Author: Bryan Walker

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.

Coppiced willow farming here

This column appeared in the Waikato Times in August 2008.  I have altered some of the wording to update it for this Hot Topic post.

The change to renewable energy sources can seem daunting. Those with stakes in fossil fuels are often negative, claiming change will be too expensive, too difficult, or not yet necessary. Cries of economic doom have greeted even the modest emissions trading scheme which may or may not be carried forward by the new government.

It was encouraging therefore to read a few months ago of the plans of renewable energy company Pure Power to launch a variety of shrubby willow as a biofuel crop in New Zealand. Biofuels which use food crops or destroy rainforests have had a justifiably bad press. But not all biofuel crops are equal. Coppiced woody plants like the willow Pure Power plans to use have a very good ratio of energy output to the energy put into converting them; they can be grown on poorer soils not used for food production; they require little fertiliser or irrigation; using new technologies they will produce not only biofuel but also a range of products for making paints, resins, adhesives and bioplastics.  Pure Power will have nursery stock ready for planting this year and hopes for a rapid expansion of planting in subsequent years.

Continue reading “Coppiced willow farming here”

Plows, Plagues and Petroleum

Plows, Plagues, and Petroleum: How Humans Took Control of Climate

William Ruddiman’s book Plows, Plagues, and Petroleum: How Humans Took Control of Climate has attracted a good deal of interest in the climate history world since it was published in 2005.

His major thesis is that even before the industrial revolution, human activity over a period of 8000 years was responsible for a significant rise in carbon dioxide and methane levels in the atmosphere.  After explaining orbital changes and their effect on ice-age cycles and monsoon cycles he turns to what he considers an anomalous rise in methane concentration in the atmosphere which began 5000 years ago – anomalous in that the naturally declining solar radiation would be expected to result in gradually lowering methane levels as wetlands diminished in size.   He patiently works his way through what can be inferred of early agriculture to a hypothesis that increasing rice irrigation was mainly responsible for the methane increase, with lesser contributions also from domestic grazing animals and biomass burning.  His next step is to look at CO2 changes, where he detects a similar anomaly beginning 8000 years ago when the natural downward trend was interrupted at around 260 parts per million to rise to around 280 ppm by the start of the industrial revolution.  In the case of CO2 he attributes the rise to deforestation for agriculture, aided perhaps by some peat and coal burning. This attribution is tested against the population levels and likely amount of deforestation resulting from agricultural activities; he explains the calculations which he undertook to establish its credibility.

If he is correct this would mean that the warm and stable climate of the last 8000 years has been due to unwitting human intervention which offset a natural cooling that would otherwise have gradually developed.  He sets out reasons for the conclusion that a degree of glaciation may by now have been occurring in Canada were it not for human farming activities.

His hypothesis has been challenged, as he expects and, as a scientist, welcomes. He responds in his book to two of the challenges, both of which he acknowledges to have merit.  One is that he did not go far enough back in the sequence of ice-age cycles when looking at the pattern of previous interglaciation periods for a comparison of what might be expected from natural processes today. The other is that humans could not possibly have cleared and burned enough forest to account for such a large CO2 anomaly.  He considers that with some adjustment his hypothesis survives these challenges.

He then considers the “wiggles” that have occurred in the CO2 increases over the 2000 years prior to the industrial revolution, particularly the so-called Little Ice Age, when the CO2 level dropped somewhat.  He doubts natural causes and looks instead for processes that might have reversed the slow deforestation which he has suggested responsible for the gradual CO2 increase.  He rules out war and famine as not disastrous enough on a large enough scale and settles on disease, especially the plague.  He theorises that as epidemics and pandemics caused major drops in population, reforestation occurred in abandoned farmland, there was a slowdown in new deforestation, and in China a decrease in the amount of coal burning.

The question Ruddiman then proceeds to address is why the relatively modest rise in greenhouse gases caused by humans before the Industrial Revolution led to so relatively large an increase in temperature – 0.8 degrees – while the relatively large rise in greenhouse gases since the Industrial Revolution has been accompanied by a still relatively small increase in temperature.  His answer lies in the response time required for the full effects to be felt and he explores this in some detail in relation to both land and ocean, showing how response times vary in different environments.

