Tag: PETM

Waking the Giant

It’s only if we fail to grasp the enormity of the threatened impacts of climate change on the global environment that we can scoff at the notion that even volcanic eruptions and earthquakes may be triggered as a consequence of our continuing to burn fossil fuels. Not that it’s an easy consequence to appreciate, but vulcanologist Bill McGuire’s latest book Waking the Giant: How a Changing Climate Triggers Earthquakes, Tsunamis, and Volcanoes explains it with patient clarity. His book is a fascinating read in its discussion of the past and an alarming one in its analysis of future likelihoods.

The book begins with a straightforward and sobering view of the catastrophe which looms if we continue to fail to act on emissions. The signs of climate change are everywhere apparent and the prospects for the future are bleak. McGuire acknowledges the difficulties of precise prediction of what that future might hold 50 or 100 years from now and suggests that looking back on the past may be the best way to gauge what lies ahead. The main focus of his book is on ways in which Earth’s crust has responded to dramatically changing climates, but he also considers, further back, times of high levels of atmospheric carbon dioxide as possible pointers to what today’s increased greenhouse gases might forebode.

Continue reading “Waking the Giant”

Challenged by Carbon

Challenged by Carbon: The Oil Industry and Climate ChangeOil industry geologists have hardly been noted for their readiness to accept the findings of climate science. The American Association of Petroleum Geologists, a large international organisation of 31,000 members, is non-committal in its 2007 statement, though that was admittedly an advance on their previous rejection of anthropogenic warming.  Bryan Lovell has worked as a BP geologist as well as an academic, but the title of his book is enough to indicate that non-committal is not for him: Challenged by Carbon: The Oil Industry and Climate Change.

 

In his acceptance of the case for anthropogenic global warming Lovell lays great stress on the evidence from the past, long before there were any of the human species to influence what happened. The Paleocene-Eocene Thermal Maximum (PETM), a warming event 55 million years ago, is his focus. It is preserved in the geological record and the changes it caused to life on the planet mark the boundary between the two epochs. First, a large quantity of carbon was released into the ocean-atmosphere over the geologically short period of some 10,000 years. Second, the temperature at the bottom of the ocean increased rapidly by more than 4 degrees over the same short period. Third, the oceans became notably more acidic. All this was accompanied by a general and significant global warming. It took some 200,000 years for the planet to return to something resembling the conditions prevailing before the massive and sudden release of carbon. Lovell remarks an ominously striking correspondence between the rate at which large volumes of carbon were introduced 55 million years ago and the rate at which large volumes are now being put into the atmosphere by us.

He considers the evidence of this event is more likely to carry weight with oil industry geologists than the computer-based models of complicated natural systems employed by climatologists. Geologists are “happiest when basing their predictions on the solid ground of rocks”. This may be a useful insight into the slowness of some geologists to take climate change seriously, but it left me wondering at the somewhat blinkered intellectual world which it suggests. I also wondered whether Lovell sufficiently appreciated the attention climatologists pay to the past in their predictions of what lies ahead. He acknowledges that the picture is somewhat mixed, but broadly sees climatologists focusing on predictions of the future, relying on a combination of past trends and computer modelling to make their forecasts, by contrast with geologists who look back in time. Is this contrast real? Leading climatologist James Hansen frequently stresses that his order of importance is first paleoclimate studies, then ongoing climate observations, with climate models in third place. Also detailed discussions of the PETM and other significant global change events in the past are common in books concerned with climate change.  However, if only the story told by rocks will suffice for oil geologists so be it. It has certainly brought Lovell on board.

“It is now plausible for the geological community at large, not least those in the oil industry, to join with the climatologists and conclude that if we continue to release carbon dioxide  into the atmosphere at the present rate we shall, this century, experience among other effects significant acidification of the world’s oceans and an overall global rise in sea level. Even at the lowest likely level these changes will have a significant adverse effect on our species and at their upper  likely levels would be disastrous for many of us. How will the oil industry react?”

Lovell comments that protestations of virtue concerning climate change by oil companies have become a commonplace this century. Some may maintain a degree of cynicism as they read his descriptions of how this plays out within the industry itself, but he makes a reasonable case that there has been some change in industry perception.  He acknowledges the contradiction in accepting the reality of anthropogenic climate change, yet predicting that fossil fuels will form an essential part of energy provision through to the middle of this century and beyond. He calls it not contradiction but paradox, as indeed it could prove if the serious industry investment in carbon capture and storage he urges were carried through to success.

