What Happened At Durban?

Cross-posted from NextGen Journal

Following the COP17 talks in Durban, South Africa – the latest attempt to create a global deal to cut carbon emissions and solve global warming – world leaders claimed they had “made history”, calling the conference “a great success” that had “all the elements we were looking for”.

So what agreement did they all come to, that has them so proud? They agreed to figure out a deal by 2015. As James Hrynyshyn writes, it is “a roadmap to a unknown strategy that may or may not produce a plan that might combat climate change”.

Did I miss a meeting? Weren’t we supposed to figure out a deal by 2010, so it could come into force when the Kyoto Protocol expires in 2012? This unidentified future deal, if it even comes to pass, will not come into force until 2020 – that’s 8 years of unchecked global carbon emissions.

At COP15 in Copenhagen, countries agreed to limit global warming to 2 degrees Celsius. The German Advisory Council on Global Change crunched the numbers and discovered that the sooner we start reducing emissions, the easier it will be to attain this goal. This graph shows that if emissions peak in 2011 we have a “bunny slope” to ride, whereas if emissions peak in 2020 we have a “triple black diamond” that’s almost impossible, economically. (Thanks to Richard Sommerville for this analogy).

If we stay on the path that leaders agreed on in Durban, emissions will peak long after 2020 – in the best case scenario, they will only start slowing in 2020. If the triple black diamond looks steep, imagine a graph where emissions peak in 2030 or 2040 – it’s basically impossible to achieve our goal, no matter how high we tax carbon or how many wind turbines we build.

World leaders have committed our generation to a future where global warming spins out of our control. What is there to celebrate about that?

However, we shouldn’t throw our hands in the air and give up. 2 degrees is bad, but 4 degrees is worse, and 6 degrees is awful. There is never a point at which action is pointless, because the problem can always get worse if we ignore it.

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The Rest of the World

Here in North America, we are surrounded with rhetoric denouncing the feasibility of climate change mitigation. It’s not possible to reduce our emissions, people say. It’s not worth it.

The situation in the U.S. Congress regarding this issue is becoming so bizarre that hopes for an international agreement to reduce greenhouse gas emissions have grown faint. Without the U.S. on board, many countries (see: Canada) will bail out entirely.

Not all countries are waiting for everyone else, however. Many developed countries, particularly in Europe, have gone ahead and achieved significant cuts in their emissions. Let’s take a step out of the little bubble of North America and see what the rest of the world managed to do while we bickered about whether or not there was even a problem.

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Countries: the European Union (EU), representing most of Europe

Emission Targets: 20% below 1990 levels by 2020

How They’ll Get There: The EU started a cap-and-trade system in 2005. They also plan to target energy efficiency and develop the use of renewable energy.

How They’re Doing : The total emissions of the EU have declined slightly since 1990. This is partly because many Eastern European countries are still transitioning from communism, and their emissions are fairly low while their economies recover. However, some rich countries such as Germany, Sweden, Denmark, and the UK have made significant cuts in their emissions, and, as of 2008, were already around 10-20% below 1990 levels.

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Country: the United Kingdom (UK)

Emission Targets: 12.5% below 1990 levels by 2012, as per their Kyoto targets. Through their Climate Change Acts, the UK has also set a goal of 80% below 1990 levels by 2050.

How They’ll Get There: The government is aiming for 40% of their energy to come from low-carbon sources (both renewable and nuclear). They are also focusing on efficiency, and planning a cap-and-trade system.

How They’re Doing: The UK is well on track to meet, and even exceed, their Kyoto agreements. By 2010, their emissions were predicted to be 11% below their Kyoto targets.

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Country: Norway

Emission Targets: Norway has some of the most ambitious targets in the world. Not only are they aiming for emissions to be 30% below 1990 levels by 2020, they are planning a carbon-neutral economy – 100% cuts – by 2050. If a major international agreement comes to pass, like Copenhagen was supposed to be, they will pledge for carbon neutrality by 2030.

How They’ll Get There: In addition to their cap and trade system, Norway is investing a lot of money into carbon capture and storage (CCS). They have also introduced taxes on natural gas and stricter efficiency standards for new houses.

How They’re Doing: Norway’s emissions have increased by 8% since 1990. Hopefully their extensive plans will reverse that trend.

