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I was scanning my blog stats the other day – partly to see if people were reading my new post on the Blue Mountains bushfires, partly because I just like graphs – when I noticed that an article I wrote nearly two years ago was suddenly getting more views than ever before:

The article in question highlights the scientific inaccuracies of the 2004 film The Day After Tomorrow, in which global warming leads to a new ice age. Now that I’ve taken more courses in thermodynamics I could definitely expand on the original post if I had the time and inclination to watch the film again…

I did a bit more digging in my stats and discovered that most viewers are reaching this article through Google searches such as “is the day after tomorrow true”, “is the day after tomorrow likely to happen”, and “movie review of a day after tomorrow if it is possible or impossible.” The answers are no, no, and impossible, respectively.

But why the sudden surge in interest? I think it is probably related to the record cold temperatures across much of the United States, an event which media outlets have dubbed the “polar vortex”. I prefer “Arctic barf”.

Part of the extremely cold air mass which covers the Arctic has essentially detached and spilled southward over North America. In other words, the Arctic has barfed on the USA. Less sexy terminology than “polar vortex”, perhaps, but I would argue it is more enlightening.

Greg Laden also has a good explanation:

The Polar Vortex, a huge system of swirling air that normally contains the polar cold air has shifted so it is not sitting right on the pole as it usually does. We are not seeing an expansion of cold, an ice age, or an anti-global warming phenomenon. We are seeing the usual cold polar air taking an excursion.

Note that other regions such as Alaska and much of Europe are currently experiencing unusually warm winter weather. On balance, the planet isn’t any colder than normal. The cold patches are just moving around in an unusual way.

Having grown up in the Canadian Prairies, where we experience daily lows below -30°C for at least a few days each year (and for nearly a month straight so far this winter), I can’t say I have a lot of sympathy. Or maybe I’m just bitter because I never got a day off school due to the cold? But seriously, nothing has to shut down if you plug in the cars at night and bundle up like an astronaut. We’ve been doing it for years.

During our time in Australia, my partner and I decided on a whim to spend a weekend in the Blue Mountains. This national park, a two-hour train ride west of Sydney, forms part of the Great Dividing Range: a chain of mountains which stretches from north to south across the entire country, separating the vast outback to the west from the narrow strip of coastal rainforest to the east.

For a region so close to Sydney, the Blue Mountains feel surprisingly remote. You can stand at any number of clifftops, gaze out over a seemingly endless stretch of land, and see no sign of civilization whatsoever. Or you can walk down into the valleys between the mountains and explore the rainforest, a vast expanse of ancient gumtrees that’s managed to hide koalas previously thought to have vanished, and possibly even an escaped panther.


Four months later, when we were safely back in Canada, the Blue Mountains bushfires began. It was October, barely even spring in the Southern Hemisphere. To have fires starting so early in the season was virtually unheard of.

The triggers for the fires were decidedly human-caused: arson, a botched army exercise, and sparking power lines. However, unusually hot, dry, and windy conditions allowed the fires to spread far more quickly than they would have in a more normal October.


To get from the clifftops of Echo Point to the walking trails in the valley below, we took the Giant Stairway, which is exactly what it sounds like. Imagine the steepest and narrowest stairway you can manage, cut into the stone cliff and reinforced with metal, and a handrail which you cling to for dear life. Make it 902 stairs long (by my count, so let’s say plus or minus 5) and wind it back and forth around the cliff. After a few minutes walking down the stairway your knees start to buckle, and you require more and longer breaks, but you still can’t see the bottom.

The exhaustion is worth it simply due to the view.

Sometimes we would see swarms of sulfur-crested cockatoos flying over the treetops hundreds of metres below. They looked like tiny white specks at such a distance, but we could still hear them squawking to one another.


