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Archive for the ‘How Science Works’ Category

Part 5 in a series of 5 for NextGen Journal
Read Part 1, Part 2, Part 3, and Part 4

Scientists can never say that something is 100% certain, but they can come pretty close. After a while, a theory becomes so strong that the academic community accepts it and moves on to more interesting problems. Replicating an experiment for the thousandth time just isn’t a good use of scientific resources. For example, conducting a medical trial to confirm that smoking increases one’s risk of cancer is no longer very useful; we covered that decades ago. Instead, a medical trial to test the effectiveness of different strategies to help people quit smoking will lead to much greater scientific and societal benefit.

In the same manner, scientists have known since the 1970s that human emissions of greenhouse gases are exerting a warming force on the climate. More recently, the warming started to show up, in certain patterns that confirm it is caused by our activities. These facts are no longer controversial in the scientific community (the opinion pages of newspapers are another story, though). While they will always have a tiny bit of uncertainty, it’s time to move on to more interesting problems. So where are the real uncertainties? What are the new frontiers of climate science?

First of all, projections of climate change depend on what the world decides to do about climate change – a metric that is more uncertain than any of the physics underlying our understanding of the problem. If we collectively step up and reduce our emissions, both quickly and significantly, the world won’t warm too much. If we ignore the problem and do nothing, it will warm a great deal. At this point, our actions could go either way.

Additionally, even though we know the world is going to warm, we don’t know exactly how much, even given a particular emission scenario. We don’t know exactly how sensitive the climate system is, because it’s quite a complex beast. However, using climate models and historical data, we can get an idea. Here is a probability density function for climate sensitivity: the greater the area under the curve at a specific point on the x-axis, the greater the probability that the climate sensitivity is equal to that value of x (IPCC, 2007):

This curve shows us that climate sensitivity is most likely around 3 degrees Celsius for every doubling of atmospheric carbon dixoide, since that’s where the area peaks. There’s a small chance that it’s less than that, so the world might warm a little less. But there’s a greater chance that climate sensitivity is greater than 3 degrees so the world will warm more. So this graph tells us something kind of scary: if we’re wrong about climate sensitivity being about 3 degrees, we’re probably wrong in the direction we don’t want – that is, the problem being worse than we expect. This metric has a lot to do with positive feedbacks (“vicious cycles” of warming) in the climate system.

Another area of uncertainty is precipitation. Temperature is a lot easier to forecast than precipitation, both regionally and globally. With global warming, the extra thermal energy in the climate system will lead to more water in the air, so there will be more precipitation overall – but the extra energy also drives evaporation of surface water to increase. Some areas will experience flooding, and some will experience drought; many areas will experience some of each, depending on the time of year. In summary, we will have more of each extreme when it comes to precipitation, but the when and where is highly uncertain.

Scientists are also unsure about the rate and extent of future sea level rise. Warming causes the sea to rise for two different reasons:

  1. Water expands as it warms, which is easy to model;
  2. Glaciers and ice sheets melt and fall into the ocean, which is very difficult to model.

If we cause the Earth to warm indefinitely, all the ice in the world will turn into water, but we won’t get that far (hopefully). So how much ice will melt, and how fast will it go? This depends on feedbacks in the climate system, glacial dynamics, and many other phenomena that are quantitatively poorly understood.

These examples of uncertainty in climate science, just a few of many, don’t give us an excuse to do nothing about the problem. As Brian, a Master’s student from Canada, wrote, “You don’t have to have the seventh decimal place filled in to see that the number isn’t looking good.”. We know that there is a problem, and it might be somewhat better or somewhat worse than scientists are currently predicting, but it won’t go away. As we noted above, in many cases it’s more likely to be worse than it is to be better. Even a shallow understanding of the implications of “worse” should be enough for anyone to see the necessity of action.

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About two years ago, I discovered the concept of “dishpan climate models”, through Iain Stewart’s Climate Wars documentary. The experiment is pretty simple: a large bowl filled with water (representing one hemisphere of the Earth) with a block of ice in the middle (a polar region) rotates on a turntable with a Bunsen Burner (the Sun) heating it from one side. By injecting some dye into the water, you can see regular currents from heat transport and the Coriolis effect. Spencer Weart dug up some fascinating results from the days when dishpan climate models were the only sort available: researchers were able to simulate the Hadley circulation, Rossby waves, and the Gulf Stream.

I wanted to try this out for myself. Iain Stewart had made it look easy enough, and he got some really neat currents flowing. So one Saturday afternoon a friend and I got to work in my kitchen.

We started by figuring out how to rotate the bowl. My family doesn’t own a record player, so we couldn’t use that as a turntable. We tried to rig something up out of an old toy helicopter motor, but it wasn’t strong enough. Eventually we settled for a Lazy Susan which we spun by hand. It wasn’t a constant rotation, but it would have to do.

Then Antarctica, which consisted of a handful of ice cubes, kept floating away from the centre of the bowl. Soon the ice cubes melted and there were none left in the freezer. We filled a Ziploc bag with frozen corn, which wasn’t quite as buoyant, and used that for Antarctica instead.

Unsurprisingly, there was no Bunsen burner in my kitchen cupboard, so the Sun was represented by a paraffin candle that sort of smelled like cinnamon.

The only serious problem remaining was the dye. Every kind of dye we tried – food colouring, milk, food colouring mixed with milk – would completely homogenize with the water after just a few rotations, so all the currents were invisible.

The only liquid in my kitchen that wouldn’t mix with water was vegetable oil, so we dyed some of it blue and poured it in. This was a really really bad idea. The oil seemed to be attracted to the plastic bag keeping Antarctica together, so it all washed up onto the continent like some kind of awful petroleum spill in the Antarctic Ocean.

At that point, our climate model looked like this:

I would like to try this again some day, perhaps when I have access to a better laboratory than my kitchen. Any ideas for improvement (besides the obvious)? In particular, what kind of dye does work, and how does Antarctica stay together without being encased in plastic?