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Country: Australia

Emission targets: If an international agreement comes to pass, Australia will reduce their emissions to 25% below 2000 levels by 2020. Otherwise, they will shift that target to 5-15%. Normally, using a baseline that’s later than the standard 1990 is a warning sign, a clever trick that governments use to make their targets look stricter than they are (see: Canada). However, since Australia’s emissions fell slightly between 1990 and 2000, the equivalent target with respect to 1990 is actually more than 25%.

How They’ll Get There: The Australian Parliament has had difficulty passing cap-and-trade legislation. They are hoping to implement this eventually, but will focus on energy efficiency and renewables in the mean time.

How They’re Doing: Originally, Australia refused to sign Kyoto, but in 2007 a new Prime Minister, Kevin Rudd, was elected. He committed the country to Kyoto targets, just a little late. So far, it looks like Australia will easily meet their targets of 8% over 1990 levels by 2012.

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Country: Japan

Emission targets: Japan has set solid targets of 25% below 1990 levels by 2020, and 80% by 2050.

How They’ll Get There: Japan has a cap-and-trade system, and is considering a carbon tax. They also want 10% of their energy to come from renewables by 2020.

How They’re Doing: Japan’s emissions have increased slightly since 1990. As of 2008, they were about 6% above 1990 levels.

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Country: Canada

Emission targets: The Canadian government has pledged to reduce emissions to 17% below 2005 levels by 2020. However, emissions in 2005 were quite a bit higher than they were in 1990. When you adjust this estimate to the standard baseline, it’s actually a 2.5% increase. The Environment Canada website describes this as an “ambitious target”. Go figure!

How They’ll Get There: So far, the Canadian government has tightened up fuel efficiency standards for passenger vehicles, but that’s about it. The current administration refuses to consider meaningful action until the United States does. In fact, the House of Commons recently passed a bill setting meaningful emission targets (20% below 1990 levels by 2020, and 80% by 2050)…but the Senate, which has a Conservative majority, voted the bill down with absolutely no debate. Given the fact that Senators are appointed by Prime Ministers, not elected by citizens, it’s hard to see this action as anything less than anti-democratic.

How They’re Doing:By 2008, Canadian emissions had soared to 24% above 1990 levels.

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This data almost makes me feel ashamed to be Canadian, to be a part of such an obstructionist country. Look at what countries in Europe have managed to do. It wasn’t impossible, like so many North American politicians warned. And then look at countries like the United States and Canada, that have not only failed to reduce their emissions, but have actively worked against any kind of a plan to do so.

Future generations will not look on us kindly. We will become the villains of our own history books.

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Update: By popular request:

Country: United States of America

Emission targets: None

How They’ll Get There: Despite not having a formal target for emissions, the Environmental Protection Agency (EPA) began to regulate emissions from fossil-fuel fired power plants and refineries in late December. The Republican Party is resorting to all sorts of silliness to try to change this.

How They’re Doing: As of 2008, US emissions were 14% above 1990 levels.

Ozone Depletion and Climate Change

“Global warming…doesn’t that have something to do with the ozone?” Well, no. Environmental issues are not all the same. It’s common for people to confuse climate change and ozone depletion, but they are separate issues – although they are indirectly connected in some interesting ways.

Ozone, which is made of three oxygen atoms stuck together (instead of two, which is what normal oxygen gas is made of), is vital to life on Earth. It forms a layer in the stratosphere, the second layer up in the atmosphere, that is very good at absorbing ultraviolet (UV) radiation from the Sun. UV radiation severely damages organisms if enough of it reaches the surface. The 3% or less that gets through the ozone already gives us sunburns and skin cancer, so you can imagine what the situation would be like if the ozone layer wasn’t there at all.

In the middle of the 20th century, synthetic gases known as chlorofluorocarbons (CFCs) became popular for use in refrigerators and aerosol products, among other applications. They were non-toxic, and did not react easily with other substances, so they were used widely. However, their chemical stability allowed them to last long enough to drift into the stratosphere after they were emitted.

Once in the stratosphere, the CFCs were exposed to UV radiation, which was able to break them down. Free chlorine atoms (Cl) were liberated, a substance that is very reactive indeed. In fact, Cl acts as a catalyst in the decomposition of ozone, allowing two ozone molecules to become three oxygen molecules, losing their UV absorbing power in the process. Since catalysts are not used up in a reaction, the same Cl radical can continue to destroy ozone until it reacts with something else in the atmosphere and is removed.

