Denial in the Classroom

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At one of Canada’s top comprehensive universities, a well-known climate change denier was recently discovered “educating” a class of undergraduate students about global warming.

The Instructor

Tom Harris spent much of his career acting as a PR consultant for fossil fuel companies. Today he directs the International Climate Science Coalition (ICSC), an advocacy group closely tied to the Heartland Institute. In fact, Harris is listed as a Global Warming Expert on Heartland’s website, and spoke at their 2008 conference. However, with a background in mechanical engineering, Tom Harris is hardly qualified to comment on climate science.

The ICSC’s position on climate change is, unsurprisingly, similar to Heartland’s. Their list of Core Principles includes the following gems:

  • Science is rapidly evolving away from the view that humanity’s emissions of carbon dioxide and other ‘greenhouse gases’ are a cause of dangerous climate change.
  • Climate models used by the IPCC fail to reproduce known past climates without manipulation and therefore lack the scientific integrity needed for use in climate prediction and related policy decision-making.
  • Carbon dioxide is not a pollutant – it is a necessary reactant in plant photosynthesis and so is essential for life on Earth.
  • Since science and observation have failed to substantiate the human-caused climate change hypothesis, it is premature to damage national economies with ‘carbon’ taxes, emissions trading or other schemes to control ‘greenhouse gas’ emissions.

More recently, Harris began teaching at Carleton University, an Ottawa institution that Maclean’s magazine ranks as the 7th best comprehensive university in Canada. Climate Change: An Earth Sciences Perspective looks innocuous enough, claiming to teach “the history of earth climates, geological causes of climate change and impact that rapid climate change has had on the biosphere”. As we’ll see, the real content of the course was not so benign.

The Watchdog

The Committee for the Advancement of Scientific Skepticism (CASS) is a Canadian society dedicated to scrutinizing scientific claims made in advertisements, classrooms, and the media. As part of the skeptic movement, they mainly address paranormal phenomena and alternative medicine, but have recently broadened their interests to include climate change denial.

Four members of CASS living in the Ottawa area became aware of Tom Harris’ teaching activities at Carleton, and requested access to videotapes made of his lectures. Earlier today, they published their findings in a disturbing report.

As Heard in University Lectures…

“We can’t even forecast how these clouds are going to move in the next week,” Harris remarked in the first lecture. “Our understanding of the physics is so bad that we can’t even do that. So to think that we could do a whole planet for 50 years in the future…” This kind of misconception, conflating weather and climate predictions, is understandable among laypeople whose only experience with atmospheric modelling is the 5-day forecast presented on the news each night. For a university instructor teaching a course dedicated to climate change, however, such an error is simply unacceptable.

But the next lecture, it got worse. At the time, sunspots were the lowest on record, and some scientists speculated that the Sun might return to Maunder Minimum conditions. However, this slight negative forcing would cancel out less than ten percent of global warming from greenhouse gases, were it to even occur. The numbers, though, didn’t stop Harris, who claimed that “we’re in for some real cooling come around 2030 because we’re going back to the conditions that existed at the time of Napoleon. So cold weather is coming.” Forget about global warming, his message was – global cooling is the real threat.

The misconceptions, oversimplifications, half-truths, and flat-out nonsense continued throughout every single lecture, leading to a whopping 142 “incorrect or equivocal claims” as tallied by the CASS report, which quoted and rebutted every single one. It’s as if Tom Harris was actively trying to hit every argument on the Skeptical Science list.

In the last lecture, the students were presented with “take-away slogans”:

  • The only constant about climate is change.
  • Carbon dioxide is plant food.
  • There is no scientific consensus about climate change causes.
  • Prepare for global cooling.
  • Climate science is changing quickly.

This clear exercise in creating young climate change deniers seems to have influenced some, as shown by the RateMyProfessors reviews of the course. “Interesting course,” wrote one student. “Nice to have some fresh perspectives on global warming rather than the dramatized fear mongering versions. Harris really loves to indulge in the facts and presents some pretty compelling evidence.”

Crossing the Line

There is a line between ensuring academic freedom and providing unqualified individuals with a platform for disseminating nonsense. It is clear to me that Carleton University crossed this line long ago. I am astounded that such material is being taught at a respectable Canadian university. If the Heartland Institute’s proposed curriculum comes through, similar material might be taught in select K-12 classrooms all over the world. As an undergraduate student, the same age as many of the students in the course, I am particularly disturbed.