Ruddiman’s hypotheses continue to be debated by climate scientists.  In fact Wallace Broecker, one of the world’s leading experts on climate history describes them as “total and utter nonsense”, according to a September 2008 New Scientist article.  The article reports Broecker reckoning there’s a natural explanation for the CO2 rise. Deep-sea sediments record a drop in carbonate concentrations that could account for the rise in atmospheric CO2.  But others find Ruddiman at least worthy of further consideration.  His book is certainly a fascinating detective science story, readily accessible to a general reader.

But I enter a caveat in relation to his closing chapters where he looks at future warming prospects as the full effect of the large post-industrial revolution rise in greenhouse gases begins to be felt. His prognostications are more optimistic than many climatologists would be willing to offer today. He gives us a century or two to melt much of the world’s sea ice and mountain glaciers and push back the seasonal limits of snow cover, but considers the two great ice sheets will be largely intact. The book was published over three years ago. One wonders whether he would be as sanguine now.

When he wrote the book he was certainly disinclined to see climate change as an overwhelming challenge. In fact he is quite testy about what he describes as the alarmism of extreme environmentalists and their organisations. He doesn’t name them, but he accuses them of oversimplifying the complexities of the global warming issue. He should have identified the organisations he refers to. Maybe he has noticed more alarmist predictions than I have. Major environmental advocacy groups such as Greenpeace and WWF seem to me to stay well within the bounds of responsible science on climate change.

He finally states that the depletion of precious resources – naming water, topsoil and fossil fuel – poses a greater threat to the human future than the threat of global warming does.  There are certainly many serious threats to the continuance of human society, but he provided me with no grounds for relegating global warming to a secondary rank.

Climate Wars

Climate Wars

Gwynne Dyer’s new book Climate Wars explores the all-important political dimension of addressing climate change. Military history is Dyer’s speciality. One origin of this book was his dawning awareness that, in a number of the great powers, climate-change scenarios are already playing a large role in the military planning process. The other factor persuading him to write the book was the realisation that the first and most important impact of climate change on human civilisation will be an acute and permanent crisis of food supply.

He produces scenarios of his own to introduce each of the book’s seven chapters, positing in coming decades dangerous geopolitical developments in response to food shortages, with massive levels of human deaths. The scenarios range through many eventualities: dangerous confrontation on the Sino-Russian border;  nuclear conflict between India and Pakistan; the collapse of the European Union under the stress of south-north mass migration; a lethally effective border barrier between the US and Mexico with disastrous consequences for Mexico and the alienation of Hispanic-Americans within the US; a unilateral geo-engineering project gone wrong; and much else. His final scenario is different in that it looks much further ahead to a possible major extinction as a result of global warming effects on the oceans, drawing on the hypotheses in paleontologist Peter Ward’s recent book Under A Green Sky.

Dyer claims no certainty for his scenarios of course, but there is no denying their underlying credibility. As the main chapters of the book make apparent, the climate changes on which the scenarios are based are inescapable if we carry on with business as usual.  The book is as much about climate science as about the political and strategic consequences of climate change. Dyer is conversant with the major themes of  current science, and well understands the feedback mechanisms which threaten to accelerate the warming already under way.  He serves the general reader well in his this respect. He knows how to explain to lay people the complexities in which the experts deal.

He also spends a good deal of space canvassing mitigation possibilities and the likelihood or otherwise of their being adopted.  “We Can Fix This…” says one chapter, “…But Probably Not in Time” says the next, which is why he goes on to consider geo-engineering measures as an emergency fall-back option if the political process doesn’t deliver the goods on time.

As a respected journalist he has had access to numerous scientists, soldiers, bureaucrats and politicians. Extracts from their interviews are a core element of the book.  They lift his material clearly out of the realm of journalistic conjecture into the sober realms of the everyday working life of those he speaks with. The interviews have the further advantage of being recent and the book consequently takes us to where things stand right now. There is little doubt that they are worse than hitherto predicted.

Neither optimistic nor pessimistic, Dyer looks for realism. His final chapter centres partly on James Lovelock whom he sees as the most important figure in both the life sciences and the climate sciences for the past half-century; indeed he has him up there with a figure like Charles Darwin in the pantheon of scientific heroes.  But he finds the resolve to differ from Lovelock’s belief that irreparable damage has already been done. Dyer’s hope is that we will move sufficiently quickly towards decarbonising our economies to avoid the worst prospects of conflict and famine portrayed in his scenarios. He reflects on the small miracle that “at exactly the same time when it became clear we have to stop burning fossil fuels, a wide variety of other technologies for generating energy became available.”  But to make use of the opportunity we have within the next few decades, we will need, he concludes, the grown-up values of self-restraint and the ability to cooperate. One hopes this is not too much to ask.