Over the poles, the stratosphere is cold enough for polar stratospheric clouds (PSCs) to form. These PSCs provided optimum conditions for the most reactive chlorine gas of all to form: ClO (chlorine monoxide). Now there wasn’t just a catalytic cycle of free Cl radicals depleting the ozone, there was also a cycle of ClO. It turns out that Antarctica was more favourable for ozone depletion than the Arctic, both because its temperatures were lower and because its system of wind currents prevented the ozone-depleting substances from drifting out of the area.

Before long, there was a hole in the ozone layer over Antarctica (due to the PSCs), and concentrations were declining in other locations too (due to the basic Cl reactions). The issue became a frontier for scientific research, and scientists Crutzen, Rowland, and Molina won the 1995 Nobel Prize in Chemistry for their work with atmospheric ozone.

In 1987, politicians worldwide decided to ban CFCs under the Montreal Protocol. This movement was largely successful, and the use of CFCs has become nearly negligible, especially in developed nations. They have been replaced with gases that safely decompose before they reach the stratosphere, so they don’t interfere with ozone. The regulations are working: the ozone hole in Antarctica has stabilized, and global stratospheric ozone concentrations have been on the rise since 1993.

In contrast, climate change is a product of greenhouse gases such as carbon dioxide. Unlike CFCs, most of them are not synthetic, and they are released from the burning of fossil fuels (coal, oil, and natural gas), not specific products such as refrigerators. Rather than destroying a natural process, like CFCs do, they strengthen one to the point of harm: the greenhouse effect. This phenomenon, which traps heat in the atmosphere, is absolutely vital, as the Earth would be too cold to support life without it. Increasing the concentrations of greenhouse gases with fossil fuels becomes too much of a good thing, though, as the greenhouse effect traps more heat, warming the planet up.

Just a few degrees Celsius of warming can cause major problems, as agricultural zones, wind and ocean currents, and precipitation patterns shift. The sea level rises, submerging coastal cities. Many species go extinct, as the climate changes faster than they can adapt. Basically, the definition of “normal” in which our civilization has developed and thrived is changing, and we can’t count on that stability any more.

Unlike the Montreal Protocol, efforts to reduce greenhouse gas emissions have more or less failed. Fossil fuels permeate every part of our lives, and until we shift the economy to run on clean energy instead, convincing governments to commit to reductions will be difficult at best. It remains to be seen whether or not we can successfully address this problem, like we did with ozone depletion.

Although these two issues are separate, they have some interesting connections. For example, PSCs form in cold areas of the stratosphere. That’s why the ozone hole is over Antarctica, and not somewhere else. Unfortunately, global warming is, paradoxically, cooling the stratosphere, as a stronger greenhouse effect means that less heat reaches the stratosphere. Therefore, as climate change progresses, it will make it easier for the ozone depletion reactions to occur, even though there are fewer CFCs.

Additionally, CFCs are very strong greenhouse gases, but their use has drastically reduced so their radiative effects are of lesser concern to us. However, some of their replacements, HFCs, are greenhouse gases of similar strength. They don’t deplete the ozone, but, per molecule, they can be thousands of times stronger than carbon dioxide at trapping heat. Currently, their atmospheric concentrations are low enough that they contribute far less forcing than carbon dioxide, but it wouldn’t take a large increase in HFCs to put us in a bad situation, simply because they are so potent.

Finally, these two issues are similar in that ozone depletion provides a smaller-scale analogue for the kinds of political and economic changes we will have to make to address climate change:

  1. Unintended chemical side effects of our economy posed a serious threat to all species, including our own.
  2. Industry representatives and free-market fundamentalists fought tooth and nail against conclusive scientific findings, and the public became bewildered in a sea of misinformation.
  3. Governments worked together to find sensible alternatives and more or less solved the problem.

We’ve already seen the first two events happen with climate change. Will we see the third as well?

The Pendulum

Cross-posted from NextGen Journal

A few years ago, climate change mitigation became a major political issue. Before 2005, governments certainly knew that human-caused climate change was a serious problem – but the public knew next to nothing about it, so there was no incentive to act. However, between 2005 and 2007, a perfect storm of events splashed the reality of climate change onto the world stage.

The Kyoto Protocol, an international agreement to reduce greenhouse gas emissions, finally came into force in early 2005, after years of negotiation. The United States refused to sign, and Australia signed on a little late, but every other developed nation in the world agreed to emission targets. Here in Canada, the Liberal government enthusiastically pledged its support for Kyoto. My local newspaper ran editorials exploring the different ways we could meet our targets, through combinations of clean energy, green infrastructure, and efficiency standards.

