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Scientific Uncertainty

As the northern hemisphere enters winter, the number of jokes that people will make about the presence of global climate change is about to increase exponentially. It happens every year: some people see snow on the ground and immediately scoff at the idea of global warming. And every year, when faced with these jokes, I think to myself, “this is going to be a loooong winter.”  

Global climate change is the new way to refer to global warming. It’s considered more accurate because climate models have shown that while some places will get warmer, others might get colder, and some places might disappear Atlantis style thanks to rising sea levels.  Sounds outrageous? Well, the island nation of Kiribati is already feeling the effects.

But semantics aside, global climate change is another one of those issues that’s a lot less controversial than some media outlets may lead one to believe. There’s a general scientific consensus on the fact that climate change is real and it is human-driven. That kind of consensus is a big deal. Because the consequences of overstating the significance and strength of a scientific finding can be enormous for the scientist and the world at large, many scientific findings are talked about in terms of uncertainty. Theories get tested for years, statistical tests are invoked and criticized, experiments are repeated and repeated to ensure that the findings are real–all in an attempt to ensure that scientists are accurately observing, describing, and understanding the phenomena they study.

Scientific knowledge cannot exist solely within the scientific community: it is often used by non-scientists, such as policymakers, to guide decisions, and sometimes, that causes a disconnect. Uncertainty has a definition in the scientific community that differs from the general definition. It’s one of those frustrating words that doesn’t seem like it’s field-specific jargon, but it is–much the way “organic” means different things if you’re talking to a chemist or a farmer.  If you were 99% sure about a fact, would you consider yourself certain? As a layperson, I probably would, but as a scientist, I would acknowledge that 1% of doubt and see it as a crucial component of my scientific knowledge.

Scientists do research to put limits on uncertainty, to create parameters for it. Scientists have learned to be comfortable with uncertainty and to be fine thinking and talking about probabilities. Many policymakers look for absolute certainty in making decisions, something which scientists can never guarantee.  However, this does not mean that findings that lack absolute certainty aren’t valuable for guiding policy, or that they are wrong or inaccurate: it just means that scientists and policymakers are looking at uncertainty in different ways. Policymakers look at the uncertainty as a potential issue, and scientists look at it as crucial information about an issue.  The disconnect is a problem, but it is no one’s fault: after all, in a very real way, scientists and policymakers aren’t even speaking the same language sometimes.

4 replies on “Scientific Uncertainty”

I think the disconnect between science terms and lay terms has caused so many problems.  When scientists talk about uncertainty and there being a chance that what they’re saying isn’t right and is due to chance, they don’t always understand that we’re talking about a 5% chance at worst of it being untrue, and that’s in the psychological field.  From what I’ve been told other sciences are more stringent about that margin of error.  In regular life we see a 50% chance and will change things, especially if we’re talking about protecting people.  Hell, we give agencies so much power because of the off chance that they might stumble on a wrong-doer-I mean, it’s worth it if they catch just one bad person, right?  Somehow it’s always different when it comes to talking science.

With regard to climate change: the 2007 report of the Intergovernmental Panel on Climate Change (IPCC), which summarized the results of over 6000 peer-reviewed studies on the topic, concluded that “[w]arming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level” (p 30 [p 8 as the pdf pages are numbered]) and that “[m]ost of the observed increase in global average temperatures since the mid-20th century is very likely [>90% likelihood] due to the observed increase in anthropogenic GHG [greenhouse gas] concentrations” (p 39). Their treatment of uncertainty comes from the published studies themselves – the IPCC didn’t do any original uncertainty analyses – and is described on page 27. It has been criticized on methodological grounds, but critics usually point out that this does not invalidate the conclusions of the report. The first link gets you to the synthesis of three IPCC reports released in 2007 – it’s still long as shit, but the information is so important that it’s worth a looksee. The IPCC’s next report is due in 2014, although I doubt the shitshow will be as monumental this time around. I can dream.

Every time the “How can there be global warming? It’s snowing!” FB statuses pop up, it’s all I can do to keep from all-capsing “OMG IT IS GLOBAL CLIMATE CHANGE AND IT DOESN’T MEAN IT’S NEVER GOING TO SNOW AGAIN WHERE IS NEIL DEGRASSE TYSON WHEN I NEED HIM TO TELL STUPID PEOPLE TO SHUT UP ABOUT SCIENCE?”

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