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Part 2 of a series of 5 for NextGen Journal

We hear the phrase “climate change consensus” tossed around all the time. But what does that even mean? And does it actually exist?

In Part 1 we discussed the concept of a scientific consensus: overwhelming agreement (but rarely unanimity) among experts. Of course, such a consensus could be wrong, but it wouldn’t be very sensible for the public to ignore it or bet against it. If 19 out of 20 doctors said you needed surgery to save your life, would you sit in the hospital bed and argue about their motives?

When it comes to climate change, the consensus view can be summarized as follows:

  1. Human emissions of greenhouse gases, mainly from the burning of fossil fuels, are a significant force on the global climate.
  2. The expected warming from this force is beginning to show up.

Often, people will write these two points in opposite order: the Earth is warming, and it’s due to our actions. However, that’s not the order that scientists discovered them. The academic community realized the Earth was going to warm decades before that warming became clear. Flipping around these observations might imply “that the entirety of climate science is based upon a single correlation study”.

So, what do the scientists say? In fact, publishing climatologists – the most specialized and knowledgeable people there with regards to climate change – are almost unanimous in their position. 96.2% say the Earth is warming, and 97.4% say humans are causing climate change. It’s hard to know why the second figure is higher than the first – perhaps one scientist in the study thought the effects of our actions hadn’t shown up yet (i.e., point 1 but not point 2).

A year later, others built on this study. They had a larger sample of climate scientists, 97-98% of whom agreed with the consensus position. Additionally, those who agreed had higher academic credibility than those who disagreed: they had published more papers (“expertise”) and been cited more times (“prominence”).

However, it doesn’t really matter what a scientist says, as much as how they back it up. Having a Ph.D. doesn’t mean you get to stop supporting your claims. In the academic community, this is done in the peer reviewed literature.

In 2004, a random sample of almost 1000 scientific studies on climate change were examined. 75% of the studies explicitly supported the consensus position, while the remaining 25% didn’t mention it – for example, some papers wrote about climate change millions of years ago, so today’s climate wasn’t relevant. Incredibly, not a single one disagreed with the consensus.

This still doesn’t imply unanimity – remember, it was a random sample, not the entire literature. A very few dissenting studies do get published each year, but they are such a tiny fraction of the total papers that it’s not surprising that none showed up in a sample of one thousand. Additionally, these papers generally fail to stand up to further scrutiny – their methods are often heavily critiqued by the academic community. See, for example, Lindzen and Choi, 2009 and its response.

It’s clear that individual polls have limitations. They are restricted to a sample of scientists or papers, rather than the entire community. They don’t take into account which claims stood the test of time, and which were refuted. Luckily, the climate science community has another way to summarize the balance of evidence on global warming: the Intergovernmental Panel on Climate Change (IPCC). Since 1988, four assessment reports have been written by thousands of volunteer scientists worldwide. They examine the entire body of academic literature on climate change and create a summary, which is then painstakingly reviewed and scrutinized by others.

The latest report, published in 2007, is already quite out of date – due to the long review process, most of the data is from 2002 and earlier. However, it is still used by governments worldwide, so let’s look at some of its key findings:

  • “Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level.”
  • “Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations.”
  • “Anthropogenic warming over the last three decades has likely had a discernible influence at the global scale on observed changes in many physical and biological systems.”
  • “Altered frequencies and intensities of extreme weather, together with sea level rise, are expected to have mostly adverse effects on natural and human systems.”
  • “Anthropogenic warming could lead to some impacts that are abrupt or irreversible, depending upon the rate and magnitude of the climate change.”

The final place to look for scientific consensus is statements from scientific organizations, such as the National Academy of Sciences. Not a single scientific organization worldwide disputes the consensus view, and many have published statements explicitly supporting it. A full list is available here, but here are some samples:

Climate change and sustainable energy supply are crucial challenges for the future of humanity. It is essential that world leaders agree on the emission reductions needed to combat negative consequences of anthropogenic climate change[.]
-Thirteen national academies of science

It is certain that increased greenhouse gas emissions from the burning of fossil fuels and from land use change lead to a warming of climate, and it is very likely that these green house gases are the dominant cause of the global warming that has been taking place over the last 50 years.
-Royal Society (UK)

The scientific evidence is clear: global climate change caused by human activities is occurring now, and it is a growing threat to society.
-American Association for the Advancement of Science

[C]omprehensive scientific assessments of our current and potential future climates clearly indicate that climate change is real, largely attributable to emissions from human activities, and potentially a very serious problem.
-American Chemical Society

Emissions of greenhouse gases from human activities are changing the atmosphere in ways that affect the Earth’s climate…The evidence is incontrovertible: Global warming is occurring. If no mitigating actions are taken, significant disruptions in the Earth’s physical and ecological systems, social systems, security and human health are likely to occur. We must reduce emissions of greenhouse gases beginning now.
-American Physical Society

The Earth’s climate is now clearly out of balance and is warming. Many components of the climate system…are now changing at rates and in patterns that are not natural and are best explained by the increased atmospheric abundances of greenhouse gases and aerosols generated by human activity during the 20th century.
-American Geophysical Union

It’s clear that a scientific consensus on climate change does exist. Since unanimity is virtually impossible in science, agreement over climate change can’t get much stronger than it is already.

Could all of these scientists, papers, reports, and organizations be wrong? Of course – nobody is infallible. Could that 3% of dissenting scientists triumph like Galileo? It’s possible.

But how much are you willing to risk on that chance?

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Part 1 of a series of 5 for NextGen Journal.

What’s wrong with these statements?

  • I believe in global warming.
  • I don’t believe in global warming.
  • We should hear all sides of the climate change debate and decide for ourselves.

Don’t see it? How about these?

  • I believe in photosynthesis.
  • I don’t believe in Newton’s Laws of Motion.
  • We should hear all sides of the quantum mechanics debate and decide for ourselves.

Climate change is a scientific phenomenon, rooted in physics and chemistry. All I did was substitute in other scientific phenomena, and the statements suddenly sounded wacky and irrational.

