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Andy Skuce

Andy Skuce is a recently-retired geophysical consultant living in British Columbia. He has a BSc in geology from Sheffield University and an MSc in geophysics from the  University of Leeds. His work experience includes a period at the British Geological Survey in Edinburgh and work for a variety of oil companies based in Calgary, Vienna and Quito. Since 2005, he worked as an independent consultant. Andy has published a handful of papers over the years in tectonics and structural geology that can be viewed here. He described how his views on climate change evolved in this blog post.

Follow Andy on Twitter @andyskuce and on his blog Critical Angle


Google Scholar profile.


Blog posts by Andy Skuce

The Carbon Bubble - Unburnable Fossil Fuels - Seminar and Discussion

Posted on 26 March 2014 by Andy Skuce &

The British Columbia Sustainable Energy Association (BCSEA) organizes a series of free seminars on climate change and sustainability issues. BCSEA was founded by Guy Dauncey. On February 11th, 2014 BCSEA held a webinar on the recent work done by the Carbon Tracker Initative. Guy has written a detailed summary of their recent work on the BCSEA webpage.

The seminar starts at 8:30 minutes and a very good Q&A session begins at 39 minutes. The slides that accompany the seminar can be downloaded here.

The presenter is Mark Campanale, the founder and executive director of the Carbon Tracker Initiative.



The Editor-in-Chief of Science Magazine is wrong to endorse Keystone XL

Posted on 3 March 2014 by Andy Skuce &

An editorial by the Editor-in-Chief of Science Magazine, Marcia McNutt, conditionally endorses the Keystone XL (KXL) pipeline. Her argument is that:

  • the absence of the pipeline has not stopped oil sands development and the building of the pipeline will not accelerate oil sands development;
  • President Obama can extract concessions from the Canadians to reduce emissions and upgrade the bitumen in Canada.

Both of these arguments are wrong; let me explain why.

Pipelines promote production

The Mildred Lake oil-sands plant in Alberta. Note the tailings pond behind the huge yellow piles of sulphur, a by-product of bitumen upgrading. The sulphur may come in handy later for use in solar radiation management. Photo Wikipedia

It should be obvious from the intense lobbying and advertising efforts of Canada's Federal Government, the Alberta Provincial Government and the Canadian Association of Petroleum Producers that the KXL pipeline is a very big deal indeed for those with a stake in expanding oil sands production. Federal Natural Resources Minister Joe Oliver accuses his domestic political opponents of putting tens of thousands of Canadian jobs at risk by urging Washington not to approve KXL. At least on this matter, he is right; without new transportation infrastructure, the massive investments that result in growth in oil sands production will be postponed or cancelled. But that's the message provided to a Canadian audience.



Talking Trash on Emissions

Posted on 7 January 2014 by jg & Andy Skuce

While attending the recent AGU conference, some of us were struck by a statistic presented by Professor Richard Alley: On average, a person's contribution of carbon dioxide waste to the atmosphere is forty times greater than their production of solid trash to landfills when measured as mass.

It can be difficult to grasp the huge quantities of CO2 that we emit. It’s an invisible gas with no odour and we are not used to thinking about amounts of gas in terms of mass. But we do have a good sense of how much solid waste we throw out, since we all have to lug our garbage to the curb. If we had to do the same with our greenhouse gases, instead of one can a week, we would have to haul forty.

Every time we see a garbage truck, let’s imagine forty others following it, all taking our carbon dioxide to a dump site. When we hear of municipal politicians struggling to find new landfill sites, imagine the problems we would have finding forty subterranean landfill sites if we ever tried to dispose of our CO2 in the subsurface instead of dumping it freely into the air.



Hans Rosling: 200 300 years of global change

Posted on 31 October 2013 by Andy Skuce &

We think we have done more than we have done and we haven't understood how much we have to do. Hans Rosling

Hans Rosling is a Swedish medical doctor and statistician who is determined (in his own words) "to fight devastating ignorance with a fact-based worldview that everyone can understand".

Here is a video of him giving a talk on September 28th, 2013 at a public forum that introduced the latest IPCC report. The meeting was hosted by the International Geosphere-Biosphere Programme in Stockholm.

During the talk he asks a couple of questions, one on how many more children there will be in the year 2100 compared to today and another on what percentage of world energy is produced by solar and wind. I was in the minority that got the first one correct, but only because I had already seen one of Rosling's earlier talks. On the second question, I was among the majority that got the answer wrong. How will you do?



Update on BC’s Effective and Popular Carbon Tax

Posted on 25 July 2013 by Andy Skuce &

Stewart Elgie and Jessica McClay of the University of Ottawa have a peer-reviewed article in press in a special issue of the journal Canadian Public Policy. The article is summarized in the report BC’s Carbon Tax shift after five years: Results. An environmental (and economic) success story. The report can be downloaded here and is summarized here.
The results are similar to a previous report that I wrote about in the article BC’s revenue-neutral carbon tax experiment, four years on: It’s working, but updated, with one more year of data.  The new data show that the carbon tax is working even better than reported previously.
Fuel consumption per capita has fallen in BC by nearly 19% relative to the rest of Canada; these are just the fuels that are subject to the carbon tax. (Note that the years in these tables begin on July 1, in the previous report, they were calendar years, so the numbers do not match exactly.)
Note that all fuel use for the various types of fuel fell faster per-capita in BC than for the rest of Canada. The one exception is aviation fuel, which is mostly exempt from the carbon tax and showed no differential fall in use in BC.



BC’s revenue-neutral carbon tax experiment, four years on: It’s working

Posted on 27 June 2013 by Andy Skuce &

Carbon taxes get the market to tell the environmental truth. Stewart Elgie

British Columbia is the only jurisdiction in North America with a revenue-neutral carbon tax that taxes greenhouse gas emissions (GHGs) from individuals and businesses alike. The tax was announced in February 2008 and was implemented in July 2008 at a rate of $10 per tonne of CO2, rising in $5 annual increments to the current price of $30/tonne. It is designed as a revenue-neutral tax, meaning that all carbon-tax proceeds collected by the government are returned in the form of income tax cuts and rebates. The tax is now raising over C$1.2 Billion per year, about C$270 per person, and the proceeds are distributed roughly equally between personal and business tax reductions.

People on low incomes get a per-person payment of C$115 annually, and homeowners who live outside the SW of the province can get additional rebates of up to $200 annually. The personal income tax reductions are focussed on earnings below C$75,000. The allocation of carbon tax revenue has to be reported in the annual budget.



A Miss by Myles: Why Professor Allen is wrong to think carbon capture and storage will solve the climate crisis

Posted on 11 June 2013 by Andy Skuce &

(This post was co-written by rustneversleeps and Andy Skuce).

A recent opinion piece in the British newspaper Mail on Sunday by University of Oxford climate scientist Myles Allen argues that the best way to combat climate change is to pass laws requiring fossil fuel producers to capture and sequester a rising proportion of the carbon dioxide emissions that the fuels produce. We argue here that such a policy, with its emphasis on carbon sequestration, would not be successful in achieving the carbon emission reductions that Allen himself advocates—for a variety of political, economic, technological and logistical reasons. A more recent article by Allen in The Guardian covers the same ground.

