Earth 'likely' hottest in 2,000 years

[Janice]

WASHINGTON (AP) -- 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-New York, 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.

[Janice]

WASHINGTON (AP) -- It has been 2,000 years and possibly much longer since the Earth has run such a fever.

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.

http://www.cnn.com/2006/TECH/science/06 ... index.html

[Yarrah]

And there are still people that think Global Warming is a hoax...

[Audrey2Katrina]

And there are still people that think Global Warming is a hoax...

Not necessarily a hoax... but an overhyped essentially natural cycle.

A2K

[Audrey2Katrina]

and potentially the last several millennia.

The "potentially" part sounds extremely dubious and speculative IMO...But hey, I have no doubt it's been "warming" since the last glacial period.... and the cycle will eventually reverse itself.

A2K

[Janice]

Yes, I agree. I think we are just going through another cycle which our earth has gone through before. Our earth will go through all these cycles regardless if man is here or not.

[MGC]

So, what caused it to be so warm 2000 years ago?......MGC

[chadtm80]

[Janice]

What caused the Ice Age..... maybe slow planet rotation.....

[Yarrah]

Yes, I agree. I think we are just going through another cycle which our earth has gone through before. Our earth will go through all these cycles regardless if man is here or not.

Indeed, we're in a natural warming cycle. Only, man has worsened this cycle by emitting a lot of greenhouse gases. 1 degree in a hundred years ins't something natural (apart from climate changes due to natural disasters).

[Regit]

Yes, I agree. I think we are just going through another cycle which our earth has gone through before. Our earth will go through all these cycles regardless if man is here or not.

Indeed, we're in a natural warming cycle. Only, man has worsened this cycle by emitting a lot of greenhouse gases. 1 degree in a hundred years ins't something natural (apart from climate changes due to natural disasters).

It's sort of like putting ice water at room temperature. It will naturally warm. The trouble is we're putting a flame under it. It's warming much more quickly than what is otherwise natural.

[Janice]

How many years before we really see a change?

[Audrey2Katrina]

Nobody can answer that with any degree of reliability, Janice. You'll get some who say we're all gonna' drown in the next 30 years... and others who tell you we'll have an ice-age by the end of the century... these things are, quite frankly, beyond our capability to predict with much more than an educated guess involving soooo many variables, that the margin of error is vast.

A2K

[Extremeweatherguy]

2000 years is not really that long in the scope of the earth's entire existance. The hottest in 2000 years is like saying right now is the hottest I have seen it within the last day, without taking into account the other 364 days in the year. It really means nothing.

[Janice]

Yes, you have a really good point there.

[Audrey2Katrina]

2000 years is not really that long in the scope of the earth's entire existance. The hottest in 2000 years is like saying right now is the hottest I have seen it within the last day, without taking into account the other 364 days in the year. It really means nothing.

Geologically that is an excellent point, although I know some will strongly disagree, I tend to feel the same way.

A2K