The bushfires of 2013 didn’t affect any of the areas we visited in the Blue Mountains – in fact, none of the main tourism regions were damaged. The main losses occurred in residential areas in and around the Blue Mountains. As of October 19th, 208 houses and 40 non-residential buildings had been destroyed.

Despite the huge amount of property loss, there were only two fatalities from the bushfires. This relatively successful outcome was due to mass evacuations organized by the government of New South Wales. At one point a state of emergency was declared, which authorized police to force residents to leave their houses.

As the fires continued to burn out of control, westerly winds blew the smoke and ash right over Sydney. During sunsets the sky over Sydney Harbour turned a bright orange, giving the illusion of a city built on the surface of Mars.


I had heard about lyre birds, widely considered to be among the best mimics of the animal kingdom, many times before. In an elaborate courtship display, the male lyre bird perfectly imitates the songs of nearly every other bird in the forest, one after another like some kind of avian pop-music mashup. Lyre birds blow mockingbirds right out of the water.

Footage from the BBC of a lyre bird imitating camera shutters and chainsaws seemed too good to be true, but its authenticity was bolstered by a similar story from my friend at the climate lab in Sydney. Her neighbours had been doing renovations, and when they were finished the construction equipment went away but the sounds kept going. That’s when they discovered the lyre bird living in the garden.

We saw three or four lyre birds while hiking in the valley that weekend, but for the most part they just wandered around the forest floor, combing through the leaf litter with an outstretched foot and keeping their beaks firmly shut. It was winter in Australia, after all – not courtship season for most birds. On the last day of hiking, we sat by the side of the trail for a rest and a drink of water, while my partner quizzed me on the local bird calls.

“What kind of bird is making that song?”

“An eastern whip-bird, I think.

“Hang on, it just changed into a kookaburra.

“And now it’s a currawong?”

A few minutes later, a male lyre bird strolled out onto the path ahead of us, showing off his fantastic tail feathers and looking extremely pleased with himself.


It is well known among scientists that human-caused climate change increases the risk of severe bushfires. Spells of hot weather will obviously become more common as the planet warms, but so will prolonged droughts, especially in subtropical regions like Australia. Add an initial trigger, like a lightning strike or an abandoned campfire, and you have the perfect recipe for a bushfire.

The current Australian government, which has a history of questionable statements on climate change, really doesn’t want to believe this. Prime Minister Tony Abbott asserted that “these fires are certainly not a function of climate change, they’re a function of life in Australia”, while Environment Minister Greg Hunt cited Wikipedia during a similar statement. I was actually heartened by these events: the ensuing public outcry convinced me that Australians, by and large, do not buy into their government’s indifference on this issue.

It came as a surprise to nobody in the climate science community, and probably nobody in Australia, that 2013 was Australia’s warmest year on record. The previous record, set in 2005, was exceeded by a fairly significant 0.17°C. Even more remarkable was the fact that 2013 was an ENSO-neutral year. For Australia to shatter this temperature record without the help of El Niño indicates that something else (*cough cough climate change*) is at work.

Would the Blue Mountains bushfires have been so devastating without the help of human-caused climate change? In a cooler and wetter October, closer to the historical average, would the initial fire triggers have developed into anything significant? We’ll never know for sure. What we can say, though, is that bushfires like these will only become more common as climate change continues. This is what the future will look like.

At public hearings on the environmental impacts of proposed oil pipelines, Canadians are no longer allowed to discuss climate change: any testimonials concerning how the oil was produced (“upstream effects”) and what will happen when it is burned (“downstream effects”) are considered inadmissible. This new policy was part of a 2012 omnibus bill by the federal government.

So if we refuse to consider the risks, they don’t exist? Or does this government just not care? I’m not sure I want to know the answer.

See the very thoughtful article by Andy Skuce, a geologist who formerly worked in the Alberta oil sands.

I haven’t forgotten about this project! Read the introduction and ODE derivation if you haven’t already.

