Why Trust Science?

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?

What Can One Person Do?

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.

The Nature of Scientific Consensus

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.

A Must-Read Letter to Science

I must say that I feel proud of the mainstream media when CBC News picks this up before any of the blogs I read.

A letter to be published in tomorrow’s edition of Science, defending the integrity of climate science and calling for an end to “McCarthy-like threats” to scientists, has been signed by 225 members of the National Academy of Sciences. I guess they weren’t joking around in their correspondence.

Here are some excerpts:

We are deeply disturbed by the recent escalation of political assaults on scientists in general and on climate scientists in particular.

Many recent assaults on climate science and, more disturbingly, on climate scientists by climate change deniers, are typically driven by special interests or dogma, not by an honest effort to provide an alternative theory that credibly satisfies the evidence. The Intergovernmental Panel on Climate Change (IPCC) and other scientific assessments of climate change, which involve thousands of scientists producing massive and comprehensive reports, have, quite expectedly and normally, made some mistakes. When errors are pointed out, they are corrected. But there is nothing remotely identified in the recent events that changes the fundamental conclusions about climate change.

We also call for an end to McCarthy-like threats of criminal prosecution against our colleagues based on innuendo and guilt by association, the harassment of scientists by politicians seeking distractions to avoid taking action, and the outright lies being spread about them.

Read the whole letter here, it’s well worth it.

I don’t find this letter particularly surprising, because I’m quite aware of the scientific community’s attitudes toward recent events (RC collectively refers to them as Whatevergate), and I’m sure that many regular readers and commenters won’t be surprised either. However, we need to look at this not as news, but as an example of the communication that scientists are starting to come out with. This is exactly the kind of letter that needs to get out to the public.

What I’m wondering is, why will it be published in Science and not somewhere like the New York Times, a publication that is actually read outside of the scientific community? Anyone who keeps up with Science will know just how solid the theory of anthropogenic climate change is. So why is it being used for public communication?

Whatever the reason, and whatever its effectiveness, I’m pleased. It’s a good first step that we need much more of.

We Have Slides!

After a marathon PowerPoint-session yesterday I finally got my 63 slides out of the way. Here is the presentation for anyone who is interested. The script is written in the notes beneath the slides.

I like to have things fading in and out of my slides, so sometimes the text boxes and images are stacked on top of each other and it won’t make sense until you view the animation.

Researching the median lethal dose of arsenic during my spare at school was really awkward. I had to do a lot of hasty explaining to my friends about how it was a metaphor for small concentrations having large effects, and no, I wasn’t planning to poison anyone.

Anyway, enjoy.

Mind the Gap (12 MB)

The Antithesis to Nitpicking

Sometimes we have to step back and look at the big picture. We have to remember that not everyone has heard or believed the one about global warming stopping in 1998. Denialists centre around nitpicking and ideas that global warming is a “house of cards”, so we respond the same way: countering all the “mistakes” they claim to have found.

In reality, climate change is an incredibly robust phenomenon that we’ve known about for decades – and the basic physics behind it, for over a century. It’s not some new, shaky discovery. It’s not going to be overturned because scientists at CRU do not always say nice things about their critics.

So I was very pleased when I opened up YouTube today to see that Peter Sinclair’s latest video was all about this big picture. If I had to choose just one of his videos to share with everyone I knew, this would certainly be it. This is the kind of message we need to get out there; this is the kind of angle we need to take.

How to Prove Global Warming Wrong

Over the past twenty years, vested interests and political lobby groups have done a fantastic job confusing the public about anthropogenic climate change. To many, they seem to have proven the whole theory wrong.

But how could you actually prove global warming wrong – not just in the minds of the public, but through the established scientific process? What scientific discoveries – if they held up through peer-review, further criticism, and replication – would render climate change a non-problem?

