their past long-term behavior, which had been marked by regular cycles… [H]uman activities … - primarily agricultural deforestation and crop irrigation – must have added the extra CO2 and methane to the atmosphere. These activities explained both the reversals in gas trends and the ongoing increases right up to the start of the industrial era.”
Dr. Ruddiman’s hypothesis is partly based on the discovery of changes in the earth’s orbit around the sun (known since the 1970’s to affect climate). Long term heating and cooling patterns are linked to “regular changes in the amount of sunlight reaching the earth’s surface”. In effect, the ice ages and the shorter, warmer interglacial periods are driven by the interplay of thee orbital cycles “which operate over 100,000, 41,000 and 22,000 years” and sometimes reinforce each other. The rise of human civilization within the last 6,000 years coincided with the retreat of the huge glaciers that “had blanketed Europe and North America for the previous 100,000 years”.
An ice core taken from Vostok Station in the Antarctic in the 1990’s preserves a record of trapped ancient air bubbles going back 400,000 years. “…for example, methane concentrations fluctuate mainly at the 22,000-year tempo of an orbital cycle called precession.”
Skipping most of the technical details of Dr. Ruddiman’s argument, we learn that both methane, CO2 and temperature levels went off-pattern in the last several thousand years and that this change tracked the development of human agriculture. For example, rice paddies generate excess methane, a more potent greenhouse gas than CO2. There was a substantial warming effect that “escaped detection” because “it was masked by natural climate changes in the opposite direction”. Ruddiman and two colleagues, Steven J. Vavrus and John E. Kutzbach, have calculated that human activities, agriculture and industrial combined, have prevented a substantial cooling. “In effect, current temperatures would be well on the way toward typical glacial temperatures had it not been for the greenhouse contributions from early farming practices and later industrialization.”
Until the outlines of the current warming trend were understood, scientists in the 1970’s were predicting that another ice age was only a “few hundred years” away. Ruddiman now asserts that - “If anything, such forecasts of an ‘impending’ ice age were actually understated: new ice sheets should have begun to grow several millennia ago because human-induced global warming actually began far earlier…” [My emphasis.]
In a publisher’s description of Ruddiman’s new book (Princeton University Press 2005), Plows, Plagues, and Petroleum: How Humans Took Control of Climate, we are told that “The ‘Ruddiman Hypothesis’ will spark intense debate.”
So where is the debate?
OUR SCYLLA BELCHES POISON GAS ACROSS THE ENTIRE PLANETARY SURFACE.
THE WARD HYPOTHESES
“Impact from the Deep” Scientific American, September 2006, by Peter D. Ward, Ph.D. Dr. Ward is a paleontologist and professor of Geological Sciences at the University of Washington in Seattle.
Dr. Ward has raised another truly scary scenario, one that would trump the global warming problem by posing an even more dire possibility than merely melting a lot of ice and disrupting world climate patterns.Excerpts from the Scientific American article:
“About half a decade ago small groups of geologists began to team up with organic chemists to study environmental conditions at critical times in the earth’s history. Their work involved extracting organic residues from ancient strata in search of chemical ‘fossils’ known as biomarkers.… And to the great surprise of those doing this work, data from the periods of mass extinction… suggested that the world’s oceans have more than once reverted to the extremely low oxygen conditions, known as anoxia, that were common before plants and animals became abundant.”
“Among the biomarkers uncovered were the remains of large numbers of tiny photosynthetic green sulfur bacteria. Today these microbes are found, along with their cousins, photosynthetic purple sulfur bacteria, living in anoxic marine environments such as the depths of stagnant lakes and the Black Sea, and they are pretty noxious characters. For energy, they oxidize hydrogen sulfide (H2S) gas, a poison to most other forms of life, and convert it into sulfur. Thus, their abundance at the extinction boundaries opened the way for a new interpretation of the cause of mass extinctions.”