It is this prospect which is the main burden of the book. Lovell sees little possibility of the world forsaking fossil fuels. “Lofty and high-level” arguments are unlikely to prevail in either the comfortable developed countries or the aspiring developing nations. They would need to be convinced that the rapid elimination of the oil and coal industries is really necessary. His book is not intended to offer such conviction.

What he does offer and advise is the engagement of the oil industry in carbon capture and storage. The scientific expertise it has gathered is highly relevant to the task:

“Petroleum engineers and petroleum geologists seek to understand the rocks beneath our feet, how fluids move through those rocks and how those elements may interact with the minerals lining the pore spaces and pore throats through which they travel. This understanding is just what is required to assess the suitability of any given location for the safe storage of carbon dioxide and to then store that gas securely within the rocks below.”

The details are followed through in some detail in a chapter headed Safe Storage: From Villain to Hero. Existing oil reservoirs offer useable opportunities, but not sufficient to satisfy the very large requirements.  For that the use of saline aquifers will be needed. Lovell reports studies on the feasibility of such storage, some of them dealing with the reaction of the reservoir rock to fluids made more acid by the addition of injected carbon dioxide. Careful assessment of prospective sites is required. He is cautious in his appraisal, but optimistic that carbon dioxide can be safely trapped in reservoirs over geological timescales. Along the way he acknowledges the work of Kelemen and Matter (reported here in Hot Topic) on the possibility of trapping carbon dioxide in a type of igneous rock – peridotite – with which it would react rapidly. The concern for him is the absence of natural seals in such a process, and he considers pilot ventures are likely to remain focused on sealed reservoirs.

Oil companies work for profit. That is why the issue of a carbon price is critical if the expertise of those companies is going to be harnessed to capture and store carbon.  The price, says Lovell, has to reflect a real understanding of the danger of not controlling the release of carbon dioxide. Increased government regulation is essential to set the scene.

The book is lively and engaging and well worth attention. Lovell straddles two worlds which often enough appear to have little intercourse. Carbon capture and storage gets a mixed press in discussions of climate change mitigation. But if it really is feasible, and if setting a price on carbon will make it doable by those with the necessary expertise and finance, it has the potential to be a significant contributor to emissions reduction. Even if we find ways to replace fossil fuel much more quickly than Lovell envisages we will still need to sequester some of the excess carbon with which the atmosphere is already overloaded.

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Under a Green Sky

Under a Green Sky: Global Warming, the Mass Extinctions of the Past, and What They Can Tell Us about Our Future

How’s this for a writer’s motivation? “I am as scared as hell, and I am not going to be silent anymore!…Thus this book, words tumbling out powered by rage and sorrow but mostly fear, not for us but for our children – and theirs.” The book is Under a Green Sky: Global Warming, the Mass Extinctions of the Past and What They Can Tell Us About our Future, first published  in 2007 with a paperback version in 2008.  The scared as hell author is Peter D. Ward, a paleontologist and and professor of Biology and of Earth and Space Sciences at the University of Washington, Seattle.

The book certainly shows why the author has reason to be scared, but he lets us know gently, with a mixture of patient explanation and lively narrative.  He has worked at many interesting sites and he knows how to bring his visits back to life for the reader, whether gently chipping at cliffs on a heavily populated French beach or spending a week of 18-hour days in unceasing rain with a small group of colleagues on a remote Queen Charlotte Islands beach and running out of food the day before weather permitted the helicopter to return.

Mass extinctions in the past are his focus.  His work helped to confirm the 1980 hypotheses of the Alvarez team that the extinction which saw the end of the dinosaurs some 65 million years ago was catastrophic and caused by an asteroid striking the earth.

There have been other sometimes greater extinction events in the past, especially the “Great Dying” at the end of the Permian period some 250 million years ago.  Were they too the result of asteroid impact?  If it could happen once, why not other times as well? Ward explains the investigations that lead to the conclusion that only the one extinction  was the result of impact.  The rest were different.