Perhaps we have become desensitized by people conflating opinion with fact when it comes to climate change. However, the positions of politicians or media outlets do not make the climate system any less of a physical process. Unlike, say, ideology, there is a physical truth out there.

If there is a physical truth, there are also wrong answers and false explanations. In scientific issues, not every “belief” is equally valid.

Of course, the physical truth is elusive, and facts are not always clear-cut. Data requires interpretation and a lot of math. Uncertainty is omnipresent and must be quantified. These processes require training, as nobody is born with all the skills required to be a good scientist. Again, the complex nature of the physical world means that some voices are more important than others.

Does that mean we should blindly accept whatever a scientist says, just because they have a Ph.D.? Of course not. People aren’t perfect, and scientists are no exception.

However, the institution of science has a pretty good system to weed out incorrect or unsupported theories. It involves peer review, and critical thinking, and falsifiability. We can’t completely prove anything right – not one hundred percent – so scientists try really hard to prove a given theory wrong. If they can’t, their confidence in its accuracy goes up. Peter Watts describes this process in more colourful terms: “You put your model out there in the coliseum, and a bunch of guys in white coats kick the s**t out of it. If it’s still alive when the dust clears, your brainchild receives conditional acceptance. It does not get rejected. This time.”

Peer review is an imperfect process, but it’s far better than nothing. Combined with the technical skill and experience of scientists, it makes the words of the scientific community far more trustworthy than the words of a politician or a journalist. That doesn’t mean that science is always right. But, if you had to put your money on it, who would you bet on?

The issue is further complicated by the fact that scientists are rarely unanimous. Often, the issue at question is truly a mystery, and the disagreement is widespread. What causes El Niño conditions in the Pacific Ocean? Science can’t give us a clear answer yet.

However, sometimes disagreement is restricted to the extreme minority. This is called a consensus. It doesn’t imply unanimity, and it doesn’t mean that the issue is closed, but general confidence in a theory is so high that science accepts it and moves on. Even today, a few researchers will tell you that HIV doesn’t cause AIDS, or that secondhand smoke isn’t harmful to your health. But that doesn’t stop medical scientists from studying the finer details of such diseases, or governments from funding programs to help people quit smoking. Science isn’t a majority-rules democracy, but if virtually all scientists have the same position on an issue, they probably have some pretty good reasons.

If science is never certain, and almost never unanimous, what are we supposed to do? How do we choose who to trust? Trusting nobody but yourself would be a poor choice. Chances are, others are more qualified than you, and you don’t hold the entirety of human knowledge in your head. For policy-relevant science, ignoring the issue completely until one side is proven right could also be disastrous. Inaction itself is a policy choice, which we see in some governments’ responses to climate change.

Let’s bring the whole issue down to a more personal level. Imagine you were ill, and twenty well-respected doctors independently examined you and said that surgery was required to save your life. One doctor, however, said that your illness was all in your mind, that you were healthy as a horse. Should you wait in bed until the doctors all agreed? Should you go home to avoid surgery that might be unnecessary? Or should you pay attention to the relative size and credibility of each group, as well as the risks involved, and choose the course of action that would most likely save your life?

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Next week, I will be giving a speech on climate change to the green committee of a local United Church. They are particularly interested in science and solutions, so I wrote the following script, drawing heavily from my previous presentations. I would really appreciate feedback and suggestions for this presentation.

Citations will be on the slides (which I haven’t made yet), so they’re not in the text of this script. Let me know if there’s a particular reference you’re wondering about, but they’re probably common knowledge within this community by now.

Enjoy!

Climate change is depressing. I know that really well, because I’ve been studying it for over two years. I’m quite practiced at keeping the scary stuff contained in the analytical part of my brain, and not thinking of the implications – because the implications make you feel powerless. I’m sure that all of us here wish we could stop global warming on our own. So we work hard to reduce our carbon footprints, and then we feel guilty every time we take the car out or buy something that was made in China or turn up the heat a degree.

The truth is, though, the infrastructure of our society doesn’t support a low-carbon lifestyle. Look at the quality of public transit in Winnipeg, or the price of local food. We can work all we want at changing our practices, but it’s an uphill battle. If we change the infrastructure, though – if we put a price on carbon so that sustainable practices are cheaper and easier than using fossil fuels – people everywhere will subsequently change their practices.

Currently, governments – particularly in North America – aren’t too interested in sustainable infrastructure, because they don’t think people care. Politicians only say what they think people want to hear. So, should we go dress up as polar bears and protest in front of Parliament to show them we care? That might work, but they will probably just see us as crazy environmentalists, a fringe group. We need a critical mass of people that care about climate change, understand the problem, and want to fix it. An effective solution requires top-down organization, but that won’t happen until there’s a bottom-up, grassroots movement of people who care.

I believe that the most effective action one person can take in the fight against global warming is to talk to others and educate others. I believe most people are good, and sane, and reasonable. They do the best they can, given their level of awareness. If we increase that awareness, we’ll gain political will for a solution. And so, in an effort to practice what I preach, I’m going to talk to you about the issue.

The science that led us to the modern concern about climate change began all the way back in 1824, when a man named Joseph Fourier discovered the greenhouse effect. Gases such as carbon dioxide make up less than one percent of the Earth’s atmosphere, but they trap enough heat to keep the Earth over 30 degrees Celsius warmer than it would be otherwise.

Without greenhouse gases, there could be no life on Earth, so they’re a very good thing – until their concentration changes. If you double the amount of CO2 in the air, the planet will warm, on average, somewhere around 3 degrees. The first person to realize that humans could cause this kind of a change, through the burning of fossil fuels releasing CO2, was Svante Arrhenius, in 1897. So this is not a new theory by any means.

