Posts Tagged Pliocene

Your Life as Planet Earth Bryan Walker Jan 06

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“We can’t make sense of our future until we make sense of our past”, writes Howard Lee in his recent book Your Life as Planet Earth: A new way to understand the story of the Earth, its climate and our origins. The book demonstrates the very considerable sense that science has been able to make of our past. There are clear lessons for us as we forge our future, though whether the political leadership is able to take on board those lessons is moot.

In the first part of the book Lee provides a highly readable account of the turbulent history of the planet in the four and a half billion years of its existence. Geology, climate and the evolution of life are the recurrent themes. He measures this long history against an imagined human life spanning a century. It’s an entertaining and effective way of depicting the enormous spans of time before humans arrive on the planet. On this measure simple life starts in the teens of the centenarian’s life; oxygen arrives during the mid-life crisis; primitive plants and fungi start to colonise land in the late 70s; at 86 complex animals show up; in the 90s four-legged life evolves from fish; at 98 the dinosaurs are extinguished; homo sapiens doesn’t emerge until the 29th December in the final year. And in the few remaining minutes of that last year we have achieved a rapid rise in atmospheric carbon dioxide to levels not seen since the Pliocene, three and a half million years ago.

Our rates and quantities of carbon dioxide generation are rivalling those of the great igneous eruptions which had highly destructive effects on the climate of their times, triggering global warming, ocean anoxic events and mass extinctions. We’re making our presence felt in no uncertain manner, and Lee sees no reason to assume we can avoid the consequences which attended past rapid escalations of carbon dioxide in the atmosphere.

The second half of the book shows how scientists have discovered so much about our past.  It’s a fascinating account of the enormous range of techniques and ingenuity by which the progression of events and processes has been discovered. Plate tectonics is a stand-out in geology: “In short, it is geology’s unifying theory.” The evidence for evolution is overwhelming. It has been established in the fossil records and in the genes, anatomy and biochemistry of living things today. We have also come to understand that the evolution of life has been an integral part of the planet’s evolution.

Turning to the evidence for past climates Lee explains the numerous proxies by which past temperatures and carbon dioxide levels can be established and confirmed, along with the accompanying behaviour of the oceans. There are uncertainties of course, and there is more to be discovered, but the overall picture to date is impressive in its detail. Carbon dioxide and temperature have moved in lockstep throughout most of Earth’s history, with the gas being both a driver of and responder to warming.  The gauging of carbon dioxide levels through the climate changes of the past is, Lee emphasises, crucial to our understanding of how the planet will respond to the rising levels of today.

Lee’s survey of what has been discovered about past climates covers territory mostly familiar to readers who follow climate science, but it is marked by the completeness of its range and the writer’s ability to make complex matters clear to non-scientists. He has a light touch, but achieves admirable clarity in his explanations.

Alarm is, Lee thinks, an entirely appropriate response to scientists’ projections of Miocene-like or maybe even end-Triassic-like conditions for our grandchildren’s world and beyond. He fervently hopes for some unforeseen cooling feedback “to swoop in like a fairytale hero, saving us from destructive climate change”. But Earth’s past shows no sign of that.

The book is testimony to the high worth of the patient processes of the scientific community. The piecing together of Earth’s past is a triumph of human intelligence. It also obviously carries high import for our future as we keep raising the level of carbon dioxide by continuing to burn fossil fuels.

But if science brings understanding it takes politicians to act on scientific information, and at the end of his book Lee reflects on the complete disregard for science shown by many top political leaders. He writes of “the burden of ignorance in the upper echelons of power”. That spectacle is particularly apparent in America where Lee lives. But while I was settling to write this review I viewed for the second time Alister Barry’s documentary Hot Air screened by Maori Television. Watching the dismal progression of political and business leaders in supposedly well-educated New Zealand scrambling to evade or deny the issue of rising emissions was a depressing experience. All the more while reading yet another clear and compelling explanation of the scientific conclusions which any of those leading figures would be capable of understanding.