I have encountered climate change misinformation in my university lectures, both times in the form of false balance, a strategy that I feel many professors fall back to when an area of science is debated in the media and they want to be seen to respect all viewpoints. In both cases, I printed out some articles from Science, Nature, PNAS, and the IPCC, and went to see the prof in their office hours. We had a great conversation and we both learned something from the experience. However, it took an incredible amount of courage for me to talk to my professors like this, not only because teenage girls are naturally insecure creatures, but also because a student telling their science teacher that they’ve got the science wrong just isn’t usually done.

Even by the time they reach university, most students seem to unconditionally trust what a science teacher tells them, and will not stop to question the concepts they are being taught. Although many of my professors have encouraged us to do research outside of class and read primary literature on the topic, nearly all of my peers are content to simply copy down every word of the lecture notes and memorize it all for the final exam.

By allowing Tom Harris to teach the anti-science messages of climate change denial, Carleton University is doing a great disservice to its students. They paid for a qualified instructor to teach them accurate scientific knowledge, and instead they were taken advantage of by a powerful industry seeking to indoctrinate citizens with misinformation. This should not be permitted to continue.

Recent Developments at the Heartland Institute

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This Valentine’s Day, one of the most vocal lobby groups attacking the science of climate change had its internal documents leaked to the public – exposing its sources of funding, secret projects, strategies, and goals for the world to see.

Manufacturing Doubt

You’re probably aware of the influences of corporate-funded lobby groups on social issues. They seek to bring down public health insurance, lower taxes for the wealthy, and prevent environmental regulation. They publish advertisements, print op-eds, and meet with politicians, all in an attempt to advance a free-market agenda. More often than not, they’re backed by corporate interests – pharmaceutical companies, tobacco firms, and the oil industry, to name a few.

You might question the fairness of allowing certain people to amplify their voices simply because they have more money, but at least these lobby groups are spreading around legitimate ideas. Everyone’s entitled to their own opinion on matters of public policy, and nobody can be “right” or “wrong”. However, on matters of science, there is a physical reality out there, so people can be wrong. Try arguing that your incorrect answer on a physics assignment deserves full marks, because it represents your personal opinion on the photoelectric effect. You probably won’t get very far.

Unfortunately, certain lobby groups have a long history of promoting blatant falsehoods about areas of science that threaten their free-market fundamentalism. Everything from the harmful health effects of smoking to the causes of acid rain to the consequences of the pesticide DDT has been attacked by these groups. The strategy has been the same every time: repeat long-debunked myths ad nauseum, overemphasize uncertainty, and question the integrity of scientists studying the issue.

Human-caused climate change is currently the most fashionable scientific phenomenon to deny. Although 97-98% of climate scientists agree that humans are causing the Earth to warm, public acceptance lags far behind, and is heavily split along political lines. Scientists have investigated and ruled out every conceivable alternative hypothesis for global warming – so why aren’t their conclusions reaching the public? The answer is that other influences are getting in the way, muddying the message for their own financial and ideological benefit.

The Front-Runner

In recent years, the Chicago-based Heartland Institute has led the way in this crusade against climate science. Their communication style seems to be “quantity, not quality”: whatever rumour currently claims to disprove global warming will be picked up and amplified by the Heartland Institute, whether or not it contradicts previous statements from the organization. For example, they will frequently claim in the same document that 1) the world is cooling and 2) global warming is caused by the sun. Logically, you can’t have it both ways. However, doubt, not logic, is the goal here – if a message casts doubt on the scientific consensus, it qualifies for the Heartland newsletter.

This lobby group’s extreme conservative agenda is apparent in paranoid overtones about socialist conspiracies and bigger government. “If AGW [anthropogenic global warming] is true,” they write, “then stopping or preventing it requires higher taxes, more income redistribution, more wilderness preservation, more regulations on corporations, ‘smart growth,’ subsidies for renewable energy, and on and on…[we] ‘looked under the hood’ and concluded concern over the possibility of catastrophic global warming was being manufactured to advance a political agenda.”

Heartland has accepted thousands of dollars in funding from oil companies, such as ExxonMobil, and industrial giants, such as the Koch brothers. However, most of the funding for their climate change projects now comes from a single individual, who is obviously extremely wealthy, and currently anonymous.