Nevertheless, Allen’s prescription does succeed in focussing the mind on the scale of the problem that we face in mitigating climate change.


This is a very long post, so here is a clickable summary.

A good starting framework, then... Allen's diagnosis is clear and his framing of targets in terms of cumulative emissions is unabiguous. But his prescription is flawed.

Politics There is no reason to assume a fixed emissions cap schedule would be easier to sell to the public than a carbon tax. Caps would produce greater certainty of longer-term emission reductions at the cost of uncertain economic consequences.

Economics (i): Efficiency Imposing emissions caps without allowing trading through brokers would be very inefficient. It is not clear whether Allen supports or opposes trading.

Economics (ii) Innovation by fiat? Prescribing one form of technology as the principle solution is risky. Nobody can predict how technology will evolve and what problems may emerge in future.

Economics (iii): The information conveyed by prices The cost of one technology should not be used as a basis for carbon pricing. There is a wide range of mitigation options, with highly variable prices, all with variable and uncertain potential to contribute to solutions. Experience in British Columbia shows that even a modest carbon tax can reduce emissions significantly without harming the economy.

Scaling it up to climate relevance Even promoters of aggressive deployment of carbon capture and storage (CCS) do not envision it as more than a partial contribution to mitigating climate change by 2050.

Timing and feasibility The mass of the CO2 to be sequestered is about double the mass of the fossil fuels themselves. To develop a new industry, from scratch, to capture, transport and dispose of these quantities will involve vast amounts of capital and many decades, even if it were technically possible.

Hazards The magnitude of the CO2 to be sequestered in the subsurface is such that environmental risks from leakage, aquifer contamination and induced earthquakes are likely to be much larger than those from the already contentious shale gas industry. Getting  public licence for CCS projects in inhabited areas is likely to be very difficult and time consuming.

Summing up The climate crisis is so vast that we need to throw everything we have at it. Claiming that any single technology will solve the problem can lead to complacency that the fix is simple. It isn't.



Global Warming: Not Reversible, But Stoppable

Posted on 19 April 2013 by Andy Skuce &

Let's start with two skill-testing questions:

1. If we stop greenhouse gas emissions, won't the climate naturally go back to the way it was before?
2. Isn't there "warming in the pipeline" that will continue to heat up the planet no matter what we do?

The correct answer to both questions is "no".

Global warming is not reversible but it is stoppable.

Many people incorrectly assume that once we stop making greenhouse gas emissions, the CO2 will be drawn out of the air, the old equilibrium will be re-established and the climate of the planet will go back to the way it used to be; just like the way the acid rain problem was solved once scrubbers were put on smoke stacks, or the way lead pollution disappeared once we changed to unleaded gasoline. This misinterpretation can lead to complacency about the need to act now. In fact, global warming is, on human timescales, here forever. The truth is that the damage we have done—and continue to do—to the climate system cannot be undone.

The second question reveals a different kind of misunderstanding: many mistakenly believe that the climate system is going to send more warming our way no matter what we choose to do. Taken to an extreme, that viewpoint can lead to a fatalistic approach, in which efforts to mitigate climate change by cutting emissions are seen as futile: we should instead begin planning for adaptation or, worse, start deliberately intervening through geoengineering. But this is wrong. The inertia is not in the physics of the climate system, but rather in the human economy.

This is explained in a recent paper in Science Magazine (2013, paywalled but freely accessible here, scroll down to "Publications, 2013") by Damon Matthews and Susan Solomon: Irreversible Does Not Mean Unavoidable

Since the Industrial Revolution, CO2 from our burning of fossil fuels has been building up in the atmosphere. The concentration of CO2 is now approaching 400 parts per million (ppm), up from 280 ppm prior to 1800. If we were to stop all emissions immediately, the CO2 concentration would also start to decline immediately, with some of the gas continuing to be absorbed into the oceans and smaller amounts being taken up by carbon sinks on land. According to the models of the carbon cycle, the level of CO2 (the red line in Figure 1A) would have dropped to about 340 ppm by 2300, approximately the same level as it was in 1980. In the next 300 years, therefore, nature will have recouped the last 30 years of our emissions.


Figure 1 CO2 concentrations (A); CO2 emissions (B) ; and temperature change (C). There are two scenarios: zero emissions after 2010 (red) and reduced emissions producing constant concentrations (blue). From a presentation by Damon Matthews, via Serendipity



Living in Denial in Canada

Posted on 1 March 2013 by Andy Skuce &

In an earlier article, I reviewed sociologist Kari Norgaard’s book Living in Denial: Climate Change, Emotions and Everyday Life in which she records the response of rural Norwegians to climate change. She analyzes the contradictory feelings Norwegians experience in reconciling their life in a wealthy country that is at once a major producer and consumer of fossil fuels and, at the same time, has a reputation of being a world leader in its concern for the environment, human development, and international peace.

Canada shares many characteristics with Norway; they are both northern lands that distinguish themselves from larger southern neighbours by their cold climates and progressive social policies. Both countries are wealthy, thanks in large part to exploitation of their abundant natural resources. In this article, I will try to look at Canada through the same lens that Norgaard used in her study of Norway. Because I am not aware of any kind of field study in Canada similar to the kind that Norgaard did in Norway, I will rely on how socially organised denial expresses itself through Canadian political discourse on climate change.

According to polling by Environics a majority of Canadians in 2012 (57%) are convinced that the science is conclusive that global warming is happening and is caused mostly by humans. Only 12% believe that the science of global warming is not yet conclusive. Majorities are also in favour of carbon taxes in most areas of the country. It is also worth noting that none of Canada's political leaders take a denialist stance on climate change. In a speech in Berlin in 2007, Prime Minister Stephen Harper affirmed his government's commitment to "...the fight against climate change, [is] perhaps the biggest threat to confront the future of humanity today." Later in the same speech he acknowledged; "But frankly, up to now, our country has been engaged in a lot of "talking the talk" but not "walking the walk" when it has come to greenhouse gases".  It is that disengagement between thought and action that is at the heart of implicatory denial.



Living in Denial in Norway

Posted on 28 February 2013 by Andy Skuce &

Norway is one of the most wealthy countries on Earth, with the very highest levels of human development, it is among the most generous donors of foreign aid and, for a country of its size, makes enormous efforts to promote peace. A former Prime Minister of Norway, Gro Harlem Brundtland, has done as much as anyone to promote global sustainable development and public health. The world would surely be a better place if everyone on Earth behaved like Norwegians.

Norway, on the other hand, is also the largest per capita oil producer outside of the Middle East, producing more oil per capita even than Saudi Arabia, about 150 barrels per person per year from its fields in the North Sea. Five million Norwegians also emit 11 tonnes of greenhouse gasses each per year, a little higher than the European mean and twice as high as the global average. The world would surely become uninhabitable if everyone on Earth behaved like Norwegians.