For a long time, scientists assumed that any CO2 we emitted would just get absorbed by the oceans. In 1957, Roger Revelle showed that wasn’t true. The very next year, Charles Keeling decided to test this out, and started measuring the carbon dioxide content of the atmosphere. Now, Arrhenius had assumed that it would take thousands of years to double CO2 from the preindustrial value of 280 ppm (which we know from ice cores), but the way we’re going, we’ll get there in just a few decades. We’ve already reached 390 ppm. That might not seem like a lot, but 390 ppm of arsenic in your coffee would kill you. Small changes can have big effects.

Around the 1970s, scientists realized that people were exerting another influence on the climate. Many forms of air pollution, known as aerosols, have a cooling effect on the planet. In the 70s, the warming from greenhouse gases and the cooling from aerosols were cancelling each other out, and scientists were split as to which way it would go. There was one paper, by Stephen Schneider, which even said it could be possible to cause an ice age, if we put out enough aerosols and greenhouse gases stayed constant. However, as climate models improved, and governments started to regulate air pollution, a scientific consensus emerged that greenhouse gases would win out. Global warming was coming – it was just a question of when.

In 1988, James Hansen, who is arguably the top climate scientist in the world today, claimed it had arrived. In a famous testimony to the U.S. Congress, he said that “the greenhouse effect has been detected, and it is changing our climate now.” Many scientists weren’t so sure, and thought it was too early to make such a bold statement, but Hansen turned out to be right. Since about 1975, the world has been warming, more quickly than it has for at least the last 55 million years.

Over the past decade, scientists have even been able to rule out the possibility that the warming is caused by something else, like a natural cycle. Different causes of climate change have slightly different effects – like the pattern of warming in different layers of the atmosphere, the amount of warming in summer compared to winter, or at night compared to in the day, and so on. Ben Santer pioneered attribution studies: examining these effects in order to pinpoint a specific cause. And so far, nobody has been able to explain how the recent warming could not be caused by us.

Today, there is a remarkable amount of scientific agreement surrounding this issue. Between 97 and 98% of climate scientists, virtually 100% of peer-reviewed studies, and every scientific organization in the world agree that humans are causing the Earth to warm. The evidence for climate change is not a house of cards, where you take one piece out and the whole theory falls apart. It’s more like a mountain. Scrape a handful of pebbles off the top, but the mountain is still there.

However, if you take a step outside of the academic community, this convergence of evidence is more or less invisible. The majority of newspaper articles, from respected outlets like the New York Times or the Wall Street Journal, spend at least as much time arguing against this consensus as they do arguing for it. They present ideas such as “maybe it’s a natural cycle” or “CO2 has no effect on climate” that scientists disproved years ago. The media is stuck in the past. Some of them are only stuck in the 1980s, but others are stuck all the way back in 1800. Why is it like this?

Part of it comes from good, but misguided, intentions. When it comes to climate change, most journalists follow the rule of balance: presenting “two equal sides”, staying neutral, letting the reader form their own opinion. This works well when the so-called controversy is one of political or social nature, like tax levels or capital punishment. In these cases, there is no right answer, and people are usually split into two camps. But when the question at hand is one of science, there is a right answer – even if we haven’t found it yet – so some explanations are better than others, and some can be totally wrong. Would you let somebody form their own opinion on Newton’s Laws of Motion or the reality of photosynthesis? Sometimes scientists are split into two equal groups, but sometimes they’re split into three or four or even a dozen. How do you represent that as two equal sides? Sometimes, like we see with climate change, pretty much all the scientists are in agreement, and the two or three percent which aren’t don’t really publish, because they can’t back up their statements and nobody really takes them seriously. So framing these two groups as having equal weight in the scientific community is completely incorrect. It exaggerates the extreme minority, and suppresses everyone else. Being objective is not always the same as being neutral, and it’s particularly important to remember that when our future is at stake.

Another reason to frame climate science as controversial is that it makes for a much better story. Who really wants to read about scientists agreeing on everything? Journalists try to write stories that are exciting. Unfortunately, that goal can begin to overshadow accuracy.

Also, there are fewer journalists than there used to be, and there are almost no science journalists in the mainstream media – general reporters cover science issues instead. Also, a few decades ago, journalists used to get a week or two to write a story. Now they often have less than a day, because speed and availability of news has become more important than quality.

However, perhaps the most important – and disturbing – explanation for this inaccurate framing is that the media has been very compliant in spreading the message of climate change deniers. They call themselves skeptics, but I don’t think that’s accurate. A true skeptic will only accept a claim given sufficient evidence. That’s a good thing, and all scientists should be skeptics. But it’s easy to see that these people will never accept human-caused climate change, no matter what the evidence. At the same time, they blindly accept any shred of information that seems to support their cause, without applying any skepticism at all. That’s denial, so let’s not compliment them by calling them skeptics.

Climate change deniers will use whatever they can get – whether or not it’s legitimate, whether or not it’s honest – as proof that climate change is natural, or nonexistent, or a global conspiracy. They’ll tell you that volcanoes emit more CO2 than humans, but volcanoes actually emit about 1% of what we do. They’ll say that global warming has stopped because 2008 was cooler than 2007. If climatologists organize a public lecture in effort to communicate accurate scientific information, they’ll say that scientists are dogmatic and subscribe to censorship and will not allow any other opinions to be considered.

Some of these questionable sources are organizations, like a dozen or so lobby groups that have been paid a lot of money by oil companies to say that global warming is fake. Some of them are individuals, like US Senator James Inhofe, who was the environment chair under George W. Bush, and says that “global warming is the greatest hoax ever imposed upon the American people.” Some of them have financial motivations, and some of them have ideological motivations, but their motivations don’t really matter – all that matters is that they are saying things that are inaccurate, and misleading, and just plain wrong.

There has been a recent, and very disturbing, new tactic of deniers. Instead of attacking the science, they’ve begun to attack the integrity of individual scientists. In November 2009, they stole thirteen years of emails from a top climate research group in the UK, and spread stories all over the media that said scientists were caught fudging their data and censoring critics. Since then, they’ve been cleared of these charges by eight independent investigations, but you wouldn’t know it by reading the newspaper. For months, nearly every media outlet in the developed world spread what was, essentially, libel, and the only one that has formally apologized for its inaccurate coverage is the BBC.