The summer of 2005 was a wake-up call for the United States, as Hurricane Katrina mercilessly demonstrated the amount of damage that extreme weather can bring. It’s impossible to say, at least with our current technology, whether or not Katrina was caused or even worsened by a warming planet. However, such devastating storms will become the norm as climate change progresses. Scientists aren’t sure whether or not hurricanes will become more frequent in a warming world, but the average hurricane is expected to become stronger and more damaging, and we are already beginning to see this rise in storm intensity. Katrina gave us an example of what we can expect from climate change – even if it wasn’t a direct effect in itself – and the world was shocked by the suffering that ensued.

2006 marked the release of An Inconvenient Truth, Al Gore’s Academy Award-winning documentary about climate change. For scientists studying climate, the film was an admirable, up-to-date example of science communication, albeit with a few minor errors and oversimplifications. However, for citizens new to the issue (I particularly remember my classmates in grade 9 social studies discussing the film), An Inconvenient Truth was a disturbing reality check – scarier than any horror movie, because it was real.

The major scientific event of 2007 was a drastic, unexpected drop in Arctic summer sea ice. That season’s melt was exacerbated by coincidental weather conditions, so the next years weren’t quite as bad, but the trend was still worrying, to say the least. The research community had assumed that summer ice would stick around for at least a century, but this timescale was soon halved and quartered as ice melt exceeded even the worst projections.

By 2007, lead-up to the 2008 US presidential election was underway, and political awareness of climate change was obvious. It was no surprise that Democrat Barack Obama had ambitious plans to cut greenhouse gas emissions, but even the Republicans seemed to be on board. During his time in office, George W. Bush had insisted that, since climate change could be natural, any mitigating action was not worth the economic risk. Republican presidential candidates seemed to realize that continuing to adopt this attitude would be political suicide. The most extreme example, John McCain, who would eventually win the Republican presidential nomination, had emissions targets only slightly less extensive than Obama’s. As he said in 2007,

The world is already feeling the powerful effects of global warming, and far more dire consequences are predicted if we let the growing deluge of greenhouse gas emissions continue, and wreak havoc with God’s creation…The problem isn’t a Hollywood invention nor is doing something about it a vanity of Cassandra like hysterics. It is a serious and urgent economic, environmental and national security challenge.

However, McCain, once an author of a bill designed to cut greenhouse gas emissions, would soon completely change his stance. By 2010, he was asserting that cap-and-trade legislation was unnecessary and carbon dioxide posed no harm to the American people. He even went so far as to question the political motivations of science he once wholly accepted:

I think [global warming is] an inexact science, and there has been more and more questioning about some of the conclusions that were reached concerning climate change. And I believe that everybody in the world deserves correct answers whether the scientific conclusions were flawed by outside influences. There’s great questions about it that need to be resolved.

The story of John McCain isn’t too surprising. Politicians frequently base their statements on public sentiment rather than personal opinion. They say what people want to hear, rather than what they truly believe is important. This aspect of our political system is depressing, but persistent. The real question, though, regards what changed public sentiment so quickly. Why did politicians like McCain feel compelled to denounce the importance of action on this problem, or even the existence of the problem itself? What happened since 2007 that made the pendulum swing so far in the other direction?

Strike one was the economy. The global recession that began in 2008 was the largest since the Great Depression, and concern for all other problems promptly went down the drain. It’s understandable for citizens to not worry about the environment when they don’t even have the means to feed and clothe their children properly. However, for governments to not realize the long-term economic implications of allowing climate change to continue, along with the potential job-creating benefits of a new energy economy, was disappointing, even though it wasn’t surprising.

Strike two was the all-out war on climate science, spearheaded by the fossil fuel industry and the far right. This PR campaign has been underway since the early 1990s, but was kicked up a notch just over a year ago. Since public understanding of the causes and effects of global warming was growing, and the science was becoming more solid by the month, the PR tactics changed. Instead of attacking the science, they attacked the integrity of the scientists. The most extreme example occurred in November 2009, when private correspondence between top climate researchers was stolen, spread on the Internet, and spun in an attempt to cast doubt on the scientists’ motives. This event, known as “Climategate”, spurred a great deal of anger among the political right, and everything from bitter editorials to death threats against scientists ensued. Perhaps most distressingly, by the time investigations found that the scientists involved were innocent, and the reality of climate change untouched, Climategate was old news and media outlets failed to adequately follow up on the story. Citizens heard the accusations, but not the exonerations, so political will to cut greenhouse gas emissions slipped even further.