Every other country and community has its own contradictions, of course.  Despite the fact that the majority of Americans and Canadians believe that climate change is a concern, no progress has been made at national levels to introduce the carbon pricing policies that institutions like the International Energy Agency and the World Bank believe to be an essential step in reducing emissions. And neither, generally speaking, have many people voluntarily made the lifestyle changes—like giving up non-essential air travel—that are necessary if we are to achieve a low-carbon future. Concern about climate change is broad, but often shallow. We mostly carry on in our daily lives as if climate change was not happening.

Among the majority of us who recognize the threat of climate change, there’s clearly a disconnection between thought and action. We know that things have to change, but we have a lot of reasons why change is not up to us, or why now is not the time, or why our inaction is somebody else’s fault. The exact reasons will vary from person to person and from country to country, but they all serve the same purpose, to help ease the anxiety and helplessness we all feel, while doing nothing substantial to alleviate the problem. Kari Norgaard, an American and a sociology professor at the University of Oregon, calls these responses “socially organized denial” and has written several articles on the subject (available here) and a book, Living in Denial: Climate Change, Emotions and Everyday Life (MIT Press, 2011) based on sociological field work that she conducted in rural Norway. 



Subcap Methane Feedbacks. Part 4: Speculations

Posted on 23 January 2013 by Andy Skuce &

Previous articles in this series have reviewed recent research on methane sources from beneath permafrost and ice sheets. Part 1 looked at subcap fossil methane seeps in Alaska; Part 2 provided a perspective for the size of these seeps in relation to other natural and human sources; and Part 3 looked at potential methane sources resulting from the withdrawal of glaciers and ice sheet. In this final section, I will try to make estimates of what subcap methane emissions may mean for future climate change; more as a speculative basis for discussion rather than an authoritative prediction. Firstly, though, I will argue for a role for subcap methane emissions on the East Siberian Arctic Shelf (ESAS). 

Subcap methane on the East Siberian Arctic Shelf?

 In their 2005 paper Indications for an active petroleum system in the Laptev Sea, NE SiberiaCramer and Franke (CF5) presented seismic data and analyses of gas samples that showed that there are deep sedimentary basins in this part of the Arctic Ocean that are actively seeping fossil methane. They conclude: 

• Seepages of thermal gas from the sedimentary column into the sea water were detected at two locations at the northern margin of the shelf, indicating the rather uneven distribution of petroleum seeps in the Laptev Sea.

• This uneven distribution probably reflects the occurrence of sub-sea permafrost. The south and the centre of the Laptev Sea is underlain by a permafrost layer several hundreds of metres thick, generally preventing petroleum from seeping into the water. In the north, the permafrost is absent, allowing the migration of hydrocarbons into the water column.


Figure 1. Seismic reflection section from the Laptev Sea (location shown by green star on the map). The interpretation shows faulted and tilted sedimentary rocks, a weak reflection at ~0.5 seconds that may mark the base of the permafrost, and indications of what may be gas migration chimneys. The section comes from Cramer and Franke, 2005 (their Figure 3); and the map is adapted slightly from Franke and Hinz, 2009, (their Figure 3). The map's contours and colours represent two-way time to basement rocks; this is the time taken by an acoustic wave to get from the surface to a reflector and back, and is proportional to depth for a given velocity.



Subcap Methane Feedbacks. Part 3: Methane from beneath the ice

Posted on 21 December 2012 by Andy Skuce &

The previous two parts (one here and two here) of this series examined the evidence for seeps of geological methane through the cap provided by permafrost and looked at estimates of the magnitude of such seeps in relation to other sources of atmospheric methane. In this section, we will look at the emerging evidence for actual and potential methane releases related to glaciers and ice sheets. The sources of this methane are varied: fossil methane released through reactivated fractures; organic matter once buried and now exhumed; and possible methane hydrates lurking under the big ice sheets.

 The Southern Alaska subcap seeps

There is a cluster of subcap seeps in southern Alaska in areas where there is only sporadic permafrost. This is an area that was covered with a major ice sheet during the last ice age. Today, it is a region where nearby modern glaciers are rapidly receding. These seeps are underlain by a sedimentary basin that contains coal beds and an active petroleum system.  Katey Walter Anthony and her colleagues (WA12) showed that major seeps in this part of Alaska are within 10km of the nearest glacier and close to large, previously mapped faults. Seeps of gas and oil are common above active petroleum systems and are often used in hydrocarbon exploration for highlighting attractive areas to explore. 

Figure 1. Map and satellite image showing the location of the Eyak Lake and Katalla Bay seeps in South Central Alaska. Source: Google Maps.



Subcap Methane Feedbacks. Part 2: Quantifying fossil methane seepage in Alaska and the Arctic

Posted on 8 December 2012 by Andy Skuce &

The previous article in this series looked at the recent discovery of significant releases of fossil methane through the thawing permafrost in Alaska. In this second instalment we will look at the potential of the rest of the Arctic to produce subcap methane, and will compare the size of these seeps to other global methane-producing mechanisms. 

Pan-Arctic extrapolation

Much of the Arctic is underlain by sedimentary basins (Figure 1) that have potential to generate fossil methane gas. Onshore areas that are both gas- and permafrost-prone include Northern Alaska, Canada (Mackenzie Delta and Arctic Islands), Svalbard and Western Siberia.

In the Mackenzie Delta of Arctic Canada, for example, large gas seeps have been observed in small lakes in the delta close to large discovered gas fields. These seeps have isotope and chemistry signatures similar to local deep gas fields and to the Mallik gas hydrate accumulation, which contain fossil, thermogenic methane. Permafrost is up to 500 metres thick in this area but oil industry seismic reflection data reveal the presence of what may be gas conduits through the permafrost, from the deeper fossil gas accumulations (personal communication from the Geological Survey of Canada). It seems highly probable that similar situations will exist elsewhere in the Arctic, especially, in Siberia. Cramer and Franke (2006) show examples of gas conduits, some of them through permafrost, in the Laptev Sea (see also part four of this series, for more discussion).





Subcap Methane Feedbacks, Part 1: Fossil methane seepage in Alaska

Posted on 28 November 2012 by Andy Skuce &

As permafrost thaws, methane is released as the vegetable matter in the soils decomposes. This methane bubbles to the surface in lakes and ponds and accumulates under the ice in the wintertime. New research has shown that the most vigorous methane seeps in Alaska are fed also by methane emitted by thermal decomposition of organic matter in deeper and much older sediments. Continuous permafrost acts as a top seal to this fossil methane, preventing it from reaching the surface and, as global warming melts and perforates this cap, we can expect the pent-up gas to be released more quickly. This source of methane, released from traps under the permafrost, is a potential third source of methane feedback in the Arctic, in addition to permafrost soils and methane hydrates. 

One of the big unknowns in forecasting the course of climate change is anticipating how the Earth’s carbon cycle will respond to the coming man-made increase in temperature. The carbon cycle describes the many processes through which carbon flows between stocks of the element in the atmosphere, the oceans, the rocks, the soil, and in plants and animals. The Earth's most sensitive place to changes in the carbon cycle is the Arctic. Not only is this the region with the fastest changing climate and some of the largest stores of carbon, but even small temperature changes there will produce large effects as ice and soils that have been frozen for thousands of years begin to thaw.

