Ice sheet collapse: The greatest unknown in climate science
The ice sheets in Greenland and Antarctica are remnants of the ice age. They're also the wild cards of climate science.
JON GERTNER: For scientists who study climate change, one of the great challenges has been trying to figure out if these great ice sheets, these old remnants of the ice age in Greenland and Antarctica, are shrinking or growing. And we're used to, I think now, all the news stories, you know, that Greenland's losing ice, and Antarctica is melting, and that this glacier seems unstable. But really this was a kind of epic discovery of how to do it. And a lot of the ways we figured it out are through satellites and other kinds of airborne observational tools, such as laser altimeters that read the ice by sending laser bursts down and trying to measure decreases in the altitude of the ice. And, at least in Greenland, what we've discovered is that since, really, the early 1990s this ice sheet has been losing mass.
So that ice that's on top of Greenland, the frosting on the cupcake, is slowly moving into the ocean. And it moves into the ocean two ways: It melts on the surface in the summertime, and that's when you see these beautiful azure beads of lakes on the surface that eventually drain into the ocean and meltwater rivers, too. It also at the edges has these glaciers that reach into the ocean, and they break off as these huge icebergs that in turn float away and melt also. And those all raise sea levels.
The bigger picture is that, at the moment, our ocean sea levels are rising by about three millimeters per year, which is actually a pretty small amount. And the reasons that it's melting are, one, as the earth gets warmer there's something called thermal expansion, which means that the oceans literally expand, just as hot water expands, [it] gets larger and higher. The other reason is that there are mountain glaciers all over the world in the Himalayas and Canada and Alaska, and those, too, are draining into the water and they make a contribution. And the third reason is that Greenland and Antarctica are losing ice, both through -- especially Greenland's -- surface melting and through these glaciers that break off into icebergs, and they're raising sea levels.
At the moment, Greenland's contribution is one millimeter per year. And we could maybe put that aside, and say, well one millimeter a year isn't very much, but that's accelerating. What we also know is that things don't necessarily move in a linear way with ice sheets. A lot of the science of glaciology and ice sheets is pretty new. It's not like we can go back 100 years and try and sort of figure out -- or that we knew at that point how ice sheets work. In fact, we can look at an ice sheet now in Greenland or in Antarctica, in West Antarctica, for instance, and we know that no human being has ever seen what we're seeing now. Nobody's ever really witnessed the collapse of an ice sheet. There's nothing in recorded history that explains how an ice sheet collapses in warmer temperatures.
So we're in this place now where what we know is that the climate is warming dramatically. We know the ice sheets become more unstable in warmer temperatures. We know they have vulnerabilities. We also don't know precisely how the physics of big ice sheets work. And we try and create models, scientists do try and create models, but those models aren't necessarily as good as some other models that predict, say, future temperatures. We've heard, well, if the earth, you know, if we put so much CO2 into the air we're going to warm the atmosphere by 2 degrees or 3 degrees -- those have proven pretty accurate. But trying to model an ice sheet and say, well, by the year 2050 Greenland is going to lose so many tons of ice, or Antarctica will, we're not sure. I mean, partly we're not sure because we don't know if human beings can actually stop burning so many fossil fuels and if we can change the way we're going, the trajectory we're going in warming. But also we can't know because glaciers can start up and slow down. They can pause when they hit bumps before they break off into the sea. Greenland can have some variability, or cold weather can set in.
What we know now is that Greenland is losing between 250 to 300 billion tons of ice per year. Over the past few years it's lost more than a trillion tons of ice. It's an enormous amount. It's getting larger. We can't stop thinking about this place, or we shouldn't stop thinking about this place, even though it almost seems so far from our imaginations; living in New York, or in London, or Los Angeles, it seems so impossibly distant. And yet this island that's covered in ice could determine our future to some extent, in the sense that it will raise sea levels. The ice that falls into the ocean can change ocean circulation patterns, which can have tremendous effects on temperature, on sea levels as well. And then there are all sorts of other maybe surprises that we don't yet understand, just because we're actually witnessing something we've never seen before.
- The science of glaciology and ice sheets is quite new, as methods to measure melting glaciers were only realized with the advent of aviation and lasers.
- The world's sea levels are rising 3mm per year, and of that Greenland's ice sheet contributes 1mm – it is losing between 250 to 300 billion tons of ice per year. Three millimeters total is not much, but ice sheets don't always operate in a linear fashion.
- No human has ever witnessed an ice sheet collapse. It is also such a rare event that models cannot accurately predict what the effect will be. Can we halt global warming before we reach that tipping point?
