Study Says Earth's Temp at 400-Year High(DOOMED!!!!)

The Earth is the hottest it has been in at least 400 years, probably even longer. The National Academy of Sciences, reaching that conclusion in a broad review of scientific work requested by Congress, reported Thursday that the "recent warmth is unprecedented for at least the last 400 years and potentially the last several millennia."

A panel of top climate scientists told lawmakers that the Earth is running a fever and that "human activities are responsible for much of the recent warming." Their 155-page report said average global surface temperatures in the Northern Hemisphere rose about 1 degree during the 20th century.

The report was requested in November by the chairman of the House Science Committee, Rep. Sherwood Boehlert, R-N.Y., to address naysayers who question whether global warming is a major threat.

Last year, when the House Energy and Commerce Committee chairman, Rep. Joe Barton, R-Texas, launched an investigation of three climate scientists, Boehlert said Barton should try to learn from scientists, not intimidate them.

The Bush administration also has maintained that the threat is not severe enough to warrant new pollution controls that the White House says would have cost 5 million Americans their jobs.

Climate scientists Michael Mann, Raymond Bradley and Malcolm Hughes had concluded the Northern Hemisphere was the warmest it has been in 2,000 years. Their research was known as the "hockey-stick" graphic because it compared the sharp curve of the hockey blade to the recent uptick in temperatures and the stick's long shaft to centuries of previous climate stability.

The National Academy scientists concluded that the Mann-Bradley-Hughes research from the late 1990s was "likely" to be true, said John "Mike" Wallace, an atmospheric sciences professor at the University of Washington and a panel member. The conclusions from the '90s research "are very close to being right" and are supported by even more recent data, Wallace said.

The panel looked at how other scientists reconstructed the Earth's temperatures going back thousands of years, before there was data from modern scientific instruments.

For all but the most recent 150 years, the academy scientists relied on "proxy" evidence from tree rings, corals, glaciers and ice cores, cave deposits, ocean and lake sediments, boreholes and other sources. They also examined indirect records such as paintings of glaciers in the Alps.

Combining that information gave the panel "a high level of confidence that the last few decades of the 20th century were warmer than any comparable period in the last 400 years," the academy said.

Overall, the panel agreed that the warming in the last few decades of the 20th century was unprecedented over the last 1,000 years, though relatively warm conditions persisted around the year 1000, followed by a "Little Ice Age" from about 1500 to 1850.

The scientists said they had less confidence in the evidence of temperatures before 1600. But they considered it reliable enough to conclude there were sharp spikes in carbon dioxide and methane, the two major "greenhouse" gases blamed for trapping heat in the atmosphere, beginning in the 20th century, after remaining fairly level for 12,000 years.

Between 1 A.D. and 1850, volcanic eruptions and solar fluctuations were the main causes of changes in greenhouse gas levels. But those temperature changes "were much less pronounced than the warming due to greenhouse gas" levels by pollution since the mid-19th century, it said.

The National Academy of Sciences is a private organization chartered by Congress to advise the government of scientific matters.

GLOBAL WARMING PRIMER
http://www.clearlight.com/~mhieb/WVFossils/ice_ages.html
http://vathena.arc.nasa.gov/curric/land/global/climchng.html
http://junkscience.com/MSU_Temps/historical_CO2.htm
http://www.geocraft.com/WVFossils/Carboniferous_climate.html

These two figures show former temperatures with major periods of glaciation labeled. The dashed lines are the present global average temperature of about 15° C (59° F). Thus the solid curves show small changes from this average; note that the temperature drops only about 5° C during a glaciation. This has occurred about every 100,000 years, with smaller wiggles in between. That is, there has been a 100,000 year glaciation cycle for the past million years or so, and there may be shorter cycles as well.

The most recent glaciation, 20,000 years ago, is called the Laurentide, and Earth is still recovering from it. This map from the The Illinois State Museum exhibit on ice ages shows the extent of that ice.

The most recent small drop in average temperature caused the Little Ice Age of 1500-1700 AD, which history describes. Mountain glaciers advanced in Europe and rivers like the Thames in England froze solid, which doesn't happen now.

Click image for animation

The growth of the ice sheets began about 120,000 years ago as ice built up on the continents in the Northern Hemisphere, especially in Canada and Europe. The largest extent of these ice sheets occurred 18,000 years ago. At that time the largest ice sheets were between 3.5 and 4 km thick. In North America the largest ice sheet was the Laurentide Ice Sheet centered on Hudson Bay with other sheets centered on Greenland and in the Canadian Rocky Mountains. As these ice sheets expanded they grew together, covering Baffin Bay and eventually the Great Lakes and New England. In northwestern Europe the Fennoscandian Ice Sheet began to grow and expand south to cover what is now Norway and Sweden and north to cover the exposed continental shelf. Over time the ice sheet grew to cover Finland and the United Kingdom. This ice sheet extended east to the Ural Mountains where it met the Siberian Ice Sheet. Before the last ice age ice sheets already existed on Antarctica and on Greenland.

Most people seem surprised when we say current levels are relatively low, at least from a long-term perspective - understandable considering the constant media/activist bleat about current levels being allegedly "catastrophically high." Even more express surprise that Earth is currently suffering one of its chilliest episodes in about six hundred million (600,000,000) years. Given that the late Ordovician suffered an ice age (with associated mass extinction) while atmospheric CO2 levels were more than 4,000ppm higher than those of today (yes, that's a full order of magnitude higher), levels at which current 'guesstimations' of climate sensitivity to atmospheric CO2 suggest every last skerrick of ice should have been melted off the planet, we admit significant scepticism over simplistic claims of small increment in atmospheric CO2 equating to toasted planet. Granted, continental configuration now is nothing like it was then, Sol's irradiance differs, as do orbits, obliquity, etc., etc. but there is no obvious correlation between atmospheric CO2 and planetary temperature over the last 600 million years, so why would such relatively tiny amounts suddenly become a critical factor now?

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