In the meantime, there has been tremendous personal impact on the scientists involved. Many of them have received death threats, and Phil Jones, the director of the research group, was nearly driven to suicide. Another scientist, who wishes to remain anonymous, had a dead animal dumped on his doorstep and now travels with bodyguards. The Republican Party, which prides itself on fiscal responsibility, is pushing for more and more investigations, because they just can’t accept that the scientists are innocent…and James Inhofe, the “global warming is a hoax” guy, attempted to criminally prosecute seventeen researchers, most of whom had done nothing but occasionally correspond with the scientists who had their emails stolen. It’s McCarthyism all over again.

So this is where we are. Where are we going?

The Intergovernmental Panel on Climate Change, or IPCC, which collects and summarizes all the scientific literature about climate change, said in 2007 that under a business-as-usual scenario, where we keep going the way we’re going, the world will warm somewhere around 4 degrees Celsius by 2100. Unfortunately, this report was out of date almost as soon as it was published, and has widely been criticized for being too conservative. The British Meteorological Office published an updated figure in 2009 that estimated we will reach 4 degrees by the 2070s.

I will still be alive then (I hope!). I will likely have kids and even grandkids by then. I’ve spent a lot of time researching climate change, and the prospect of a 4 degree rise is terrifying to me. At 4 degrees, we will have lost control of the climate – even if we stop emitting greenhouse gases, positive feedbacks in the climate system will make sure the warming continues. We will have committed somewhere between 40 and 70 percent of the world’s species to extinction. Prehistoric records indicate that we can expect 40 to 80 metres of eventual sea level rise – it will take thousands of years to get there, but many coastal cities will be swamped within the first century. Countries – maybe even developed countries – will be at war over food and water. All this…within my lifetime.

And look at our current response. We seem to be spending more time attacking the scientists who discovered the problem than we are negotiating policy to fix it. We should have started reducing our greenhouse gas emissions twenty years ago, but if we start now, and work really hard, we do have a shot at stopping the warming at a point where we stay in control. Technically, we can do it. It’s going to take an unprecedented amount of political will and international communication

Everybody wants to know, “What can I do?” to fix the problem. Now, magazines everywhere are happy to tell you “10 easy ways to reduce your carbon footprint” – ride your bike, and compost, and buy organic spinach. That’s not really going to help. Say that enough people reduce their demand on fossil fuels: supply and demand dictates that the price will go down, and someone else will say, “Hey, gas is cheap!” and use more of it. Grassroots sentiment isn’t going to be enough. We need a price on carbon, whether it’s a carbon tax or cap-and-trade…but governments won’t do that until a critical mass of people demand it.

So what can you do? You can work on achieving that critical mass. Engage the apathetic. Educate people. Talk to them about climate change – it’s scary stuff, but suck it up. We’re all going to need to face it. Help them to understand and care about the problem. Don’t worry about the crazy people who shout about socialist conspiracies, they’re not worth your time. They’re very loud, but there’s not really very many of them. And in the end, we all get one vote.

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The Arctic is getting so warm in winter that James Hansen had to add a new colour to the standard legend - pink, which is even warmer than dark red:

The official NASA maps – the ones you can generate yourself – didn’t add this new colour, though. They simply extended the range of dark red on the legend to whatever the maximum anomaly is – in some cases, as much as 11.1 C:

The legend goes up in small, smooth steps: a range of 0.3 C, 0.5 C, 1 C, 2 C. Then, suddenly, 6 or 7 C.

I’m sure this is a result of algorithms that haven’t been updated to accommodate such extreme anomalies. However, since very few people examine the legend beyond recognizing that red is warm and blue is cold, the current legend seems sort of misleading. Am I the only one who feels this way?

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Cross-posted from NextGen Journal

It is common for one to fail to grasp the difference between “consensus” and “unanimity”.

A consensus does not require agreement from absolutely every member involved. Rather, it is a more general measure of extremely high agreement, high enough to accept and base decisions on. It’s stronger than a majority-rules style of democracy, but does not necessarily equal unanimity. In fact, in the area of science, where the concept of consensus is particularly important, unanimity is nearly impossible.

With the exception of pure mathematics, scientific theories cannot be proven beyond a doubt. Every physical process that researchers study has some amount of irreducible uncertainty – because there is always, no matter how small, a chance that our understanding could be completely wrong. Additionally, science is never “settled”, because there is always more to learn, whatever the field. Even a law as basic as gravity is still being studied by physicists, and it turns out that it gets more complicated the more you look at it.

Despite this inherent uncertainty, scientists have developed consensuses around all sorts of topics. The Earth is approximately oblate-spherical in shape. Smoking cigarettes increases one’s risk of lung cancer. HIV causes AIDS. There’s a tiny chance that these statements are incorrect, but researchers can still have confidence in their accuracy. Incomplete knowledge is not the same as no knowledge.

However, when there is room for doubt, there will usually be doubters. Physicist Richard Lindzen continues to dispute the health risks of smoking (a conversation is recounted in a recent book by James Hansen). Peter Duesberg, an active molecular and cell biologist, prominently opposes the link between HIV and AIDS. Believe it or not, the Flat Earth Society was alive and well until the death of its leader in 2001 – and signs of the society’s renewal are emerging.

As these examples suggest, for a layperson to wait for scientific unanimity before accepting a topic would be absurd. When consensus reaches a certain point, the null hypothesis shifts: the burden of proof is on the contrarians, rather than the theory’s advocates.

Another case study that may seem surprising to many is that of anthropogenic global warming. A strong scientific consensus exists that human activity, mainly the burning of fossil fuels, is exerting a warming influence on the planet’s temperature, which is already beginning to show up in the instrumental record. This phenomenon is contested by less than 3% of publishing climatologists, a negligible amount of peer-reviewed scientific studies (so few that not one showed up in a 2004 survey’s random sample of almost one thousand papers), and no major scientific societies internationally. Additionally, scientists who dispute the existence or causes of climate change tend to have lower academic credibility than those who do not. It becomes apparent that this scientific question warrants “consensus” standing: never quite settled, never quite unanimous, but certainly good enough to go by. The mainstream media does not always reflect this consensus accurately, but it nonetheless exists.