Last time I derived the following ODE for temperature T at time t:

where S and τ are constants, and F(t) is the net radiative forcing at time t. Eventually I will discuss each of these terms in detail; this post will focus on S.

At equilibrium, when dT/dt = 0, the ODE necessitates T(t) = S F(t). A physical interpretation for S becomes apparent: it measures the equilibrium change in temperature per unit forcing, also known as climate sensitivity.

A great deal of research has been conducted with the aim of quantifying climate sensitivity, through paleoclimate analyses, modelling experiments, and instrumental data. Overall, these assessments show that climate sensitivity is on the order of 3 K per doubling of CO2 (divide by 5.35 ln 2 W/m2 to convert to warming per unit forcing).

The IPCC AR4 report (note that AR5 was not yet published at the time of my calculations) compared many different probability distribution functions (PDFs) of climate sensitivity, shown below. They follow the same general shape of a shifted distribution with a long tail to the right, and average 5-95% confidence intervals of around 1.5 to 7 K per doubling of CO2.

Box 10.2, Figure 1 of the IPCC AR4 WG1: Probability distribution functions of climate sensitivity (a), 5-95% confidence intervals (b).

These PDFs generally consist of discrete data points that are not publicly available. Consequently, sampling from any existing PDF would be difficult. Instead, I chose to create my own PDF of climate sensitivity, modelled as a log-normal distribution (e raised to the power of a normal distribution) with the same shape and bounds as the existing datasets.

The challenge was to find values for μ and σ, the mean and standard deviation of the corresponding normal distribution, such that for any z sampled from the log-normal distribution,

Since erf, the error function, cannot be evaluated analytically, this two-parameter problem must be solved numerically. I built a simple particle swarm optimizer to find the solution, which consistently yielded results of μ = 1.1757, σ = 0.4683.

The upper tail of a log-normal distribution is unbounded, so I truncated the distribution at 10 K, consistent with existing PDFs (see figure above). At the beginning of each simulation, climate sensitivity in my model is sampled from this distribution and held fixed for the entire run. A histogram of 106 sampled points, shown below, has the desired characteristics.

Histogram of 106 points sampled from the log-normal distribution used for climate sensitivity in the model.

Histogram of 106 points sampled from the log-normal distribution used for climate sensitivity in the model.

Note that in order to be used in the ODE, the sampled points must then be converted to units of Km2/W (warming per unit forcing) by dividing by 5.35 ln 2 W/m2, the forcing from doubled CO2.

Explorers

On Monday evening, a Canadian research helicopter in northwest Nunavut crashed into the Arctic Ocean. Three men from the CGCS Amundsen research vessel were on board, examining the sea ice from above to determine the best route for the ship to take. All three were killed in the crash: climate scientist Klaus Hochheim, commanding officer Marc Thibault, and pilot Daniel Dubé.

The Amundsen recovered the bodies, which will be entrusted to the RCMP as soon as the ship reaches land. The helicopter remains at the bottom of the Arctic Ocean (~400 m deep); until it can be retrieved, the cause of the crash will remain unknown.

Klaus Hochheim

During my first two years of university, I worked on and off in the same lab as Klaus. He was often in the field, and I was often rushing off to class, so we only spoke a few times. He was very friendly and energetic, and I regret not getting to know him better. My thoughts are with the families, friends, and close colleagues of these three men, who have far more to mourn than I do.

Perhaps some solace can be found in the thought that they died doing what they loved best. All of the Arctic scientists I know are incredibly passionate about their field work: bring them down south for too long, and they start itching to get back on the ship. In the modern day, field scientists are perhaps the closest thing we have to explorers. Such a demanding job comes with immense personal and societal rewards, but also with risks.