Lee ventures reflection on what we must do if we are to pull back from invoking the worst consequences of climate change. In this discussion I thought he surrendered too readily to the notion that decarbonisation of our energy systems within the necessary time frame is too much for us to accomplish. He appears influenced by Roger Pielke on this point. If the message from Earth’s past is allowed to finally break through into the public consciousness we may surprise ourselves by the speed with which we can move. But that’s a very big if.

Life at 400ppm: catching up with a Pliocene atmosphere Gareth Renowden Apr 10

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With global atmospheric carbon dioxide bumping along just under 400ppm, and sure to break through to higher levels in the near future, it’s worth taking a long hard look at what the climate system was like the last time CO2 was at these levels — the Pliocene period 3-5 million years ago. Professor Maureen Raymo of Columbia University’s Lamont-Doherty Earth Observatory is a paleoclimate expert, and in this new video by Peter Sinclair for the Yale Climate Forum she explains how we can find out what might be in store when the planet finally catches up with its atmosphere. Not good news, especially if you consider that we’re certain to blow well past 400 ppm in coming decades, unless dramatic action is taken to reduce carbon emissions.

Morality, government and fossil fools (Bryan’s back!) Bryan Walker May 24

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I signed off regular writing for Hot Topic some months ago. But failing eyesight doesn’t mean failing concern, and my anger at the way our government heedlessly pursues the expansion of fossil fuel exploration led me recently to reflect I could still see sufficiently to write letters to editors. Publication of a letter by the NZ Herald emboldened me to try something for the dialogue page. It wasn’t accepted, on the reasonable  ground that they were about to publish an article by Jim Salinger which they described as along the same lines.

However I thought Hot Topic readers might be interested in my attempt to attack the government on moral grounds. I acknowledge that politics and morality make uneasy bedfellows, and that moral absolutism is hardly a suitable tool for political effectiveness. Nevertheless sometimes issues arise where shades of grey can legitimately be challenged by something closer to black and white, and that transition is certainly much earlier along the path of fossil fuel exploitation than our government (and many other governments) is currently inclined to allow.

The moral appeal is strongly made by many who write and speak on the climate issue. Al Gore sounds it regularly. Among the many books I have reviewed on Hot Topic I recall being struck by what William Calvin’s book Treating a Fever had to say on the question, as I summarised in the review:

“He also pins hope on religious leaders coming to see that climate change is a serious failure of stewardship and our present use of fossil fuel is a deeply immoral imposition on other people and unborn generations. Their arguments will trump the objections of the vested interests, just as they did when slavery was ended in the 19th century.”

Whether there’s any hope of an onslaught by religious leaders in church-going US, or for that matter in less religion-oriented NZ, is hardly yet clear, but the appeal to morality can be sounded just as well by those of no religion, and is worth making if we set any value on the finer human traits.

Here’s the piece I submitted to the Herald. Hot Topic readers will understand that it was written for a general public audience.

The relationship between morality and government is rarely easy to affirm, but if ever there was a clear moral imperative for government it is to mitigate climate change. Human suffering on giant scales is threatened as the predictions of climate science begin to prove correct in reality. Economist Lord Nicholas Stern, head of the Grantham Institute on Climate Change, warned recently of the massive movements of people likely to be triggered by the temperature rises our current greenhouse gas emissions trajectory will cause. He foresees hundreds of millions of people forced to leave their homelands because of disrupted weather patterns and spreading deserts, resulting in serious and prolonged armed conflict.

Emissions continue to rise. This month the global concentration of atmospheric carbon dioxide has reached 400 parts per million, another milestone on the path to catastrophic consequences for humanity. According to paleoclimate research the last time this level of carbon dioxide was reached was some four million years ago, in the Pliocene epoch. Global temperatures rose perhaps four degrees higher than today, as much as 10 degrees higher at the poles. Sea level may have been 20 or more metres higher than today.  It’s a frightening legacy we are preparing for coming generations. For that matter there is plenty to be alarmed at already, in the intensification of severe weather events, the increasing acidification of the ocean, the diminishing volume of global ice, the rising sea level and many other manifestations of warming.