- Greenland loses 4 trillion pounds of ice in one day - Big Think ›
- The climate change clues trapped in Greenland's ice sheet - Big Think ›
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Whether or not women think beards are sexy has to do with "moral disgust"
- A new study found that women perceive men with facial hair to be more attractive as well as physically and socially dominant.
- Women tend to associate more masculine faces with physical strength, social assertiveness, and formidability.
- Women who display higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, are more likely to prefer hairy faces.
Beards and perceptions of masculinity<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg0MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NzkxMjM3N30.cH-GqNwP5GVqvstgJWAhBPn1B_lYpVEAI0I7iax7EQw/img.jpg?width=1245&coordinates=0%2C1900%2C0%2C849&height=700" id="caae6" class="rm-shortcode" data-rm-shortcode-id="cb0a355a4e8e1899789bc45f3f7aef56" data-rm-shortcode-name="rebelmouse-image" />
Photo Credit: Wikimedia<p>The study used 919 American (mostly white) women ages 18-70 who rated 30 pictures of men they were shown with various stages of facial hair growth. The photographs depicted men with faces that had been digitally altered to look more feminine or more masculine, with a beard and without a beard. The women rated the men according to perceived attractiveness for long-term and short-term relationships. The study found that the more facial hair the men had, the higher the men were rated on their attractiveness, particularly for their suitability for a long-term relationship.</p><p>Part of this might be attributed to facial masculinity — i.e. protruding brow ridge, wide cheekbones, thick jawline, and deeply set narrow eyes — which conveys information to a woman about a man's underlying health and formidability. Women tend to associate more masculine faces with physical strength and social assertiveness. It can also indicate a man with a superior immune response. The researchers suggested that their findings favoring bearded men could be due to the fact that facial hair enhances the masculine facial features on a man's face, like creating the illusion of a thicker jaw line. This could communicate direct benefits to women like resources and protection that would enhance survival among mothers and their infants. In other words, while a beard doesn't mean superior genetics in and of itself, it might be a primitive, ornamental way of saying, "Hey girl, I'm a testosterone-fueled lean, mean, pathogen fighting machine." <br></p><p>It could also be that a beard becomes its own destiny. The researchers in this study cite prior research that found that by growing a beard, men felt more masculine and had higher levels of serum testosterone, which was linked to a higher level of social dominance. They also tended to subscribe to more old-school beliefs about gender roles in their relationships with women as compared to men with clean-shaven faces.<span></span><br></p>
What does disgust have to do with beard preference?<p>Obviously, not all women dig beards. The researchers were particularly interested in what traits make a women prefer bearded men over clean-shaven faces. They looked into several factors including a woman's disgust levels on various concepts, her desire to become pregnant, and her exposure to facial hair in her personal life. </p><p>According to the study, women who were not into facial hair were turned-off by potential parasites or other critters they imagined could be in the hair or skin. Women ranking high on this "ectoparasite disgust" scale might have viewed beards as a sign of poor grooming habits. However, women who ranked higher in levels of "pathogen" did find the bearded men to be desirable, possibly because they perceived beards as a signal of good health and immune function. An intriguing discovery in the study was links to morality. Women who displayed higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, were more likely to prefer hairy faces. The authors opined that this could reflect a link between beardedness, politically conservative outlooks, and traditional views regarding performances of masculinity in heterosexual relationships.</p>
Additional findings<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg1My9vcmlnaW4uZ2lmIiwiZXhwaXJlc19hdCI6MTYyNDI1NjUyOX0.P9B8WbmJR0q4nfzYZKbuNSA-2SAigVWJgrQE-_Gxlds/img.gif?width=980" id="49143" class="rm-shortcode" data-rm-shortcode-id="2ed3b1d6f20fc170bf2974646e565e8d" data-rm-shortcode-name="rebelmouse-image" />Giphy<p>The correlations that existed between married and single women's rating on the attractiveness of beards were not particularly clear, although the researchers noted that single and married women who wanted children tended to find beards more attractive than the women who didn't want children. They also found that women with bearded husbands found beards to be more attractive, which might indicate that social exposure to beards influences how desirable they are perceived of as being. Or it could be that men with wives who like beards grow beards.</p><p>It's important to note that culture plays a huge role in how attractive women perceive certain male characteristics as being. This study looked at a small, culturally specific group of American women, so no big, universal claims should be made about masculinity, facial hair, and male desirability to women. However, research like this is important in highlighting how human grooming decisions are driven by much more than fashion trends. Sociobiological, economic, and ecological factors all play a part in the way we choose to present ourselves.</p>
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