One of the surest ways to stop all this cap-and-trade discussion would be to disprove the greenhouse effect itself – the mechanism by which the Earth absorbs and emits the same energy multiple times, due to the presence of greenhouse gas molecules that “bounce it back”. This keeps the Earth substantially warmer than it would be otherwise. Additionally, if the concentrations of greenhouse gases increase, so will the temperature of the Earth. This process was first hypothesized by Joseph Fourier in 1824, and was experimentally confirmed by John Tyndall in 1856. The first prediction of eventual man-made global warming came from Svante Arrhenius, in 1896. It wasn’t a theory as much as a logical result of a theory, one that was deeply rooted in physics and chemistry.

Unless our understanding of entire fields of physical science is totally off base, we can be sure that our greenhouse gas emissions will cause climate change eventually. But hey, if you could overturn all of thermodynamics, you wouldn’t have to worry about carbon taxes.

  • Cheap-out option: Svante Arrhenius was Swedish, but his name sounds sort of Russian, and 1896 wasn’t very long before the Russian Revolution. Therefore, Arrhenius was a Communist, and none of his scientific work can be trusted.

Knowing that something is sure to happen eventually, though, is different from knowing that it is happening right now with substantial speed. We know that the Earth is warming – even if you found some statistical way to disprove three separate temperature records, the physical and biological systems of our planet still stand: 90% of observed changes in the natural world, like the blooming of flowers, the peak flows of rivers, and the spawning of fish, are in the direction expected with warming (Rosenzweig et al, 2008).

But how do we know that the warming is caused by us? Climate change has been caused many times in the past by factors unrelated to greenhouse gases – like solar influences, whether they’re direct (a change in solar output) or indirect (a change in the Earth’s orbit). How do we know that’s not happening now?

If the warming was caused by the sun, the atmosphere would warm uniformly at all levels. However, if the Earth was warming from greenhouse gases, the troposphere (the layer of the atmosphere closest to the planet) would warm while the stratosphere (the next level up) would cool. This is because more heat is getting bounced back to the surface by greenhouse gases, and is subsequently prevented from reaching the stratosphere.

A cooling stratosphere has been described as the “fingerprint” evidence of greenhouse-induced warming. And, in fact, the stratosphere has been cooling over the past 30 years (Randel et al, 2009). Therefore, if you could somehow show that something else was causing this pattern of a warming troposphere and a cooling stratosphere, and that the significant, anthropogenic rise in greenhouse gases was somehow not affecting it, you would have a case for global warming being natural.

Update (18/2/10): About half of this cooling can be attributed to ozone depletion, and the other half can be attributed to greenhouse gases (NOAA, 2006). The flat trend in stratospheric temperatures from 1995-2005 (see the Randel citation above) can be explained by the recovery of ozone, which is temporarily offsetting the greenhouse gases. Interesting how the temperature of the stratosphere has just as many factors as the temperature of the troposphere…..but in both cases, you can’t explain the temperature trends without including human activity. Scott Mandia has a great explanation here.

  • Cheap-out option: Omit the explanation of why greenhouse warming causes stratospheric cooling. Just point to the graph that goes down and say, “The atmosphere is cooling! Therefore, the IPCC is a hoax!”

Finally, even if you couldn’t disprove that global warming is expected, observed, and anthropogenic, you could still show that it isn’t very significant. The way to do this would be to show that climate sensitivity is less than 2 C. Climate sensitivity refers to the amount of warming that would result from a doubling of carbon dioxide equivalent, and 2 C is generally accepted as the maximum amount of warming that our society could endure without too much trouble. The current estimates for climate sensitivity, in contrast, average around 3 C (a range of 2-4.5), and it is very unlikely to be less than 1.5 C (IPCC AR4).

However, a climate sensitivity of less than 2 C only means that climate change isn’t a problem if our greenhouse gases stop at a doubling of carbon dioxide equivalent from pre-industrial levels. Even without taking methane and other greenhouse gases into account, this brings us to a CO2 concentration of 560 ppm, which we are well on track to surpass, even with cap-and-trade. So you’d have to argue for a climate sensitivity of even less. Seeing as we’ve already warmed 0.8 C, it doesn’t leave you with a lot of wiggle room.

  • Cheap-out option: Build a climate model that does what you want it to, without any regard for the laws of physics. ExxonMobil will probably sponsor the supercomputers. Widely publicize the results and avoid peer-review at all costs.

