Wednesday, September 3, 2014

Climate Change: Models and Proofs

Every now and then I still run into the argument that climate science is far from settled, that we cannot rely on the fact that the vast majority of scientists in the field are in fundamental agreement and that “real” science requires proof. Models, people taking this view, are imperfect, and not “real” science, which is not a popularity poll.

Let’s examine how science actually works.

First, what is a model? It is an abstraction of reality that allows you to make predictions. A good model will make accurate predictions; a useful model makes predictions accurate enough to allow reasonable action ahead of knowing the correct result. Weather models, for example, are not 100% accurate, but good enough to allow us to do things like plan whether to do laundry, or to evacuate a city ahead of a major storm.

We need two things of model predictions to be sure it is useful. We need error bounds and evidence that those error bounds are accurate. Error bounds are a measure of how much our model varies from reality. If the error bounds are too big, any model predictions may be no better than guesses. If the bounds are not accurate, we do not know how much confidence to put in the accuracy of any prediction.

Nothing in science is ever proved except in pure mathematics.

Take an example: Newton’s Laws of Motion and his theory gravity. These all look nice and mathematical, but they ultimately rest on matching prediction to models. Those models are relatively simple – a bunch of 1-line formulae, but these formulae result from observations, not mathematical proofs. Take gravity, for example. Newton came up with a formula, then used that formula to calculate movement of planets and found it matched.

Newton’s formulae are models. They are an abstraction of an aspect of the universe that can be used to predict outcomes including many Newton would never have though of – whether a space probe reaches Jupiter, whether a car stops in a certain distance when you hit the brakes, and so on.

Since his time, millions of measurements have fitted his models so well, they have become accepted as correct – mostly. Late in the 19th century, the puzzling problem that the speed of light did not vary according to the relative speed of the source and the observer arose. Only with Einstein’s intuition that an invariant speed of light required rewriting Newton’s Laws did we solve this conundrum. Even so, Newton’s formulae still work well enough in most situations that we still use them.

Consensus in science

Models of complex real-world systems cannot provide the accuracy that Newton’s Laws do. Nonetheless they can be useful – even if the results have significant unknowns as well as known sources of error.

How do we determine if a model is sufficiently accurate to be useful? By taking lots of measurements. If the model consistently gives answers close enough to reality that we are confident that the accuracy we predict for the model is correct (the difference from prediction is within accepted error limits), our confidence in the model grows.

That is how consensus in science works. Einstein’s theories, for example, were not fully accepted, despite their mathematical logic, until they could be verified by measurement.

Michelson-Morley set up (source: Wikipedia)
On the other hand, it only takes one measurement that completely contradicts a theory to call it into question. Staying with Einstein and Newton, the starting point was the Michelson–Morley experiment, first published in 1887, which demonstrated that the speed of light is a constant. This was followed by the Lorentz transformations, developed over 1887 to 1905, which became the basis for Einstein’s special relativity.

Despite these radical changes, Newton’s Laws still apply because a Einstein’s new theories come out with the same numbers in most cases where we are not dealing with speeds close to light speed, or gravitation on a relatively small scale.

So despite Einstein’s radical new theories, Newton’s theories still stand – even if we now know they are not totally accurate.

How this relates to climate science
Climate science is not a simple collection of formulae but is based on complex models that are hard to understand a piece at a time. Even so, the same basic concept applies. If you can make predictions that, when later tested against reality, are within the predicted error bounds, you can make claims about the accuracy and usefulness of the theory.

Where are we now?

Some have made a big deal of the relatively slow rate of global temperature increase since the late 1990s. The models do not claim that all temperature variation is human-caused. A major factor is solar variation. Another factor is inaccuracy of models of how the oceans take up increased energy.

In the first half of the twentieth century, the sun was on a slow warming trend, which made it hard to pick out the effect of anthropogenic global warming (AGW: human-caused warming). The most recent solar cycle, on the other hand, has been relatively cool. That alone is a big factor in the apparent slowdown in warming, and is not a factor we can rely on because either the sun will return to its long-term relative warmth, or the AGW trend will rise sufficiently to mask this effect.

The oceans absorb 90% of any change in the planet’s energy balance in the short term, because a temperature change in water can be mixed into lower layers, since water is constantly in motion. A small perturbation in the way the oceans take up heat can have a huge effect on surface temperature. There is increasing evidence that the oceans are warming a little faster than predicted, and that effect too can explain an apparent slowdown in surface warming.

Arctic sea ice volume trend (April and September).
Source: PIOMAS
There is plenty of evidence that the Earth is not in balance with energy flows in from the sun, such as growing ice loss both on land and Arctic sea ice, and that energy imbalance can only ultimately be corrected by a higher surface temperature.

And finally, the apparent slowdown is within the error limits of the commonly accepted models though at the lower end of the predicted range. Other published predictions that have held up well include predictions of extreme weather in the US, and that is the sort of prediction we need to worry about.

So the argument that the models are fundamentally flawed is wrong: they are not totally accurate, but they are accurate enough to be useful.

Thursday, August 28, 2014

Save our Station

Grahamstown has an historic railway station, built over 140 years ago.

Train service to the town stopped a while back but the building was in use as recently as 2011, but is now in an advanced state of stripping by vandals.

The station in 2013. It is worse now.
Grahamstown Residents’ Association (GRA) has launched a campaign to save the station, starting with a petition targeting the owners, Transnet, who have an obligation in law to maintain a heritage building, as well as all levels of government.

In the long term, ideally, we should get train service back. In he meantime, the building could be a great community resource. If  Transnet doesn’t want it, it could be transferred to a community organization to renovate, secure and maintain. In a town with so much unemployment, allowing a valuable resource like this go to ruin is a terrible waste – and we want out trains back.