As world leaders meet in Cancun this week to discuss a global policy to prevent or limit future climate change – a prospect that looks less likely by the day – science can only offer so much advice. Climatologists can approximate what levels of emissions cuts are required to prevent unacceptable consequences, but only when the governments of the world decide which consequences they are willing to accept. Can we deal with worldwide food shortages? Rising sea levels? What about a mass extinction? Even after we define “dangerous consequences”, scientists are unsure of exactly how much temperature change will trigger these consequences, as well as how much greenhouse gas emissions will need to be cut, and how quickly, to prevent the temperature change. All they can offer is a range of probabilities and most likely scenarios.

But remember, incomplete and uncertain knowledge is not the same as no knowledge. Of one thing climate scientists are sure: the more greenhouse gas emissions we emit, the more the world will warm, and the harder it will be to deal with the consequences. There’s no reason for you and I to doubt that simple correlation any longer.

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Cross-posted from NextGen Journal

Of all the inane arguments made against the phenomenon of anthropogenic global climate change, the strangest – in my opinion – are the conspiracy theories.

Yes, scientific fraud does happen, but on the scale of one author, not an entire multi-disciplinary field stretching back for over a century. Imagine the scale of fabrication that would be necessary for this to be true, and the amount of journal editors, expert reviewers, and students who would have to be in on the conspiracy. Scientists are just not that organized.

And for what reason would they do this? Yes, there’s the old Communist-overthrow-of-the-world argument that Fox News pundits argue would somehow result from using capitalist market strategies to put a price on carbon…but many scientists who fully accept the reality of climate change are self-proclaimed Independents and Republicans.

Even if they don’t claim out-and-out fraud, many politicians, journalists, and citizens believe that scientists’ conclusions on climate change are influenced by the lure of grant money. This position shows a fundamental misunderstanding of the way scientific grants work. As Dr. Andrew Weaver, top Canadian climatologist, argued in his fantastic book Keeping Our Cool: Canada in a Warming World, if scientists were purely interested in grant money, it would be more beneficial for them to claim uncertainty in their work. Research dollars give preference to areas of science that remain fundamentally mysterious, not those that are just ironing out the details of well-understood basic processes. Additionally, as meteorology professor Scott Mandia recently showed, the grants that scientists receive for their research don’t actually influence their salaries.

Incredibly, even the Intergovernmental Panel on Climate Change (IPCC) – a highly credible organization that painstakingly summarizes the scientific literature on climate change – is comprised of volunteer scientists. Even the chair, Rajendra Pachauri, doesn’t receive a cent for his work with the IPCC.

Of course, the prospect of a global warming fraud isn’t impossible. Nothing is. But remember, fraud is a criminal charge, and should not be thrown around lightly. Climate scientists, just like anyone else, have the right to be presumed innocent until proven guilty. They shouldn’t have to endure this endless harassment of being publicly labelled as frauds without evidence.

Here’s an example, from a retired American physics prof named Harold Lewis. He recently resigned from the American Physical Society because he didn’t think his views on climate change were being taken into account in the society’s statement. His resignation letter reads almost like satire:

It is of course, the global warming scam, with the (literally) trillions of dollars driving it, that has corrupted so many scientists, and has carried APS before it like a rogue wave. It is the greatest and most successful pseudoscientific fraud I have seen in my long life as a physicist. Anyone who has the faintest doubt that this is so should force himself to read the ClimateGate documents, which lay it bare…I don’t believe that any real physicist, nay scientist, can read that stuff without revulsion. I would almost make that revulsion a definition of the word scientist.

The scientists involved in ClimateGate, the scandal that wasn’t, have been cleared by five independent investigations to date. While some reasonable issues about data archival and sharing have been raised, absolutely no science was compromised by the contents of the stolen private correspondence. For Lewis to say otherwise and fail to provide evidence for this potentially libelous accusation is unduly irresponsible.

I disagree that the definition of scientist is “someone who feels revulsion and jumps to the conclusion of fraud from emails that show, at most, that climate scientists are not always very nice”. On the contrary, I would expect that a scientist would assess media coverage of these emails with a critical eye, examine the context in which they were written, and read the published work of the scientists in question – many of the so-called damning phrases (“hide the decline”, “lack of warming at the moment”) had already been discussed at length in the literature (Briffa et al 1997 and Trenberth et al 2009 respectively).

On a side note, where did he get “literally trillions of dollars” from? The world GDP, according to the World Bank, is approximately $61 trillion. It seems staggering to imagine that a minimum of 3% of the world economy is devoted to climate change research alone.

Let’s see what else Harry Lewis has to say:

In the interim the ClimateGate scandal broke into the news, and the machinations of the principal alarmists were revealed to the world. It was a fraud on a scale I have never seen, and I lack the words to describe its enormity. Effect on the APS position: none. None at all.

And rightly so. Even if, for the sake of argument, the CRU emails had discredited all of the research group’s data and publications, their conclusions about the current planetary warming have been independently replicated by multiple land- and satellite- based databases. In the United States alone, there is NASA GISS, NOAA NCDC, RSS, and UAH. All show the same global warming that CRU detected. Some, due to complexities in the measurement of Arctic temperatures, show even more.

The scientific literature fully supports the general premise of the APS statement on climate change: the world is warming, humans are causing it, and unless we reduce carbon emissions quickly and dramatically, it’s going to be bad. No alternative explanation for the situation has been able to withstand the scrutiny of peer-review.

Science is about looking at all sides of an issue, but it’s not a free-for-all. If someone can’t back up a claim, they don’t have an inherent right to get it published regardless. Unfortunately, in the Internet age, that doesn’t matter – if what they’re looking for is media attention, not scientific accountability.