Daunting tasks, certainly. But if you really believe that global warming is natural/nonexistent/a global conspiracy, this is the way to prove it. If you managed to prove it, and change the collective mind of the scientific community (not just the public), you’d probably win a Nobel Prize. So it’s certainly worth your time and effort.

Manufacturing Doubt

I recently wrote this term paper for my world issues course. Enjoy.

There are many questions which remain controversial among scientists, but the existence of human-caused climate change is not one of them. Over 97% of publishing climatologists (Doran and Zimmerman, 2009), virtually 100% of peer-reviewed studies (Oreskes, 2004), and every scientific organization in the world (Logical Science, 2006) agree that humans are causing the Earth to warm. As Donald Kennedy, former editor-in-chief of the prestigious journal Science, says, “Consensus as strong as the one that has developed around this topic is rare in science.”

However, this consensus does not extend to the general public. On a particularly cold day, the cashier at the grocery store will say to you, “So much for global warming.” Over Thanksgiving dinner, your uncle will openly wonder if the warming in the Arctic is just part of a natural cycle. Your local newspaper will print letters to the editor almost daily claiming that, as CO2 is natural and essential to life, we shouldn’t worry about climate change.

What is the reason for this disconnection between scientific opinion and public opinion? There are obviously many factors involved, but it is probable that this discrepancy exists partly because of the widespread media coverage of scientists who do not accept anthropogenic climate change. Anyone with an Internet connection or a newspaper subscription will be able to tell you that many scientists think global warming is natural or nonexistent. As we know, these scientists are in the vast minority, and they have been unable to support their views in the peer-reviewed literature. The key question, therefore, is this: Why are so many of them still publicizing their beliefs so prominently?

Two plausible outcomes exist. Firstly, a scientist who could not prove a hypothesis could still feel that it was an idea worth consideration, and would want to capture the imagination of other scientists so it would be studied more closely. Alternatively, a scientist might be willing to keep the public confused about climate change. For example, scientists employed by the fossil fuel industry, or by organizations with strong laissez-faire agendas, could be motivated to spread rumours about weaknesses in the anthropogenic climate change theory. So, do these skeptics honestly doubt the integrity of climate science? Or are they being paid to manufacture doubt?

To distinguish between these two motives, it is important to understand a distinct difference in the formation of scientific opinions and political opinions. In science, one should examine all the evidence and then develop a logical conclusion. However, it is all too common in politics, lobbying, and the media for one to choose a convenient conclusion, then build evidence around it. This process is akin to an “ends justify the means” approach. The means (evidence and methods) are justified as long as they support the ends (a preconceived conclusion). In contrast, science, which is continually striving for a hypothetical physical truth, works the other way around – the means justify the ends. The conclusion is less important than the evidence and analysis used to reach it. Therefore, to tell the difference between an honest scientific argument and one that was constructed for political means, one simply has to distinguish between the ends and the means, and decide which is more central to the structure of the argument.

Let us now apply this strategy to the arguments of three of the skeptics who are most visible in the media. In articles from the popular press and news segments from major television stations, the names of these skeptics appear more than any others. Firstly, S. Fred Singer is an atmospheric physicist and retired environmental science professor. He has rarely published in scientific journals since the 1960s, but he is very visible in the media. In the past five years, he has claimed that the Earth has been cooling since 1998 (Avery, 2006), that the Earth is warming, but it is natural and unstoppable (Avery and Singer, 2007), and that the warming is artificial and due to the urban heat island effect (Singer, 2005).

Richard Lindzen, also an atmospheric physicist, is far more active in the scientific community than Singer. However, most of his publications, including the prestigious IPCC report to which he contributed, conclude that climate change is real and caused by humans. His only published theory that disputed climate change was met with vigorous criticism, and he has publicly retracted it, referring to it as “an old view” (Seed Magazine, 2006). Therefore, in his academic life, Lindzen appears to be a mainstream climate scientist – contributing to assessment reports, abandoning theories that are disproved, and publishing work that affirms the theory of anthropogenic climate change. However, when Lindzen talks to the media, his statements change. He has implied that the world is not warming by calling attention to the lack of warming in the Antarctic (Bailey, 2004) and the thickening of some parts of the Greenland ice sheet (Beam, 2006), without explaining that both of these apparent contradictions are well understood by scientists and in no way disprove warming. He has also claimed that the observed warming is minimal and natural (Fox News, 2006).