Please support this campaign by sharing on Facebook, twitter, mailing lists – and any other way you can spread the word.

How to sign on paper

Here are places where you can sign a paper petition form in Grahamstown:
  • Birch’s
  • Cory Library, Rhodes University
  • Earth’s Produce
  • Fort England Hospital
  • Friar Tuck
  • Fusion Speciality Food Shop
  • Kisma
  • Lungi and Ingram’s Farm Stall
  • Makana Tourism
  • PG Glass
  • Pam Golding Properties
  • Provost Coffee Shop, Rhodes University
  • Relish coffee shop
  • Richard’s Car Wash
  • Sally Scott Art Classes
And some places that had a forms, now submitted:
  • The Cover Up
  • Sunnyside Nursery/Tea Garden
If you can’t get to any of these, you can instead fill in the electronic version of the petition. Real signatures probably count for more, but all signatures add up.

The petition closes 12 September 2014, so please do not delay, and spread this around  to your contacts.

I also encourage you if you live in Grahamstown to join GRA. At R10 per year, it is affordable and we need weight of numbers for campaigns like this – especially as the town has been placed under administration. Click here for a form.

How to sign on line

A short form of the petition address to put in emails (copy from here and paste): http://goo.gl/pzuIsn. For your convenience here is the petition form for on-line signatures:




UPDATE
As of 19:00 5 September, we have about 1500 signatures from all around the country as well as from around the world. Countries include UK, Netherlands, Australia, New Zealand, Botswana, Thailand, Japan, Egypt, Brazil, UAE, USA, Spain and Zimbabwe.