There’s a difference between “lacking the words to describe the enormity” of a so-called fraud, and lacking the evidence to support such an accusation. As scientists (and prospective scientists, such as myself!), we need to be critical in our assessment of all claims – including the claims of critics and contrarians. Being objective isn’t always the same as being neutral.

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I really enjoyed reading “Global Surface Temperature Change“, by James Hansen and his team at GISS. Keep in mind that it’s still in the draft stages – they haven’t submitted to a journal yet, but they certainly plan to, and it’s a very credible team of scientists that will almost definitely get it published.

The paper is mostly about the methods of global temperature analysis. It’s more of a review paper than an account of a single experiment. However, their main discussion point was that even by using the same data, problems can be addressed in different ways. The two main problems with temperature analysis are:

  • “incomplete spatial and temporal coverage” (sparse data)
  • “non-climatic influences on measurement station environment” (urban heat island effect).

The authors explain the methods they use and why, and explore the impacts that different methods have on their results.

GISS measures anomalies in the temperatures, largely because they are much smoother and more consistent, geographically, than absolute temperatures. In 1987, they determined that anomalies could be safely extrapolated for a radius of 1200 km from a station and still be accurate. GISS smooths the whole map out by extrapolating everything and averaging the overlapping bits.

Extrapolating is also very useful in areas with very few stations, such as the polar regions and parts of Africa. In this map, grey indicates missing data:



The Arctic is particularly problematic, not only because its data is so sparse, but also because it has the largest anomaly of any region in the world. If you have incomplete coverage of an area that is warming so dramatically, it won’t pull its full weight in the global trend, and your result will almost certainly be too low.

This difficulty with the Arctic is the reason that GISS says 2005 is the warmest year on record, while HadCRUT, the team in England, says that 1998 is. GISS extrapolates from the stations they have, and end up getting pretty good coverage of the Arctic:

They’re assuming that areas with missing data have the same anomaly as whatever temperature stations are within 1200 km, which, as they determined in 1987, is a pretty fair assumption.

However, HadCRUT doesn’t do this extrapolating thing. When they don’t have data for an area, they just leave it out:

This might sound safer, in a way, but this method also makes an assumption. It assumes that the area has the same anomaly as the global average. And as we all know, the Arctic is warming a lot more and a lot faster than the global average. So it’s quite possible that GISS is right on this one.

Another adjustment that NASA makes is for local, anthropogenic, non-climatic effects on temperature data. The most obvious of these is the urban heat island effect. As an area becomes more urban, it gets more pavement, less vegetation, and its albedo goes down – it absorbs more heat. This often makes cities substantially warmer than the surrounding rural areas, which can obviously contaminate the temperature record. However, there are ways of eliminating urban influences from the data so we can see what the real trend is.

The first step is determining what stations are considered urban. The obvious way to do this is through population, but that’s actually not very accurate. Think of somewhere like Africa, where, even if there are thousands of people living in a small area, the urban influences such as concrete, absence of vegetation, or exhaust aren’t usually present. A much better indication is energy use, and a good proxy for energy use, that’s easy to measure, is lights at night-time.

So GISS put a bit of code into their analysis that singles out stations where nightlight brightness is greater than 32 µW/m2/sr/µm, and adjusts their trends to agree with rural stations within 1200 km. If there aren’t enough rural stations within that radius, they’ll just exclude the station from the analysis.

They did an even more rigorous test for this paper, to test just how much urban influences were contaminating the long-term trend, and it was pretty interesting.

There were enough stations considered “pitch-dark” at night, where they couldn’t detect any light, to run a global analysis all by themselves. The trend that came out was <0.01 °C/century smaller than GISS’s normal calculation, an amount of error that they described as “immeasurably small”.

The result of all this temperature analysis is a graph, with one new point every year, that is “eagerly awaited by some members of the public and the media”:

However, this graph isn’t actually as useful as this one – the 12-month running mean:

“From a climate standpoint there is nothing special about the time  of year at which the calendar begins”, so instead of only measuring January-December, you can also do February-January, March-February, and so on. This way, you get a data point every month instead of every year, and more data means more accuracy. It also solves problems with short-term influences, such as El Nino, La Nina, and volcanic eruptions, that the annual graph was having. These fleeting, but fairly substantial, influences can fall completely into one calendar year or be split between two – so their influence on global temperature could be overestimated or underestimated, depending on the starting month of the calendar. The 12-month running mean is much less misleading in this fashion.

As it is, we just set a new record for the 12-month running mean, and unless La Nina really takes off, 2010 will likely set a new record for the annual graph as well. But the authors argue that we need to start moving away from the annual graph, because it isn’t as useful.

The authors also discuss public perception of climate change, and media coverage of the issue. They say, “Our comments here about communication of this climate science to the public are our opinion…[We offer it] because it seems inappropriate to ignore the vast range of claims appearing in the media and in hopes that open discussion of these matters may help people distinguish the reality of global change sooner than would otherwise be the case.”

They make the very good point that “Lay people’s perception tends to be strongly influenced by the latest local fluctuation”, and use this winter as a case study, where a strongly negative Arctic Oscillation index caused significantly cooler-than-normal conditions across the United States and Europe. Consequently, a lot of people, especially in the US, began to doubt the reality of global warming – even though, in the world as a whole, it was the second warmest winter on record:

The authors also talk about data sharing. GISS likes to make everything freely available to the public – temperature station data, computer code, everything. However, putting it out there immediately, so that anyone can help check for flaws, has “a practical disadvantage: it allows any data flaws to be interpreted and misrepresented as machinations.” Multiple times in the past few years, when there have been minor errors that didn’t actually change anything, GISS was widely accused of making these mistakes deliberately, to “intentionally exaggerate the magnitude of global warming”. They realized this wasn’t working, so they changed their system: Before releasing the data to everyone, they first put it up on a private site so that only select scientists can examine it for flaws. And, of course, this “has resulted in the criticism that GISS now “hides” their data”.