In the light of what we now understand of the consequences of climate change it is the clear duty of governments to lend their weight to a rapid transition from fossil fuel reliance to energy sources which do not emit greenhouse gases. That is why the present government’s intent to gain wealth for New Zealand by expanding the search for fossil fuels is ethically indefensible. According to Climate Change Minister Tim Groser the government has no dispute with the science. The Prime Minister acknowledges that changes are already occurring, sooner than might have been hoped. Yet somehow that does not mean the government is prepared to forgo what it sees as the possibility of considerable wealth from expanded fossil fuel exploration and exploitation.

Indeed it embraces the possibility with enthusiasm. The Prime Minister unashamedly appeals to consumer desire. He speaks of a possible $13 billion annually from royalties, assisting our “desire to spend like other first world countries”. When challenged, government refers to the way other nations are acting and proudly affirms that it will not allow the New Zealand economy to suffer by comparison. In an interview early in his premiership Key acknowledged that it would be irresponsible of us not to play our part when it comes to climate change but in the same breath asserted we should also not be prepared to “completely sacrifice our economy” in the name of climate change when other countries are just not prepared to do that.

It’s a convenient cop-out. It begs the question of whether there are other ways of running a successful economy than by exploiting fossil fuels. And once that question is by-passed it’s easy to accuse others of naiveté and of promoting economic ruin. Justifying immoral practice in the name of the economy has a long history. Slavery abolitionists in Britain and the US had to struggle for many decades against the accusation that what they were advocating would be disastrous for commerce and national wealth. It wasn’t, of course. Neither will turning our backs on further expansion of our oil, gas and coal resources spell disaster for the New Zealand economy.

The government needs to see its commitment to expanding fossil fuel exploration against the perspective of what a rapidly warming world is threatening for some current populations and all future populations. There are some ways of making money which offend human morality so deeply that decent societies cannot allow them.

Ice, Mice and Men Bryan Walker Aug 21

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Geoff Simmons and Gareth Morgan, with help from John McCrystal, have produced a book which one hopes will be read by many New Zealanders.  Ice, Mice and Men: The Issues Facing our Far South not only carries illuminating scientific information about the islands and seas to our south and the Antarctic continent beyond them, but it communicates it in a relaxed and engaging style which should ensure a wide general readership. The more people understand what is happening in this vital region the better, and it’s easy to see this book adding to their number.

The opening section explains why the region is important, breaking it into three zones: first, the subantarctic islands, “liferafts” of the Southern Ocean; second, the Southern Ocean itself, home to the Antarctic Circumpolar Current (ACC) and “the engine room of the global ocean and the world’s climate”; third, Antarctica, including the sea ice that surrounds it which helps drive the marine food chain and affects the transport of nutrients essential for marine life around the world. The section provides a detailed account of the function of the three zones not just in relation to each other but in crucial relation to the globe as a whole.

The treatment of the ACC, for example, explains how the mixing of its waters due to high winds carries warmer surface waters into the depths and presents colder water to the warming effect of the sun, helping to store heat from the atmosphere. It also helps store carbon as it increases the amount of water that has contact with the air, and cold water at that which can absorb more carbon dioxide.  However this service means that the Southern Ocean is acidifying more rapidly than for millions of years.  The role of the ACC in feeding nutrients into all the major oceans is another vital function described by the book, one in which it is aided by the extraordinary ecosystems of the sea ice and floating ice shelves of Antarctica.

The second section of the book deals with the question of the race for resources. It has resulted in much past damage to the subantarctic islands’ wildlife, but on a wider scale it is fortunately so far comparatively muted. However the authors adduce plenty of evidence that realpolitik considerations lurk behind the Antarctic Treaty System and urge the likely need ultimately to strike a balance between complete protection of the area and managing the worst aspects of commercial exploitation by agreeing environmental standards and setting aside some areas as complete reserves.