Some comments from the on-line petition
  • As a former resident of Grahamstown and DSG Old Girl, I strongly suggest that you alert the Rhodes University alumni office and all similar networks for past pupils of the local independent schools to this petition, as I am sure that there are thousands of former users of this iconic building who would love to see it preserved for posterity.
  • As a heritage site and an important part of South Africa's history, neglect by the owners which has led to vandalism, and in turn a security risk to near-by residents etc. is unacceptable. One would hope that the owners would act in a more responsible fashion rather than showing complete disregard for the community  situated in close proximity to the site.
  • As a Rhodes history graduate I am horrified that the station is being degraded in this way. TRANSNET, MAKANA MUNICIPALITY, EASTERN CAPE PROVINCIAL LEGISLATURE, SAHRA, and the NATIONAL LEGISLATURE must act now before this piece of our heritage is beyond restoration. How many people living both in Grahamstown  and all over the world first arrived in this historic town by rail?
  • Be remembered for more than a fossil record of trash!
  • Directors of Transnet to take responsibility in terms of their positions!
  • Do not destroy our heritage
  • During my stay in Grahamstown I loved the historic feel of the town. I think sites like the railway station and the Old Gaol should be preserved for both residents and tourists.
  • How is it possible for a supposedly responsible SOE (Transnet) to allow its property to fall into such a state of disrepair? The fact that the railway between Alicedale and Grahamstown is closed is no excuse! 
  • I grew up in the eastern cape.
  • I have communication i have emailed in the last 6 motnhs to heads of transnet and departments about the station requesting assitance, to no avail - i would love to get involved and help/petition - whatever it takes.
  • I sign on behalf of the Heritage Railway Association of Southern Africa (HRASA) - the umbrella body for the steam and heritage sector in Southern Africa.
  • I think that it's an absolute disgrace that this building has been allowed to deteriorate it's current condition.
  • I went to college in Grahamstown in the 1950's and have very fond memories of the station.
  • I wish to support the petition to protect the Grahamstown station from vandalism and disrepair
  • I'd love to see trains running again. 
  • I've always appreciated the station architecturally, historically and as a gathering site and lately as a performance venue.  It is shameful that this invaluable asset to the entire community has been neglected to the point of deterioration and vandalism.  Its renewal will be meaningful to the present.
  • It has to be saved!
  • It is about time our Heritage buildings were preserved.
  • It is vital to save it.  There must be a way to secure the property and use it in a way to benefit Grahamstown.
  • Many of my students would use the train, and so would I. It would bring more people to Grahasmtown as toursists too. So it helps the locals, by providing alternative transport, and by creating jobs through tourism. Please bring back our train!! 
  • Please include the Old Gaol as well. Thank you for taking the initiative. 
  • Please save our station - we used to have the railway line behind our home in Francis Street - so many wonderful memories of waving to our school mates as they left for holiday!.  This is a historical monument - please save this!  
  • Please save this historical building.
  • Preserving out heritage of whatever nature preserves our history and is not negotiable.
  • Rail played such an important part in the development of South Africa. Rail heritage is also a great tourist attraction. We get thousands of visitors a year enjoying our rail heritage product. www.santosexpress.co.za
  • Save it!
  • Save the station!
  • Something has got to be done.  This was a special place a long time ago but more recently it was also used by non profit organisations as their offices. 
  • The appropriate people are not at all looking after Grahamstown's historical buildings. They are all going too rack and ruin.
  • This beautiful old station is a national asset and worthy of safeguarding for future use. It is against the letter and spirit of the regulations to just allow it to be plundered. The fact that is owned by an SOE which is permitting this devastation is cause for greater concern as any state or state owned institution should be setting a good example in these matters.
    It could surely be rented out for business use and produce income but the SOE does not seem to care about that either.
  • This is a dreadful shame on Grahamstown to allow this heritage building to be vandalised.
  • This is atrocious what is happening. We need to stand together and do what is right. Let us not destroy the history of our country !!!
  • This is definitely worth preserving and restoring. Could provide a rich and lucrative tourist offering.
  • This is the MOST THRILLING news to hear - CONGRATULATIONS on your Petition - it will definitely get the required review and support by everyone - GOOD LUCK
  • This magnificent entity is now a disgrace to Grahamstown. The municipality should stop hiding away and step forward. Nearly 200 years of history..... left to rot!!! 
  • Transnet and affiliates have been dereclict in their duty in maintaining the railway infrastructure in this country. The fate of this magnificent old station is a symptom of a nation wide problem. As fuel prices rise there may be a good chance that rail will once more come into its own again and Transnet will rue the day they did not perform routine maintainance and monitoring instead of facing the massive expense of starting from scratch. The fact that they could not care about their own heritage sites is also shocking. If they could not care less, why did they agree to the declaration?
    Very disheartened by the state of the railway station as it is now.
  • We need to save this beautiful building before it falls down!!!
  • What a shame that Transnet is neglecting its assets like this!
  • The decline of this beautiful old building has economic implications for the city - and already we see impacts on tourism and business.
    Many, many times before, there have been efforts to establish the old railway station as a terminus for the various long distance bus services which come to Grahamstown, but this has never come to be, due to lack of vision or good leadership. If such an initiative were facilitated, the building could serve as a safe and hospitable waiting point for travellers, and enable the creation of economic opportunities for local entrepreneurs (e.g. internet cafe, sale of tea/coffee, snacks, newspapers, etc etc). Saving the station is the RIGHT THING TO DO.
  • Until recently, we lived in Grahamstown for over 21 years and feel strongly that any building that adds to the great architectural heritage is worthy of preservation.   The railway station is a beautiful building that, if restored, could be put to good use.
  • Grahamstown is a magical and beautiful place. The restoration of the station is really important and invaluable to its people.  
  • This historic station needs to be saved.
    This could become a character hotel, craft centre (to support local industry) or creative hub for tourists.  Think, Transnet, think!
    Save our heritage buildings.
  • I went to Rhodes and love Grahamstown and it holds a special place, I think it could be an amazing opportunity for the town!
  •  Save our Station!!!!!
  • With fuel shortages, one day we might need this station.  Solar trains hopefully.
  • The neglect of the station is a disgrace. Makana Municipality and Transnet should be ashamed.
  • As an artist who visits Grahamstown each year (sometimes more than once) for both work and pleasure, I would FAR prefer to get the train than drive or fly. Reinstate the railway line and the station. We will use it I promise!
  • Excellent idea
  • This could be restored so beautifully and become both educational and a tourist attraction. Don't let vandals destroy our history!! Heritage is a vital part of who we are.
  • Once heritage is lost it can never be recovered. 
  •  I have fond memories as a kid going by train from Krugersdorp to Grahamstown to visit my grandparents.
  •  Heritage is to the physical world as birthright is to a human being. We do not leave our old folk to waste away uncared for and unloved. We preserve their memories and pass them on to our off-spring. They have real value, as all historical knowledge has, as a major contribution to our wisdom and understanding of our past and therefore, also, vitally of our present, which guides us through the challenges of our future. Destroy the past and you destroy the future. (Frank Ross R.U. 1969)
  •  Surely if the building is being stripped and vandalised the police should be involved in prevention and prosecution?
    • That is part of the problem: Transnet do not show up to support any criminal charges and the police claim they cannot act if the owners are not prepared to appear in court.
  • Heritage sites should be maintained and remain open to the public.
  • Authorities should be brought to book for allowing this to happen, not just Transnet, but Makana municipality and the Police. Charges should be laid.
    Another suggestion is to turn the area into a crafters centre, veggie market and such like, as they did in Mossel Bay. Regular use of space (and onsite security)  will prevent vandalism and vagrants loitering around unchecked.
  • Please save this important heritage site which if utilized creatively could create employment in Grahamstown.  
  • It would be wonderful to save our heritage and see our trains running again. A lot of Old Stations are used as Restaurants in Kzn.
  • The National Heritage Resources Act
    SCHEDULE
    BE IT ENACTED by the Parliament of the Republic of South Africa, as follows:—
    Application and interpretation
    1. This Act binds the State.
    This legislation aims to promote good management of the national estate, and to enable and encourage communities to nurture and conserve their legacy so that it may be bequeathed to future generations. Our heritage is unique and precious and it cannot be renewed. It helps us to define our cultural identity and therefore lies at the heart of our spiritual well-being and has the power to build our nation. It has the potential to affirm our diverse cultures, and in so doing shape our national character.
    Our heritage celebrates our achievements and contributes to redressing past inequities. It educates, it deepens our understanding of society and encourages us to empathise with the experience of others. It facilitates healing and material and symbolic restitution and it promotes new and previously neglected research into our rich oral traditions and customs.
  • Save the station !!
  • Disgrace that a valuable building which could be an asset to Grahamstown as an attraction for tourists is left to rot and for thieves to steal a building piece by piece and the powers that be do nothing about it. 
  • I support preservation of historical buildings
  • I grew up in Grahamstown and have such special memories. It's so sad to see how many parts have been neglected.  I hope that it can be restored to its lovely nature that it had many years ago. 
  • Please help save a heritage building in a beautiful town
  • We need to preserve our heritage for the good of all South Africans.
  • The train line from Alicedale through Grahamstown down to Port Alfred should be promoted as a tourist must do.  Team up with B&Bs and hotels and other accommodation in Port Alfred to give a package deal.
  • Proud 1820 Settler descendent and horrified that important historical sites are being neglected.
  • This situation is a disgrace. The station, the old gaol, Grahamstown genrerally. 
  • This should never had happened - we need to value and treasure this piece of history - so sad!! 
  • Restoring it for a useful purpose would be fantastic!
  • Born and raised in Grahamstown.
    Please save the station!!
  • Rail transport to and from Grahamstown would be fantastic for the area. It could not only be utilized by students and folk connected with all the schools and the university in the area, but also for the Arts festival goers, and tourists in general.  Special tours could be arranged highlighting our Settler heritage, and this could have a knock on effect for b&b's etc, bringing much needed revenue and employment to the area.
    Saving these old buildings too, is so important, tourists also love to visit such places, and possibly a steam train trip could be part of the whole idea to inject life and employment into the area.
  • Allowing the old train station to fall into disrepair is a major security risk not only for people who live in the surrounding area but also for people who use the pathway back to the township from there.  There have been a number of reports of people being robbed by violent thugs who have taken to hanging out by the old train station.  Aside from the security risks that arise from the current situation, the old train station is a part of Grahamstown's history and should be preserved as a monument of sorts for the benefit of tourists and locals alike.  
  •  Was born in Grahamstown. Lived and worked there many years. Children went to school there. Used the train station on average once a year while there. Very sad to see it in such sad state. Hope it can be fully restored or at very least, buildings used for community.
  • I would love to see the train station be operational again, with everyone that has so much transport problems I don't see why not? What about using it to transport goods is petrol not so expensive that this will be a valid option to transport?
  • It would be shame to see the buildings be destroyed. If restored and USED they would be a valuable asset for all of Grahamstown's citizens
  • As old residents of Grahamstown we would hate to see this historical station being pulled down.