“…if the deepwater H2S concentrations were to increase beyond a critical threshold during such an interval of oceanic anoxia, then the chemocline separating the H2S-rich deepwater from oxygenated surface water could have floated up to the top abruptly. The horrific result would be great bubbles of toxic H2S gas erupting into the atmosphere.
“…conditions would have become amenable for the deep-sea anaerobic bacteria to generate massive upwellings of H2S. Oxygen-breathing ocean life would have been hit first and hardest, whereas the photosynthetic green and purple H2S-consuming bacteria would have been able to thrive at the surface of the anoxic ocean. As the H2S gas choked creatures on land and eroded the planet’s protective shield, virtually no form of life on the earth was safe.”
“The so-called thermal extinction at the end of the Paleocene began when atmospheric CO2 was just under 1,000 parts per million (ppm). At the end of the Triassic, CO2 was just above 1,000 ppm. Today with CO2 around 385 ppm, it seems we are still safe. But with atmospheric carbon climbing at an annual rate of 2 ppm and expected to accelerate to 3 ppm, levels could approach 900 ppm by the end of the next century, and conditions that bring about the beginnings of ocean anoxia may be in place. How soon after that could there be a new greenhouse extinction? That is something our society should never find out.” [My emphasis.] WHAT TO MAKE OF ALL THIS
We can reasonably doubt whether civilization could survive a major ice age without major advances in energy and agricultural technology. Too much arable land would be lost. Feeding more than a tiny fraction of the current population would probably become impossible, and the disruptions engendered by shrinking vital resources would almost certainly trigger a world war. Human extinction would not be out of the question.
Ruddiman’s Hypothesis suggests that the current global warming trend antedates human industrial activity by about eight thousand years and may have bought our species time to prepare for the next period of planetary glaciation. His point is that warming can disrupt our patterns of land use, but probably won’t kill us. But the Ward Hypothesis poses another deadly danger: that CO2 concentrations, quite apart from the other features of global warming, may lead to mass extinctions via poison gas.
The good news in the Ward scenario is that we have about 185 years or so, depending on trends, to bring CO2 concentrations under control. Before we invite politicians to navigate between the Scylla and Charybdis of Climate Control, we would do well consider the obvious cautions:
(1) Climatologists remain puzzled by the persistent findings that the ice cores evidence shows that increased CO2 levels lag behind increased temperatures by about 800 years. Which is cause and which is effect?
(2) CO2’s warming effect and that of methane (which is about 20 times stronger than CO2) are overmatched by another greenhouse gas – water vapor. There is more water vapor in the atmosphere by several orders of magnitude than all the trace greenhouse gases, like CO2 and methane; the heat trapping effect of water vapor potentially overwhelms that of the trace gasses.
(3) Can science describe in detail the mechanism that links changes in the trace gasses to larger temperature swings over time? Surprisingly, that work has yet to be done. We are left with “correlations” complicated by a seeming (and awkward) reversal of the cause - effect sequence.
(4) There are a number of abrupt climate changes, most recently a 1,200 year long reversion to near ice age temperatures, a drop of about 10 degrees Centigrade in a very few years. About 12,000 years ago this recent cold spell (The “Younger Dryas Event”) ended and the earth returned to a warmer climate. This and other abrupt changes have not yet been satisfactorily explained.
(5) The Ward hypothesis is not yet well developed. It appears that dissolved O2 can prevent or inhibit the growth of the sulfur belching bacteria. Little if any field testing has been done about the actual conditions that could trigger explosive growth of these “death smog organisms”. Some important questions might be answered through better observations and controlled experiments. For example: How are the chemocline and the growth of these submerged sulfuric/anoxic organisms actually affected by changes in CO2 concentrations in the air? What other factors contribute to the loss of dissolved O2 in oceans and lakes?