Personally, I find the range and prevalence of these accusations against scientists absolutely terrifying. Look at what has become mainstream:

Scientific fraud is a very serious allegation, and it’s one thing for citizens to make it without evidence, but it’s another thing altogether for the media to repeat such claims without first investigating their validity:

I have been disgusted by the media coverage of climate science, especially over the past year, especially in the United States, and I worry what this will mean for our ability to solve the problem.

However, there is still fantastic science going on that is absolutely fascinating and essential to our understanding of global climate change. This paper was a very interesting read, and it helped me to better understand a lot of aspects of global temperature analysis.

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I really enjoyed New Scientist’s Special Report: Living in Denial. What a fascinating phenomenon, and a fascinating batch of articles exploring it.

The denial of science is a growing problem. It’s not restricted to a particular ideology – while denying the harmful effects of smoking or the existence of climate change is typically a position of the far right, vaccine denial and H1N1 conspiracy theories are largely restricted to the left.

It occurs even among the well-educated, or among youth who are still immersed in up-to-date curricula. For example, this year at the university, a student group put up signs saying “Don’t get the swine flu shot – it contains mercury!” The chemistry students got mad, and said that labelling thimerosal as toxic mercury was comparable to saying “Don’t eat table salt, it contains chlorine gas!”

As Michael Shermer’s article explains, the defining mark of science denial is a refusal to change one’s mind based on evidence. This is easy to identify for something like Holocaust denial, where evidence is abundant in the public sphere.

It gets a little harder for more technical issues like climate change or vaccines. Scientific opinion is overwhelmingly on one “side”, but the average person does not know or understand the evidence to support this consensus. An article about the thermodynamics of the stratosphere won’t sell a lot of papers. Most people unconsciously follow the credibility spectrum and trust what their doctor or NASA scientists say.

However, some don’t realize that scientific credibility is not the same as an appeal to authority, and so express contrarian opinions. Vaccines cause autism. Global warming is nonexistent/natural/inconsequential. The way that the Twin Towers fell proves that it was orchestrated by the US government.

There are two groups of contrarians: the skeptics, and the deniers. The skeptics are the ones who will change their minds based on evidence – they just haven’t encountered that evidence yet. My favourite example of this is from the Friends episode when Phoebe declares she doesn’t believe in evolution. When Ross starts talking to her about fossils, she says, “Oh. I didn’t know there was actually evidence.”

It’s amazing how many insights you can get out of a supposedly “fluffy” sitcom. I could write an entire essay analyzing that clip…..

I have met dozens of very reasonable people who doubt climate change because they don’t know about the evidence for it. People my age throw around the phrase “it’s a natural cycle” a lot, until I explain that the climate doesn’t act like a pendulum. It doesn’t have to compensate for past periods of warming or cooling – it simply responds to forcings. If the forcing is cyclical, then the climate will be cyclical, but some forcings are a different shape altogether. Similarly, I know a teacher who previously thought that natural causation of the current warming was a legitimate scientific theory, due to a presentation from a teacher’s conference….until I did a bit of probing and discovered that this presentation was given by Tim Ball.

These people are very reasonable. They are willing to change their minds based on evidence. They’ve just been unlucky enough to be misinformed by our flawed system of science journalism.

Then there are the deniers. They call themselves skeptics, but they will not change their minds, no matter what evidence you give them. They either move the goalposts, change the subject, or continue to repeat the same claim even after you have rebutted it patiently multiple times. Go check out some YouTube comments to see what I’m talking about.

Often their ideology or worldview is extreme in some way. For many members of the far right, any problem that would be solved by the government (think cap-and-trade or smoking legislation) will be rejected out of hand. On the far left, anything that would benefit corporations (usually vaccines or traditional medicine) will face a similar reaction. As Michael Specter says, “We hate Big Pharma. We run away from Big Pharma….and leap right into the arms of Big Placebo.”

This phenomenon suggests that science communication is not the answer – for deniers. I learned long ago that trying to change the minds of deniers is a complete waste of time. However, I still feel that science communication and the rebuttal of common misconceptions is absolutely vital. The true skeptics need access to the evidence they are lacking, so that they will be more informed, and our population will move farther towards solving the many science-related problems we face.

These skeptics deserve our time, our efforts, and our respect. They are the target audience of my blog, even if my most active commenters and supporters are a different group altogether. The reason that any of us here do all this work in communication, I believe, is for the true skeptics.

Michael Fitzpatrick argues that we shouldn’t use the label “deniers” at all. I wouldn’t want to alienate the true skeptics by coming across as someone who insults others. However, I think that calling deniers “skeptics” is unfair to the skeptics. They are two completely different groups that we must distinguish between. Skepticism is a worthy quality in science, and giving the complimentary title of “skeptic” to someone who doesn’t deserve it is unfair to those who do. We need to cater to the people who are willing to learn and who don’t want to waste our time. Science communication shouldn’t have to be like No Child Left Behind.

Michael Shermer’s second article, similarly, says that we should participate in debates with deniers and give them a chance to be heard. The truth will prevail, he argues, even if the deniers refuse to give in. I would agree with this position if it were a matter of opinion or policy, which is wholly democratic. Yet science is completely different. Science isn’t about free speech and giving equal time for all views. It is about giving time to those who have the most accurate analyses and robust conclusions. In science, you shut up and listen until your ideas are strongly supported by evidence. Then you publish.

When papers skeptical of climate change get published (all three per year!), such debates are worthy. The authors passed the test of peer-review, and even if their papers are obviously sub-par and are soon to be retracted, they deserve some debate and discussion. Let’s debate contrarian science when it is actually science – when it is actually published.

By paying close attention to and publicly debating with the authors of blog science, however, we are further confusing the public’s already skewed image of science. “It doesn’t matter whether or not you publish,” we seem to be telling them, “it’s all about free speech.” The scientific process has rules, and if deniers can’t pass the necessary, but not sufficient, condition of peer-review, their work doesn’t deserve to be treated as scientific research, and we shouldn’t give them our attention.

Let’s ignore the people who aren’t worth our time, because we have limited time, and there are people out there who deserve every minute of it.

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