A skeptic responds to a climate sceptic

This-morning on Facebook I had an exchange with a gentleman named Rod, who posted this reply to my claim that our deadlocked Parliament had resulted from voter dissatisfaction with parties being more-or-less interchangeable on most issues, and for treating us with contempt over global warming.

Reproduced with permission.

Rod kindly gave me permission to repost his comments here so that I may respond via a more appropriate forum than my friend’s Facebook status page.

Whilst I generally feel debating with climate change sceptics is a waste of time (this post alone kept me up until about 2am last night), as often they will cling to previously debunked denialist claims and will not skip a step in result of your arguments, a) I don’t know if Rod is indeed a climate change sceptic or just a layman who has been influenced by denialist media, and b) if discussed publicly there is at least some chance that others who haven’t already made up their minds may begin to realise they are able to inform themselves on these issues, and they don’t have to rely on the media or other commentary to influence their beliefs.

Make no mistake – although many will tell you the jury is still out on whether the climate is warming, and whether we’re responsible, mainstream climate scientists are in almost unanimous agreement on these points, as 97 percent agree [i] – it is happening, and we’re mainly responsible. [ii]

As I am not a climate scientist, although I am well read on the issues, I have primarily referenced one website (a practice generally frowned upon – don’t use one source!), as the site in question serves to aggregate peer-reviewed scientific studies and papers which have acceptance within the mainstream, actively publishing climate science community. The articles I have referenced typically reference a variety of other works.

For the purpose of discussion I have broken Rod’s main points down to the following so that I may address them each in turn. I encourage you to do some further reading, as I don’t have the time required to cover these subjects in depth.

1. Amazon jungle world’s largest emitter of CO2
2. Ice age, inland sea and cyclical changes in climate
3. The Earth’s orbit and axial tilt
4. Naïve to base political decision upon this issue, and Australia can’t do anything anyway

1. The number one emitter or CO2 in the world is the Amazon Jungle (rainforest)

I wasn’t able to find any corroborating sources for this claim, unless Rod was actually referring to deforestation, in which case his claim has some basis in fact. Although figures vary from source to source, I found references to United Nations data which suggests that “deforestation accounts for around 25 percent of man-made emissions of carbon dioxide — roughly the same amount of carbon dioxide produced by the United States, the world’s largest polluter.”[iii]

If indeed Rod was referring to this effect from deforestation, rather than some natural process, the argument seems mute as these emissions are directly due to human activity. If the point Rod wished to make was that reductions in burning fossil-fuels are insignificant compared to deforestation, I would point out that as the statement above (similarly stated in the other sources quoted below), points out, the US alone is responsible for the same volume of greenhouse gas emissions, so in global terms this is not an argument against reducing our fossil-fuel-based emissions urgently.

There is, however, argument to put a price on carbon in order to put a dollar value on these forests as a mechanism to reduce deforestation through compensating underdeveloped countries for maintaining their forests, reducing pressure to convert forested land to agricultural purposes.

If, on the other hand, Rod was referring to the natural exchange of CO2 between vegetation and the atmosphere, where respiration by plants emits around 220 gigatonnes of CO2 per year[iv], compared to human emissions of around 29 gigatonnes per year, on the surface it sounds credible to claim that man-made emissions are dwarfed by natural processes.

This must be viewed in perspective, however, as “natural CO2 emissions (from the ocean and vegetation) are balanced by natural absorptions (again by the ocean and vegetation). Land plants absorb about 450 gigatonnes of CO2 per year and the ocean absorbs about 338 gigatonnes. This keeps atmospheric CO2 levels in rough balance.” Human emissions, however, tip this balanced system, as the plants and oceans only absorb around 40% of these, with the rest remaining in the atmosphere. [v]

“As a consequence, atmospheric CO2 is at its highest level in 15 to 20 million years[vi]. A natural change of 100ppm normally takes 5,000 to 20.000 years. The recent increase of 100ppm has taken just 120 years.” [vii]

2. Ice Ages, inland seas and cycles

I’ve chosen to group these points together, as I suspect Rod is pointing out cyclical events relating to ice-ages, glaciation and glacial melt, and confirmed climactic cycles such as Dansgaard-Oeschger events[viii]. I wasn’t able to find any references to inland seas which seemed to dispute man-made climate change, so I have ignored this item for now, unless Rod or someone else can provide some additional information.