Tuesday, May 6, 2014

Fossil Fuel Liberation

One of the arguments against rapid deployment of renewable energy is cost.

Renewable technologies over time become cheaper as R&D improves; fossil fuels on the other hand become more expensive as they deplete. Eventually we will reach a point when fossil fuels will become too expensive and at that point, so the argument goes, the market will fix the problem. The difficulty with that argument is that the longer we wait, the more installed infrastructure there is to replace.

What we have seen with oil is that, aside from times when there have been short-term price shocks, the inflation-corrected price of oil up to 2006 remained around $30 per barrel. Then in 2007, the price rapidly took off and headed to about $150, before a worldwide economic crisis slowed the world economy. Even so, the price has persistently stayed at 3-4 times the long-term level.

Why? Because conventional oil output was heading to a peak, meaning we were increasingly relying on more expensive resources that previously were not viable.

What that illustrates is that when supply becomes constrained, price can rapidly exceed the levels where alternatives become viable, meaning the price signal favouring alternatives kicks in a lot faster than those alternatives can be rolled out. Had the financial sector not collapsed in 2007, the rapid increase in oil prices would have triggered a downturn.

Take a look at these three scenarios in which energy use increases by 2.5% per year (close to the long-term average), doubling roughly every 30 years.


In the first scenario, we have only fossil fuels contributing to that doubling. That means after 30 years, we have twice as much fossil fuel infrastructure to replace as we had at the start. If prices of fossil fuels only increase rapidly once supply fails to keep up with demand, we have an enormous amount of infrastructure to replace very quickly. The red arrow illustrates the amount of energy production that must be replaced.

What if we have a cautious approach and aim to increase renewables by 1.5% of total energy demand per year, i.e., not as much as demand increases? Then we have the second scenario (bottom left panel). In this scenario, when we have to replace fossil fuel infrastructure, the total amount is still large – about 70% of the amount in the no renewables scenario.

If we try harder and aim to increase renewables by 3% of total energy use every year, i.e., more than the increase in demand, we get the final scenario. In this version, after 30 years, the red arrow represents less than 40% of the infrastructure that would have to be replaced in the first scenario.

How soon do we need to worry about this? Don’t we have 200 years worth of fossil fuel reserves?

Leave aside the issue of climate change that says we shouldn’t actually burn all this stuff.

At a rate of increase of 2.5% per year, 200 years of use results in a little over 70 years before it’s all gone. And in practice, long before we get there, the high quality resources will be depleted.

If we do not want a real monster of an economic crash when all cheap fossil fuel reserves run out and we don’t have time to replace all that outdated infrastructure, we should aim for a faster deployment scenario in which new clean energy increases faster than total demand. As I illustrate here, that faster increase need not be dramatic if we start early enough. Wait too long, and we start running into scenarios where we have to replace a lot of infrastructure at once – and that can only be expensive.



Friday, January 24, 2014

Science and Advocacy

Science and values

Two recent articles at RealClimate by Gavin Schmidt and Mike Mann discuss the issue of scientific advocacy.

Back in apartheid South Africa, academic advocacy was controversial. There were those who argued science was value-free and hence above political concerns. Others argued that science may be value-free but scientists aren’t – you can choose the problem you work on, and can avoid those that may do harm.

We had another instance of this in the tobacco and HIV wars. The denial camp used every trick in the book to confuse the public, and scientists who weighed in were often accused of venturing into politics, as if the other side had not. And in any case, why should scientist not employ their well-informed views to public debate? Does anyone object if a lawyer uses their legal knowledge to articulate a policy position, or an accountant, or any other professional? Must a political scientist confine their critique to theoretical or historical political systems, rather than the world today?

Why do scientists need to be apologetic about informed advocacy, when advocacy is a core value of those opposing the mainstream – to the extent that their advocacy will embrace any argument even when they contradict themselves?
Somehow, being an advocate when you are almost certainly right is unacceptable whereas being an advocate when you are almost certainly wrong is just fine.
People like Richard Lindzen (MIT, climate science contrarian) are no strangers to the op-ed pages, and the people who took Mike Mann on in the faux hockey stick controversy did not restrict their commentary to scientific publication – subjecting someone to multiple levels of inquisition including a congressional investigation went way beyond standard scientific etiquette.

Who let the dogs out?

The gloves have been off for a long time, and the people who threw the Queensberry rules out of the window are on the anti-science side.
It’s time we started saying this loud and clear, and stopped letting them get away with the myth that the mainstream has somehow perverted science to a political and rather doubtfully-constructed economic agenda, when it is clearly the case that the denial camp is guilty of all the above (except the economic case for denial is crystal clear).