He takes the reader carefully through the discoveries which point to the proposal that they were greenhouse extinctions, the result of complex processes which began with releases of carbon dioxide and methane (sophisticated estimates of past carbon dioxide levels show sharp increases at the time of each extinction), caused initially by volcanic activity on a large scale. This meant a warmer world which affected the ocean circulation systems and disrupted the conveyor currents. The oceans were a key factor. Bottom waters started to have warm, low-oxygen water dumped into them, ocean winds and surface currents came to a near standstill so that there was less mixing of oxygenated surface water with the deeper waters and, gradually, ever-shallower water changed from oxygenated to anoxic.  When it moved high enough for light to penetrate, green sulphur bacteria expanded in numbers and filled the low-oxygen shallows.  Accompanying them were other bacteria which produced toxic amounts of hydrogen sulphide which rose into the atmosphere.  There it broke down the ozone layer and the subsequent increase in ultraviolet radiation killed much of the green plant phytoplankton.  As the hydrogen sulphide moved up into the sky it also killed some plant and animal life and its combination with high heat increased its toxicity.

This summary conclusion is supported by a wealth of careful detail.  Like most climate history it is based on a great variety of evidence from people working in many fields of study.  Much of the work and hypothesising is quite recent, and will no doubt be put to much examination  before it can be regarded as established.  In the meantime it’s a fascinating read, fully accessible to the non-scientist. (It helps to have a chart of the geological periods alongside though if, like me, you’re a bit hazy about them.)

But the book doesn’t finish there.  Ward is all too aware that we also are living in a time of rapidly rising carbon dioxide levels – not from volcanic sources this time but from burning fossil fuels.  The question he addresses is whether the rate of increase today is on a par with the rate during those times when greenhouse extinctions occurred. He concludes that the present rise seems to eclipse any other rate of increase in the past. Oceanic acidification is an indication of this, since the natural buffering systems need time to strip the carbon dioxide out of the water. We are “hurtling towards carbon dioxide levels not seen since the Eocene epoch of 60 million years ago, which, important enough, occurred right after a greenhouse extinction.”

Would it matter if human civilisation was transported to the Eocene world?  New Caledonia everyone?  Any apparent attractions are rapidly punctured.  He instances the harshness of tropical life, the catastrophe of sea level rise, high mortality rates, widespread infectious diseases, famine and war.

If we can sharply curtail emissions in the 21st century we have a chance of getting carbon dioxide levels down to 400 ppm, even if we overshoot it briefly, and hence have some chance of limiting temperature rise to 2 degrees.  If not we are heading for an ice-free world, a change in the thermohaline conveyor belt currents and a new greenhouse extinction. “The past tells us that this is so.”

Towards the end of the book he records a memorable interview with David Battisti of the University of Washington, a notable climate scientist, one of whose lectures stimulated Ward to write this book. He asks Battisti to describe verbally the world we are headed for on our current trajectory. It’s a very different world and it’s not nice, though Battisti still hopes that under the pressures of climate change we will put into place a political structure able to implement the global regulations and incentives that might rescue us.

Ward concludes with three possible scenarios based on what he has written in his book and the “massive scientific literature” dealing with global warming and climate change.  The first is the only one I can bear to contemplate.  It’s bad enough, but the sea level will have risen by ‘only’ a metre, the conveyor belt current system will not have stopped, the ocean will stay mixed.

The political solution is out of the hands of the scientists.  But the policy makers can’t say they aren’t being warned. “This book is my scream”, Ward writes. It’s a very civilised scream, like that of many other scientists, but we must hope like hell enough politicians have ears to hear it.

The Long Thaw

The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth's Climate

The legacy of our release of fossil fuel CO2 to the atmosphere will be long-lasting. It will affect the Earth’s climate for millenia. We are becoming players in geologic time. That is the conclusion that climatologist David Archer shares with a general audience in his newly published book The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth’s Climate.

The author is a professor in the Department of The Geophysical Sciences at the University of Chicago and a contributing editor at Real Climate. His book is relaxed in style, almost conversational sometimes, repetitive on occasion, but nevertheless closely focused and packed with instructive detail. It was a pleasure for a non-scientist like me to read. He seems to understand how to illuminate processes for the general reader. For example, his chapter on the distribution of carbon in the atmosphere, the land and the ocean, and his explanation of the interactions between them in the carbon cycle, provided angles and information that pulled together satisfyingly the bits and pieces of my hesitant understanding.   Similarly what he writes about the acidifying of the ocean by CO2 and the part calcium carbonate plays in slowly neutralising its effect is a model of lucidity.

