Muadib
Paranormal Adept
DENIER MYTH #19: We don’t have enough climate data to make valid predictions of any kind. We have so many problems predicting the weather that there’s no way we’ve got enough data to predict how the entire climate functions (Source: multiple sources).
Debunking:
Allow me to draw a detailed analogy from my professional field, electrical engineering. Please bear with me – I’ll try to keep the math and technical jargon to a minimum. The image to the left shows a simple electrical circuit called a difference amplifier. Using two fundamental relations derived from some of the laws of physics (specifically Kirchoff’s Voltage and Current Laws, derived from conservation of energy and conservation of charge respectively), and knowing a couple of key bits of information about resistors and operational amplifiers (op-amps), we can crunch through some basic algebra to come up with the following equation that describes mathematically how the output voltage VOUT is related to the input voltages VIN1 and VIN2.
If you notice, the name “difference amplifier” comes from the fact that VOUT is related to a difference between VIN1 and VIN2, and in fact if you select the resistor values correctly (R2=RF, R1=RG), you get a simplified equation below.
Given that I’ve described the circuit mathematically, do I have enough information to accurately predict how the circuit will respond? Yes and no. This equation accurately describes the operation of the circuit if the circuit perfectly represents reality. 
But the circuit doesn’t perfectly represent reality. Reality is quite a bit more complex, as the image shows. This circuit illustrates a much more accurate picture of reality in that it includes terms such as bias current, offset current, and offset voltage, and this equation is the corrected equation for the operation of the circuit (this equation is still missing two of the larger corrections, input and output resistance, because I didn’t want to re-derive the equations – it gets really tedious really fast).
But sometimes that’s still not a good enough model of reality. Every single term is a function of temperature, so as the temperature of the op-amp and the resistors change, their values change. Not only that, but depending on the precise nature of the parts, how the parts change with temperature will vary – some will increase as temperature increases, some decrease, some increase for a while and then decrease, some don’t change at all. Not only that, but if the circuit is expected to operate for an extended period of time, every term (including the temperature term) may change totally differently as the part ages. How each component operates varies with air pressure, humidity, radiation exposure, proximity to electromagnetic interference, how the component is packaged, what materials it’s made out of, mechanical stresses, manufacturing imperfections, device noise, input noise, and power supply variations. And this list is still too small to include all the possible variables – it’s just the list I came up with after 10 minutes of thinking of all the factors I’ve been expected to consider over the years. There are probably dozens more I haven’t even considered. Given the massive number of factors that might, or might not, affect the operation of the difference amplifier above, it’s simply not always possible to make detailed and exact predictions of how it will react at any given instant even though the circuit’s gross functionality will alway be predictable.
Predicting climate using models is like me predicting how the difference amplifier works at a basic level – I don’t need to know how the exact devices will react to air pressure and temperature in order to derive the basic equations. But if we want to use climate models to predict the weather, that’s a lot more like me trying to predict how my difference amplifier will operate given every possible input condition and variable.
We don’t need to have all the data in order to have valid predictions. We need to have an understanding of the basic physics, the basic feedback and forcing mechanisms, and of the inputs and outputs of the Earth’s climate system. Climate scientists have a great deal of this information and have included it in the climate models (the illustration above illustrates the progression in increasing model detail from early models to the latest used by the IPCC). The climate models aren’t perfect, but neither are the basic equations of a difference amplifier circuit.
Do we have enough data to be able to claim, as I have, that the climate models are good enough to qualify as “basic equations”? Well, the IPCC Working Group I Fourth Assessment Report Summary for Policymakers says that they have “very high confidence,” 90% or more (see the image to the right for how the IPCC AR4 defines all the various confidence levels), that human beings have heated up the planet since 1750 (
Box TS.1 on page 22-23 of the describes the percent confidence/likelihood indicated by the language). The Summary also says that the data and models have improved since 2001 when the likelihood was only “likely,” or greater than 66%, that humans were causing global heating (see the image to the right for how the IPCC Working Group I Fourth Assessment Report Technical Summary defines different likelihoods)
What increased the likelihood in the view of about 620 authors representing 42 different countries? It was partly that two of the key predictions of the IPCC Third Assessment Report (TAR) were accurate when compared with the actual data. First, the IPCC predicted that the temperature would increase by about 0.5 degrees C as per the image to the left. If you look at this blown up image, you’ll see that the actual data, approximately 0.7 degrees C, exceeded the global expected change significantly (indicated by the orange intersection I added).
Some variation from the model over the short term is reasonable, so the fact that we’ve exceeded the expected range isn’t necessarily cause for concern that the models are underestimating global heating. Second, the TAR predicted that sea level would rise by between 1 and 5 cm from 1990 to 2006, with the expected range from the models somewhere between roughly 2.5 and 4 cm (Click on the image below for a more readable blow-up). If you look at the red and blue lines representing ocean station data and satellite altimeter data, you’ll notice that both track very closely to the maximum, but are both within the range of the IPCC TAR model. 
(Unfortunately, there’s significant confusion and contention about whether the TAR and AR4 models are similar, whether the unknown factors are included or not. See here for one side of the discussion, here for the other.)