Finally, there is the question of fake balance – the notion many news media have that you have to give equal time to both points of view. This is not consistently applied – the “balance” usually happens if both sides have similar clout, or the one that is left out complains loudly enough. When, for example, is the TV news market report followed by a Trotskyist rebuttal? You may argue that Trotskyism is not a valid economic model, but then you are making a judgment about the “other side”. If the “other side” has no plausibility, why give them equal time?

Or as Isaac Asimov succinctly put it, the denial argument is “my ignorance is just as good as your knowledge”. So why do arguments with scant evidence such as tobacco isn’t that harmful, HIV doesn’t cause AIDS and climate change isn’t happening rate “equal time”?

Usually this happens when the people pushing the denial agenda have significant clout – political or economic. In the case of AIDS denial, a case that was largely being ignored because it had no serious evidence to back it was pushed to the forefront when former South African president Thabo Mbkei embraced the denial argument because it suited his politics, which denied that African people could have any special susceptibility to disease other than colonially-imposed social causes. With tobacco and climate change, economically powerful businesses are threatened by the science, so they defend themselves with obfuscation, aiming to delay policy changes negative to their continued profitability, and damn the consequences. With tobacco, this eventually caught up with them when they lost major lawsuits and were forced to publish documents revealing the extent to which they supported scientific fraud and in general a campaign of confusion. It should be no surprise to anyone who has witnessed the pro-tobaccco and anti-climate science campaigns that they are not only similar in style but have common roots.

What to do?

So what are scientists to do in the face of a concerted denial campaign? Withdraw to the lab and allow something harmful to continue? Aside from the obvious ethical issue with doing so, I can guarantee that once the evidence of harm becomes impossible to ignore, scientists who were in the know will be blamed.

So no, keeping quiet is not an option. So what is?

I had the now sadly not to be repeated pleasure of watching late Stanford professor Stephen Schneider talking to a skeptical audience in Australia. He did not get emotional. He did not insult them. He patiently explained why each point they were making did not fit the evidence.

This is a model for how scientists can operate. It does not mean we cannot go into politics, or orgue for particular policy settings. But it does require discipline in talking about the science.

Saturday, August 31, 2013

The State of Oil

Former Saudi oil minister Sheikh Yamani is reputed to have said
The stone age didn’t end because we ran out stones.
By this I guess he meant that the industry should watch its success at maintaining a price cartel, because that would lead to intensified research on alternatives. Since the oil crises of the 1970s and 1980s, OPEC has tried to keep pumping oil at the rate the market demands, to avoid the kind of price shocks that lead to renewed electric car research, better public transport, and so on.

Oil prices adjusted to 2013 dollars. Source:
http://inflationdata.com/Inflation/Inflation_Rate/Historical_Oil_Prices_Table.asp
How successful have they been? Prices fell rapidly since the last major conflict-induced price shock in 1979, the Iranian revolution. While the Gulf War of 1990 caused a price spike, this was nothing on the scale of the previous price shocks. The Iraq war in 2003 is not a serious candidate for the ongoing increase in prices, since this has continued well past the point where Iraqi oil production resumed. The Arab Spring movement of 2011 can’t be blamed for a major decline in output either, as the countries most affected are not major oil producers. Libya, for example, is only responsible for about 2% of worldwide oil production, though it’s 17th in the world in total production. And Libyan oil output us more or less back where it was before the 2011 uprising.  Remember also that there has been a worldwide economic crisis since 2007, with many countries battling to recover since. So the oil price spike hasn’t been driven by major conflict or an upsurge in demand. The worst of the 2007–2008 global crisis only pulled prices back a little, bringing them nowhere near the inflation-corrected stable average of about $20 (corrected to 2013 US$).

It is plausible that this price spike is being driven by growing difficulties in extracting oil fast enough to meet demand. If you don’t know about peak oil theory, this may be a good time to find out.




Saturday, August 24, 2013

Climate Change Lines of Evidence

Much of the contrarian position on climate change relies on question the sensitivity of the climate to varying CO2 content of the atmosphere. The mainstream science says that doubling the CO2 concentration should add about 3°C, with some variation depending on the starting conditions (e.g., the amount of ice at the start). Contrarians claim that climate sensitivity to increased CO2 is much lower, perhaps at most 1°C per doubling – and some even claim the greenhouse effect is already saturated, meaning more CO2 will have no effect. All these contrarian claims are simply claims without evidence to back them up.

The evidence I’ve found so far strongly suggests the contrarians are wrong. Which is a real shame, because the contrarian argument is winning as long as there is no strong worldwide move to cleaner energy. Since I don’t want disaster, I would really like them to be right. Unfortunately, nature has no concern for our preferences.

One of the problems with understanding why adding CO2 to the atmosphere drives climate change is there isn’t a simple equation that shows how the physics works. To calculate the actual effect requires taking into account the overall complexity of the planet, including the nature of the atmosphere that not only varies in density with altitude but also composition – water vapour for instance is not only highly variable in its geographic spread but the range of altitudes over which it is present.

If you want a comprehensive understanding of the greenhouse effect and how it applies to a whole planet, you have little option short of reading a textbook (e.g. RT Pierrehumbert’s Principles of Planetary Climate).

Nonetheless there are plenty of lines of evidence that make the case even if you don’t have a deep understanding of physics and calculus. Here are some.

Faint Young Sun

4-billion years ago, the sun’s intensity was only 70% of its current energy output. That would not have been sufficient under today’s conditions for the oceans to be liquid, yet the geological evidence is that there were liquid oceans that long ago. During that time, there was no life as we know it, and greenhouse gas concentrations would have been a lot higher than they are now. Greenhouse gases are the best explanation for liquid oceans at that time, though there is a lot of uncertainty given how long ago this was, and the limited range of geological data. Even so, we can be reasonably sure that a CO2 level ten times or more the current level would have had a very significant warming effect, and that coupled with other greenhouse gases could have made the planet warm enough for liquid water.