Finally, Patrick Michaels is an ecological climatologist who occasionally publishes peer-reviewed studies, but none that support his more outlandish claims. In statements to the media, Michaels has said that the observed warming is below what computer models predicted (Chatterjee, 2009), that natural variations in oceanic cycles such as El Niño explain most of the warming (Knappenberger and Michaels, 2009), and that human activity explains most of the warming but it’s nothing to worry about because technology will save us (Miller, 2009).

While examining these arguments from skeptical scientists, something quickly becomes apparent: many of the arguments are contradictory. For example, how can the world be cooling if it is also warming naturally? Not only do the skeptics as a group seem unable to agree on a consistent explanation, some of the individuals either change their mind every year or believe two contradictory theories at the same time. Additionally, none of these arguments are supported by the peer-reviewed literature. They are all elementary misconceptions which were proven erroneous long ago.

With a little bit of research, the claims of these skeptics quickly fall apart. It does not seem possible that they are attempting to capture the attention of other researchers, as their arguments are so weak and inconsistent. However, their pattern of arguments does work as a media strategy, as most people will trust what a scientist says in the newspaper, and not research his reputation or remember his name. Over time, the public will start to remember dozens of so-called problems with the anthropogenic climate change theory. From this perspective, it certainly seems that prominent skeptics are focusing on the ends, rather than the means. They are simply collecting as many arguments as they can to denounce global warming, and publicizing them vigorously. But why?

Earlier, we identified that organizations with a laissez-faire agenda would have reason to spread doubt on climate change, as the most effective form of mitigation would involve government regulation of fossil fuels. Many of these organizations, known as conservative think tanks, exist. Think tanks are supposed to be centres of independent, policy-related research, but conservative think tanks have migrated into an entirely new category. Over the past forty years, they have evolved into lobby groups that denounce any threat to the free market or laissez-faire economics. This objective often leads to the denial of established science, such as the relationship between smoking and cancer (which, if accepted, would lead to government regulation of tobacco and controls on where people could smoke), the destructive effects of CFCs on ozone (which could ban the products of an entire chemical industry), and, most recently, the climatic forcing of fossil fuel combustion, and the attribution of late-20th-century warming to this forcing.

The tactics that conservative think tanks (CTTs) use to manufacture doubt on climate change are often questionable and dishonest. On the rare occasion that their citations are peer-reviewed, they are discredited, cherry-picked, or misrepresented. For example, CTTs repeatedly cite data that shows slight cooling of the Earth – but only from before mechanical flaws in the satellites were corrected and the data began to show warming. They also cite a 2003 study by Sallie Baliunas and Willie Soon, claiming that the recent warming is attributable to sunspots. What CTTs don’t say is that, following the publication of this paper, 13 of the authors of data sets it incorporated refuted Baliunas’ interpretation of their work, and half of the editorial board resigned in protest against failure of the peer-review process. Additionally, CTTs argue that the wavelength band of CO2 absorption is already saturated, so adding more CO2 to the atmosphere wouldn’t cause any more warming – a theory that scientists proved wrong when spectroscopes improved in the 1950s.

Again, note the inconsistency of these statements, all of which were present at the same time on the Heartland Institute’s website. This CTT simultaneously claims that the world is cooling, that the world is warming naturally, and that the world is warming anthropogenically, but has maximized its potential. Evidently, these arguments were chosen because they fit with a preconceived conclusion, not with our understanding of science.

When their arguments are so similar, it should come as no surprise that most skeptics have ties to CTTs. Many of the most prominent skeptics write books – S. Fred Singer has written at least eight books skeptical of climate change, and Patrick Michaels has written at least five (Amazon). In 2008, a survey was conducted of books skeptical of climate change or other environmental issues, and found that an incredible 92% of the authors were affiliated with a CTT (Jacques, Dunlap, and Freeman, 2008). Additionally, some of the authors had connections to more than one CTT. For example, S. Fred Singer has been a part of ten different CTTs throughout his career. Patrick Michaels has been part of two, and Richard Lindzen has been part of three (Greenpeace USA).

