Scientists work from above to learn how Greenland is melting from below


Click to enlargeNASA

❝ If the climate keeps warming the way it has, Greenland may finally live up to its name…The island’s glacier-crusted surface is melting, and a lot of this is from balmier atmospheric temperatures. But as the saying goes, that’s just the tip of the iceberg. The oceans are becoming more tepid as well, and that warmer water is causing the glaciers to thaw from below.

❝ Scientists have good measurements of how much ice melts due to warmer air. And now, thanks in part to torpedo-like probes, they are getting better data on the ice being lapped away by sea water. Those submarines are part of NASA’s Oceans Melting Greenland campaign — OMG, for short. And that’s a fairly accurate acronym, because…those glaciers are melting fast…

❝ Greenland’s glacier-gouged coastline provides the deep, warm water a path to the inland ice. Ancient ice sheets carved subsurface fjords and canyons, many of which reach down to the same level as the Atlantic-Arctic currents at the continental shelf. Problem is, “the seafloor around Greenland’s coast isn’t very well known,” says Josh Willis, a climate scientist at NASA’s Jet Propulsion Laboratory and the project lead for OMG. “The location and depths of these underwater fjords and canyons have just been poorly mapped out…”

Willis and his crew have spent the past five weeks flying over Greenland’s coastline, dropping torpedo-shaped probes into the underwater fjords. These units are called…AXCTDS, or Airborne Expendable Conductivity, Temperature and Depth Sensors…

❝ Mission OMG…spans five years and will look for ocean-caused changes to Greenland’s ice sheet. This spring, the team measured glacier height with aircraft radar, comparing past and future data to ascertain which glaciers are vanishing the fastest. The subsurface torpedo work took place this fall, when Arctic sea ice was at its minimum. It was the first time underwater probes had collected data on Greenland’s continental shelf depth, salinity and temperature.

Ultimately, the group wants to know how much of Greenland’s melting is because of air temperature, and how much is caused by water. Koppes, who has worked with the OMG team, believes air temperature and ocean water will play a 50/50 role in glacial melting.

❝ OMG will need time to analyze the data and confirm, but so far they’ve encountered some surprises. “The amount of warm water was bigger than expected, and we saw it in more places than expected,” continues Willis. “Almost everywhere along the shelf where the water was deep enough, we found Atlantic water interacting with the glaciers.”…

And the stakes are high. The deep current warming turns Greenland’s 27,000 miles of coastline — a distance greater than the Earth’s circumference at the equator — into a melt factory. The island’s interior is three times the size of Texas, and holds enough frozen water to raise global sea levels by 20 feet. More than enough to drown the Maldives, Venice, and New Orleans.

RTFA for detail about how research is proceeding, understanding all the processes contributing to the increased melt.

Early warning signals of wide-ranging climate change to affect Europe and Africa


Reindeer in Scotland might not be so rare

Research, published…in the journal Nature Communications, used a simulation from a highly complex model to analyse the Atlantic Meridional Overturning Circulation (AMOC), an important component of the Earth’s climate system.

It showed that early warning signals are present up to 250 years before it collapses, suggesting that scientists could monitor the real world overturning circulation for the same signals.

The AMOC is like a conveyor belt in the ocean, driven by the salinity and temperature of the water. The system transports heat energy from the tropics and Southern Hemisphere to the North Atlantic, where it is transferred to the atmosphere.

Experiments suggest that if the AMOC is ‘switched off’ by extra freshwater entering the North Atlantic, surface air temperature in the North Atlantic region would cool by around 1-3°C, with enhanced cooling of up to 8°C in the worst affected regions.

The collapse would also encourage drought in the Sahel — the area just south of the Sahara desert — and dynamic changes in sea level of up to 80cm along the coasts of Europe and North America.

“We found that natural fluctuations in the circulation were getting longer-lived as the collapse was approached, a phenomenon known as critical slowing down,” said lead author Chris Boulton.

We don’t know how close we are to a collapse of the circulation, but a real world early warning could help us prevent it, or at least prepare for the consequences” adds co-author Professor Tim Lenton.

The study is the most realistic simulation of the climate system in which this type of early warning signal has been tested.

It’s everyone’s wildest sci-fi movie. Wild only because climate change deniers have focused their paid-for-stupidity only on the aspects of climate change indicating environments with rising temperatures. Actually the whole North Atlantic current from the Gulf Stream via the Atlantic Meridional Overturning Circulation warms the north and west of Europe and the UK from what would be normal temps absent that elevator.

The Benelux countries and the UK might become more like Lapland.

My curiosity extends to changes in humidity and precipitation. The report indicates desertification south of the Sahara. I wonder if the affected areas of Europe might end up with increased precipitation. Folks in the west of Scotland, Wales and England might have to sprout webbed feet.

Thanks, Mike – GMTA