A Scientist Steps In

Enter Dr. Peter Gleick, a prominent climate scientist and president of the Pacific Institute for Studies in Development, Environment, and Security. He has had run-ins with the Heartland Institute before, and – like many scientists in the field – is deeply disturbed by their disinformation campaigns. So when he received an anonymous package in the mail in 2012, containing a confidential memo that appeared to be from the Heartland Institute, he was intrigued.

The memo, entitled “Heartland Climate Strategy”, contained many phrases that would later raise eyebrows. Perhaps most distressingly, Heartland was planning to bring denial into the classroom, by developing a school curriculum “that shows that the topic of climate change is controversial and uncertain – two key points that are effective at dissuading teachers from teaching science”. They were also hoping to pursue funding from “corporations whose interests are threatened by climate policies” – presumably the fossil fuel industry – and to continue sponsoring the NIPCC reports, whose purpose was “to undermine the official United Nation’s IPCC reports” (widely considered to be the most authoritative reviews of climate science in existence).

Finally, Heartland discussed its “funding for high-profile individuals who regularly and publicly counter the alarmist AGW message”, and more general coordination with “groups capable of rapidly mobilizing responses to new scientific findings, news stories, or unfavorable blog posts”. To those familiar with who’s who in the world of climate denial, the list of people and groups Heartland mentioned supporting were extremely enlightening. At the end of the document, Dr. Gleick discovered why the memo had been sent to him in particular – Heartland was bemoaning the fact that Gleick had published articles in Forbes magazine. “This influential audience has usually been reliably anti-climate and it is important to keep opposing voices out,” wrote Heartland – a rather hypocritical statement from an organization that regularly accuses the mainstream media of censoring their views.

This memo was certainly very interesting, but was it authentic? It could have been faked by someone seeking to discredit Heartland. Gleick wasn’t willing to spread around the document unless and until he thought it was legitimate. And out of frustration, he went one step too far: in what he now describes as “a serious lapse of my own and professional judgment and ethics”, he pretended to be a Heartland board member, and requested that Heartland send several other documents to his “new email address”, which they did.

These actions were unethical, and possibly illegal, but they raise some interesting moral questions. Is it acceptable to lie in order to expose a bigger lie? Where does investigative journalism end and unjustified dishonesty begin? Since Gleick identified himself and apologized for his actions, he has been demonized by Heartland and its allies, but others have described him as a “whistleblower” who put his reputation on the line in order to uncover the truth. We must also consider whether scientists are being judged more harshly than lobby groups. As activist Naomi Klein tweeted, “What about the fact the Heartland Institute impersonates a scientific organization every day?”

Release and Reactions

The documents that Dr. Gleick obtained by email, including a budget, a fundraising plan, and minutes from board meetings, confirmed many of the contents of the Climate Strategy memo. Names, monetary figures, and project descriptions all matched up – with the exception of one figure that may have been a typo. Satisfied that the Climate Strategy memo was legitimate, he scanned it, and sent all the documents anonymously to DeSmogBlog, a Vancouver-based website composed of journalists that seek to expose the financial and ideological motivations behind the climate change denial movement. DeSmogBlog published the documents on Valentine’s Day, and they went viral within hours.

The Heartland Institute was outraged. They insisted that the Climate Strategy document was fake, a claim for which they provided no evidence and which has since been contested. They threatened legal action against anyone who dared report, link to, or comment on the leaked documents – an obvious scare tactic to prevent the story spreading. (Such threats have no legal basis, otherwise the media would not have been able to write about governmental memos from Wikileaks, which were illegally obtained.)

It’s interesting to note Heartland’s hypocrisy in this situation. Several years ago, when emails from climate scientists were stolen and published online, the Heartland Institute was of the first and loudest voices to report, link to, and comment on the emails (in this case, completely out of context), in a blatant attempt to discredit climate science right before the Copenhagen Summit. Where is that attitude of freedom of speech and information now?

The Fallout

Whether or not the Climate Strategy memo was faked, the contents of the other documents have spurred a public pushback against Heartland. There have been calls for federal hearings regarding the flow of money in the organization, and complaints to the IRS to revoke Heartland’s tax-free status as a charitable foundation.

Does this incident matter, in the grand scheme of things? Not really. Climate science will continue to show that the Earth is warming, humans are the cause, and the consequences will be severe. Lobby groups will continue to attack these conclusions. However, it’s high time that we looked at these lobby groups a little more closely.