In reviewing the book for Hot Topic my main interest was its third section which deals with climate change issues in the region. Three years ago I reviewed Gareth Morgan’s and John McCrystal’s earlier book on climate change Poles Apart, which posited a shouting match between alarmists and sceptics and proposed to adjudicate the matter.  There was, of course, no shouting match and there was nothing that required adjudication. The science was as clear in its basics then as it is now, and the authors finally came down solidly on the side of the science. However they still allowed some accusations of a conspiracy on the part of the IPCC to send an overstated message to the public, described Michael Mann’s hockey stick thesis as a grievous overstatement and in policy matters advised against using a sledgehammer to crack a nut.

I’m happy to report that the climate change section of this book is a well-assembled and unequivocal statement of the current scientific understanding, often expressing insights which readers will find helpful. Denial gets short shrift in the initial overview: “Just because a temperature rise historically precedes an increase in CO2 levels doesn’t mean it necessarily does. That is the natural order, after all, and the present warming is not natural.”

Focusing on the southern region the book points to evidence that the Southern Ocean has become warmer, fresher and slightly more acidic, and the patterns of circulation have changed. Wind speeds have increased markedly in recent decades and are shifting south. The impact of this on the ACC is as yet uncertain: whether it will make it stronger or more turbulent, whether the current itself will move further south, and how all that will impact on the role of the ACC in the planet’s ocean mixing.

Acidification alone is alarming enough. We appear headed for a bigger change in acidity than anything seen in the last 20 million years. This means serious stress for anything in the ocean which needs a shell. The shells of modern plankton called foraminifers are becoming lighter than those of their recent ancestors – and this has happened in direct proportion to the increase in acidity. They form a substantial part of the marine food chain. The warning signs of acidification are ominous, and lead the authors to remark plainly: “Along with climate change this is one hell of a risky experiment we humans are embarking on with our oceans.”

The effects of warming on the continent of Antarctica may be less apparent than what is happening in the Arctic polar region, but the book warns that this may in part be due to the now-diminishing ozone hole which has likely helped keep its locality cooler, ozone being a greenhouse gas. Yet warming impacts can be quick and dramatic as we can see in the Antarctic Peninsula and the Amundsen-Bellingshausen Sea. The most severe threats to the Antarctic ice are likely to come from the ocean and the authors acknowledge the difficulties in predicting how this may play out and what it is likely to mean for global sea level rise and for the thriving ecosystems supported by Antarctic sea ice. However geological evidence and sediment cores reveal that in the early Pliocene, with CO2 levels similar to today, temperatures eventually rose enough to melt the West Antarctic Ice Sheet, probably adding some 3.5 metres to a global sea level which was probably 10-30 metres above today including contributions from Greenland, Arctic Islands and other land-based ice.

The final section of the book looks at the conservation imperatives arising out of the damage caused by the race for resources and climate change. The threats are clearly described and useful suggestions are offered for their amelioration under the headings of basic science, fisheries management, marine protection and pest eradication.

The book is designed to be read with ease but is nevertheless packed with stimulating scientific detail and leaves the reader absolutely clear that matters of extreme seriousness for the human future are at issue in our far south.

Return of the Climate Cluelessâ„¢: there’s none so blind… Gareth Renowden Apr 17

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Sir Peter Gluckman, scientific adviser to NZ prime minister John Key, recently published a discussion paper entitled Towards better use of evidence in policy formation (pdf). It’s an interesting read for anyone who has ever noted the sometimes large discrepancy between political dogma and policy outcomes. Sciblogger Peter Griffin went so far as to describe it as “possibly one of the most important [papers] he has released thus far”.