Figure 1. Schematic diagram of the many ways that greenhouse gasses can be released as a warming climate in the Arctic leads to collapse of the cryosphere. Most of these will be covered in this series of articles. Graphic by John Garrett.



Book review: Rising Sea Levels: An Introduction to Cause and Impact by Hunt Janin and Scott Mandia

Posted on 7 November 2012 by Andy Skuce &

"My other piece of advice, Copperfield," said Mr. Micawber, "you know. Sea-wall height twenty feet, maximum storm surge nineteen feet six inches, result happiness. Sea-wall height twenty feet, maximum storm surge twenty feet six inches, result misery. The blossom is blighted, the leaf is withered, the god of day goes down upon the dreary scene, and — and in short you are for ever flooded."

With apologies to Charles Dickens for the paraphrasing.

Wilkins Micawber knew from his own experience that a small but persistent excess of spending over income eventually leads to disaster; in his case, debtors' prison. Similarly, a small and sustained rise in sea level—once it is combined with unusual weather and high tides—can push ocean waters, quite literally, over a tipping point; as the people in New York and New Jersey, in the wake of Hurricane Sandy, have just witnessed.

Michael Mann has remarked that sea levels around New York are about a foot higher than they were a century ago.  One foot may seem small compared to everyday waves and tides, but as we have seen, this sustained change to the baseline can make all the difference between a bad storm surge and a disastrous one. And, of course, the effects of an extra foot of seawater, compared to no water at all, is a very big deal indeed when that water is lying on a farmer’s field, your living room floor or an airport runway. The best estimates of future sea levels predict several additional feet of sea-level rise in New York over the next few decades: the recent flooding in the US north-east is a just a taste of things to come.

New York's La Guardia Airport, October 29, 2012. Source 



Big Oil and the Demise of Crude Climate Change Denial

Posted on 26 October 2012 by Andy Skuce &

From 1989 to 2002, several large US companies, including the oil companies Exxon and the US subsidiaries of Shell and BP, sponsored a lobbying organisation called the Global Climate Coalition (GCC), to counter the strengthening consensus that human carbon dioxide emissions posed a serious threat to the Earth’s climate. As has been documented by Hoggan and Littlemore and Oreskes and Conway, the GCC and its fellow travellers took a leaf out of the tobacco industry’s playbook and attempted to counter the message of peer-reviewed science by deliberately sowing doubt through emphasizing uncertainties and unknowns. The climate scientist Benjamin Santer accused the GCC of deliberately suppressing scientific information that supported the IPCC consensus.

In the late 1990s, the oil industry’s response to the climate question started to change, when BP and Shell decided to abandon the GCC and instead embrace the scientific consensus. According to the account by ex-BP geologist Bryan Lovell in his book Challenged by Carbon, BP’s change of mind was triggered by a memo sent in 1997, by then Chief Geologist David Jenkins, to the managing directors of the company that maintained that it was time for BP to be prepared to respond to the climate crisis in a constructive manner. Jenkins’ argument—which is detailed in Lovell’s book—was framed to appeal to BP’s corporate self-interest; pointing to future opportunities to employ the company’s subsurface expertise for carbon sequestration, and also to shift the climate mitigation focus away from the oil industry onto the coal-fired power sector. (Experienced corporate insiders know that appeals to ethics gain less traction than appeals to self-interest.) Jenkins’ recommendation was well received and over the following years the company changed its name to “BP plc”, changed to a new sunflower logo (at a cost of $211 million) and adopted the slogan “Beyond Petroleum”.  In 2002, the chief executive of BP, Lord John Browne gave a speech in which he said:



Modelling the permafrost carbon feedback

Posted on 4 October 2012 by Andy Skuce &

A recent modelling experiment shows that climate change feedbacks from thawing permafrost are likely to increase global temperatures by one-quarter to a full degree Celsius by the end of this century. This extra warming will be in addition to the increase in temperature caused directly by emissions from fossil fuels.  Even in the unlikely event that we were to stop all emissions in the near future, this permafrost climate feedback would likely continue as a self-sustaining process, cancelling out any future natural draw-down in atmospheric carbon dioxide levels by the oceans or vegetation. Avoiding dangerous climate change by reducing fossil-fuel emissions becomes more difficult once permafrost emissions are properly considered. 

Many papers have looked at the expected contribution of thawing permafrost to climate change. For example, Schaeffer et al. (2011) and Schuur and Abbott (2011) have both published estimates of the effect that the thawing and decomposition of organic matter in Arctic soils will have on future climates. Aspects that these studies neglected were the feedback that the permafrost carbon release would have on causing further permafrost degradation and the varying response that the carbon release would have on the climate in different emission scenarios and for a range of climate sensitivities.

To explore this matter further, a recent paper in Nature Geoscience (paywalled) by Andrew MacDougall, Christopher Avis and Andrew Weaver couples together climate and carbon-cycle models. Using the University of Victoria Earth System Climate Model adapted to include a permafrost response module, the researchers calculated the contribution to climate warming of thawing permafrost over a range of varying parameters.

Figure 1. Taken from MacDougall et al. (2012) showing the additional warming induced by permafrost thawing for four diagnosed emissions pathways (DEP, see text below for explanation). The coloured areas are the ranges of likely additional temperature ranges and the black lines show the median responses. The uncertainty within each DEP run results from uncertainties in the density of carbon in the permafrost and the climate sensitivity (the temperature effect of a given rise in carbon dioxide concentration in the air). Figure with original caption here.



Rally for Canadian Science in Victoria, BC

Posted on 28 September 2012 by Andy Skuce &

Skeptical Science readers may already be familiar with the dismal performance of the Canadian Federal Government on climate change. The Canadian contributors to Skeptical Science expressed our concerns about the erosion of our country's science for political ends in a blog post here in March of this year: PMO Pest Control: Scientists. We have also run a number of posts on the rapid development of the oil sands, for example: Tar Sands Oil - An Environmental Disaster  and; Alberta’s bitumen sands: “negligible” climate effects, or the “biggest carbon bomb on the planet”?. This summer, Canadian scientists have been taking their protest to the street and last week there was a rally in Victoria, British Columbia.

In an event organized by Ken Wu, Canadian scientists and concerned citizens rallied outside a Federal Government building in Victoria on Friday September 14th in protest against the Federal government's policies that have been cutting science budgets, shutting down vital projects (e.g., PEARL, ELA) and muzzling government scientists. People jammed the sidewalks in downtown Victoria to hear speeches by climate scientist Andrew Weaver, Canadian Green Party leader Elizabeth May and "Dr X", a marine biologist working for the Department of Fisheries and Oceans who appeared in disguise for fear of losing his job.

Green Party Leader Elizabeth May and marine biologist "Dr X" (hiding behind a false moustache) speaking at the Victoria rally. (All photographs by the author).



The Continuing Denial of the Scientific Consensus on Climate Change

Posted on 16 August 2012 by Andy Skuce &

One of the perennial Skeptical Science top ten climate myths is “There is no consensus” (currently at number 4 in popularity). Consensus means the elements of knowledge that research scientists tend not to discuss or actively investigate any more. Consensus is the stuff that fills textbooks and is the established knowledge that teachers try to cram into high school and undergraduate students’ heads. It doesn’t mean an impregnable bastion of knowledge—there are many well-known examples of consensus-changing revolutions in the history of science—and even school textbooks have to get updated every now and then.