The Hockey Stick and the Climate Wars

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Throughout all the years of public disputes about climate change, arguably no scientist has taken as much flak as Dr. Michael Mann. This mild-mannered paleoclimatologist is frequently accused of fraud, incompetence, scientific malpractice, Communism, and orchestrating a New World Order. These charges have been proven baseless time and time again, but the accusations continue. Dr. Mann’s research on climate change is inconvenient for those who wish to deny that current global temperatures are unusual, so he has become the bulls-eye target in a fierce game of “shoot the messenger”. In “The Hockey Stick and the Climate Wars: Dispatches from the Front Lines”, a memoir of his experiences, Michael Mann finally speaks out.

The story begins quite harmlessly: an account of how he became a scientist, from childhood curiosity to graduate work in theoretical physics to choosing climate science on a whim out of the university course calendar. For those who have followed Dr. Mann’s research over the years, there is some great backstory – how he met his coauthors Ray Bradley and Malcolm Hughes, the formation of the IPCC TAR chapter about paleoclimate, and how the RealClimate blog operates. This book also filled in some more technical gaps in my understanding with a reasonably accessible explanation of principal component ananlysis, a summary of millennial paleoclimate research before 1998, and an explanation of exactly how Mann, Bradley and Hughes’ 2008 paper built on their previous work.

Dr. Mann’s 1998 paper – the “hockey stick” – was a breakthrough because it was the first millennial reconstruction of temperature that had global coverage and an annual resolution. He considered the recent dramatic rise in temperatures to be the least interesting part of their work, because it was already known from instrumental data, but that part of the paper got the most public attention.

It seems odd for a scientist to downplay the importance of his own work, but that’s what Dr. Mann does: he stresses that, without the hockey stick, the case for climate change wouldn’t be any weaker. Unfortunately, his work was overemphasized on all sides. It was never his idea to display the hockey stick graph so prominently in the IPCC TAR, or for activists to publicize his results the way they did. Soon the hockey stick became the holy grail of graphs for contrarians to destroy. As Ben Santer says, “There are people who believe that if they can bring down Mike Mann, they can bring down the IPCC,” and the entire field of climate science as a result.

Michael Mann is an eloquent writer, and does a fabulous job of building up tension. Most readers will know that he was the target of countless attacks from climate change deniers, but he withholds these experiences until halfway through the book, choosing instead to present more context to the story. The narrative keeps you on your toes, though, with frequent allusions to future events.

Then, when the full story comes out, it hits hard. Death threats, and a letter full of suspicious white powder. Lobby groups organizing student rallies against Mann on his own campus, and publishing daily attack ads in the campus newspaper. Discovering that his photo was posted as a “target” on a neo-Nazi website that insisted climate change was a Jewish conspiracy. A state politician from the education committee threatening to cut off funding to the entire university until they fired Mann.

Throughout these attacks, Dr. Mann consistently found trails to the energy industry-funded Scaife Foundation. However, I think he needs to be a bit more careful when he talks about the links between oil companies and climate change denial – the relationship is well-known, but it’s easy to come off sounding like a conspiracy theorist. Naomi Oreskes does a better job of communicating this area, in my opinion.

Despite his experiences, Michael Mann seems optimistic, and manages to end the book on a hopeful note about improvements in climate science communication. He is remarkably well-adjusted to the attacks against him, and seems willing to sacrifice his reputation for the greater good. “I can continue to live with the cynical assaults against my integrity and character by the corporate-funded denial machine,” he writes. “What I could not live with is knowing that I stood by silently as my fellow human beings, confused and misled by industry-funded propaganda, were unwittingly led down a tragic path that would mortgage future generations.”

“The Hockey Stick and the Climate Wars” leaves me with a tremendous empathy for Dr. Mann and all that he has gone through, as well as a far better understanding of the shouting match that dominates certain areas of the Internet and the media. It is among the best-written books on climate science I have read, and I would highly recommend it to all scientists and science enthusiasts.

“The Hockey Stick and the Climate Wars” will be released on March 6th, and the Kindle version is already available.

Apparently, I’m an enemy of Canada

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A big story in Canada these days is oil pipelines. The federal government wants to ramp up the tar sands industry through international exports. The easiest way to transport crude is through pipelines stretching across the country, and several such projects have been proposed during the past year.

First there was the Keystone XL pipeline, which would stretch from Alberta to Texas and provide the United States with oil. Despite enormous pressure to approve the project immediately, American president Obama is refusing to make a decision until a more thorough environmental review can be conducted. This announcement left the Canadian government fuming and stomping off to look for other trading partners.