Strike three – well, there has been no strike three, and a good thing too. Strikes one and two were so bad that some are hoping the pendulum has swung as far as it can go. It’s certainly difficult to imagine how the situation could get worse. The Kyoto Protocol is set to expire next year, and the Copenhagen meetings failed to create a replacement. As it was, many developed nations failed to meet their targets, and the Canadian government backed out completely.

The possibility of federal climate legislation for the United States is laughable now that not a single Republican Senator thinks action is necessary, and most doubt the reality of the problem, choosing to believe that the entire scientific community is out to lunch and/or an agent of conspiracy. President Obama’s director of climate policy, Carol Browner, recently left her position, although none of her major goals had been met. Obama’s recent State of the Union address included lots of hopeful statements about clean energy, but absolutely no mention of climate change, as if merely acknowledging the most pressing reason for a new energy economy would be political suicide. The time-honoured tradition of saying what the public wants to hear has even reached Obama, the man who promised change.

In Canada, legislation to simply set targets for emission reduction passed the House of Commons (made of elected representatives), but the Senate (composed of appointed politicians) chose to use their newfound Conservative majority to strike down the bill with no debate whatsoever, in a blatantly undemocratic move that has not happened since the 1930s. The Canadian government is all for a new energy economy, but not one based on environmental and social responsibility. The Alberta tar sands, which are substantially more polluting and carbon-intensive than traditional oil, continue to expand, and both federal and provincial governments are worryingly enthusiastic.

From 2005 to 2007, politics was high on promises of mitigation, but low on delivery. Since then, it has been devoid of both. It’s starting to seem as if it will take a major global disaster that can be unquestionably tied to climate change for governments to get their act together.

This would all be very well if there was no lag time between cause and effect in the climate system, but it doesn’t work that way. It takes several decades for all the warming in the pipeline to show up. If we waited until climate change became unbearable, and then cut off our emissions completely, the situation would still get worse for decades before it stabilized.

The worldwide failure of governments to take action on climate change is baffling. It seems that the best they can do is occasionally promise to fix the problem, but never actually get started. If this continues for much longer, we’re all going to pay the price for their mistakes – and so will people for generations to come.

The Unofficial Climate Change Book Awards

Cross-posted from NextGen Journal

As an aspiring climate scientist, I have read dozens of books about climate change over the past few years. Here are my all-time favourites, which I present with Unofficial Climate Change Book Awards. (Unfortunately, the prizes consist entirely of bragging rights.)


Best Analysis of Future Scenarios
Climate Wars, by Gwynne Dyer
View on Amazon.com

Most of us are aware of how climate change will impact the world: more extreme weather, prolonged floods and droughts, dwindling glaciers and sea ice. In this book, renowned Canadian journalist and military historian Gwynne Dyer goes one step further, and explores how these physical impacts might affect geopolitical relations. Will India and Pakistan engage in nuclear warfare over clean water? Will the United States and Russia begin a “Colder War” over Arctic sovereignty? Many of the scenarios he writes about are, frankly, terrifying, and all have a frightening grain of plausibility to them. Read the full review


Best Introduction to Climate Science
The Discovery of Global Warming, by Spencer Weart
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Scientists overwhelmingly agree that human-caused climate change is underway, but instead of simply stating this conclusion, Weart tells the story of how it was reached: tracing the theory from the 1800s to today. This innovative approach to science education, combined with Weart’s elegant prose, makes the book a joy to read. It doesn’t feel like a textbook, although it contains as much information as one. Read the full review


Best Exposé
Climate Cover-Up, by James Hoggan and Richard Littlemore
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If scientists are so sure about the reality of anthropogenic climate change, why does so much of the public think that it’s natural/nonexistent/a global conspiracy? Why does the media present the issue as an equal-sided scientific debate? This confusion didn’t just happen by accident – it was deliberately constructed. Over the past two decades, lobby groups representing industries or ideologies that seek to delay action on climate change have engaged in a campaign to spread doubt about the reality of the problem. This book, rather than throwing around baseless accusations, methodically examines the paper trail of this widespread campaign. Reading Climate Cover-Up is an infuriating but absolutely necessary journey to take. Read the full review