It is obvious that CTTs want “experts” on their staff, because they want to sound scientific and credible. Additionally, the CTTs are willing to pay generous sums of money for expertise with a convenient conclusion. In 2006, the American Enterprise Institute offered ten thousand dollars plus expenses to any scientist who wrote a critique of the IPCC (Hoggan and Littlemore, 2009). Sure enough, a handful of scientists responded, and with good reason – they wouldn’t get a ten-thousand-dollar bonus for publishing a regular old peer-reviewed study.

What do these ties with CTTs tell us about skeptics? Have they decided to switch careers from researchers to PR representatives, trading in their scientific integrity for the promise of monetary gain? After all, if they work for a CTT, their arguments don’t have to be accurate – they just have to be effective in manufacturing doubt.

Another interesting fact about publicized skepticism is that it did not appear until governments started promising action on climate change – George  HW Bush in 1988 (Hoggan and Littlemore, 2009), Margaret Thatcher in 1990 (Thatcher, 1990), and Brian Mulroney in 1992 (United Nations). In fact, 87% of the books from the Jacques, Dunlap, and Freeman survey were published in or before 1988. Those published before likely did not even mention climate change – many of their titles suggested skepticism about toxic chemicals, the environmental concern of the 1970s. Therefore, it is very easy to pinpoint a short period of years and political events that sparked mass PR coverage of skeptical viewpoints. This trigger provides yet more evidence that skeptics are publicizing their views not to further scientific knowledge, but to manufacture public doubt and delay action.

So, when skepticism started in response to political promises, where were its roots? Unsurprisingly, the manufacture of doubt started with fossil fuel companies. In 1991, the Western Fuel Association, the National Coal Association, and the Edison Electric Institute formed a PR coalition named, ironically, the Information Council on the Environment (ICE). ICE launched a major advertising campaign denouncing the idea of anthropogenic global warming. The campaign’s objective, in ICE’s own words, was “to reposition global warming as a theory (not fact)” and “to supply alternative facts that suggest global warming will be good” (Hoggan and Littlemore, 2009). These objectives are a blatant example of manufacturing doubt, because they are based on the ends, not the means. ICE chose a conclusion that was convenient for their industry, and cherry-picked “alternative facts” to support it.

Several years later, a leaked document from another fossil fuel company, the American Petroleum Institute, gave away the organization’s entire game plan. The document laid out an ideal scenario in which the media reflected climate change as an equal-sided, unsettled debate, citizens began to accept this framing, and public support for the Kyoto Protocol fell apart. To achieve this utopia, API planned to “produce, distribute via syndicate and directly to newspapers nationwide a steady stream of op-ed columns and letters to the editor authored by scientists” (Walker, 1998). By manipulating how the media framed climate change, API could push public opinion in a predetermined direction. This document shows that fossil fuel companies such as the API have stopped caring about science anymore, otherwise the objectives would be “to publish our latest discovery that invalidates global warming in a prestigious journal”. Rather, their efforts are focused on the media, the public, and policymakers. They are consistently promoting ends that don’t have means to support them.

Over the last decade, however, fossil fuels have gradually shifted away from creating their own propaganda, choosing to fund CTTs instead. ExxonMobil, for example, has spent $20 million since 1998 funding CTTs that express climate change skepticism (Hoggan and Littlemore, 2009), and it releases annual breakdowns of its funding. Let’s look at some of the CTTs that our three major skeptics are a part of. Firstly, the Science and Environmental Policy Project, of which S. Fred Singer is president, has received $20 000 from Exxon since 1998. The Cato Institute, which has Patrick Michaels as a senior fellow, Richard Lindzen as a contributing expert, and S. Fred Singer as an advisory board member, has received $125 000. The Heartland Institute, which lists all three as “HeartlandGlobalWarming.org experts”, has received $676 500. (Greenpeace USA). At times, Exxon specifically notes that this funding is for “climate change efforts”, so it’s pretty obvious what kind of message they’re pushing.

