|By Bob Weaver|
A new scientific study by the National Academy of Science is adding evidence that temperatures in the northern hemisphere fluctuated over time, but that the sharp increase during the past few decades is bigger than anything in at least 1,300 years.
Global warming has been highly politicized as bad science, opponents claiming it is a cyclical event not related to human production of greenhouse gasses - "an act of God."
The United States and the Bush administration is one of few nations that have declined to sign-on to agreements declaring it a world-wide problem that challenges life on earth.
The latest report published Tuesday concludes that temperatures increased and decreased a little over the centuries, but the fluctuations were small enough that the line was roughly flat.
Starting about 1980 to now, temperature increased sharply, more than any increase before.
For the past 10 years, climate-change skeptics, mostly in the US, have been calling global warming bogus.
The National Academy study "establishes further evidence that the recent warming isn't just part of a typical cycle," said climatologist Michael Mann, director of the Earth System Science Center at Pennsylvania State University.
"Of course, this alone doesn't establish the cause of that warming — that it must be due to human influences," Mann said. That's left to other scientific studies of the climate.
Mann said forces of nature — changes in the output of the sun's energy and volcanic eruptions — and random variation explain the changes in climate before industrial times.
The study further stated that if human factors are taken into account — particularly the production of long-lasting, heat-trapping gases from burning fossil fuels — can scientists explain the unusually high recent temperature increase.
The study collected additional data for the centuries before the mid-19th century, when scientists began recording temperatures.
Scientists have observed a warming of about 0.8 degrees Celsius during the past century.
There was a burst of about 0.3 degrees from about 1900 to 1950.
In the 1950s to 1970s, temperatures were flat or showed a slight cooling.
A larger increase of temperature has been recorded in the past 30 years, due largely to the increase of greenhouse gases.
The US government has supported a full-steam ahead approach toward the use of fossil fuels, an approach that has gained attention of the American people with the rapid rise of gasoline costs.
The dependence on fossil fuel in the US is enormous, and there is yet to be any official declaration, other than stop-gap projects, toward a national energy policy away from that dependence.
There has been no emergency.
The Bush administration, in what could be its most consequential blunder, began subsidizing the corn industry at taxpayer expense, as an answer to high energy costs, a non-solution to the global warming problem that also has significant fall-out for consumers in food costs and a pending problem with starvation in many countries in the world.