Geological research shows that whenever Earth heats up a few degrees, the Arctic gets three times as warm.


A look at Arctic climate changes over the past 5 million years shows it always amplifies global temperatures.

The Arctic amplification happens regardless of the cause of the global climate change.

Today's Arctic fits the ancient pattern.

Whether it's 5 million years ago or June 2010, it's becoming very clear that whenever the Earth's climate warms up a few degrees -- for whatever reason -- the Arctic multiples that warming by a factor of about three.

Two new studies of past warming and cooling periods going back millions of years have found that the Arctic reliably amplifies whatever global climate is doing. If the world drops 3 degrees colder, the Arctic will see 9 to 12 degrees of cooling. If Earth warmed up 3 degrees, the Arctic steams up 9 to 12 degrees.

"What it reinforces is that the Arctic has very strong positive feedbacks," said Gifford Miller of the University of Colorado, who spoke to Discovery News via satellite phone from a research expedition in northwest Australia.

This year, that could mean the Arctic could be the warmest ever recorded since data from NASA's Goddard Institute for Space Studies show that global temperatures in 2010 have reached record levels.

The most powerful of feedbacks in the Arctic is sea ice and snow cover, said Miller, the lead author on a paper about past "Arctic amplification" in the journal Quaternary Science Reviews.

When ice melts more sunlight reaches the oceans or the ground, causing even more ice to melt. The opposite is also true: When there is more ice it reflects more solar energy back into space, and cools the Arctic down, which leads to more sea ice forming.

Other positive climate feedbacks that operate in the Arctic include the thawing of permafrost and vegetation changes. Thawing permafrost leads to releases of methane and other carbon compounds that can reach the atmosphere and increase greenhouse warming.

Warming is also reinforced when shrubs move northward and replace lower tundra plants. Taller plants help melt snow. The reverse happens when cooling is the trend.

Miller and his colleagues looked at four Arctic climate changes for which there was good data and fond the amplification pattern held.

In a separate paper in the latest issue of Geology, Ashley Ballantyne, also of the University of Colorado, and his colleagues took the record back to 5 million years and found that when CO2 concentrations were similar to today, the Arctic was about 19 degrees C warmer.

"We're looking back farther in time to see where we are trending in terms of greenhouse warming," said Ballantyne.

All this looking into the past is vital for understanding what the Arctic will do in the future, said Miller.

"We only have 50 years of observations of the Arctic," Miller said, referring primarily to satellite sea ice observations. "(This new work) puts that 50 years in a bigger perspective."

It even helps to put this month's sea ice melting into perspective.

"June is going to be a new record low (for sea ice extent)," said Julienne Stroeve of the National Snow and Ice Data Center. The rate ice has been receding is also faster than any other June on record, she said, as was May.

Nor is this a particularly new trend, Stroeve said.

"You'll find since about 2000 every month you have positive temperature anomalies," Stroeve said. Translation: The Arctic is doing exactly what it has done for 5 million years: amplifying the global climate change signal.