In the past 50 years, the air temperature has increased by about 3.6 degrees Fahrenheit (2 degrees Celsius). While this rate of warming is highly unusual, it is not unprecedented, indicates a new study.
The rapid, modern warming is bringing the peninsula's temperatures close to the warmth that followed the end of the last ice age, lead researcher Richard Mulvaney, a paleoclimatologist with the British Antarctic Survey, told LiveScience."We are now approaching the temperatures last seen 12,000 years ago," he wrote in an email.
Mulvaney and colleagues predict continued warming will have serious implications for the ice shelves that jut from the peninsula over the ocean. In recent decades, ice shelves at the northern part have begun collapsing into the sea. Continued warming puts ice shelves further south at risk, they say.
Researchers load boxes of ice cores onto an airplane. The ice cores, taken from James Ross Island near the Antarctic Peninsula, were used to reconstruct temperature history of the region and better understand the recent collapse of ice shelves.
CREDIT: Robert Mulvaney
CREDIT: Robert Mulvaney
Back in time
To look back at millennia of temperature history for the peninsula, a research team extracted a 1,200-foot (364-meter) ice core from the summit of an island mountain near the northern tip of the peninsula.
Chemical clues in the sections of ice enabled researchers to reconstruct a record of temperature changes going back about 15,000 years, to a time when the last ice age was coming to an end.
Twice before in the past 2,000 years — around A.D. 400 and A.D. 1500 — the rate of warminghas approached the modern one, Mulvaney said. The current warming trend began about 600 years ago, accelerating in the past 50 to 100 years, bringing the peninsula close to its post ice-age highs.
Warmth means melt
Warming isn't just important for its own sake. While the thick layers of ice that extend from the frozen land have been stable for thousands of years, in the last 30 years rapid collapses, in which the ice shelves disintegrate into the sea, have begun, according to the U.S. Snow and Ice Data Center. [Antarctic Album: An Expedition Into Iceberg Alley]
In 1995, the northernmost portion of the Larsen Ice Shelf, about 770 square miles (2,000 square kilometers) collapsed, forming small icebergs. After retreating for some time, the nearby Prince Gustav Ice Shelf collapsed the same year.
Scientists have wondered if the loss of ice shelves and rising temperatures on the Antarctic Peninsula are the result of natural cycles or if humans' alterations to the environment, including the ozone hole of Antarctica, are responsible. The results of the study don't provide an answer to this question, but they do offer insight into the pre-Industrial temperature history and how it related to the state of the region's ice shelves.
Using the ice core, Mulvaney and his colleagues were able to look far back into the temperature history of the region, and compare that with records for the collapsed ice shelves, drawn from the marine sediments deposited below them.
To reconstruct the record of temperature, they looked at the ratio of heavier to lighter versions of hydrogen in the ice core from James Ross Island. Warmer temperatures allow for the incorporation of more heavy atoms, Mulvaney explained.
Their reconstruction revealed that after the last ice age ended 12,000 years ago, the climate became slightly warmer than it is today. After being stable near modern levels for millennia, a cooling trend, which included some warming spikes, began about 2,500 years ago, ending about 600 years ago. During this time, the ice shelves along the northern peninsula re-established themselves.
Between 100 and 50 years ago, this warming trend accelerated, taking the peninsula toward temperatures last seen 12,000 years ago, Mulvaney told LiveScience.
"This means some of those ice shelves farther south are starting to look vulnerable," he said.
The loss of more ice shelves has implications for sea level. The ice shelves themselves don't cause sea level to rise when they disintegrate, but in their absence, ice from the continent flows more quickly into the ocean, contributing to rising sea levels.
"The Antarctic Peninsula is small, it's not adding a lot to sea-level rise. It's more symptomatic of the changes taking place in Antarctica,” Mulvaney said.
Observations from a number of Antarctic ice shelves elsewhere show signs of the thinning responsible for the collapse of the northernmost ice shelves as well as the Wilkins Ice Shelf on the west side of the peninsula, according to Mulvaney.
Follow LiveScience writer Wynne Parry on Twitter @Wynne_ParryorLiveScience @livescience. We're also on Facebook & Google+.
The research was conducted by an international team of climate scientists, including Dr Nerilie Abram from the Australian National University. The team drilled a 364 metre long ice core spanning thousands of years on James Ross Island.ReplyDelete
“The ice shelves along the west coast are showing signs of becoming less stable, but we haven’t seen the big collapses that we’ve seen on the Antarctic Peninsula so far,” she said. “The big concern about that area is that it is where the West Antarctic ice sheet is.
It paints a worrying picture, according to Abram: “The main finding of our research is that warming as fast as this is very unusual. We should be very concerned about that.”
Fire and IceReplyDelete
Some say the world will end in fire,
Some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice.
The End of the World
By Dana Gioia
“We're going,” they said, “to the end of the world.”
So they stopped the car where the river curled,
And we scrambled down beneath the bridge
On the gravel track of a narrow ridge.