Snowball Earth

Several times in the distant past, with the last such event about 630-million years ago, the Earth froze over completely, almost to the equator. Under these conditions, CO2 cannot be drawn down from the atmosphere. There is unlikely to be sufficient plant life – even phytoplankton – able to consume CO2, and natural chemical processes that draw down CO2 require liquid water. In a snowball earth, CO2 in the atmosphere gradually increases until there is enough of a greenhouse effect to start melting the ice. This CO2 builds up from emissions from volcanoes, normally a minor effect offset by weathering, where rocks high in calcium dissolve in carbonic acid (CO2 in water) to form carbonate rocks such as limestone. Weathering requires liquid water, so the chemistry required stops if the planet ices over completely. Consequently any CO2 vented by volcanoes that escapes the ice cover into the atmosphere stays there. Without a greenhouse effect, the ice would not melt because ice has a high albedo (fraction of incident light reflected), and any region covered in ice reflects a high fraction of incoming solar energy back to space. Absent an increased greenhouse effect, a planet can only shed such a complete ice cover after a wait of millions – possibly billions – of years for the sun to become warmer.

A snowball earth can eventually end in a return to a warmer world as a result of the steady accumulation of CO2 in the atmosphere, leading to sufficient warming to melt the ice back to the polar regions – some simulations show this taking as little as 2000 years, a sharp contrast to waiting billions of years for the sun to warm up.

Milankovitch Cycles and Climate. The top three graphs
derive orbital parameters and the fourth (from the top)
shows resulting variation in northern hemisphere solar
energy. The bottom two graphs are indications of past
climate variability that can be related to the fourth
graph. For more detail, see WikiPedia.

Milankovitch Cycles

Serbian scientist Milutin Milanković, through laborious calculations, demonstrated that variations in the Earth’s orbit over millions of years corresponded to movement in and out of ice ages. Physics calculations of the change in incoming solar energy cannot account for the temperature swings needed to change between states of kilometres-thick ice caps and no ice over continental-scale regions. On the other hand, we know that the oceans’ capacity for dissolving CO2 is temperature dependent. As temperatures increase, the oceans release CO2. This increases the greenhouse effect, and hence amplifies a temperature increase. The opposite applies when temperatures are decreasing.

In this scenario, CO2 is acting as a positive feedback, an amplifying effect, rather than as a primary driver of climate change.

Reverse the scenario: if a change in the Earth’s orbital parameters causes cooling, the oceans dissolve more CO2 and once again CO2 amplifies the change.

Other feedbacks include a change in ice (less ice means less heat is reflected to space) and increased water vapour (a strong greenhouse gas) but these effect are insufficient to explain the temperature swings.

Mass Extinctions

PETM in context. In geological time the PETM event is for
practical purposes instantaneous – yet happened about 50
times slower than current climate change. Source: WikiPedia.
Our planet has undergone several mass extinctions where a large fraction of life was eliminated. These mass extinction events generally follow a massive planetary climate change. In some such events, the change has been a rapid temperature rise, preceded by a rapid increase in greenhouse gases. Good examples are the end-Permian extinction (the biggest of the mass extinction events, about 253-million years ago) and in the Paleocene–Eocene Thermal Maximum (PETM). The PETM is the more recent of these two events, and hence a bit easier to study in detail. The evidence if that temperatures increased by 6°C over about 20,000 years. Such an increase could be caused by a quadrupling of CO2. It’s sobering to consider that such an increase over 20,000 years caused a major extinction event, with an average increase of 0.003°C per decade, compared with the current rate of increase of about 50 times faster.

Other Planets

Planetary temperatures. Note that though Mercury
is much nearer the sun than Venus, Venus has a much
higher average surface temperature.
 Source: NASA.
The temperature of a planet is dependent on three major variables (with other factors like oceans contributing):

  • distance from the sun (or in effect the amount of incoming solar energy)
  • albedo (the fraction of incoming energy that is reflected)
  • atmosphere (ability of the atmosphere either to reflect energy back to space, or to slow the rate of energy flow out to space)
The planets from the sun outwards should be increasingly warm, if the first effect is the only one. This is mostly the case, but Mercury has a lower average surface temperature than Venus, despite being much closer to the sun (57,910,000 km, versus Venus at 108,200,000 km). Much modern climate science derives from study of the temperatures of other planets. Venus has a dense atmosphere mostly containing CO2, so it has an extreme greenhouse effect. Other planets have different atmospheres (Mars’s atmosphere, for example, is also mostly CO2 but much less dense than the Earth’s) , and modelling these variations is a starting point in the theories that today are used to model the effect of increasing CO2 on our planet’s climate.

Summary

All these lines of evidence are a small part of the picture. If here is indeed a very low climate senstitivity to increased CO2, all of the theory explaining these events would be wrong. So contrarians not only have to explain why prediction of future climate change are wrong, but also have a reasonable alternative explanation for all these lines of evidence.

The current theory of climate, which takes into account variations in solar output, changes in the atmosphere and various modes of redistribution of energy around the planet, has been well tested in several ways, including modelling the paleoclimate, forecasting climate change then checking as new data comes in, and hindcasting (testing predictions against known data). In addition, there are other lines of evidence like shifts in the range of temperature-dependent plants and animals.

The current theory of climate started from understanding the shifts between ice ages and temperature on other planets of our solar system. The theory continues to be refined as more data becomes available and more computational power is available for more complete models. So far, the major effect of improved models has been refinement rather than refutation. Every now and then a contrary result appears, but it does not stand up to rebuttal.