Consensus doesn’t mean unanimity, either. There is always a minority of gadfly scientists who decide to take on the consensus: scientists who challenge the biotic origin of oil or medical researchers who doubt HIV as a cause of AIDS. In such cases, the contrarian scientists don’t typically deny the existence of the consensus; they just think that the content of it is wrong.

Nor does consensus mean that everybody is happy with every single element that others believe to be settled. Consensus in any field has a hard core but fuzzy edges.

There have been a few studies that have attempted to measure the degree of scientific consensus on climate change. Naomi Oreskes in 2004; Doran and Zimmerman in 2009; Anderegg et al in 2010; and the Vision Prize in 2012. All found evidence for a very strong consensus among climate scientists for the idea that recent climate change can mostly be attributed to human activities (see the recently updated rebuttal written by Dana Nuccitelli for details).  Most of the world’s scientific academies have made explicit affirmations of the consensus on climate, along with numerous scientific associations.  The IPCC reports are a major effort to define the extent of general agreement and to identify the areas of remaining uncertainty.



Scientific literacy and polarization on climate change

Posted on 15 June 2012 by Andy Skuce &

It is not news that people are polarized over their assessment of the risks posed by climate change. But is it true that the most polarized people are those who are more scientifically literate? Counter-intuitive though it may seem, the answer is: Yes, it is. This is the result of a recent article by Dan Kahan and six colleagues in Nature Climate Change (henceforth, the Kahan Study).  This study has received a lot of attention, with blog articles, for example in The Economist, Mother Jones and by David Roberts at Grist.

At Skeptical Science, our goal is to debunk false arguments and explain the science behind climate change. In the light of this peer-reviewed research, we have to ask ourselves: if we are striving to increase scientific literacy, won’t we just be making the polarization that exists around climate change worse?  We will come back to that question at the end of this piece, but first, we’ll look in some detail at the Kahan Study itself.

Testing two hypotheses

Kahan et al identified two contrasting hypotheses that seek to explain the polarization in the public’s appreciation of the risks posed by climate change. (Note that the Kahan Study did not look at the public’s perception of the truth or reliability of climate science but, rather, the public’s assessment of the risks that climate change poses.) These hypotheses are:



Alberta’s bitumen sands: “negligible” climate effects, or the “biggest carbon bomb on the planet”?

Posted on 28 April 2012 by Andy Skuce &

*The climate effects of bitumen development are significant once viewed in the perspective of probable emissions over the rest of this century.

*The climate impact of coal consumption is greater than that of bitumen, particularly when non-mineable coal is considered.

*Accelerated expansion of bitumen extraction will make climate mitigation efforts much more difficult.

*Because of its high carbon emissions and high extraction costs, further bitumen development would not be viable if stringent global emissions policies were adopted.

The accelerating development of the huge bitumen* resources in Alberta has produced a great deal of recent public interest, due mainly to controversial proposals to build two big new pipelines: one connecting Alberta to the US Gulf Coast (Keystone XL) and the other to the Pacific coast of British Columbia (Northern Gateway). Much of the discussion has revolved around the dangers of leaks from the pipelines themselves and, in the case of the Northern Gateway proposal, the risks of tanker accidents in the narrow fjords of BC’s pristine northern coast and the turbulent Hecate Strait. Recent publications have also drawn attention to the massive damage to peatlands caused by bitumen mines and to the pollution of the Athabasca River. However, for the purposes of this article, I will focus only on the effect of bitumen sand exploitation on climate change.

The general topic was discussed previously at Skeptical Science in Tar Sands Impact on Climate Change.



DeConto et al: Thawing permafrost drove the PETM extreme heat event

Posted on 11 April 2012 by Andy Skuce &

Sudden spikes in global temperatures that occurred 50-55 million years ago were caused by thawing of permafrost in Antarctica and northern high latitudes, according to recent research. The trigger for this sudden destabilization was a variation in orbital configurations that resulted in warmer polar summers. This model also provides an analogue for the releases of carbon from modern permafrost caused by current man-made global warming. Modern permafrost volumes are smaller than the estimates for those of 55 million years ago, but will nevertheless amplify the climatic effect of fossil fuel consumption and will provide continuing warming feedbacks for centuries after human emissions cease.

The Paleocene-Eocene hyperthermal events

The Paleocene-Eocene Thermal Maximum (PETM) is an extreme global warming event or hyperthermal that occurred 55.5 million years ago when a sudden “burp” of a huge quantity of carbon was emitted into the atmosphere, causing global temperatures to rise by five degrees Celsius and the oceans to become more acid. Because of the rapidity of the carbon burp, the event has often been considered an analogue of what might happen as humans release a comparable slug of CO2 into the atmosphere. The PETM was discovered in 1991 by Kennett and Stott and since then over 400 scientific papers have been written on the subject. There is a good review of the PETM by McInerney and Wing (2011). See also Rob Painting's post CO2 Currently Rising Faster Than The PETM Extinction Event and the comments in the discussion that follows it.

There are uncertainties about where the carbon in the PETM came from and what triggered its sudden release. One of the leading hypotheses (e.g. Dickens, 2003) has been that the carbon was released from methane hydrates, ice-like accumulations of methane and water that were present in sediments below the deep ocean floor. According to this hypothesis, the hydrates became destabilized as sea water temperatures gradually rose. The release of the hydrates into the atmosphere increased the greenhouse effect, which led to more hydrate destabilization. See also Lunt et al (2011).



Eocene Park: our experiment to recreate the atmosphere of an ancient hothouse climate

Posted on 6 April 2012 by Andy Skuce &

Fifty million years ago, during the Eocene Epoch , the world had a very different climate, with temperatures much higher than today's, especially at the poles. This hothouse climate was caused mainly by CO2 levels that were twice as high, or more, than now. On our current emissions trajectory, we could recreate the chemistry of the hothouse atmosphere before the end of this century, with potentially drastic consequences for our climate.

The Hothouse

Imagine a world where crocodiles swim in an Arctic ocean among blooms of freshwater ferns, and where palm trees grow in Alaska and the high valleys of the Rocky Mountains. In this world, a great forest covers the continent of Antarctica and there are no large ice sheets. Sea levels are 50 metres or more higher than today’s. This world was the hothouse Earth in the time of the Eocene Epoch, 56 to 34 million years ago.  Estimates of the concentration of carbon dioxide in the Eocene air show that they were two times or more higher than today. Such a CO2-rich atmosphere has not been seen since the Eocene, but it is quite possible that we will create an atmosphere like it again soon, perhaps later in this century.

