Thursday, July 12, 2007

Greenlands ice

As reported by the Boston Globe Friday

An international team of scientists, drilling deep into the ice layers of Greenland, has found DNA from ancient spiders and trees, evidence that suggests the frozen shield covering the immense island survived the earth's last period of global warming.

The findings, published today in the journal Science, indicate Greenland's ice may be less susceptible to the massive meltdown predicted by computer models of climate change, the article's main author said in an interview.

"If our data is correct, and I believe it is, then this means the southern Greenland ice cap is more stable than previously thought," said Eske Willerslev, research leader and professor of evolutionary biology at the University of Copenhagen. "This may have implications for how the ice sheets respond to global warming. They may withstand rising temperatures."

A painstaking analysis of surviving genetic fragments locked in the ice of southern Greenland shows that somewhere between 450,000 and 800,000 years ago, the world's largest island had a climate much like that of Northern New England, the researchers said. Butterflies fluttered over lush meadows interspersed with stands of pine, spruce, and alder.

Greenland really was green, before Ice Age glaciers enshrouded vast swaths of the Northern Hemisphere.

More controversially -- and as an example of how research in one realm of science can unexpectedly affect assumptions in another -- the discovery of microscopic bits of organic matter retrieved from ice 1.2 miles beneath the surface indicates that the ice fields of southern Greenland may be more resilient to rising global temperatures than has been forecast. The DNA could have been preserved only if the ice layers remained largely intact.

A scenario often raised by global warming specialists is that Greenland's ice trove will turn liquid in the rising temperatures of coming decades, with hundreds of trillions of gallons of water spilling into the Atlantic. This could cause ocean levels worldwide to rise anywhere from 3 to 20 feet, according to computer projections -- bad news for seaport cities like Boston.

But the discovery of organic matter in ice dating from half-a-million years ago offers evidence that the Greenland ice shield remained frozen even during the earth's last "interglacial period" -- some 120,000 years ago -- when average temperatures were 9 degrees Fahrenheit warmer than they are now. That's slightly higher than the average temperatures foreseen by most scientists for the end of this century, although some environmentalists warn it might get even hotter.

Researchers from the Danish-led team said the unanticipated findings appear to fly in the face of prevailing scientific views about the likely fate of Greenland's thickly-layered ice, although Willerslev stressed that the findings do not contradict the basic premise that the earth's temperature is rising to worrisome levels, with gases emitted by industry, cars, and other human activity playing a big role.

"But it suggests a problem with the [computer] models" that predict melting ice from Greenland could drown cities and destroy civilizations, according to Willerslev.

Well it's not the worlds biggest island, but hey.


John Nicklin said...

I wonder how long it will take for the warming crowd to "debunk" this one. Its not good for them and they don't take kindly to such transgressions as you well know.

Count Iblis said...

It won't be debunked. It is not so relevant, because it doesn't show that the Greenland Ice won't melt this time. It just shows that it may not melt that easily. However, the predicted temperature increase do take into account that governments take strong actions to curb CO_2 emissions.

If politicians say: "we don't need to do anything", then the temperatures will rise way more and then the melting of the Green land ice will be a certainty.

John Nicklin said...


Check out the reply from RealClimate. More obsfucation.

Count Iblis said...

Climate scientists explaining their research is "obsfucation"?

philip said...

I'd find RealClimate a lot more persuasive if they would stop the evasion and outright deception.

I'll use the recent posts on CO2 saturation as an example. 2 posts argued the conventional CO2 saturation models are wrong due to band widening. But no mention of what the new saturation levels are, for relevant CO2 concentrations.

The clear implication is saturation isn't occuring or is too small to worry about, which to use an Australian term is bollocks.

Count Iblis said...

Saturation indeed does not happen, that's almost elementary high school physics. I guess to understand these things one has to study physics a bit and stay away from blogs (RealCimate being the exeption to this rule).

In this case it is actually pretty easy to explain. The Earth absorbs a certain amount of energy from the Sun, and will emit the same amount in the form of infrared radiation.

If we add CO2 to the atmosphere and wait until equilibrium has been achieved, the Earth will again emit the same amount of radiation per unit time as it did before the CO2 was added.

But the radiation that escapes to space comes mostly from one scaterring length into the atmosphere. If more CO2 is added, then that point is shifted upward. Since the amount of radiation that escapes into space remains the same, it follows that at that higher pont in the atmosphere it becomes a bit hotter, hence it becomes a bit hotter at the surface.

The fact that CO_2 has certain absorbtion bands doies not imply that you will get saturation. The reason is that the emitted radiation that makes it into space is the thermal radiaton that is produced by the air molecules one scatering length into the atmosphere.

The radiation the Earth emits is partially absorbed by the atmosphere, reflected, remitted etc. etc. by the atmosphere.

It is not like the earth emiting radiation and the CO2 acting as a mirror that reflects radiation with wavelengths in the absorbtion bands partially back. In this naive picture you would have saturation, but this is an oversimplification. E.g. if an infrared photon outside the CO_2 absorbtion band is emitted by Earth, then this can be absorbed by an H2O molecule, casing the rotational state of this molecle to change. That molecule can emit radiaton in the CO_2 absorbtion band...

But in equilibrium these detailed processes will lead to a simple outcome: When you look from space into the Earths atmospere the infrared photons you see effectively come from one scattering length into the atmosphere (which depends in the wavelength). The effective temperature of that radiation corresponds to the local temperature at one scattering length into the atmosphere.

Anyway, this is all elementary physics that students in the first years of university learn, even some high school studens learn this stuff.