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I think the bigger thing to pull from that quote centers on the word "prediction". The IPCC FAR didn't really make any predictions. Instead, it made a series

I think the bigger thing to pull from that quote centers on the word "prediction". The IPCC FAR didn't really make any predictions. Instead, it made a series of projections (twelve of them, to be precise) based on running various sets of hypothetical parameters through a climate model. Some of those projections were based on very pessimistic scenarios (very high CO2 sensitivity, very high future CO2 emissions). They projected very high increase in temperature. Other projections were based on more optimistic scenarios. They projected a lower increase in temperature. Now, the number that the author quotes (0.3C +/- 0.1C per decade) corresponds to the range for the block of projections that assumes a very high climate sensitivity - a sensitivity that turns out to be high. Since the projection was based on a scenario that did not correspond to reality, if we assume that the models were reasonably accurate then it should not surprise us that the projection didn't end up corresponding to reality, either. So there's an interesting omission. . . and an example of how what someone doesn't say can say as much about their position as what they do say. Another omission that speaks volumes is highlighted if you compare the projections for scenarios that ended up being more representative of how those parameters did evolve over the next two decades to what global temperatures have been doing over that time period. Far from the alarmist claims of gloom and doom that the author would like to suggest were made, the projection for the scenario that ended up most closely corresponding to what actually happened slightly underestimated the actual change in temperature. But by an amount that was quite small in comparison to the error bars, so an honest and scientific analysis of the TAR projections would force us to conclude that in this particular respect the IPCC's analysis was actually dead on. Poorly reasoned arguments are certainly unfortunate. . . but if you really want to make your position look bad, try blatantly cherry-picking the data.

Torgo 14y ago
Well, he used the same numbers that the IPCC FAR report's "Policymaker's Summary" section chose to use, which repeatedly uses the term "is predicted" (admittedly, qualified with "based on current model results" or specific scenarios.) The explicit purpose of that section was to suggest possible policy options based on a set of long-term events stated to be found _with certainty_ (their words) by the working group that were going to occur. Let's say that I am a "policymaker" and not a climate scientist, and I sensibly choose to defer to experts how I should plan for any potential climate change. That's the section that was written specifically to me for that purpose, by the working group--with the same numbers that this guy quotes.
- bunderbunder 14y ago
  Those cases where the BaU figures are used are disclaimed with the qualifier, "Under the Business-as-Usual scenario", and the ensuing discussion is pretty clearly intended as an exposition on how we should not have wanted to mimic the BaU scenario because, as the model projections for that scenario indicate, there was compelling reason to believe that the consequences would have been bad. Again, cherry-picking things out of context does not a compelling argument make. Unless the people you're trying to compel can be trusted to not check your sources too carefully. And of course the corollary to that is, if the topic is controversial you should always thoroughly fact-check your sources. (Speaking of, I couldn't find the phrase "with certainty" in either of the three FAR policymakers summaries. . . perhaps you meant "with confidence"? Regardless, it's skirting the edge of dishonesty to use the phrase "their words" to describe something that isn't their words.)

Torgo 14y ago

Well, he used the same numbers that the IPCC FAR report's "Policymaker's Summary" section chose to use, which repeatedly uses the term "is predicted" (admittedly, qualified with "based on current model results" or specific scenarios.) The explicit purpose of that section was to suggest possible policy options based on a set of long-term events stated to be found _with certainty_ (their words) by the working group that were going to occur. Let's say that I am a "policymaker" and not a climate scientist, and I sensibly choose to defer to experts how I should plan for any potential climate change. That's the section that was written specifically to me for that purpose, by the working group--with the same numbers that this guy quotes.

bunderbunder 14y ago
Those cases where the BaU figures are used are disclaimed with the qualifier, "Under the Business-as-Usual scenario", and the ensuing discussion is pretty clearly intended as an exposition on how we should not have wanted to mimic the BaU scenario because, as the model projections for that scenario indicate, there was compelling reason to believe that the consequences would have been bad. Again, cherry-picking things out of context does not a compelling argument make. Unless the people you're trying to compel can be trusted to not check your sources too carefully. And of course the corollary to that is, if the topic is controversial you should always thoroughly fact-check your sources. (Speaking of, I couldn't find the phrase "with certainty" in either of the three FAR policymakers summaries. . . perhaps you meant "with confidence"? Regardless, it's skirting the edge of dishonesty to use the phrase "their words" to describe something that isn't their words.)