The frost-intolerant palm trees that grew in Montana show that that Eocene winter temperatures, even at high elevations in mid-latitude continental interiors, must have stayed above zero most of the time.  The variation of average temperature with latitude—the poles in the Eocene were 30°C warmer than today but the tropics were only a few degrees warmer—is another characteristic of the Eocene sauna. Trying to model this climate presents a challenge known as The Equable Climate Problem.  Higher levels correctly predict a much warmer world but there are some mismatches in the regional predictions. In essence, the difficulty is that if the boundary conditions in the climate models are set to values that produce mild winters in continental interiors and high latitudes, the modelled tropics turn out to be hotter than our best proxies show. However, the discovery of a one-ton fossil snake in Colombia suggests that Eocene and Paleocene tropical temperatures may have been underestimated.  Many innovative solutions (see page 243 of Huber and Caballero (2011) for a referenced list) have been proposed to resolve the Equable Climate problem but there is, as yet, no consensus on a resolution.

The Eocene hothouse and the elevated CO2 levels came to an end in the Oligocene Epoch and the Earth’s climate changed into its current icehouse state.



Changing Climates, Changing Minds: The Great Stink of London

Posted on 11 March 2012 by Andy Skuce &

Effective action for solving Victorian London's sewage crisis was put off for decades, due to chaotic governance, concerns about financing, the interference of vested interests and the complacency and inertia of central government. Once the ill effects appeared underneath the politicians’ noses, a lasting solution was quickly deployed. The modern challenge of finding the political will to deal with climate change is analogous, although there are additional factors that make fixing the climate problem much more difficult.

Richard Alley, in his recent book Earth, the Operator’s Manual, devotes part of Chapter 16, Toilets and the Smart Grid, to a comparison between the infrastructure challenges caused by the sewage problems of Victorian Edinburgh and London and the obstacles we face today in acting to solve the climate crisis. In this essay, I cover some of the same ground as Alley, but use as a main reference the book, The Great Stink of London, Sir Joseph Bazalgette and the Cleansing of the Victorian Capital (GSOL), written by Stephen Halliday in 1999. Here's a link to a pdf of  pages 58-76 of the book.

London’s sanitation before the Victorians

In medieval London, human waste was deposited into household cesspools, some of which spilled into streams and ditches. By the mid-fourteenth century, pollution from sewage was already becoming a serious problem, and at the end of that century—during the time that Richard Whittington was Lord Mayor of London—laws were proclaimed that said:



Changing Climates, Changing Minds: The Personal

Posted on 11 March 2012 by Andy Skuce &

Nobody comes into this world with a fully-formed opinion on anthropogenic climate change. As we learn about it, we change our minds. Sometimes, changing your mind can be easy and quick; sometimes it’s hard and slow. This is an anecdotal and subjective account of the author’s changes of mind.

A goal of Skeptical Science is to change people’s minds, especially the minds of people who doubt the reality of man-made climate change. John Cook and Stephan Lewandowsky’s The Debunking Handbook provides a how-to and how-not-to resource for debunking myths and misinformation: a guide to changing people’s minds, based on published research in psychology.

 In this article I’ll examine my own history and sketch out how I twice changed my mind on climate change; I’ll speculate on why one step was easy yet memorable while the other was hard work but forgettable.



Michael Mann, hounded researcher

Posted on 30 December 2011 by Andy Skuce &

Here is a translation of  recent article (December 25th, 2011) in the French newspaper Le Monde by science journalist  Stéphane Foucart. He reports on a talk that Michael Mann gave at the 2011 AGU Fall Meeting in San Francisco, in which Mann introduces his forthcoming book  The Hockey Stick and the Climate Wars: Dispatches from the Front LinesFoucart interviews Mann and discusses the background of the Hockey Stick and Climategate controversies. What is refreshing is the absence of the false balance, both-sides-of-the-story, style of reporting that is found so often in English language newspapers. 

Original article (in French) from Le Monde

In early December, at the Fall Meeting of the American Geophysical Union (the annual grand gathering of the bigwigs of the geoscience world), Michael Mann introduced his forthcoming book to his peers. The lecture was entertaining and the audience laughed heartily.  The American climatologist, Director of the Earth System Center at Pennsylvania State University, cracked numerous jokes and made many witty asides. He scoffed at the anti-science of the Republican politicians and mocked their ridiculous statements on climate change; everybody laughed out loud.

But this, surely, is no laughing matter. Michael Mann’s forthcoming book, The Hockey Stick and the Climate Wars: Dispatches from the Front Lines (Columbia University Press), is not really a science book; rather, as its title suggests, it deals instead with the war on climate science, which has at times turned into a manhunt, frequently with Mann as the quarry.



Changing the Direction of the Climate

Posted on 1 December 2011 by dana1981 & Andy Skuce

As Andy recently discussed, the International Energy Agency (IEA) has published the World Energy Outlook 2011 (WEO11), which incorporates the most recent data on global energy trends and policies, and investigates the economic and environmental consequences of three scenarios over the 2010 to 2035 time period:

  • The New Policies Scenario. This is used as a reference case. It assumes that governments will follow through on the (non-binding) pledges that they have made to reduce emissions and deploy renewable energy sources.

  • The 450 Scenario. This is an outcome-driven scenario, which lays out an energy pathway designed to limit the long-term concentration of greenhouse gasses to 450 ppm CO2 equivalent. Achieving this would provide a 50% chance of limiting global temperature increases to 2°C. Some climatologists, such as James Hansen, argue that a more aggressive 350 ppm target is required to avoid the possibility of “seeding irreversible catastrophic effects”.

  • The Current Policies Scenario.  This projection models a future in which only those climate and energy policies actually adopted in mid-2011 are incorporated.

The IEA focuses on CO2 emissions from energy production, as we'll see below.  Their 450 Scenario proposes to keep CO2 equivalent (including all atmospheric greenhouse gases) concentrations in the vicinity of 450 ppm by very quickly reducing both non-fossil fuel CO2 emissions (i.e. reducing deforestation) and non-CO2 greenhouse gas emissions (i.e. methane), such that their emissions in 2020 are lower than today.  However, the main focus of the report is on fossil fuel CO2 emissions.



World Energy Outlook 2011: “The door to 2°C is closing”

Posted on 16 November 2011 by Andy Skuce &

If we don’t change direction soon, we’ll end up where we’re heading

These words come from the Executive Summary of the World Energy Outlook 2011 (WEO11), just published by the International Energy Agency (IEA). The study incorporates the most recent data on global energy trends and policies, and investigates the economic and environmental consequences of three scenarios over the 2010 to 2035 time period. This is an important document that should be widely read but, unfortunately, the full report costs €120 for a single-user 650-page pdf.  Some key graphs and fact sheets are provided for free.

The WEO11 report is a commentary on the assumptions and output of the World Energy Model (WEM) in the IEA's words: a large-scale mathematical construct designed to replicate how energy markets function and is the principal tool used to generate detailed sector-by-sector and region-by-region projections for various scenarios.  A detailed description of the WEM is available here. The IEA updates their model and analysis every year, since important and unpredictable developments — a tsunami in Japan, the Arab Spring, new technologies in natural gas production — change the model’s boundary conditions significantly. In 2012, we can look forward to: an election in which the world’s largest economy may elect a government that denies the urgency and even the reality of climate change; further unrest in the Middle East; developments in renewable and fossil-fuel technology; and an unfolding economic crisis in Europe. And those are just some of the more foreseeable events that will make a new WEO study needed next year. In comparison, climate modellers have it easy.