Now the Northern Gateway pipeline is on the table, which would transport oil across British Columbia to the West Coast, where tankers would transport it to Asia. I don’t personally know anyone who supports this project, and there is organized opposition from many First Nations tribes and environmental groups. Much of the opposition seems to hinge on local environmental impacts, such as oil spills or disruption to wildlife. I think it’s possible, if we’re very careful about it, to build a pipeline that more or less eliminates these risks.

I am still opposed to the Northern Gateway project, though, due to its climate impacts. Tar sands are even more carbon-intensive than regular oil, and there is no way to mitigate their emissions the way we can mitigate their effects on wildlife. I realize that it’s unreasonable to shut down the entire industry, but expanding it to massive new markets such as Asia is a mistake that my generation will have to pay for. The short-term economic benefits of building a pipeline will be overwhelmed by the long-term financial costs and human suffering due to the climate change it causes. My country is pushing the world down a path towards a worst-case climate scenario, and it makes me ashamed to call myself a Canadian.

According to our Natural Resources Minister, Joe Oliver, anyone who opposes the pipeline is “threaten[ing] to hijack our regulatory system to achieve their radical ideological agenda”. Apparently, the goal of people like me is to ensure there is “no forestry. No mining. No oil. No gas. No more hydro-electric dams”. Prime Minister Stephen Harper seems to agree, as he plans to change the public consultation process for such projects so they can’t get “hijacked” by opponents.

In case anyone needs this spelled out, I am not a radical ideologue. I am a fan of capitalism. I vote for mainstream political parties. Among 19-year-old females, it doesn’t get much more moderate than me.

I have no problem with forestry, mining, and hydro, as long as they are conducted carefully and sustainably. It’s the oil and gas I have trouble with, and that’s due to my education in climate science, a field which developed out of very conservative disciplines such as physics and applied math.

I can’t understand why Joe Oliver thinks that referring to First Nations as a “radical group” is acceptable. I also fail to see the logic in shutting down opposition to a matter of public policy in a democratic society.

If Canada’s economy, one of the most stable in the world throughout the recent recession, really needs such a boost, let’s not do it through an unethical and unsustainable industry. How about, instead of building pipelines, we build a massive grid of low-carbon energy sources? That would create at least as many jobs, and would improve the future rather than detract from it. Between wind power in Ontario, tidal power in the Maritimes, hydroelectric power throughout the boreal forest, and even uranium mining in Saskatchewan, the opportunities are in no short supply. Despite what the government might tell us, pipelines are not our only option.

Breaching the Mainstream

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It’s hard to overestimate the influence of John and Hank Green on the Internet, particularly among people my age. John (who writes books for teenagers) and Hank (who maintains the website EcoGeek and sings songs about particle physics) run a YouTube channel that celebrates nerdiness. This Internet community is now a huge part of pop culture among self-professed teenage nerds.

Hank’s new spin-off channel SciShow, which publishes videos about popular science topics, has only being going for a month but already has 90 000 subscribers and 1 million views. So I was very excited when Hank created this entertaining, polished, and wonderfully accurate video about climate change. He discusses sea level rise, anoxic events, and even the psychology of denial:

How much is most?

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A growing body of research is showing that humans are likely causing more than 100% of global warming: without our influences on the climate, the planet would actually be cooling slightly.

In 2007, the Intergovernmental Panel on Climate Change published its fourth assessment report, internationally regarded as the most credible summary of climate science to date. It concluded that “most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations”.

A clear question remains: How much is “most”? 51%? 75%? 99%? At the time that the IPCC report was written, the answer was unclear. However, a new frontier of climate research has emerged since, and scientists are working hard to quantify the answer to this question.

I recently attended the 2011 American Geophysical Union Fall Meeting, a conference of over 20 000 scientists, many of whom study the climate system. This new area of research was a hot topic of discussion at AGU, and a phrase that came up many times was “more than 100%”.

That’s right, humans are probably causing more than 100% of observed global warming. That means that our influences are being offset by natural cooling factors. If we had never started burning fossil fuels, the world would be cooling slightly.

In the long term, oscillations of the Earth’s orbit show that, without human activity, we would be very slowly descending into a new ice age. There are other short-term cooling influences, though. Large volcanic eruptions, such as Mount Pinatubo in 1991, have thrown dust into the upper atmosphere where it blocks a small amount of sunlight. The sun, particularly in the last few years, has been less intense than usual, due to the 11-year sunspot cycle. We have also experienced several strong La Niña events in the Pacific Ocean, which move heat out of the atmosphere and into the ocean.