Every now and then, a model prediction turns out to be incorrect. It would be surprising were that not the case, with such a large-scale, complex system to model. Pointing at such flaws as indicating there is no problem and we should continue with business as usual is silly – like a morbidly obese patient deciding not to lose weight when a heart attack scare turns out to be a false alarm.

Without a strong greenhouse effect, the Earth could not have had liquid water when the sun was only emitting 70% of its current energy. Without a greenhouse effect, the Earth could not have escaped a snowball state. The greenhouse effect is required to amplify the effect of Milankovitch Cycles, otherwise orbital variations are insufficient to explain deep difference between glacial and interglacial climate. In all these cases, CO2 has to play a prominent role. There is no other greenhouse gas that can vary on a sufficient scale to make a difference. The kind of very rapid climate change – particularly warming events – that has triggered some of the biggest mass extinction events can also only be explained by the greenhouse effect. Finally, the greenhouse effect has been thoroughly studied for other planets and nothing else can explain the extremely high surface temperature of Venus.

Sunday, August 18, 2013

It’s the Energy

Bill Clinton’s campaign strategist James Carville coined the phrase The Economy Stupid, often since echoed as It’s the X, stupid as a mantra for keeping focused. I prefer not to call people stupid. So let me just say we should pay more attention to energy flows when we talk climate change, otherwise stupid or not, nothing will matter.

There is a certain rate of energy flow to the planet from the sun. Unless the planet can match that inflow by exactly the same outflow, the system is not in balance. The only way our planet can shed excess energy is by radiation to space. The only way we can increase the net outgoing radiation is by a temperature increase. So the thing of real concern is radiative energy balance [Pierrehumbert 2011].

So why then does everyone keep going on about temperature?

It makes sense to measure the temperature on the ground because it has to increase if energy is flowing in faster than energy is flowing out (energy flow in > energy flow out), until the rate of outgoing energy matches incoming.

The problem is that by focusing on temperature as the one measure of interest, we miss a rather vital point:
If the temperature is not increasing while net energy flow in exceeds net energy flow out, we are not shedding the excess energy.
Why is this important? To see why, we need to understand where the extra energy can go if it’s not increasing surface temperatures.

There are two primary ways the planet stores extra energy without raising surface temperatures: ocean sequestration and latent heat. Let’s look at these in more detail:
  • ocean sequestration – only the upper layer of the open is sufficiently transparent to infrared to radiate to space; if energy is transported deeper by currents, most of it stays there
  • latent heat – when a substance undergoes a phase change (solid to liquid or liquid to gas) a significantly higher amount of energy is needed for the phase change than for a temperature change of 1 degree (sensible heat is the term used for energy that results in a temperature change); here are some figures for water, all for 1kg (to a good approximation, a litre; we measure energy in units of a joule or J):
    • energy to increase temperature by 1°C: 4.2kJ
    • latent heat of melting: 334kJ (about 80 times the energy needed to raise the water by 1°C)
    • latent heat of evaporation: 2.3MJ (over 500 times the energy needed to raise the water by 1°C)
Latent heat vs. sensible heat. It takes almost as much
energy to melt 1kg of ice without changing the temperature
as to raise 1kg of water through 100°C; evaporating 1kg of
water takes 5 times as much energy as raising water by
100°C.
It is instructive illustrate the relative amounts of energy needed for latent and sensible heat by comparing the energy needed to raise water by 100°C (the range over which it can be a liquid at sea level), with the energy needed to melt ice and the energy needed to evaporate water.

Ocean sequestration is important because many ocean ecosystems rely on the current stratification of ocean temperature, warm on top, icy-cold in the depths. Mess with that in a big way, and consequences for biodiversity and the food change could be dire, and are unpredictable with current knowledge. Also, temperature stratification is a major driver of ocean currents, something we disrupt at our peril. Another important factor is that this energy can periodically be released to the atmosphere resulting in sudden spikes in temperature (e.g. an El Niño event).

What are some consequences of the latent heat part of the equation?

If ice is melted, that is a positive feedback or amplifying effect. In other words, the radiative energy imbalance increases. Why? Because ice is highly reflective (in physics terminology, it has a high albedo). As long as the ice is only thinning there’s no change in albedo but once bare ground or water is exposed, the newly exposed darker surface absorbs more energy. If a region of the planet absorbs more energy, that pushes the net energy balance upwards, meaning temperatures have to increase further to balance the equation.

Latent heat of evaporation is not our friend either, for a different reason.

Latent heat is in general terms a big deal because it can use up so much more energy than temperature change while a phase reversal can release that energy as a temperature change. For example, if water vapour precipitates out of the air, the energy of vaporisation returns to the air as a temperature rise. Latent heat is a major driver of extreme weather [Liu et al. 2011] because of the massive differential between the energy needed for a phase change and the energy needed for a 1°C shift.

The really important thing about all this however is that these energy sinks can take up large amounts of incoming energy without changing the radiative energy balance. In other words, they do not fix the problem of energy flow in > energy flow out.

Why does this matter? Because an apparent slowdown in temperature increase is not good news if the energy imbalance is still there. The extra energy is having a number of effects most of which are not positive – and temperature increase is still going to happen.

If this is so important, why do we mostly talk temperatures not energy? Because temperature is something we can experience directly, something that is easy to measure and also a direct reflection of the energy increase, if not the only one. But most importantly, the surface temperature has to increase eventually so outgoing radiation can match the inflow. Why has energy not figured more prominently? Because at the early stage of concerns about climate change, we lacked the means to measure net energy flux, but we did have a long record of surface temperatures going back to the 19th century. Even now, with extensive satellite data, it is not practical to measure energy out with sufficient accuracy to measure the imbalance. First, the imbalance across the planet varies by time, latitude and date. During summer in one hemisphere, that hemisphere has a positive energy balance, while the opposite hemisphere has a negative energy balance. Those two imbalances sum to close to zero, and the difference is the net imbalance. The technology does not yet exist to measure the imbalance to an accuracy of 0.1W/m2, needed to measure the imbalance that the models infer [Hansen et al. 2011].