In the 2011 Outlook, the IEA explored three scenarios.

  • The New Policies Scenario. This is used as a reference case. It assumes that governments will follow through on the (non-binding) pledges that they have made to reduce emissions and deploy renewable energy sources.

  • The 450 Scenario. This is an outcome-driven scenario, which lays out an energy pathway designed to limit the long-term concentration of greenhouse gasses to 450 ppm CO2 equivalent. Achieving this would provide a 50% chance of limiting global temperature increases to 2°C. Some climatologists, such as James Hansen, argue that a more aggressive 350 ppm target is required to avoid the possibility of “seeding irreversible catastrophic effects”.

  • The Current Policies Scenario.  This projection models a future in which only those climate and energy policies actually adopted in mid-2011 are incorporated.



Berkeley Earth Surface Temperature Study: “The effect of urban heating on the global trends is nearly negligible”

Posted on 21 October 2011 by Andy Skuce &

A paper submitted for peer review by the Berkeley Earth Surface Temperature study (BEST) finds that urban heating has an influence on global temperature trends that is “nearly negligible” and that what effect has been observed is even slightly negative, which is to say that temperature trends in urban areas are actually cooler than the trends measured at rural sites, and that the Earth's land surface has warmed approximately 1°C on average since 1950.

The Urban Heat Island Effect

It has long been observed that temperatures in cities are higher than in the surrounding countryside, caused, in part, by human structures that reduce albedo and evapo-transpiration, as well as by the effects of waste heat emissions, McCarthy et al 2010. Even though most (99%) of the Earth’s surface is not urbanized, some 27% of the Monthly Global Historical Climatology Network (GHCN-M) temperature stations are located in cities having populations of more than 50,000. Since urbanization has grown dramatically over the past few centuries, it seems reasonable to ask how much of the observed rise in global temperatures is due to urbanization. For example, McKitrick and Michaels claimed in 2007 that about half of the recent warming over land is due to urban heat island effect, although this result  was disputed by Schmidt in 2009.

Several studies have looked in depth at possible heat island contamination of land temperature records. For example, Hansen et al in 2010 used satellite measurements of night lights to remove possibly affected urban sites from the temperature records. Allowing for urban effects reduced the global temperature trend over the period 1900-2009 by 0.01°C. Menne et al performed an analysis on US surface temperature records and found only very small effects due to poor siting of temperature stations. They reported that poorly-sited stations did show some small positive bias in recorded minimum temperatures but there was a small, but slightly larger, negative bias in recorded maximum temperatures, resulting in an overall small residual cool bias.



Heat from the Earth’s interior does not control climate

Posted on 17 September 2011 by Andy Skuce &

This blog post is the intermediate-level rebuttal to the climate myth “Underground temperatures control climate”. 

The myth:

"There are other possible causes for climate change which could be associated with solar activity or related to variations in the temperature of the liquid core of the Earth, which is about 5,400 degrees Celsius.  We don't need a high heat flow - just a high temperature for the core to affect the surface climate.  There is massive heat inside the Earth." Link. See here, also.


  • The center of the Earth is at a temperature of over 6000°C, hotter than the surface of the Sun.
  • We have all seen pictures of rivers of red-hot magma pouring out of volcanoes.
  • Many of us have bathed in natural hot springs.
  • There are plans to exploit geothermal energy as a renewable resource.

Common sense might suggest that all that heat must have a big effect on climate. But the science says no: the amount of heat energy coming out of the Earth is actually very small and the rate of flow of that heat is very steady over long time periods. The effect on the climate is in fact too small to be worth considering.

The Earth’s heat flow



The Ridley Riddle Part Three: Like a Northern Rock

Posted on 12 August 2011 by Andy Skuce &

This is the third and final article in the series on climate contrarian Matt Ridley. Here are Parts One and Two. 

This article will look at Matt Ridley’s involvement in the collapse of the British bank, Northern Rock, in 2007. I am not the first to attempt to link this business disaster with with his views on climate change; George Monbiot wrote an articleThe Man Who Wants to Northern Rock the Planet, remarking, among other things, on the contradiction between Ridley’s small-government libertarianism and his begging the Treasury for a bail out of his company.

The rise and fall of Northern Rock

Matt Ridley was the non-executive Chairman of Northern Rock, a British bank that, in 2007, was the first in over a century and a half to experience a run on its deposits. British banks had all survived two World Wars, the Great Depression, and the end of the British Empire, until Northern Rock failed. Ridley had served on the Northern Rock board of directors since 1994 and was appointed Chairman in 2004. A previous Chairman of the bank was his father, Viscount Matthew Ridley.

Northern Rock’s depositors responding rationally but not optimistically to market signals. Source

Northern Rock’s business model was a very aggressive one, centered on rapid growth of its mortgage business. Before 1997, Northern Rock was a building society, a co-operative savings and mortgage institution. Like many other British building societies, it transformed itself into a bank and was listed on the stock exchange. This led to rapid growth for Northern Rock, which grew its assets at an annual rate of more than 23% from 1998 to 2007. Before its crisis, Northern Rock had assets of about $200 billion and was the fifth-largest bank in Britain.  The bank’s retail deposits did not grow at the same rate as its mortgage assets; the difference was made up with funding from capital markets. When the credit crisis hit in 2007, Northern Rock saw its funding vanish. Northern Rock’s debts were more than fifty times its shareholder common equity, making the bank an outlier even among the many other highly-levered financial institutions at that time. This made the bank particularly vulnerable to changes in the credit markets. The bank was unable to pay its creditors and had to turn to the Bank of England for help in September 2007. These events led to panic among its depositors, who formed huge queues outside its branches to withdraw their savings.



The Ridley Riddle Part Two: The White Queen

Posted on 7 August 2011 by Andy Skuce &

 This is the second of three articles on the climate contrarian Matt Ridley. Part One is here

In 2010, David MacKay wrote a letter to Matt Ridley in response to an op-ed article by Ridley published in The Times. MacKay’s letter and Ridley’s reply to it are both posted on the Ridley’s Rational Optimist blog. In this article, I am going to focus on Ridley’s reply, not because it is a particularly interesting or original addition to the skeptical canon, but because I believe it is revealing about the mindset of a climate contrarian.

David MacKay is a physicist but not a climate scientist. He is the author of the book Sustainable energy - without the hot air, which examines the daunting challenge that the United Kingdom faces in decarbonizing its energy supply. It’s a must-read, entertainingly written, easy-to-understand work, and can be downloaded for free.  MacKay was appointed in 2009 to be Chief Scientist at Britain’s Department of Energy and Climate Change. His letter to Ridley raises points that will be familiar to regular readers of Skeptical Science; he cites recent evidence of climate change and discusses the analogue of the Paleocene-Eocene Thermal Maximum and the central question of the likely range of climate sensitivity. MacKay also mentions that his personal and professional contact with climate scientists bears no relation to the way they are often negatively depicted on contrarian blogs.

There are three main elements of Ridley’s reply that I want to focus on in this article but, first, I’ll simply list in point form some of the other arguments that comprised the rest of Ridley’s Gish Gallop, along with rebuttal links and brief comments.