However, all of these cooling influences pale in comparison to the strength of the human-caused warming influences. The climate change communication project Skeptical Science recently summarized six scientific studies in this graphic:

Most of the studies estimated that humans caused over 100% of the warming since 1950, and all six put the number over 98%. Additionally, most of the studies find natural influences to be in the direction of cooling, and all six show that number to be close to zero.

If you are interested in the methodologies and uncertainty ranges of these six studies, Skeptical Science goes into more detail, and also provides links to the original journal articles.

To summarize, the perception that humans are accelerating a natural process of warming is false. We have created this problem entirely on our own. Luckily, that means we have the power to stop the problem in its tracks. We are in control, and we choose what happens in the future.

How do climate models work?

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Also published at Skeptical Science

This is a climate model:

T = [(1-α)S/(4εσ)]1/4

(T is temperature, α is the albedo, S is the incoming solar radiation, ε is the emissivity, and σ is the Stefan-Boltzmann constant)

An extremely simplified climate model, that is. It’s one line long, and is at the heart of every computer model of global warming. Using basic thermodynamics, it calculates the temperature of the Earth based on incoming sunlight and the reflectivity of the surface. The model is zero-dimensional, treating the Earth as a point mass at a fixed time. It doesn’t consider the greenhouse effect, ocean currents, nutrient cycles, volcanoes, or pollution.

If you fix these deficiencies, the model becomes more and more complex. You have to derive many variables from physical laws, and use empirical data to approximate certain values. You have to repeat the calculations over and over for different parts of the Earth. Eventually the model is too complex to solve using pencil, paper and a pocket calculator. It’s necessary to program the equations into a computer, and that’s what climate scientists have been doing ever since computers were invented.

A pixellated Earth

Today’s most sophisticated climate models are called GCMs, which stands for General Circulation Model or Global Climate Model, depending on who you talk to. On average, they are about 500 000 lines of computer code long, and mainly written in Fortran, a scientific programming language. Despite the huge jump in complexity, GCMs have much in common with the one-line climate model above: they’re just a lot of basic physics equations put together.

Computers are great for doing a lot of calculations very quickly, but they have a disadvantage: computers are discrete, while the real world is continuous. To understand the term “discrete”, think about a digital photo. It’s composed of a finite number of pixels, which you can see if you zoom in far enough. The existence of these indivisible pixels, with clear boundaries between them, makes digital photos discrete. But the real world doesn’t work this way. If you look at the subject of your photo with your own eyes, it’s not pixellated, no matter how close you get – even if you look at it through a microscope. The real world is continuous (unless you’re working at the quantum level!)

Similarly, the surface of the world isn’t actually split up into three-dimensional cells (you can think of them as cubes, even though they’re usually wedge-shaped) where every climate variable – temperature, pressure, precipitation, clouds – is exactly the same everywhere in that cell. Unfortunately, that’s how scientists have to represent the world in climate models, because that’s the only way computers work. The same strategy is used for the fourth dimension, time, with discrete “timesteps” in the model, indicating how often calculations are repeated.

It would be fine if the cells could be really tiny – like a high-resolution digital photo that looks continuous even though it’s discrete – but doing calculations on cells that small would take so much computer power that the model would run slower than real time. As it is, the cubes are on the order of 100 km wide in most GCMs, and timesteps are on the order of hours to minutes, depending on the calculation. That might seem huge, but it’s about as good as you can get on today’s supercomputers. Remember that doubling the resolution of the model won’t just double the running time – instead, the running time will increase by a factor of sixteen (one doubling for each dimension).

Despite the seemingly enormous computer power available to us today, GCMs have always been limited by it. In fact, early computers were developed, in large part, to facilitate atmospheric models for weather and climate prediction.

Cracking the code

A climate model is actually a collection of models – typically an atmosphere model, an ocean model, a land model, and a sea ice model. Some GCMs split up the sub-models (let’s call them components) a bit differently, but that’s the most common arrangement.