Six Degrees

This posting is based on a Waikato Times column written in July.

The Royal Society in the UK awarded its 2008 science writing prize to Mark Lynas for his global warming book Six Degrees: Our Future on a Warming Planet. I found the book telling when I read it last year, and it was good to see it receive this confirmation.

Lynas’s first book High Tide, published in 2004, grew out of three years visiting parts of the globe where the signs of global warming were becoming evident – Alaska, Tuvalu, Mongolia, Peru, the US.  Six Degrees had a different genesis. It is the result of many months in the Radcliffe Science Library at Oxford trawling through scientific journals to find the peer-reviewed papers on which the book is entirely based.  The source material ranges from computer model projections to studies of climate in the past. Lynas is not a scientist, but he makes it his business to adequately understand and interpret what the scientists have written in their specialist fields.

Sceptics often scoff at computer models as somehow fiddled in advance, but Lynas points out that they are based not on subjective judgements by their constructors but on the fundamental laws of physics.  They have grown increasingly sophisticated and the insight they offer into likely future conditions on the planet is something humanity has never had access to before.  One check on their accuracy is ‘hindcasting’ the 20th century, and some of the most powerful recent models have done this with almost unerring accuracy.  Not that Lynas suggests that they are infallible in their forecasts.

Six Degrees is a highly readable narrative for the general reader, tracking through what changes can likely be expected from each degree of global warming from one degree through to six degrees, the upper limit for worst case scenarios.

Even at what may seem comparatively low rises of one or two degrees centigrade he finds plenty to cause alarm. A few of his examples:  possible desertification and abandonment of agriculture over millions of square kilometres in the US, an extremely hot and drought-ridden Mediterranean Europe, an ice-free Arctic ocean with implications still difficult to understand, the bleaching and likely death of many coral reefs, major loss of food production in India, serious population displacement in Bangladesh. On through three and four degrees the book points to desertification intensifying in many places, water supply severely declining in Pakistan, the Amazon rainforest dying, far more of Australia burning and suffering serious drought, the West Antarctic ice sheet facing collapse, sea levels rising threateningly. Five and six degrees hardly bear contemplating as the possibility is faced of methane hydrates on subsea continental shelves becoming destabilised and venting into the atmosphere, adding an enormous feedback to global warming.

As a writer for the general public Lynas doesn’t shrink from putting emotional depth into his analysis.  He explains in a Guardian column: “If I’ve read a paper about coral bleaching or precipitation trends in the Sahel, I need to be able to describe what this means in the real world – grey weed creeping over once-vibrant coral reefs, and Sudanese herders struggling to feed their children as their livestock starves around them and a dust-storm looms on the horizon.”   However he sees his first duty as accurately representing what he has read in the scientific literature.   The Royal Society judges are clear that he has met this test. They state that the book provides a good overview of the latest science on the issue. An interesting response came from  Eric Steig, one of the contributing scientists to the Real Climate website, when he reviewed the book in Conservation Magazine. Initially he had assumed from news reports that the book was alarmist and probably not worth reading; however, after reading it he reported it firmly based on published scientific literature and nowhere exceeding those bounds. Alarming, yes, but not alarmist.

There is no escaping that the science is alarming. That is why this issue is of such overwhelming importance. Yet like most writers on the subject Lynas hopes that we can yet avoid the worst prospects. There is already unavoidable further warming ahead of between 0.5 and 1 degree Celsius, but it is possible that we might manage a ‘safe landing’ within the 1-2 degree corridor if appropriate action is begun now to drastically reduce greenhouse gas emissions.

This is the point at which the question moves from science into the realm of the political. We largely know how the needed reductions could be achieved.  The question is whether we find the collective will to do it.  The fact that that is still an open question indicates the full reality of the science has not dawned for enough of us.   Books like Six Degrees need wide readership. Hopefully the Royal Society prize will assist that.

It is worth noting that Six Degrees was published in America by National Geographic, which has also made a television documentary based on the book and broadcast on the National Geographic channel internationally. On a lighter note Lynas also achieved minor fame as a somewhat younger man in 2001 by throwing a cream pie at Bjorn Lomborg, the ‘sceptical environmentalist’. “I wanted to put a Baked Alaska in his smug face in solidarity with the native Indian and Eskimo people in Alaska who are reporting rising temperatures, shrinking sea ice and worsening effects on animal and bird life.”