Ice-age claims are generally used by climate sceptics to argue that the earth has experienced warming (then cooling), events in the past, and that we are due or overdue for such a cycle to repeat now. These arguments relate to the supposedly regular and predicable cycle of warming and cooling periods the geologic, ice-core and fossil records indicate have dominated the last 700,000 years of Earth’s history, reoccurring on a 100,000 year Milankovitch cycle[ix], which I address later in response to the orbit and axial tilt claims, or every 11,500 years coinciding with Maunder Minimums[x], relating to Solar activity.

Further ‘proof’ that cycles dictate climate change was proposed by Fred Singer and Dennis Avery in their book Unstoppable Global Warming published in the 1990s, where they claimed that the climate changes on a 1500 year natural cycle as evidenced by Greenland ice cores and Atlantic Ocean sediments. They said that this cycle, which records indicate is due now, is proof that the warming we are currently seeing is in fact natural, and no cause for alarm.

Climate scientists have in fact found such a cycle, known as the Dansgaard-Oeschger events, where Arctic conditions warm periodically on a roughly 1500 year period. What they have also found however, is that coinciding with these arctic warming events are almost mirror-image cooling events in the Antarctic, leading to the conclusion that these events are a see-saw of regional climate change driven by ocean currents, and are not representative of warming events on a global scale.

A brief video discussing this can be found here http://www.skepticalscience.com/1500-year-natural-cycle.htm

There are other various arguments about cyclical climatic changes being ‘the culprit’ for our current warming trend, many centred around sun activity[xi] [xii], and the argument typically goes that since the climate has changed before, it is natural and not of our doing. Subtle changes of small increments are to be expected, as the earth’s climate is in constant flux, dependent on many inputs, and therefore there is no need to invoke ‘human influences’ to explain the climate changes we are seeing.

These arguments are premised upon the logical fallacy of the single cause: since the environment has changed before without the involvement of humans, humans therefore can’t be causing the changes we are seeing now.

The science is telling us that there is indeed a warming trend, that this trend is much sharper and faster than has been the case for other cyclical or oscillation events, and none of the previously identified natural ‘forcings’ collate with the upward global air, sea and tropospheric temperature trends we have recorded over the last few decades. What does collate with these increases however is mankind’s upward trend in fossil-fuel use, generally followed by a time-lag attributed to the oceans’ heat absorption.

Historical CO2 producing events, as evidenced by the geologic, ice-core and fossil record, show massive increases in CO2 have led to warming periods similar to what we’re experiencing now[xiii], but these are traceable to events not evident now, whereas man-made CO2 emissions correlate quite specifically with the warming trends we are seeing. [xiv]

3. The Earth’s orbit and axial tilt

Linked with other ‘cycle’ arguments, changes in the Earth’s orbit and axial tilt relate are called Milankovitch Cycles, which are caused by changes in the eccentricity of the earth’s elliptical orbit, changes in the Earth’s rotational axis, and wobbles in the earth’s axial tilt.

These changes combine on a cyclical roughly 100,000 year basis to alter the amount of sunlight energy which reaches the Earth’s surface, which in turn affects sea and air temperatures. Once a warming period begins, decreases in glacial coverage reduce the Earth’s albedo[xv], which is its ability to reflect sunlight energy back out to space. A feedback loop then ensues, where increased solar energy warms the air and oceans, glacial melt occurs reducing albedo, less sunlight is reflected out to space, so more air and ocean warming occurs.