Best Policy Discussion
Storms of my Grandchildren, by Dr. James Hansen
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James Hansen is possibly the most prominent climate scientist alive today, and that title is well-deserved. Throughout his career at NASA, he has frequently made discoveries that were ahead of his time. Dr. Hansen is a very intrinsic scientist who doesn’t enjoy being in the spotlight or talking about policy, but he wrote this book for fear of his grandchildren looking back at his work and saying, “Opa understood what was happening, but he did not make it clear.” Although he couldn’t resist slipping in a few chapters about the current frontiers of climate science, the bulk of the book is about policy, featuring compelling arguments for expanded nuclear power, a moratorium on coal, and a rising price on carbon. Read the full review


Best Canadian Focus
Keeping Our Cool, by Dr. Andrew Weaver
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Andrew Weaver is Canada’s top climate modeller, and a fantastic role model for science communication. This book gives a high-level, yet accessible, explanation of the mathematics of climate change – if you have some basic knowledge of calculus and statistics, you should be fine. However, what really makes this book stand out is its focus on Canadian climate journalism and politics, a rare quality in a field dominated by American research. We all know about George W. Bush’s track record of inaction, but what has Prime Minister Stephen Harper done (or not done)? High-profile studies exist on American media coverage of global warming, but how does the Canadian press compare? Read the full review


Best Insider’s Account
Science as a Contact Sport, by Dr. Stephen Schneider
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The late Stephen Schneider, who unexpectedly died last summer of a heart attack, is a true pioneer of climate modelling. He has been active in the field since the 1970s, when computers became fast enough to handle mathematical models. This memoir explains what it’s like to be a climate scientist, and how that has changed over the years. In the 70s, Schneider and his colleagues filled their mind with purely analytical questions, but today, they have to deal with the media, politicians, and hate mail as well. Science used to just be about science, but now it’s about communication as well. Read the full review


Most Gripping
Snowball Earth, by Gabrielle Walker
View on Amazon.com

Gabrielle Walker is a brilliant woman, as she possesses the ability to make a book about geology every bit as gripping as a murder mystery. Granted, Snowball Earth, a recent theory of climatic conditions during the Precambrian Era, is fascinating. In short, the continents were arranged in such a manner that the Earth would swing back and forth between “Snowball Earth” (frozen oceans and frozen land all over, even at the Equator) and “Hothouse Earth” (massive global warming from volcanic emissions of carbon dioxide). Until this period of massive climatic swings, the only thing that lived on Earth was unicellular goop…but immediately following the Snowball Earth cycles, complex life appeared. Many scientists don’t think this evolutionary timing was a coincidence. It’s possible that multicellular organisms, including us, only exist because of an accident of plate tectonics. Read the full review


If you would like to contest any of my decisions for these awards, please feel free to do so in the comments!

Just Links for Now…

I apologize for my relative silence recently. I am in the midst of studying for my first set of final exams. To tide you over until that has calmed down a bit, I will share some of the interesting pieces I have read and watched recently.

My study break today was spent watching a fantastic video that Peter Sinclair recently dug up. It’s an hour-long talk by Dr. Ben Santer (see my recent interview with him), with an introduction by the late Stephen Schneider and questions at the end. He tells a very troubling story about “science, non-science and nonsense”. Lots of great quotes in there – I highly recommend giving it a watch.

John Cook from Skeptical Science has compiled his articles and rebuttals into a gorgeous document about the evidence for anthropogenic climate change, written in accessible language with effective graphics on every page. It’s so effective, I would like to print out a few dozen of these booklets and hand them out at the university.

On RealClimate, Ray Pierrehumbert addressed the common policy option of focusing on cutting emissions of methane and soot in the short-term in order to “buy us time” to reduce carbon dioxide. In fact, because these emissions have such a short atmospheric lifetime, it doesn’t really matter whether we focus on them now or later – while concentrations of carbon dioxide, with a lifetime of centuries to millennia, highly depend on when we address it. Take a look at these projections comparing our options:

Michael Tobis, however, thinks that we should focus on non-CO2 emissions despite these realities. Short-term economic and population “crashes” due to sudden warming in the near term could conceivably be more damaging to human security, because it means that we won’t be able to afford any mitigation, further worsening the long-term emissions. Both articles are worth a read.

Well, off to go memorize organic functional groups. Enjoy!

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.