Each component represents a staggering amount of complex, specialized processes. Here are just a few examples from the Community Earth System Model, developed at the National Center for Atmospheric Research in Boulder, Colorado:

  • Atmosphere: sea salt suspended in the air, three-dimensional wind velocity, the wavelengths of incoming sunlight
  • Ocean: phytoplankton, the iron cycle, the movement of tides
  • Land: soil hydrology, forest fires, air conditioning in cities
  • Sea Ice: pollution trapped within the ice, melt ponds, the age of different parts of the ice

Each component is developed independently, and as a result, they are highly encapsulated (bundled separately in the source code). However, the real world is not encapsulated – the land and ocean and air are very interconnected. Some central code is necessary to tie everything together. This piece of code is called the coupler, and it has two main purposes:

  1. Pass data between the components. This can get complicated if the components don’t all use the same grid (system of splitting the Earth up into cells).
  2. Control the main loop, or “time stepping loop”, which tells the components to perform their calculations in a certain order, once per time step.

For example, take a look at the IPSL (Institut Pierre Simon Laplace) climate model architecture. In the diagram below, each bubble represents an encapsulated piece of code, and the number of lines in this code is roughly proportional to the bubble’s area. Arrows represent data transfer, and the colour of each arrow shows where the data originated:

We can see that IPSL’s major components are atmosphere, land, and ocean (which also contains sea ice). The atmosphere is the most complex model, and land is the least. While both the atmosphere and the ocean use the coupler for data transfer, the land model does not – it’s simpler just to connect it directly to the atmosphere, since it uses the same grid, and doesn’t have to share much data with any other component. Land-ocean interactions are limited to surface runoff and coastal erosion, which are passed through the atmosphere in this model.

You can see diagrams like this for seven different GCMs, as well as a comparison of their different approaches to software architecture, in this summary of my research.

Show time

When it’s time to run the model, you might expect that scientists initialize the components with data collected from the real world. Actually, it’s more convenient to “spin up” the model: start with a dark, stationary Earth, turn the Sun on, start the Earth spinning, and wait until the atmosphere and ocean settle down into equilibrium. The resulting data fits perfectly into the cells, and matches up really nicely with observations. It fits within the bounds of the real climate, and could easily pass for real weather.

Scientists feed input files into the model, which contain the values of certain parameters, particularly agents that can cause climate change. These include the concentration of greenhouse gases, the intensity of sunlight, the amount of deforestation, and volcanoes that should erupt during the simulation. It’s also possible to give the model a different map to change the arrangement of continents. Through these input files, it’s possible to recreate the climate from just about any period of the Earth’s lifespan: the Jurassic Period, the last Ice Age, the present day…and even what the future might look like, depending on what we do (or don’t do) about global warming.

The highest resolution GCMs, on the fastest supercomputers, can simulate about 1 year for every day of real time. If you’re willing to sacrifice some complexity and go down to a lower resolution, you can speed things up considerably, and simulate millennia of climate change in a reasonable amount of time. For this reason, it’s useful to have a hierarchy of climate models with varying degrees of complexity.

As the model runs, every cell outputs the values of different variables (such as atmospheric pressure, ocean salinity, or forest cover) into a file, once per time step. The model can average these variables based on space and time, and calculate changes in the data. When the model is finished running, visualization software converts the rows and columns of numbers into more digestible maps and graphs. For example, this model output shows temperature change over the next century, depending on how many greenhouse gases we emit:

Predicting the past

So how do we know the models are working? Should we trust the predictions they make for the future? It’s not reasonable to wait for a hundred years to see if the predictions come true, so scientists have come up with a different test: tell the models to predict the past. For example, give the model the observed conditions of the year 1900, run it forward to 2000, and see if the climate it recreates matches up with observations from the real world.

This 20th-century run is one of many standard tests to verify that a GCM can accurately mimic the real world. It’s also common to recreate the last ice age, and compare the output to data from ice cores. While GCMs can travel even further back in time – for example, to recreate the climate that dinosaurs experienced – proxy data is so sparse and uncertain that you can’t really test these simulations. In fact, much of the scientific knowledge about pre-Ice Age climates actually comes from models!

Climate models aren’t perfect, but they are doing remarkably well. They pass the tests of predicting the past, and go even further. For example, scientists don’t know what causes El Niño, a phenomenon in the Pacific Ocean that affects weather worldwide. There are some hypotheses on what oceanic conditions can lead to an El Niño event, but nobody knows what the actual trigger is. Consequently, there’s no way to program El Niños into a GCM. But they show up anyway – the models spontaneously generate their own El Niños, somehow using the basic principles of fluid dynamics to simulate a phenomenon that remains fundamentally mysterious to us.

