I felt compelled to reply to N.E. MacNab on the assertion that CO2 levels are the lowest that they have been “in hundreds of millions of years.” In fact, all reputable scientists agree that C02 levels have been rising since the industrial age. Anybody who thinks about this seriously must agree that the rise of the petroleum extraction and the decrease of forest mass can not help but raise the amount of carbon in the atmosphere that is in turn absorbed by the ocean. A recent New Yorker article estimates that it would take 50 years for ocean acidification to decrease even if we stopped using hydrocarbons tomorrow. A Wikipedia article states: “The concentration of C02 is approaching 397 ppm (parts per million) by volume as of May 2012 and rose by 2.0 ppm/year during 2000-2009.”
Of course we can believe any source. We believe, no matter how hair-brained, but the Wikipedia article documents its sources unlike N.E. MacNab.
I know the problem exists because I spent over 20 years in the Arctic. In 1972 the ice didn’t go out in Broughton Island and there was conjecture that a second ice age may be coming. Today there is a vast difference. Sea- ice that used to stay as late as September in Frobisher Bay may be gone in June and the ocean is not frozen solid again until late December. There are robins now in Frobisher Bay. They were unknown when I left there in 1980. The Arctic is the tipping point. While the information may be anecdotal, I tend to trust the knowledge of Inuit elders whose lives have depended for generations on knowing their terrain and environment.
Curiously N.E. MacNab cites the rise of ocean levels as a point in favour of the argument. In fact the melting of ice caps and the disappearance of Arctic sea ice is precisely related to rising atmospheric CO2 levels and overall global warming.
Let me add another point. Well-documented investigations testify to the increase of ocean acidification. This is contributing to the decline and eradication of small crustaceans.
Krill populations are plummeting because of ocean acidification and the loss of habitat under the disappearing Arctic sea-ice fields. What does that mean to salmon fishing? That means -— even more than over fishing, salmon farms and the destruction of fish spawning habitat — that the days of our cherished salmon fishing are numbered.