Although various other causes of global warming such as sun cycles[xvi] [xvii] [xviii], earth’s orbit and axial tilt[xix], are offered by climate change sceptics as alternate explanations, these have been dismissed by the scientific community[xx] as causes for our current warming.

4. Naïve to base political decision upon this issue, and Australia can’t do anything

Although I hold many issues dear, including but not limited to education, which is of critical importance to our future and is currently massively underfunded; the rights of all people to marry, regardless of sexual preference; internet accessibility, free from censorship – although these are important to me, and each play a part in my voting decisions, climate change is by far the most important issue to me, and, it would seem, a significant portion of the population who I believe showed their dissatisfaction with the two major parties by delivering what may well result in a hung-parliament.

I do not accept the criticism that ‘minority interests’ are holding this country to ransom, and I do not agree that Australia has no responsibility in reducing greenhouse gas emissions. We’re a global community, currently locked in a battle between economic rationalism and reason, and for the sake of future generations who will have to clean up our mess, I sincerely hope we can pull it together in time to make a difference.

The references below are a mere fraction of what is available to everyone if they take the time to look. Don’t accept what you hear from the media, who have grossly misrepresented climate science in the interest of ‘balanced’ reporting, and who should hang their heads in shame over the so-called climate-gate scandal. If they were really interested in ‘balance’, they’d have reported the clearing of the scientists involved[xxi] as enthusiastically as the scandal itself. Don’t dismiss the science, an open, self-critical, self-correcting body of knowledge with no ‘agendas’. Don’t dismiss the experts, who by definition know more than anyone else – it is absurd to hear “someone has to stand up to these experts”, as if an appeal to lack of authority is somehow more compelling than years spent in professional scientific pursuit.

We each have unprecedented access to information and expert analysis, which has been vigorously critiqued by peers who’s job as scientists is to ‘disprove’ the hypothesis. They’ve already tested and thrown out countless theories about global warming, and have settled on this current understanding – The climate is changing, we are causing it, and it will have significant social, economic and moral ramifications if we continue to do nothing about it.

We can’t put the brakes on climate change, but at the very least we should be urgently taking our foot of the accelerator.

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[i] http://sciencedude.ocregister.com/2010/06/24/global-warming-97-of-experts-agree/102497/

[ii] http://www.csiro.au/resources/Humans-Changing-Climate.html

[iii] http://news.mongabay.com/2005/1210-fao.html, http://www.nature.org/initiatives/climatechange/features/art19363.html & http://www.un.org/esa/policy/policybriefs/policybrief15.pdf

[iv] http://www.skepticalscience.com/human-co2-smaller-than-natural-emissions.htm

[v] http://www.skepticalscience.com/human-co2-smaller-than-natural-emissions.htm

[vi] http://www.sciencemag.org/cgi/content/abstract/1178296

[vii] http://www.skepticalscience.com/human-co2-smaller-than-natural-emissions.htm

[viii] http://en.wikipedia.org/wiki/Dansgaard-Oeschger_event

[ix] http://www.skepticalscience.com/co2-lags-temperature.htm

[x] http://www.skepticalscience.com/heading-into-new-little-ice-age.htm

[xi] http://www.skepticalscience.com/500-scientists-global-warming-consensus.htm

[xii] http://www.skepticalscience.com/argument.php?a=18

[xiii] http://www.skepticalscience.com/climate-change-little-ice-age-medieval-warm-period-basic.htm

[xiv] http://www.skepticalscience.com/its-not-us.htm

[xv] http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/albedo.html

[xvi] http://www.skepticalscience.com/solar-cycle-length.htm

[xvii] http://www.skepticalscience.com/solar-cycles-global-warming.htm

[xviii] http://www.skepticalscience.com/solar-activity-sunspots-global-warming-intermediate.htm

[xix] http://www.skepticalscience.com/co2-lags-temperature.htm

[xx] http://www.skepticalscience.com/solar-activity-sunspots-global-warming-intermediate.htm

[xxi] http://www.skepticalscience.com/Climategate-CRU-emails-hacked.htm