(6) I recommend that everyone who is serious about getting this problem right take the time to read or reread the Author’s Message and Appendices to Michael Crichton’s thriller, “State of Fear”. Leaving aside Michael’s conscientious and well researched skepticism about the global warming hype, the larger point he makes is absolutely spot on: Politicized Science is Dangerous. LIVING WITH A CHANGED DECISION PARADIGM
Unlike the ship captains who sailed in the time of Homer’s Odysseus, our 20th century decision makers (blithely unaware of the Ruddiman and Ward Hypotheses) were presented by “science” with a simple problem in threat avoidance.
Of course, certain hysterics tended to hype the immediacy of the threat and its existential certainty, but the navigation strategy was clear enough: Avoid warming by curbing CO2. What harm could come from that? Some “minor” economic disruptions were disregarded, raising the question - Will there ever be a time when political leaders understand both science and economics?
Now that 21st century science has revealed that we probably face two threats, the navigation problem becomes more sensitive. Because of the lead times, the margin for error and consequences of taking the wrong course are less forgiving; and the relevant science deserves much more critical evaluation.
I can think of at least three provisional steps:
(1) Given the truly scary nature of the Ward Hypothesis, we should avoid the CO2 sequestration scenarios that involve deep ocean storage, and we should be concerned, independently, with O2 levels in our large lakes, seas and oceans.
(2) Given that most of the predicted CO2 emissions over the next century will come from the Third World, possibly outside our political control (note for example that China will soon eclipse the US as a CO2 emitter), we urgently need research and develop strategies to mitigate the impact on ocean O2 levels.
(3) Because fossil fuels and solar power will probably be inadequate to sustain human civilization during any ice age, we should proceed to develop third and fourth generation nuclear power sources without delay. This strategy is consonant with the CO2 reduction goals that would be required if we take the Ward Hypothesis seriously.THE TAKE-HOME POINTS
We urgently need political leaders and scientists who rediscover the real meaning of hypothesis. If a near “consensus” can’t by itself turn a hypothesis into proof, then surely the current politically manufactured faux consensus about the global warming crisis cannot. Climate science is provisional and is going to give us provisional results for the foreseeable future.
Thank God we have some time here. Twenty first century science is no more up to the task of intelligent climate regulation than the current crop of 21st century political institutions. Our species is not prepared to attempt large scale climate control right now.
Before we even contemplate taking that dramatic (and irreversible) step, we we’ll need to cultivate a different political and scientific culture, one that promotes intellectual humility, a commitment to constant testing, to an intelligent, non-doctrinaire scientist-economist-policy dialogue, and to cautious, incremental action followed by ongoing reevaluation.
Will the scientific and political domains be up to this challenge by the end of the current century? Even that remains an open question. Getting up to the challenge within the current US election cycle? Out of the question.
Science needs to be well insulated from politics, and politics must be guarded against doctrinaire “environmentalism” masquerading as a religion.
As long as there are leaders willing to exploit popular anxiety about the misuses and unintended effects of technology, we can expect that “environmentalism-as-religion” will be a strong and growing social force. Some followers of the “new” religion will be strongly drawn to the unattainable vision of a pastoral utopia, a more idyllic world without technology. Given certain conditions, we should not discount the risk that a major neo-Luddite movement against technology will arise and mutate into a mass movement ideology with the traction of one of the 20th century’s worst lunacies.
In the real world, that boat to a simpler world – that mythical place without all the problems of “high tech” - left the dock about 85 years ago. When we and our pathogens began the forever arms race -- smart infections vs. smart medicines, and when we humans merely by traveling engendered a vast co-mixing of incompatible species on the planet, we unintentionally created a “must-manage-this-mess” scenario. I submit that we’ve already reached the technology point of no return: There is no alternative to the better-smarter technological path. Taking the road marked “Luddite Paradise ahead” would be species’ suicide.
Our one rational choice is to point our development in a general progressive direction (more human centered environmentalism, more human centered technology), but allowing for quick course corrections all along the way as we learn from our inevitable mistakes. We need to go forward cautiously, navigating between Scylla, and Charybdis. Our alternative is to sink. JBG