The Ridley Riddle Part One: The Red Queen

Posted on 30 July 2011 by Andy Skuce &

This is a three-part series on science writer, businessman and climate contrarian Matt Ridley. The first section looks at his science books and is critical of his latest book, The Rational Optimist; the second scrutinizes one of his blog posts on climate change and shows that his avowed lukewarmer stance is built on shaky scientific foundations; the final part examines Ridley’s history as a businessman, drawing parallels between his role in the credit crunch and his approach to climate change. 

Sometimes, it’s easy to dismiss climate change contrarians as being a little slow when it comes to truly understanding science, but it’s not possible to do that with Matt Ridley, who has a well-earned reputation as a first-class science writer.  He is on the Academic Advisory Council of the contrarian Global Warming Policy Foundation, along with Robert Carter, William Happer, Richard Lindzen, and Ian Plimer. As well as being the author of several excellent science books, he’s a journalist, a businessman, and has a D.Phil. in Zoology from Oxford. And he runs a blog that, among other things, takes a skeptical stance on the mainstream science of climate change. 

Why such a talented science writer should have come to reject the scientific consensus on climate change is the Ridley Riddle that this series of posts will attempt to answer.



Thinning on top and bulging at the waist: symptoms of an ailing planet

Posted on 14 July 2011 by Andy Skuce &

Like many an aging baby boomer, the Earth is starting to bulge at the waist and is getting thinner on top. In the Earth’s case this isn’t due to a weakness for drinking beer or due to an inherited tendency towards male pattern baldness. Rather, it is because of climate change. As the big ice sheets in Greenland and Antarctica thaw, the melt water is distributed throughout the world’s oceans, causing mass to move away from the poles.

The earth is not exactly round, it’s slightly flattened at the poles and bulging at the Equator. The radius of the Earth measured from its center to sea level at the poles (or where sea level would be at the South Pole if there were no continent there) compared to the radius at the Equator, differs by about 21 km. This means that the point on the Earth’s surface furthest away from its center is not the summit of Everest but rather the top of the volcano Chimborazo in Ecuador. Although the summit of Chimborazo is 2,500 meters less high above sea level than Everest, it is also much closer to the Equator and hence further from the center of the Earth. The reason that the Earth is not quite round is mainly because it spins on its axis through the poles; the centrifugal forces acting on the rocks of the Earth, which are somewhat ductile, tend to push out the parts furthest away from the axis.

The amount of flattening (or oblateness) of the Earth can be represented by a gravitational parameter known as J2. See here for a definition. This parameter has been measured since the mid-1970’s by satellite laser ranging (SLR) and is found to vary from year to year due, among other things, to the ENSO, the El Niño/La Niña oscillation in the Pacific. See Figure 1 below and here, also.

Figure 1. Measurements of changes in J2 (the Earth’s flatness or oblateness) from satellite laser ranging (SLR, not to be confused with sea-level rise), from Nerem and Wahr (2011). Note the declining trend in J2 from the mid-1970's until the mid 1990's. 



Carbon Cycle Feedbacks

Posted on 24 February 2011 by Andy Skuce &

The document entitled 'Carbon Dioxide and Earth's Future: Pursuing the Prudent Path', referenced in the "skeptic" scientist letter to US Congress, makes the claim that rising CO2 concentrations have "actually been good for the planet" because of the fertilization effect of CO2. Although it is true that there has been a measurable CO2 fertilization effect, particularly in the tropics (see this video seminar), this is only one factor that will influence the response of the global carbon cycle to climate change. It's instructive to look at some important factors that are not mentioned in The Prudent Path.



The Global Carbon Cycle by David Archer—a review

Posted on 15 February 2011 by Andy Skuce &

"The climate system is an angry beast and we are poking it with sticks" - Wallace Broecker

The belly of Broecker’s climate beast is surely the global carbon cycle. Currently, the beast is digesting about half of our fossil-fuel CO2 emissions, acting as a major stabilizing influence on the climate, a negative feedback. But as Professor David Archer warns us in his latest book, The Global Carbon Cycle, the carbon cycle behaves unpredictably in different circumstances and over different timescales. For example, during the Paleocene-Eocene Thermal Maximum (PETM), it acted to bring things back to the then hothouse normal after a massive belch of carbon into the atmosphere.  At other times, it amplified small temperature perturbations into climate events that changed the face of the planet, as it did in the ice age cycles, the period we are still currently in.  Humans are administering a perhaps PETM-scale dose of carbon into the atmosphere during a time when the global carbon cycle has acted as an amplifier rather than a damper. Ominously, Archer tells us, the planet’s reservoirs of carbon in the form of peat, gas hydrates and rain-forest carbon are now probably as charged up as they can be. That's some beast; some stick.



The 2010 Amazon Drought

Posted on 6 February 2011 by Andy Skuce &

A short paper by Simon Lewis, Paulo Brando and three co-authors, just published in Science Magazine, reports on the 2010 drought in the Amazon Basin. This drought occurred only a few years after the exceptional drought of 2005, which was supposed to have been a one-in-a-hundred-year event. The paper presents evidence that last year's drought was both more severe and more extensive than the earlier one.



The Hitchhiker’s Guide to the AGU Fall Meeting

Posted on 26 December 2010 by Andy Skuce &

"Space," it says, "is big. Really big."
The Hitchhiker's Guide to the Galaxy, by Douglas Adams

If the AGU Fall Meeting had to be summed up in one word, that word would surely have to be big. There were over 19,000 people attending and many thousands of talks and poster presentations. The Scientific Program guide is 560 pages long with each page listing about thirty presentation titles. I doubt that anyone (except maybe some hapless AGU proof-reader) has been able to read this mostly verb-free text from beginning to end. Fortunately, the AGU provides an online scheduling tool that allows you to search the program for keywords and set up a personalized itinerary; but the process of presentation selection remains rather random. Everyone experiences a different meeting.



Measuring CO2 levels from the volcano at Mauna Loa

Posted on 25 October 2010 by Andy Skuce &

The observatory near the summit of the Mauna Loa volcano in Hawaii has been recording the amount of carbon dioxide in the air since 1958. This is the longest continuous record of direct measurements of CO2 and it shows a steadily increasing trend from year to year; combined with a saw-tooth effect that is caused by changes in the rate of plant growth through the seasons. This curve is commonly known as the Keeling Curve, named after Charles Keeling, the American scientist who started the project.



Comparing volcanic CO2 to human CO2

Posted on 27 August 2010 by Andy Skuce &

The solid Earth contains a huge quantity of carbon, far more than scientists estimate is present in the atmosphere or oceans. As an important part of the global carbon cycle, some of this carbon is slowly released from the rocks in the form of carbon dioxide, through vents at volcanoes and hot springs. Published reviews of the scientific literature by Moerner and Etiope (2002) and Kerrick (2001) report a minimum-maximum range of emission of 65 to 319 million tonnes of CO2 per year. Counter claims that volcanoes, especially submarine volcanoes, produce vastly greater amounts of CO2 than these estimates are not supported by any papers published by the scientists who study the subject.



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