Over in the land of the Climate Cluelessâ„¢ however, Richard “Climate Conversation” Treadgold has taken Gluckman’s paper as a cue to demand evidence of climate change. Treadgold appears to have forgotten that one of Sir Peter’s first acts following his appointment was to review the evidence and issue a statement on the subject, and is perhaps still smarting from Gluckman’s comments on climate denial last year. He therefore issues this stern challenge:

I would remind Sir Peter that evidence is required to establish the following key factors in the global warming debate – evidence that has not surfaced so far. We have been looking for evidence to show:

  1. The existence of a current unprecedented global warming trend.
  2. That the greenhouse effect is powerful enough to endanger the environment.
  3. A causal link between human activities and dangerously high global temperatures.
  4. That climate models have a high level of skill in predicting the climate.
  5. A causal link between atmospheric levels of carbon dioxide and global temperatures.
  6. A causal link between global warming and the gentle rise in sea level.

Time to play some whack-a-mole…

Treadgold appears not to have been “looking” very hard, because there is plenty of evidence to address every one of his points.

We have been looking for evidence to show:

1. The existence of a current unprecedented global warming trend.


All of these things confirm that the planet is currently warming (more at Skeptical Science). But is it unprecedented, I hear the pedants squeal? Well, no. But over the earth’s history, sudden rapid global warming is often associated with major extinction events — and you’d think that was something we might try to avoid.

2. That the greenhouse effect is powerful enough to endanger the environment.

The greenhouse effect is powerful enough to deliver the environment we live in, by retaining enough heat to lift surface temperature by about 33ºK. In other words, without greenhouse gases, the earth’s surface would average about -17ºC. Increasing that already large warming by adding more greenhouse gases can certainly “endanger the environment” as past warmings show (see above, and here).

3. A causal link between human activities and dangerously high global temperatures.

Human Fingerprints480

There’s no doubt that the current warming is being caused by increasing atmospheric CO2 levels, a direct result of human activity (burning fossil fuels, deforestation etc). As this Skeptical Science graphic shows, this view is supported by (at least) 10 lines of supporting evidence. But will the warming be “dangerously high”, the pedants pipe up? See the information on past warming events linked above, and then ponder on the Eemian, the last interglacial, when CO2 at 300ppm delivered sea levels 6 m higher than today and global temperatures 1ºC higher than present. Or what about the Pliocene, when CO2 levels equivalent to today delivered sea levels 25 m higher, and an Arctic as much as 13ºC warmer?

4. That climate models have a high level of skill in predicting the climate.

We don’t need climate models to understand where we may be heading, as the paleoclimate evidence demonstrates, but they are extremely useful tools for trying to work out what might happen. If we had two planets to play with, we could leave one with low CO2, and continue burning fossil fuels on this one to see what happens. Unfortunately that’s a luxury we don’t have. But do climate models have a high level of skill? They do pretty well by a wide variety of measures, but do you really want to risk waiting a decade or two to see how current models perform? Doesn’t strike me as wise, given 1. and 2. above…

5. A causal link between atmospheric levels of carbon dioxide and global temperatures.

This is Treadgold’s blockhead moment. The “causal link” is basic physics, understood for 150 years (Fourier, Tyndall). More CO2 means more heat retained in the system, or the greenhouse effect he seems to admit exists wouldn’t. That’s about as clear a link as you can get.

6. A causal link between global warming and the gentle rise in sea level.

More basic physics that seems to have eluded Treadgold. If you warm up water, like most things it expands. Thermal expansion has been (until recently) the single biggest contributor to sea level rise and will continue to play a big part until the oceans reach thermal equilibrium — and that will take hundreds of years, even if we do manage to end our binge on fossil carbon.

Treadgold claims to be “looking for evidence”, but clearly hasn’t been looking hard — or perhaps at all. There is an obvious irony in his using a paper he hasn’t read to demand evidence he can’t be bothered to uncover or understand, but — and much worse — it’s a continuation of a long-term pattern of behaviour, as Hot Topic readers with long memories may recall.

When offered evidence, Treadgold adopts the Nelson defence. He can’t see it, so it doesn’t exist. But he’s been playing this game for so long that his demands and protestations cut no ice. Being blind to the evidence is not scepticism, it’s denial, and that’s an estate Treadgold has occupied for a very long time.

[Robert Palmer]

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