Monday, 17 October 2016

Antarctica: science at the end of the Earth

With global models drawing an ever-clearer picture of unchecked warming, there has never been a more urgent time to answer the big questions about climate change's vast, frozen elephant in the room: Antarctica. As top Kiwi scientists fly south for New Zealand's 60th research season on the ice, science reporter Jamie Morton takes a look at some of the fascinating studies planned for this summer.

1. Antarctica from the air

Antarctica's sea ice, swelling and retreating with the seasons like a breathing organ, plays a crucial yet poorly understood role in our planet's climate system.

The immensely complex natural sequence helps maintain the cold conditions that ultimately sustain the continent, while also influencing storms across the Southern Hemisphere and affecting the amount of heat the Southern Ocean can absorb as the Earth warms.
Experimental observations during the polar winter have shown increased losses of ozone that were caused by solar-generated
But some of the sea ice's most intriguing behaviour isn't captured by the giant Earth System Model (ESM) used to predict our planet's future climate, prompting a team of Kiwi researchers to fill in the gaps.

They'll do it using an airborne electromagnetic device called the "EMBird", which will be slung below a DC3 utility aircraft to map snow and sea ice thickness as it flies over the southwest Ross Sea.

The research team, from Otago University, Canterbury University, the National Institute of Water and Atmosphere (Niwa) and US collaborators, wants to tease out the influence on coastal sea ice of the very cold water that emerges from beneath ice shelves, the huge glaciers that float on the ocean.

"We have flown the EMBird from a helicopter before, but it has never been flown below an aircraft in Antarctica," says project leader Professor Pat Langhorne, of Otago University.
"There will be the challenges of the weather and inevitable delays and the preparation of the aircraft - we have to change from skis to wheels and back."
The observations they collect will contribute toward a new part of an improved ESM able to create region-specific forecasts of future climate for New Zealand and its nearest neighbours.
There will be the challenges of the weather and inevitable delays and the preparation of the aircraft - we have to change from skis to wheels and back.
Professor Pat Langhorne

2. Drilling down into the ice world's past

Earth's future sea level - projected to be around a metre higher by 2100, but potentially much higher if carbon emissions continue unabated - is one of the most worrying prospects of climate change.

We know the biggest potential contributor to sea level rise is ice stored in Antarctica - oceans could rise by an estimated average 60m if all of it melted - but scientists still can't put their finger precisely on how the continent is responding.

A collaboration led by Dr Gavin Dunbar, of Victoria University's Antarctic Research Centre, is zeroing in on a region thought to be particularly susceptible to collapse in a warmer world.

At the Ross Ice Shelf, near the Kamb ice stream and 1000km from Scott Base, they plan to drill deep into rocks beneath the ocean and ice to reveal a detailed record of the environment in which they were once deposited, millions of years ago.
 "By reading the rock we can get some idea of how extensive the ice was under climates of the past when Earth was warmer than today," Dunbar says.

"This helps us calibrate our computer models that are trying to project how much and how fast sea level will rise in future."

Over November and December, the team will pin-point a drilling target, revealed by generating sound waves with explosives that travel through the ice and rock and bounce back when they hit changing rock type, up to 500m below the surface.

Beyond seeing whether the record will give them the kind of information they're after, the seismic data should also be useful for ongoing studies of Antarctic glaciology and informing the bigger picture of how Antarctica works.

"We also hope to deploy an array of weather stations in this remote part of Antarctic to get some idea of how the atmosphere circulates there for the first time."

The expedition would face the ever-present dangers that come with working in freezing conditions.
"However, the ice shelf itself is probably the most featureless part of Antarctica, so fingers are crossed that we don't get any unpleasant surprises from nature."

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