These events remind me of another team of explorers that died while pursuing their calling, at the opposite pole and over a hundred years ago: the Antarctic expedition of 1912 led by Robert Falcon Scott. While I was travelling in New Zealand, I visited the Scott Memorial in the Queenstown public gardens. Carved into a stone tablet and set into the side of a boulder is an excerpt from Scott’s last diary entry. I thought the words were relevant to Monday night’s tragedy, so I have reproduced them below.

click to enlarge

We arrived within eleven miles of our old One Ton camp with fuel for one hot meal and food for two days. For four days we have been unable to leave the tent, the gale is howling about us. We are weak, writing is difficult, but, for my own sake, I do not regret this journey, which has shown that Englishmen can endure hardships, help one another, and meet death with as great a fortitude as ever in the past.

We took risks; we knew we took them. Things have come out against us, and therefore we have no cause for complaint, but bow to the will of providence, determined still to do our best to the last.

Had we lived I should have had a tale to tell of the hardihood, endurance, and courage of my companions which would have stirred the heart of every Englishman.

These rough notes and our dead bodies must tell the tale.

Bits and Pieces

Now that the academic summer is over, I have left Australia and returned home to Canada. It is great to be with my friends and family again, but I really miss the ocean and the giant monster bats. Not to mention the lab: after four months as a proper scientist, it’s very hard to be an undergrad again.

While I continue to settle in, move to a new apartment, and recover from jet lag (which is way worse in this direction!), here are a few pieces of reading to tide you over:

Scott Johnson from Ars Technica wrote a fabulous piece about climate modelling, and the process by which scientists build and test new components. The article is accurate and compelling, and features interviews with two of my former supervisors (Steve Easterbrook and Andrew Weaver) and lots of other great communicators (Gavin Schmidt and Richard Alley, to name a few).

I have just started reading A Short History of Nearly Everything by Bill Bryson. So far, it is one of the best pieces of science writing I have ever read. As well as being funny and easy to understand, it makes me excited about areas of science I haven’t studied since high school.

Finally, my third and final paper from last summer in Victoria was published in the August edition of Journal of Climate. The full text (subscription required) is available here. It is a companion paper to our recent Climate of the Past study, and compares the projections of EMICs (Earth System Models of Intermediate Complexity) when forced with different RCP scenarios. In a nutshell, we found that even after anthropogenic emissions fall to zero, it takes a very long time for CO2 concentrations to recover, even longer for global temperatures to start falling, and longer still for sea level rise (caused by thermal expansion alone, i.e. neglecting the melting of ice sheets) to stabilize, let alone reverse.

The Mueller Glacier

Recently I was lucky enough to pay a visit to the South Island of New Zealand. I am actually a Kiwi by birth (that’s why it’s so easy for me to work in Australia) but grew up in Canada. This was my first visit back since I left as a baby – in fact, we were in my hometown exactly 20 years to the day after I left. We didn’t plan this, but it was a neat coincidence to discover.

Among the many places we visited was Aoraki / Mt. Cook National Park in the Southern Alps. It was my first experience of an alpine environment and I absolutely loved it. It was also my first glacier sighting – a momentous day in the life of any climate scientist.

There are 72 named glaciers in the park, of which we saw two: the Hooker Glacier and the Mueller Glacier. The latter is pictured below as seen from the valley floor – the thick, blue-tinged ice near the bottom of the visible portion of the mountain. As it flows downward it becomes coated in dirt and is much less pretty.

Along with most of the world’s glaciers, the Mueller is retreating (see these satellite images by NASA). At the base of the mountain on which it flows, there is a large terminal lake, coloured bright blue and green from the presence of “glacial flour” (rock ground up by the ice). According to the signs at the park, this lake has only existed since 1974.

In the photo above, you can see a large black “sill” behind the lake, which is the glacial moraine showing the previous extent of the ice. Here’s a photo of the moraines on the other side, looking down the valley:

It’s hard to capture the scale of the melt, even in photos. But when you stand beside it, the now-empty glacial valley is unbelievably huge. The fact that it was full of ice just 50 years ago boggles my mind. Changes like that don’t happen for no reason.

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