Fossil fuel companies are some of the largest businesses in the world, and they are using their money and power to promote messages that are convenient for their further domination. Conservative think tanks – and, therefore, the experts they employ – are being paid, by vested interests, to say that global warming isn’t real. It provides yet another motive for skeptics to give more weight to the ends, rather than the means.

It seems quite obvious that these skeptics should not be trusted, as their arguments are inconsistent and unsupported, and they have potential fortunes resting on what they say, not how they prove it. However, the vested interests of CTTs and fossil fuel companies have been wildly successful in using these skeptics as their spokespeople. For example, the majority of articles from well-respected newspapers present the issue as an equal-sided debate, giving equal time to arguments for and against the idea of human-caused climate change (Boykoff and Boykoff, 2004). This framing has permeated to the public, as 39% of American adults think humans are not changing the climate (Gallup, 2007), and 42% think scientists disagree a lot about the issue (Newsweek, 2007). The constant presence of manufactured doubt in the media has taken its toll.

Additionally, since the skeptical view exploded following the near-action in the late 1980s, our society has spent 20 years without any significant plans for mitigation. The Kyoto Protocol failed in both Canada and the US. The Copenhagen summit did not lead to any politically binding targets. US President Barack Obama is finding it difficult to pass even the most meagre cap-and-trade legislation through the Senate, and the position of the Canadian government is to wait and see what the Americans do.

A democracy cannot function without an electorate that is accurately informed. We see an example of this scenario with regards to climate change legislation. Even though the scientific community is, essentially, as sure as it can get about the existence of human-caused climate change, the manufacture of doubt has prevented the public opinion from following suit, and prevented voters from demanding necessary political action. A well-funded campaign has led us astray from the ideals of democracy.

It’s not over yet, though. Climate change action is not a question of all or nothing. Even if we fail to keep the warming at a tolerable level, there is still a wide range of outcomes. Three degrees of warming is better than five, and five degrees is better than eight. We should never throw up our hands and say that all is lost, because we can always prevent the situation from getting worse.

To pull our society together in order to minimize global warming, we need the public to be better informed about climate change. This does not require everyone to know climate science – rather, all that is needed is for the public to be able to recognize whether or not they can trust an argument. Everyone needs to understand the importance of peer-review and the difference between the ends and the means. People do not need to know science – they just need to know how the system of scientific opinion works. Once this literacy becomes widespread, people will understand the urgency of action, and they will stop listening to those skeptical scientists on the news.

Works Cited

Amazon. “Patrick Michaels.” Amazon.com. Web. 7 Jan. 2010.

Amazon. “S. Fred Singer.” Amazon.com. Web. 7 Jan. 2010.

Bailey, Ronald. “Two Sides to Global Warming.” Weblog post. Reason.com. 10 Nov. 2004. Web. 9 Dec. 2009. <http://reason.com/archives/2004/11/10/two-sides-to-global-warming&gt;.

Beam, Alex. “MIT’s Inconvenient Scientist.” Boston Globe. 30 Aug. 2006. Web. 9 Dec. 2009. <http://www.boston.com/news/globe/living/articles/2006/08/30/mits_inconvenient_scientist&gt;.

Boykoff, Maxwell, and Jules Boykoff. “Balance as bias: global warming and the US prestige press.” Global Environmental Change 14 (2004): 125-36. Print.

Chatterjee, Neera. “Prof. says climate change exaggerated.” The Dartmouth. 24 Feb. 2009. Web. 10 Dec. 2009. <http://thedartmouth.com/2009/02/24/news/climate&gt;.

Dennis, Avery. “Global Cooling?” Web log post. Free Republic. 30 June 2006. Web. 9 Dec. 2009. <http://www.freerepublic.com/focus/f-news/1658580/posts&gt;.

Doran, Peter, and Maggie Zimmerman. “Examining the Scientific Consensus on Climate Change.” EOS 90.3 (2009): 22-23. Print.