The book’s structure is simple.  There are three sections.  The first describes the situation we are in right now – meaning the 20th and 21st centuries.  The second section is about the past, investigated as a forecast for the future.  The final section looks into the deep future.

Archer produces no surprises about our current situation.  The basic physics of the greenhouse effect – that gases in the atmosphere that absorb infrared radiation could eventually warm up the surface of the earth – was described in 1827 by the French mathematician Fourier. Then in 1896 Swedish chemist Arrhenius estimated the amount of warming that the Earth would undergo on average from a doubling of the atmospheric CO2 concentration – what we now call the climate sensitivity. Such work sets the scene for the climate science which has exploded in the past few decades as global warming grew from a prediction into an observation.    He describes many aspects of our current understanding of global warming, with several particularly helpful sequences, such as that on the relative strengths of four external agents of climate change called climate forcings – greenhouse gases, sulfur from burning coal, volcanic eruptions, changes in intensity of the sun. The warming that is occurring cannot be explained by natural forcings.  Looking ahead in the present century he is very aware that sea level rise by 2100 may well be higher than predicted by the IPCC, as it begins to appear that the ice models used to forecast may be too sluggish to predict the behaviour of real ice.

In the second section he moves steadily back in time, starting with the last 100,000 years where the abruptness of some of the changes detected leads him to reflect that the IPCC forecast of a smooth rise in temperature from 0.5 degrees excess warmth today  to about 3.0 degrees excess warmth in 2100 represents a best-case scenario in that it contains no unfortunate surprises. He then treats the longer-term glacial climate cycles through the last 650,000 years, paying attention to orbital forcing and to the ups and downs of atmospheric CO2 through the cycles.  He envisages the ice sheets and CO2“entwined in a feedback loop of cause and effect, like two figure skaters twirling and throwing each other around on the rink.” His final step back is to the hothouse world of 50 million years ago and beyond that to transitions between hothouse and ice age climates over 500 million years. He selects the Paleocene Eocene Thermal Maximum event (recently discussed on Hot Topic) as an analogue for the global warming future.

The third section looks at that future.  In discussing the land’s and ocean’s ability to take up carbon being released from fossil fuels he considers it likely that there are limits to that process which will mean that a significant fraction of fossil fuel CO2 will remain in the atmosphere for millenia into the future.  There are calming effects from the carbon cycle, but there can also be opposite effects as seems likely to have been the case at times in the past.  Hopefully large scale methane hydrate release won’t be a large part of such feedbacks, but if the ocean gets warm enough it is possible and could double the long-term climate impact of global warming.

For now the carbon cycle is responding to the CO2 increase by inhaling the gas into the ocean and high-latitude land surface, damping down the warming effect. But on the timescale of centuries and longer the lesson from the past is that this situation could reverse itself, and the warming planet could cause the natural carbon cycle to exhale CO2, amplifying the human-induced climate changes.

The clearest long-term impact of fossil-fuel CO2 release is on sea level rise.  The book has a restrained chapter on this, but there is no escaping what will happen if the ice sheets melt. “We have the capacity to ultimately sacrifice the land under our feet.“

Have we averted an ice age?  Archer discusses this possibility, but finds the evidence uncertain.  He would in any case not put such a possibility forward as an argument in favour of CO2 emissions. All it means is that natural cooling driven by orbital variation is unlikely to save us from global warming – at this stage the much greater danger. Incidentally he mentions Ruddiman’s book Plows, Plagues, and Petroleum briefly and appreciatively in this section, but gives reasons for doubting its conclusions. (The book was reviewed on Hot Topic recently.)

In his epilogue on economics and ethics, where he ponders whether we are likely to turn away from the path we are currently on, he offers a comparison with slavery, another ethical issue: “Ultimately it didn’t matter whether it was economically beneficial or costly to give up. It was simply wrong.”

James Hansen describes the book as the best about carbon dioxide and climate change that he has read.  “David Archer knows what he is talking about.” To which I would add that he also knows how to explain it clearly to anyone prepared to give him reasonable attention.