We tramped for miles on a wooded walk
Where dog-hobble grew on its twisted stalk.
Then we stopped to rest on the pine-needle floor
While two ospreys watched from an oak by the shore.
We came to a bend, where the river grew wide
And green mountains rose on the opposite side.
My guides moved back. I stood alone,
As the current streaked over smooth flat stone.
Shelf by stone shelf the river fell.
The white water goosetailed with eddying swell.
Faster and louder the current dropped
Till it reached a cliff, and the trail stopped.
I stood at the edge where the mist ascended,
My journey done where the world ended.
I looked downstream. There was nothing but sky,
The sound of the water, and the water’s reply.
The Second ComingDelete
Turning and turning in the widening gyre
The falcon cannot hear the falconer;
Things fall apart; the centre cannot hold;
Mere anarchy is loosed upon the world,
The blood-dimmed tide is loosed, and everywhere
The ceremony of innocence is drowned;
The best lack all conviction, while the worst
Are full of passionate intensity.
Surely some revelation is at hand;
Surely the Second Coming is at hand.
The Second Coming! Hardly are those words out
When a vast image out of Spiritus Mundi
Troubles my sight: somewhere in the sands of the desert
A shape with lion body and the head of a man,
A gaze blank and pitiless as the sun,
Is moving its slow thighs, while all about it
Reel shadows of the indignant desert birds.
The darkness drops again; but now I know
That twenty centuries of stony sleep
were vexed to nightmare by a rocking cradle,
And what rough beast, its hour come round at last,
Slouches towards Bethlehem to be born?
A Song On the End of the WorldDelete
On the day the world ends
A bee circles a clover,
A fisherman mends a glimmering net.
Happy porpoises jump in the sea,
By the rainspout young sparrows are playing
And the snake is gold-skinned as it should always be.
On the day the world ends
Women walk through the fields under their umbrellas,
A drunkard grows sleepy at the edge of a lawn,
Vegetable peddlers shout in the street
And a yellow-sailed boat comes nearer the island,
The voice of a violin lasts in the air
And leads into a starry night.
And those who expected lightning and thunder
And those who expected signs and archangels' trumps
Do not believe it is happening now.
As long as the sun and the moon are above,
As long as the bumblebee visits a rose,
As long as rosy infants are born
No one believes it is happening now.
Only a white-haired old man, who would be a prophet
Yet is not a prophet, for he's much too busy,
Repeats while he binds his tomatoes:
No other end of the world will there be,
No other end of the world will there be.
by Czeslaw Milosz
translated by Anthony Milosz
The End of the WorldReplyDelete
Quite unexpectedly as Vasserot
The armless ambidextrian was lighting
A match between his great and second toe
And Ralph the Lion was engaged in biting
The neck of Madame Sossman while the drum
Pointed, and Teeny was about to cough
In waltz-time swinging Jocko by the thumb —
Quite unexpectedly the top blew off.
And there, there overhead, there, there, hung over
Those thousands of white faces, those dazed eyes,
There in the starless dark, the poise, the hover,
There with vast wings across the cancelled skies,
There in the sudden blackness, the black pall
Of nothing, nothing, nothing — nothing at all.
by Archibald MacLeish (1892-1982)
Letters From the Ice AgeDelete
Cities buried streets forgotten
warehouses ransacked and abandoned for the south.
We love we breathe
light footprints of our passing through the snow.
What would we say? And how say it?
Who would we talk to? And how could they answer?
Buildings break beneath the ice
the bridges fall and there are less of us each year.
Like arctic animals we burrow through the wreckage
of the city underground.
And high above where once the escalators climbed into the light
the tunnels terminate in breathing walls of ice.
Here in the dark
within the stone walls of the ancient hospital
below the copper roofs
and buried by the glaciers on all sides
Here in blood and wailing
anchored in breathing and inflexible resolve
we have sent this letter to the next world.
Archangel of the frozen colony
whose sign is fire whose feet are locked in ice
We leave you more than this than blowing snow
or permafrost a football field below.
This is the breath of the last words spoken
the frozen evidence of love
like nitrogen in glass
our histories etched into the worlds
we will not live to know.
- Ian Ferrier
When Rufus is soberDelete
And Ash somewhat nobler
And Quirk in business undeceitful
And bob finally sleepful
When Melody returns
And Trish yearns
To be with us again
When Gag stays put
And not on the road
And Deuce is finally out of ideas
When rat and WiO
Are no longer foe
And Sam no longer jokes
Us all too serious folks
Doug is still persuasive
Though now unabrasive
We might all take a rest
In the dove's built nest
At the end,
The far end of the world
Currently, it is an arrogant conceit that man can reverse the macro trends in weather. I am not arguing that we shouldn't do what we can to, within reason, to mitigate those changes, only that in the long run we will be better off allocating resources to adapt to projected changes rather than mandate rules that stymy growth and likely will prove ineffective anyway.
Isn't it possible that we might be, if warming is caused somewhat by man, helping ourselves rather than harming ourselves?Delete
Anyone up for a new ice age?
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