Guest Post by Willis Eschenbach
Once again, I return to that endless font of misinformation, the Waxman Markey website. In this case, I look at their claims about Alaska. This one will be short and sweet. Their claim is that Alaska is roasting, as in the picture below:
Figure 1. The dessert known as “flaming baked Alaska”. Ice cream covered with meringue, doused with brandy, and set on fire. Sweet.
The Waxman Markey website page on Alaska says:
Over the past 50 years, Alaska has warmed by 4 to 7 degrees Fahrenheit, much more than anywhere in the lower 48 states. This dramatic temperature change is causing the landscape of Alaska to change faster than anywhere else in the United States, threatening infrastructure, wildlife, and Native Alaskan culture.
I fear that these numbers must from the well-known Government Misinformation Agency.
Figure 2 shows the real numbers:
Figure 2. Alaskan temperatures, as the average of all first-order stations in the state.
There are a few things we can see here. First, Fig. 1 clearly shows the dependence of Alaska temperatures on the Pacific Decadal Oscillation (PDO). The PDO is a long-term shift in Pacific sea surface temperatures. The PDO has a warm phase and a cool phase, as shown in Figure 3. It shifts from one phase to the other every thirty years or so.
Figure 3. Cool (positive) and warm (negative) phases of the PDO. IMAGE SOURCE
The PDO shifted to the cool phase in the late 1940s. It went back to the warm phase in 1976-77. And recently, it has gone back to the cool phase. This is clearly visible in the Alaska temperatures. As much as Waxman Markey wants to blame the shift in Alaskan temperatures on “global warming”, the science says otherwise. The changes are due to the shifts in the PDO.
Second, their claim that Alaska has “warmed by 4 to 7 degrees Fahrenheit” is not true. The largest trend to 2009 in the Alaska temperatures is 1954-2009, which is 3.24 degrees.
I also note that they are using a very different period from the one they used in their claims about the US Northeast, where they used the trend from “the 1970′s”. Obviously, they are picking their time period to exaggerate their claims …
The main point here is that because the PDO gives Alaska warm periods and cool periods, it is meaningless to use any trend starting from a cool period and ending in a warm period, or vice versa. Yes, you can get a positive trend from anywhere on the left half of the graph to anywhere on the right side of the graph … but that doesn’t tell us anything about what’s happening.
Short and sweet.