Global Warming: Misguided Comments about the Northwest Passage
There was recently an article about global warming in the Tulsa World which took an interesting approach to the topic. It was an article from two Earth scientists which started , “As climate researchers from divergent political leanings we regularly hear misguided comments about global warming. To help move the dialogue forward we offer a brief response to the top 10. ” They went on to agree that the Earth is warming, that carbon dioxide is the main cause, that we are causing undesirable changes in the environment, and that we should leave things as best we can for future generations.
Probably the most relevant quote in the article is, “As climate researchers from divergent political leanings we regularly hear misguided comments about global warming.” Many of those misguided quotes come from anti-science websites like those of Anthony Watts, Roy Spencer, or Steve McIntyre’s. They use a little information which may be true but they do not tell you the rest of the story which puts it into perspective.
For instance, many anti-science web sites make a lot of the fact that the Northwest Passage was navigated around 1936. Satellite pictures show that since 1979, the extent of the Arctic sea ice has declined by about 40%. The claim about the Northwest Passage being open in 1936 is an effort to discount that by trying to show that in 1936he Arctic Ocean was open water. That was certainly not true, as the few early passages made then were with the help of icebreakers. You can get a better idea of how the Arctic Ocean is changing by looking at the actual shipping records:
Commercial Shipping on the Northern Sea Route 5,Table 1
Year Cargo,Thousands of Tons Length of Season
1935 246 93 days
1940 289 93 days
1950 503 122 days
1960 1013 128 days
1970 2400 140-150 days
1980 4951 year round for western section
1987 6579 year round for western section
Source: Derived from figures presented at the Conference of Nordic Navigation Institute, Tromsø, Norway, March, 1992.
The data certainly paints a different picture and it is interesting that none of the anti-science websites bothered to mention it.
You may have also heard one of the many versions of the story that, “the Earth hasn’t warmed in the last 15 years”. The anti-science sites got that from a BBC interview with Phil Jones, director of the British Climate Research Unit (CRU). The BBC interviewer asked “Do you agree that from 1995 to the present there has been no statistically-significant global warming?” Dr. Jones replied “ Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level.” Dr. Jones went on to explain that the result was not “statistically significant” because of the short time period.
Dr. Jones is often quoted but somehow the “statistically significant part” is omitted. You can prove a lot of untrue things about the Earth’s temperature by using using carefully selected or short time periods. For instance, if I were to choose the 16 years from 1982 to 1998, I could show that global warming has gone up by a whopping 0.31°C per decade. That, of course, is not statistically significant either. It takes about 30 years to average out the effects of natural variations and, over the last 30 years, the Earth has warmed about 0.15°C per decade.