Exxon Secrets. Greenpeace USA. Web. 10 Nov. 2009. <http://www.exxonsecrets.org/maps.php&gt;.

Fox News. “Global Warming: Climate of Fear?” Fox News. 25 May 2006. Web. 9 Dec. 2009. <http://www.foxnews.com/story/0,2933,195551,00.html&gt;.

Gallup. Environment Poll. 2007. Raw data.

Heartland Institute. Heartland Institute. Web. 13 Dec. 2009. <http://heartland.org&gt;.

Hoggan, James, and Richard Littlemore. Climate Cover-Up. Vancouver: Greystone, 2009. Print.

Jacques, Peter, Riley Dunlap, and Mark Freeman. “The organisation of denial: Conservative think tanks and environmental scepticism.” Environmental Politics 17.3 (2008): 349-85. Print.

Kennedy, Donald. “An Unfortunate U-Turn on Carbon.” Science 291.5513 (2001): 2515. Print.

Logical Science. “The Consensus on Global Warming/Climate Change: From Science to Industry & Religion.” Logical Science. 2006. Web. 9 Nov. 2009.

Luntz, Frank. “Straight Talk: The Environment: A Cleaner, Safer, Healthier America.” Letter to Republican Party. 2002. Political Strategy. Web. 10 Nov. 2009. <http://www.politicalstrategy.org/archives/001330.php&gt;.

Miller, Dan. “Look Who’s Talking.” Heartland Institute. 28 May 2009. Web. 10 Dec. 2009.

Miller, Dan. “Look Who’s Talking.” Heartland Institute. 28 May 2009. Web. 10 Dec. 2009.

Newsweek. Environment Poll. 2007. Raw data.

Oreskes, Naomi. “Beyond the Ivory Tower: The Scientific Consensus on Climate Change.” Science 306.5702 (2004): 1686. Print.

Oreskes, Naomi. “You CAN Argue with the Facts.” Stanford University. Apr. 2008. Lecture.

Paul, Knappenberger C., and Michaels J. Patrick. “Scientific Shortcomings in the EPA’s Endangerment Finding from Greenhouse Gases.” Cato Journal. Cato Institute, 2009. Web. 9 Dec. 2009. <http://www.cato.org/pubs/journal/cj29n3/cj29n3-8.pdf&gt;.

Revkin, Andrew. “Industry Ignored Its Scientists on Climate.” New York Times. 23 Apr. 2009. Web. 10 Nov. 2009. <http://www.nytimes.com/2009/04/24/science/earth/24deny.html&gt;.

Seed Magazine. “The Contrarian.” SeedMagazine.com. 24 Aug. 2006. Web. 3 Jan. 2010. <http://seedmagazine.com/content/article/the_contrarian/?page=all&gt;.

Singer, S. Fred, and Dennis Avery. Unstoppable Global Warming: Every 1500 Years. Lanham: Rowman & Littlefield,, 2007. Print.

Singer, S. Fred. “British Documentary Counters Gore Movie.” Heartland Institute. 1 June 2005. Web. 9 Dec. 2009.

SourceWatch. “Global Climate Coalition.” SourceWatch. Web. 7 Nov. 2009. <http://www.sourcewatch.org/index.php?title=Global_Climate_Coalition&gt;.

Thatcher, Margaret. “Speech at 2nd World Climate Conference.” Speech. 2nd World Climate Conference. Geneva. 1990. Margaret Thatcher Foundation. Web. 9 Nov. 2009. <http://www.margaretthatcher.org/speeches/displaydocument.asp?docid=108237&gt;.

United Nations. “Country Profile – Canada.” United Nations. Web. 9 Nov. 2009. <http://www.un.org/esa/earthsummit/cnda-cp.htm&gt;.

Walker, Joe. “Draft Global Climate Science Communications plan.” Letter to Global Climate Science Team. Apr. 1998. Web. 9 Nov. 2009. <http://euronet.nl/users/e_wesker/ew@shell/API-prop.html&gt;.

Weart, Spencer. The Discovery of Global Warming. Harvard UP, 2004. Print.