In addition to the data closely matching the models, the scientists also have five or six more years of climate data of all types, improved data due to better measurement techniques, and more data from a wider geographical area. Combine the new and improved data, measured correlation between the old models and the new data, and improved climate models that, when properly vetted and compared with historical climate reconstructions, and you end up with a very compelling global heating theory that has convinced 620 authors from 42 countries that both the theory and the predictions are accurate. (Other sources: Real Climate’s page on sea level rise)
DENIER MYTH #20: Volcanos emit more CO2 in a single eruption (or per year) than humanity does, dwarfing anthropogenic emissions (source: comment below by BobCook)
Debunking: Volcanoes emit a lot of gases, including significant amounts of CO2. Unfortunately, according to papers from back in the late 1990s, “Volcanoes contribute about 110 million tons of carbon dioxide per year while man’s activities contribute about 10 billion tons per year.” This means that anthropogenic CO2 emissions are 100x greater than volcanic CO2 emissions. In addition, as mentioned above in Myth #18, volcanoes generally cause global cooling through the emissions of cloud-forming sulfur dioxide and water-cycle feedback. Finally, the USGS says “The most significant impacts from these injections come from the conversion of sulfur dioxide to sulfuric acid (H2SO4), which condenses rapidly in the stratosphere to form fine sulfate aerosols” at this site
Over geologic time, volcanoes and mantle outgassing have emitted more CO2 than humanity ever will, but that’s over the course of 4.5 billion years. See Myth #1 above for more information.
Additional information for how volcanic CO2 emissions compare to anthropogenic CO2 emissions is available at Gases: Man vs. the Volcano.
At one point or another, each of these claims represented a real problem with the science of global heating. But no longer – the scientific evidence has become overwhelming. However, it’s the minority composed of global heating deniers who continue to hunt for flaws in climate science, so the deniers serve a valuable scientific purpose – when they find a real hole, or just think they have, addressing their claims are what has made the science of global heating as bullet-proof as it now is.It comes down to this simple fact: the overwhelming majority of the scientific evidence points to human-induced global heating, and every claim made by global heating deniers has been effectively debunked. And because the consequences of doing nothing are so severe, we must act now even as the data continues to improve – we can no longer afford to wait.[Crossposted: The Daedalnexus]NOTE: This post was inspired by a blog Whythawk posted a couple of weeks ago entitled Life Earth will end climate change the way Live Aid ended poverty in Africa – Er… where one of the comment posters, “2008Voter”, posted the links to some of the sources used for this blog.
Debunking:
We don’t need to have all the data in order to have valid predictions. We need to have an understanding of the basic physics, the basic feedback and forcing mechanisms, and of the inputs and outputs of the Earth’s climate system. Climate scientists have a great deal of this information and have included it in the climate models (the illustration above illustrates the progression in increasing model detail from early models to the latest used by the IPCC). The climate models aren’t perfect, but neither are the basic equations of a difference amplifier circuit.
In addition to the data closely matching the models, the scientists also have five or six more years of climate data of all types, improved data due to better measurement techniques, and more data from a wider geographical area. Combine the new and improved data, measured correlation between the old models and the new data, and improved climate models that, when properly vetted and compared with historical climate reconstructions, and you end up with a very compelling global heating theory that has convinced 620 authors from 42 countries that both the theory and the predictions are accurate. (Other sources: Real Climate’s page on sea level rise)
DENIER MYTH #20: Volcanos emit more CO2 in a single eruption (or per year) than humanity does, dwarfing anthropogenic emissions (source: comment below by BobCook)
Debunking: Volcanoes emit a lot of gases, including significant amounts of CO2. Unfortunately, according to papers from back in the late 1990s, “Volcanoes contribute about 110 million tons of carbon dioxide per year while man’s activities contribute about 10 billion tons per year.” This means that anthropogenic CO2 emissions are 100x greater than volcanic CO2 emissions. In addition, as mentioned above in Myth #18, volcanoes generally cause global cooling through the emissions of cloud-forming sulfur dioxide and water-cycle feedback. Finally, the USGS says “The most significant impacts from these injections come from the conversion of sulfur dioxide to sulfuric acid (H2SO4), which condenses rapidly in the stratosphere to form fine sulfate aerosols” at this site
Over geologic time, volcanoes and mantle outgassing have emitted more CO2 than humanity ever will, but that’s over the course of 4.5 billion years. See Myth #1 above for more information.
Additional information for how volcanic CO2 emissions compare to anthropogenic CO2 emissions is available at Gases: Man vs. the Volcano.
At one point or another, each of these claims represented a real problem with the science of global heating. But no longer – the scientific evidence has become overwhelming. However, it’s the minority composed of global heating deniers who continue to hunt for flaws in climate science, so the deniers serve a valuable scientific purpose – when they find a real hole, or just think they have, addressing their claims are what has made the science of global heating as bullet-proof as it now is.It comes down to this simple fact: the overwhelming majority of the scientific evidence points to human-induced global heating, and every claim made by global heating deniers has been effectively debunked. And because the consequences of doing nothing are so severe, we must act now even as the data continues to improve – we can no longer afford to wait.[Crossposted: The Daedalnexus]NOTE: This post was inspired by a blog Whythawk posted a couple of weeks ago entitled Life Earth will end climate change the way Live Aid ended poverty in Africa – Er… where one of the comment posters, “2008Voter”, posted the links to some of the sources used for this blog.
) to fit the respective theory seems more like it. 
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