Uncontrollable ice-melt? Uncorking East Antarctica could yield unstoppable sea-level rise, simulations show

The melting of a rather small ice volume on East Antarctica's shore could trigger a persistent ice discharge into the ocean, resulting in unstoppable sea-level rise for thousands of years to come. This is shown in a study now published in Nature Climate Change by scientists from the Potsdam Institute for Climate Impact Research (PIK). The findings are based on computer simulations of the Antarctic ice flow using improved data of the ground profile underneath the ice sheet

"East Antarctica's Wilkes Basin is like a bottle on a slant," says lead-author Matthias Mengel, "once uncorked, it empties out." The basin is the largest region of marine ice on rocky ground in East Antarctica. Currently a rim of ice at the coast holds the ice behind in place: like a cork holding back the content of a bottle. While the air over Antarctica remains cold, warming oceans can cause ice loss on the coast. Ice melting could make this relatively small cork disappear -- once lost, this would trigger a long term sea-level rise of 300-400 centimeters. "The full sea-level rise would ultimately be up to 80 times bigger than the initial melting of the ice cork," says co-author Anders Levermann.

"Until recently, only West Antarctica was considered unstable, but now we know that its ten times bigger counterpart in the East might also be at risk," says Levermann, who is head of PIK's research area Global Adaptation Strategies and a lead-author of the sea-level change chapter of the most recent scientific assessment report by the Intergovernmental Panel on Climate Change, IPCC. This report, published in late September, projects Antarctica's total sea level contribution to be up to 16 centimeters within this century. "If half of that ice loss occurred in the ice-cork region, then the discharge would begin. We have probably overestimated the stability of East Antarctica so far," says Levermann.

Emitting greenhouse-gases could start uncontrollable ice-melt

Melting would make the grounding line retreat -- this is where the ice on the continent meets the sea and starts to float. The rocky ground beneath the ice forms a huge inland sloping valley below sea-level. When the grounding line retreats from its current position on a ridge into the valley, the rim of the ice facing the ocean becomes higher than before. More ice is then pushed into the sea, eventually breaking off and melting. And the warmer it gets, the faster this happens.

Complete ice discharge from the affected region in East Antarctica takes five thousand to ten thousand years in the simulations. However, once started, the discharge would slowly but relentlessly continue until the whole basin is empty, even if climate warming stopped. "This is the underlying issue here," says Matthias Mengel. "By emitting more and more greenhouse gases we might trigger responses now that we may not be able to stop in the future." Such extensive sea level rise would change the face of planet Earth -- coastal cities such as Mumbai, Tokyo or New York are likely to be at risk.

Researchers find unique fore wing folding among Sub-Saharan African Ensign wasps

Researchers discovered several possibly threatened new species of ensign wasps from Sub-Saharan Africa -- the first known insects to exhibit transverse folding of the fore wing. The scientists made this discovery, in part, using a technique they developed that provides broadly accessible anatomy descriptions.

The researchers used principles of origami paper folding to physically visualize the transverse folding of the wings. In their paper, they included a print, cut and fold template to help readers comprehend the wing fold system.

"Ensign wasps are predators of cockroach eggs, and the transverse folding exhibited by these species may enable them to protect their wings while developing inside the cramped environment of cockroach egg cases," said Andy Deans, associate professor of entomology, Penn State. "It also may be useful while they are active in their cockroach prey's leaf-litter environment."

According to Deans, only a few other insects -- mainly some earwigs, cockroaches and beetles -- are capable of folding their hind wings transversely, along a line between the front and back wing margin, as opposed to longitudinal folding, which occurs along a line from the wing base to the wing tip.

"These other insects fold their wings transversely so that the wings can be shortened and tucked under a modified, shell-like fore wing," he said. "This, however, is the first time anyone has observed an insect that folds its fore wings transversely."

The researchers examined wasps belonging to the family Evaniidae from Sub-Saharan Africa. They named five new species -- one of them, Trissevania slideri is named after their colleague David "Slider" Love, coordinator of farm and greenhouse operations, Penn State. The scientists also created an identification key for the new tribe,Trissevaniini.

" We didn't know these new species existed until now, and at least two of them --Trissevania heatherae and T. mrimaensis -- are found only in a small patch of forest in Kenya that is threatened by mining activity," Deans said.

According to Deans, to officially give a new species a name one must, among other things, provide a diagnosis that describes how this species differs from others.

"In most cases, the diagnosis lists certain phenotypic aspects of the wasps, such as having a black head or fuzzy hind legs," he said. "Diagnoses are typically written in natural language and using one's own custom lexicon. There is no standard syntax to describe the way an organism looks, which makes these data difficult to extract in any large-scale way."

To get around this problem, the researchers developed a technique that provides broadly accessible descriptions.

"The gist is that one could actually query across existing anatomy data using computers," he said. "For example, one could search for all the species that have fuzzy heads, or all the species that have a patch of hairs on the ventral surfaces of their abdomens. One could then cross-reference the result with information about the surrounding environment, the cockroach host, or the evolutionary history of the wasp. The more we test and refine this approach the better we'll understand its capabilities and utility."

In addition to photographing the wasps' wings, the team used principles of origami paper folding to physically visualize the transverse folding of the wings.

"We used origami, one of the most ancient and simple art forms to understand the wing folding, which, based on our observations through microscopes was otherwise impossible to understand," said István Mikó, research associate in entomology. "In our paper, we included a print, cut and fold template for the readers that helps them and us to comprehend the simple, yet enigmatic, wing fold system of the new tribe,"

According to Mikó, insect wings are common subjects of researchers who investigate bio-inspired technologies.

"The relatively simple wing-folding mechanism of the new tribe can be utilized in advance technologies, such as applying morphing systems in aerospace vehicle research or expandable structural systems in space missions," Mikó said.

The team's results appeared in the May 1 issue of PLOS ONE.

The researchers said that by characterizing the phenotypes of these species of wasps, they are one step closer to understanding the evolutionary history of the family Evaniidae.

"Understanding the evolutionary history of this family of wasps is important because this knowledge will inform our attempts to reclassify the wasps in a way that is robust and predictive," Deans said.

In the future, the team plans to use the same methods it developed to investigate other groups of wasps in the family Evaniidae as well as those in the lineage Ceraphronoidea, small wasps that parasitize many other groups of insects and for which very little is known about their diversity and morphology.

Journal Reference:

1. István Mikó, Robert S. Copeland, James P. Balhoff, Matthew J. Yoder, Andrew R. Deans. Folding Wings like a Cockroach: A Review of Transverse Wing Folding Ensign Wasps (Hymenoptera: Evaniidae: Afrevania and Trissevania). PLoS ONE, 2014; 9 (5): e94056 DOI: 10.1371/journal.pone.0094056