ClimateSight/CCC Movies!

Here is a re-upload of some public education videos (aimed at students) I created in the summer, in association with Climate Change Connection.

Read the citations, and take the survey if you’re feeling brave.

Enjoy!

Where to Go for Answers

To all of our new readers, thanks to CBC and StumbleUpon, this is for you!

Most of us don’t read scientific journals. We read the newspaper instead. We read our news feeds. We watch CNN.

These sources, as we know, are fairly low on the credibility spectrum. But how are people like you and I supposed to understand the more credible sources? Scientists don’t seem to speak plain English. And you can’t even read most of their studies without a subscription.

Usually this isn’t much of a problem, because the popular press and the scientific journals say basically the same things – that there’s going to be a lunar eclipse on a certain date, that red meat increases your risk of a heart attack, that a new kind of dinosaur was just discovered.

However, when you start reading about climate change, the newspapers start going crazy.

The world is warming. The warming is caused from the world coming out of an ice age. The warming stopped in 1998. Glaciers are melting. The warming is caused by human activity. The warming is caused by sunspots. The warming is inconsequential. The warming is catastrophic and is going to kill us all. New York is going to be underwater. Scientists faked the whole thing.

As someone who keeps up-to-date with the scientific literature – that is, sources from the top few tiers of the credibility spectrum – I can tell you that it is not under the same confusion as the mass media. There are a lot of myths about climate change that go around the newspapers and the Internet, but were never in any sort of legitimate scientific study. I cannot stress this point enough.

For example, have you heard the one about NASA getting the Y2K bug, and later discovering that the warmest year on record wasn’t 1998, but in fact – whoops – 1934? Global warming must be fake!

Actually, that’s not correct at all. NASA discovered that 1934 was the warmest year on record in the United States. And that “United States” part got dropped in translation somewhere in the blogosphere. Contrary to what American media would have you believe, the United States is not the whole world. It makes up less than 2% of the Earth’s surface. And the warmest year on record globally is either 1998 or 2005, depending on how you measure the Arctic temperatures.

There are dozens of stories like that. So many of the explanations you hear for global warming being natural/nonexistent/a global conspiracy are based on misconceptions, miscommunications, discredited data, or flat-out lies. They were never in the scientific literature. They are not endorsed by the sources at the top of our credibility spectrum. They are, shall we say, urban myths.

But how are we, humble non-scientists, scanning through the newspaper on the way to work each morning, supposed to know that? We need some kind of a link between the scientists and the public. Some journalist who actually knows what they’re talking about, and cites all of their claims with credible sources. Some sort of encyclopedia that will dispel all the myths about climate change.

Luckily, there are many of these encyclopedias. There are a lot of people out there trying to fulfill this very purpose.

One of my favourites is Peter Sinclair’s Climate Denial Crock of the Week video series on YouTube. He debunks common claims like “global warming stopped in 1998”, “global warming is caused by the sun”, and “temperature leads CO2 in the ice cores”. Sinclair is a professional journalist, so all of the videos are well explained, easy to understand, and fun to watch.

Another great source is Coby Beck’s How to Talk to a Climate Skeptic series. These articles cover just about every objection out there. Equally comprehensive is Skeptical Science. They’ve even compressed their explanations into “sound bites”, so you can answer your uncle’s objections in just a few sentences over Thanksgiving dinner.

Some of the sources from the top of our credibility spectrum have also chimed in. Environment Canada has created a fantastic FAQ document about climate change. It covers everything you need to know to wade through YouTube comments or online debates, along with citations you can actually trust.

Finally, Scott Mandia, a regular reader here at ClimateSight and a meteorology professor in New York, has just posted a copy of his presentation to the public about climate change. What I like about this document is that it’s very up-to-date. All of the graphs are the most recent of their kind. It also provides some philosophical perspectives to really sink your teeth into, like an analogy about medical advice, and some memorable quotes at the end.

We shouldn’t have to double-check everything the newspaper says about climate change. But the objections to anthropogenic global warming have such an awful track record that we really should, at least before we go and spread them around. These sources will cover just about everything you need to know.