What evidence do we have that the energy imbalance is real?

Until accurate direct measurements are possible, the best we can do is look for evidence that the effects other than temperature change are happening. Measuring ocean heat content is still a work in progress (with one paper indicating unexpectedly deep increases in temperature [Balmaseda et al. 2013]), and will be a key indicator. The most obvious one that is directly measurable is latent heat of melting. The Arctic has been losing ice rapidly throughout the period when temperature change has supposedly slowed down, indicating that the energy content of the planet is increasing in that region. In the absence of evidence that the energy content of the planet is decreasing anywhere else, that is an indicator that warming is continuing, even as temperatures are not rising sharply.
Arctic sea ice. 2012 set a new record for a low in
summer sea ice for the Arctic, with no special local
conditions or unusually high global temperature.

In any case is it really true that temperature change has paused? Aside from that the Arctic doesn’t care what we think and is losing ice regardless, what do the numbers actually say?

If you take out the influences of volcanoes (particles they spew into the upper atmosphere have a cooling effect), the solar cycle (hint: cycle implies an effect that cancels out in the long term) and the El Niño Southern Oscillation (hint: oscillation implies an effect that cancels out – you guessed it – over the long term), the trend since 2000 is still up and statistically significant [Foster and Rahmstorf 2011].

My references are all from 2011 – except for a 2013 paper on ocean heat content, an area where further work is called for – recent enough to be current, old enough to have been refuted if wrong.

References
[Balmaseda et al. 2013] Magdalena A. Balmaseda, Kevin E. Trenberth, Erland Källén, Distinctive climate signals in reanalysis of global ocean heat content, Geophysical Research Letters, 40(9) 1754–1759, 16 May (HTML)
[Foster and Rahmstorf 2011] Grant Foster and Stefan Rahmstorf. Global temperature evolution 1979–2010, Environmental Research Letters 6(4) 2011. (online)
[Hansen et al. 2011] J. Hansen, M. Sato, P. Kharecha and K. von Schuckmann. Earth’s energy imbalance and implications, Atmospheric Chemistry and Physics, 11(24) pp 13421–13449, 2011 (PDF)
[Liu et al. 2011] J Liu, JA Curry, CA Clayson and MA Bourassa. (2011). High-resolution satellite surface latent heat fluxes in North Atlantic hurricanes. Monthly Weather Review, 139(9), 2735-2747 (PDF)
[Pierrehumbert 2011] Raymond T. Pierrehumbert. Infrared radiation and planetary temperature, Physics Today 64(1) 2011, pp 33–38. (PDF)

more sciency stuff
A joule (J) is an energy measure. We measure the rate of energy use in watts (W). We also think of watts as a unit of power (intuitively, a more powerful engine burns energy faster). In electricity household consumption measures, a rate of usage is usually in kW, and we measure total energy use in kWh (thousand watts times hours: these are the units you may see on your electricity bill). kWh are just joules scaled to units that you can relate to your own consumption. 1kWh = 3.6MJ. You can derive this conversion from the fact that an hour is 3600 seconds.

Energy to increase temperature of a material is specific heat. I express this here as energy in kJ to raise temperature of 1kg of material by 1°C. We already have this for water. Some numbers, mainly for metals, for comparison:
  • water: 4.2
  • ice: 2.1
  • aluminium: 0.91
  • copper: 0.39
  • gold: 0.13
  • iron: 0.45
  • lithium: 3.57
  • silver: 0.23
From this we see that water has a remarkably high capacity for storing energy. Although common liquids and fluids generally have higher specific heats than metals, water is near the top of the list. This property, combined with the ability of the oceans to mix temperature change faster than conduction allows (soil and rock, for example, can’t move warmth from their surface except by conduction), explains why the oceans, though only about 66% of the earth’s surface, absorb about 90% of any energy imbalance.

Albedo (the fraction of light reflected) varies a lot. Here are some numbers (1 means reflects 100%, 0 reflects nothing):
  • asphalt 0.02–0.12 (fresh asphalt is darker)
  • conifer forest in summer 0.08–0.15
  • bare soil 0.17
  • green grass 0.25
  • sea ice 0.5–0.7
  • new snow 0.8–0.9
Water albedo varies depending on the angle of incident light; a reasonable comparative figure to use versus ice is 0.06. Building long-term ice is aided by snowfalls because snow has such a high albedo, which reduces any tendency to warm from above after snow has fallen.


And in case you were going to blame solar variation for global warming, check out this picture of solar variation measured by satellite (PDF original here). 1998 and 2005 are among the hottest years on record. 1998 was not far off a solar low. 2005 was well on the way down to the the next low. And the current solar cycle, due to peak some time soon if it hasn’t already, is way below the average. We should be experiencing 100-year lows in temperatures if it was only the sun causing climate variability.


Compare solar variation with temperature (you can get the latest version of this from NASA). The satellite data starts in 1978, so ignore the earlier part of the temperature data. 1978-2012 temperatures clearly trend up (and this is even clearer if you do the stats – get the data from NASA and see for yourself if you don’t believe me). The solar cycle on the other hand is just an oscillation and the trend is down not up in the variation. Again, there’s data free for you to download if you want to check.






To make it a bit easier to compare the two, I rescaled the NASA temperature data so it matches the time scale of the incoming solar energy data and chopped it to fit the satellite record. You can do statistical analyses to compare the two but, even without, it’s pretty clear that temperatures have been increasing while the solar cycle has not only doing its usual fluctuations but flattening out. And, remember, over the time that the latest solar cycle has been failing to peak at the same level as previous cycles, we’ve had record loss of Arctic summer sea ice.