In some areas, the models are having trouble. Certain wind currents are notoriously difficult to simulate, and calculating regional climates requires an unaffordably high resolution. Phenomena that scientists can’t yet quantify, like the processes by which glaciers melt, or the self-reinforcing cycles of thawing permafrost, are also poorly represented. However, not knowing everything about the climate doesn’t mean scientists know nothing. Incomplete knowledge does not imply nonexistent knowledge – you don’t need to understand calculus to be able to say with confidence that 9 x 3 = 27.

Also, history has shown us that when climate models make mistakes, they tend to be too stable, and underestimate the potential for abrupt changes. Take the Arctic sea ice: just a few years ago, GCMs were predicting it would completely melt around 2100. Now, the estimate has been revised to 2030, as the ice melts faster than anyone anticipated:

Answering the big questions

At the end of the day, GCMs are the best prediction tools we have. If they all agree on an outcome, it would be silly to bet against them. However, the big questions, like “Is human activity warming the planet?”, don’t even require a model. The only things you need to answer those questions are a few fundamental physics and chemistry equations that we’ve known for over a century.

You could take climate models right out of the picture, and the answer wouldn’t change. Scientists would still be telling us that the Earth is warming, humans are causing it, and the consequences will likely be severe – unless we take action to stop it.

Technical Difficulties

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Sorry for the draft climate model post with a broken link. I clicked Preview, WordPress decided to Publish, I yelled at the computer and reverted to Draft. Apparently, in the two seconds the post was published, it found its way into all the RSS feeds and email subscriptions.

The completed post should be up in a day or two. Thanks for your patience.

Open Thread

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Apologies for my silence recently – I just finished writing some final exams that I missed for the AGU conference, so I’ve been studying hard ever since Boxing Day.

I am working on a larger piece about climate models: an introduction to how they work and why they are useful. That will take about a week to finish, so in the mean time, here is an open thread to keep things moving.

Some possible discussion topics from posts I’ve enjoyed:

Enjoy!

Winter in the Woods

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Do not burn yourself out. Be as I am – a reluctant enthusiast… a part time crusader, a half-hearted fanatic. Save the other half of yourselves and your lives for pleasure and adventure. It is not enough to fight for the land; it is even more important to enjoy it. While you can. While it is still there. So get out there and mess around with your friends, ramble out yonder and explore the forests, encounter the grizz, climb the mountains. Run the rivers, breathe deep of that yet sweet and lucid air, sit quietly for a while and contemplate the precious stillness, that lovely, mysterious and awesome space. Enjoy yourselves, keep your brain in your head and your head firmly attached to your body, the body active and alive, and I promise you this much: I promise you this one sweet victory over our enemies, over those deskbound people with their hearts in a safe deposit box and their eyes hypnotized by desk calculators. I promise you this: you will outlive the bastards.

So writes Edward Abbey, in a passage that Ken sent to me nearly two years ago. The quote is now stuck to my fridge, and I abide by it as best I can.

It’s pretty easy to find areas of untouched forest within my city. Living in a floodplain, it’s only practical to leave natural vegetation growing around the rivers – it acts as a natural sponge when the water rises. In the warmer months, hiking in the woods is convenient, particularly because I can bike to the edge of the river. But in the winter, it’s not so easy. The past few months have consistently been about 10 C above normal, though, and today I found a shortcut that made the trip to the woods walkable.

The aspen parkland in winter is strange. Most wildlife travel south or begin hibernating by early October, and no evergreen species grow here naturally. As you walk through the naked branches, it’s easy to think of the woods as desolate. But if you slow down, pay attention, and look around more carefully, you see signs of life in the distance:

Black-capped Chickadee

White-tailed Deer

If you stand still and do your best to look non-threatening, some of the more curious animals might come for a closer inspection:

If you imitate a bird's call well enough, it will come right up to you

A mother deer and her fawn, probably about eight months old

The species that live here year-round are some of the most resilient on the continent. They have survived 40 above and 40 below, near-annual droughts and floods, and 150 years of colonization. The Prairies is a climate of extremes, and life has evolved to thrive in those extremes.

So maybe this isn’t the land I am fighting for – it will probably be able to handle whatever climate change throws at it – but it is the land I love regardless.

Happy Christmas to everyone, and please go out and enjoy the land you’re fighting for, as a gift to yourself.