Ice, Mud and Blood

Ice, Mud and Blood: Lessons from Climates Past

In the recently published Ice, Mud and Blood: Lessons from Climates Past British geologist Chris Turney describes how scientists are building up knowledge of the earth’s climate in the past and what it might mean for our future.  He describes attending a showing of The Great Warming Swindle in Australia in 2007. He remarks on the panel discussion which followed when questions were taken from the audience: “…I suddenly realised that many of my companions were either loonies or had been very badly informed. It struck home just how poor a job we’ve done as scientists in communicating our work.”

I’m not sure that the scientists are altogether to blame, but certainly his book makes amends if they are required.

He selects various periods in the past when the climate changed and reports on the current thinking about what caused those changes. Along the way he provides fascinating stories of how the jigsaws have been assembled from a great variety of pieces of scientific investigation.

His first two periods are very distant. One 55 million years ago, the drastic warming over a period of 160,000 years, known as the Peleocene-Eocene Thermal Maximum (PETM), on which Gareth had a recent post. The second from 540 million to 1000 million years ago when it appears that the globe was almost covered in ice during at least three ice ages. Acknowledging that these events happened when the patchwork of continents was different from our time he moves closer to the present in the remainder of the book. He begins a mere 2.5 million years ago when the earth became locked into the bout of ice ages and inter-glacials which continue to the present. His subsequent chapters narrow the focus to episodes within that period: a warm stretch in the last interglacial from 130,000 to 116,000 years ago; the up and down progression from then  towards the Last Glacial Maximum 21,000 years ago; the tumultuous time which marked the end of that last ice age from 21,000 to 11,700 years ago; and what it has meant to the conditions of life for humans to be in the comparatively settled, but by no means uniformly even, climate of recent millenia.

The book carries intrinsic interest in its accounts of how the changes in the past are reconstructed. The evidence gained from ice cores and ocean bed cores is always astonishing in its detail and complexity. The range of information that can be prised from the shells of foraminifera, ancient ocean-dwelling organisms, is extraordinary.  The sheer excitement of discoveries which confirm other discoveries carries a drama which the author is well capable of communicating. Clearly paleoclimate is an absorbing and rewarding area in which to work.

But Turney is much concerned with its lessons for the present. Understandably, considering the likely causes of past changes. Greenhouse gases are always an important part of his picture. For example the PETM was probably triggered by the release of a vast amount of carbon into the ocean and atmosphere over less than 2000 years, likely to have been methane from ocean sources. This was enough to drive a massive warming over 30,000 years or so.  The warm conditions persisted for another 60,000 years.It then took another 70,000 years before temperatures started to drop and return to what they were before, with the oceans playing a different part at this stage in gradually sucking greenhouse gases out of the air. The implications for us today?  If we exhaust the available fossil fuels we will release more carbon than was released at the beginning of the PETM.

Another lesson from the past is the importance of positive feedbacks in the climate system, when the changes that have occurred trigger new and greater changes than the original cause on its own would account for. There is a warning for us that a cascade of unintended consequences can follow from apparently small beginnings. “A little more greenhouse gas in the air does not cause a little change in climate.”

A further lesson is the rapidity with which changes have sometimes happened in the past as tipping points were reached. Abrupt shifts in the climate system are quite possible, as is illustrated, for example, in his account of the sudden reversals which marked the progress towards the Last Glacial Maximum.

Summaries like this unfortunately obscure the pleasure and interest of the book which lies in the wealth of detail it contains and the cheerful clarity with which it is ordered and conveyed to the reader. The underlying earnestness of the author’s concern about the direction we are headed is unmistakable but there is nothing ponderous about his narrative.

Incidentally the author has spent time in New Zealand and describes being able to correct a faulty carbon-dating of wood in the Franz Josef glacier’s Waiho Loop moraine to show that the glacier surge was 13,100 years old and thus contributory evidence of a southern hemisphere cooling at a time when the northern hemisphere was warming. This phenomenon he discusses in the context of his account of the abrupt veerings which marked the end of the last ice age.  His connection with New Zealand includes a directorship in the new young company Carbonscape which is using a world-first microwaving technology to make charcoal.  I expect to post about that soon.