Everything for Everyone

Are the people who refuse to accept climate change ill-informed?

Polls relating to publicly controversial scientific issues often trigger a great wailing and gnashing of teeth from science advocates. When large proportions of a population seem poorly informed about evolution, climate change, or genetically-modified foods, the usual response is to bemoan the state of science literacy. It can seem obvious that many people don’t understand the science of evolution, for example—or the scientific method, generally—and that opinions would change if only we could educate them.

Research has shown, unfortunately, it's not that simple. Ars has previously covered Yale Professor Dan Kahan’s research into what he calls “cultural cognition,” and the idea goes like this: public opinion on these topics is fundamentally tied to cultural identities rather than assessment of scientific evidence. In other words, rather than evaluate the science, people form opinions based on what they think people with a similar background believe.

That shouldn’t come as a shock, especially given the well-known political or religious divides apparent for climate change and evolution.

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A simple explanation for awe-inspiring sandstone arches

Delicate Arch at Arches National Park in Utah.

There’s no need to ask what the appeal of Arches National Park is—it’s in the name. The gorgeous sandstone arches there seem almost impossible. How and why should the relentlessly erosive wind carve such a fantastic structure? The arches seem too vulnerable, too artificial.

And arches aren’t the only trick that sandstone has up its sleeve. Bizarre, mushroom-shaped pillars seem even more absurd, as if they were carefully placed by an incredibly patient and even more incredibly strong Zen garden enthusiast. In some places, networks of sandstone pillars even hold up ledges like a miniature Moria.

We know plenty about how this erosion takes place, and some details about why some sections of the rock erode faster than others, but the primary cause of these shapes has eluded geologists. A new study led by Jiri Bruthans of Charles University in Prague has revealed a surprisingly simple explanation.

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Detailed imaging of Mount Rainier shows subduction zone in glorious detail

A cross section of Washington's Cascade Range from west to east (left to right) passing near Mt. Rainier, indicated by a red triangle. The colors represent electrical resistivity, with red being low. Contour lines show temperature in degrees Celsius. Small red circles show the centers of earthquakes.

Most people know that the Pacific Ring of Fire is related to boundaries between tectonic plates, but there’s a common misconception about where the magma comes from to fuel those volcanoes. At those boundaries, called subduction zones, a plate made of denser oceanic crust dives beneath a continent (or another oceanic plate). It’s not that the diving plate heats up and melts as it sinks downward, though.

Actually, the minerals in the diving plate contain lots of water, and that water migrates upward as the plate slowly warms up. The addition of water to hot mantle rocks lowers the melting point of the rock, and this effect is enough to convert some mantle rock into magma. Since magma is less dense than solid rock, it works its way upward toward the surface, resulting in the arcs of volcanoes we see along subduction zones.

Within this simplified picture, however, there are complexities and open questions. Does the water simply rise directly into the mantle rocks above, or does it take a more tortuous path? Is that water the cause of all the magma production in an area, or does some magma form because the flow of mantle rock brings some up to lower pressures where it can melt?

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Gravity satellites could provide warning months ahead of floods

Flooding along the Missouri River on the Iowa-Nebraska border in 2011.

When the twin GRACE satellites were launched in 2002, the casual observer might have been underwhelmed by their mission—to make precise measurements of Earth’s gravity. They’ve proved, however, to be unbelievably useful Swiss Army knives of geoscience, measuring everything from the loss of ice from Greenland and Antarctica to groundwater depletion in California. Now, the GRACE that keeps on giving has been shown to improve warnings ahead of major floods in some areas.

For many, floods seem to show up suddenly and then overstay their welcome. In some situations, they can be incredibly damaging and often quite dangerous. But a lot more goes into determining the size of a flood than just the amount of rain that falls, and that data provides the key to better forecasting of flood risk.

When looking at graphs of streamflow—the volume of water traveling downstream per second—for a river or stream, hydrologists can identify two kinds of behavior. There’s the consistent base flow, supplied mainly by groundwater entering the river, and the temporarily higher flow that follows rain storms.

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Greenland melt may have pushed sea level six meters higher in the past

The edge of the Greenland ice sheet near Kangerlussuaq, with exposed bedrock in the foreground.
Alberto Reyes

Earth’s climate system will respond to the stronger greenhouse effect we’ve produced in various ways. But one key question about its response is how much ice will be lost from the great ice sheets of Greenland and Antarctica. Push them too far outside their climatic comfort zone, we know, and a large retreat of glacial ice can follow, raising global sea levels.

Given that the innards of these ice sheets are complicated and inaccessible, researchers rely heavily on what we can discover about their pasts. One key point in the past has been the warm interglacial period around 400,000 years ago. The cycles in Earth’s orbit that govern the timing of the ice ages conspired to produce an exceptionally long respite from the cold at this time—twice as long or more than the most recent interglacial period about 120,000 years ago. It may have been warmer, as well, and some estimates put sea level in the vicinity of six to 13 meters higher than it is today.

Did that sea level rise come mostly from a smaller Greenland ice sheet, loss of ice from Antarctica, or some mixture of the two? We don’t know, and it’s difficult to answer since glaciers destroy the evidence of their past retreat when they expand again. A new study led by Alberto Reyes (now at the University of Alberta) and Oregon State’s Anders Carlson sifted sediments off Greenland’s coast to find clues about what the ice sheet was up to at that time.

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Could tree rings skip a beat? Astronomical event tests tree ring dating

Swiss pines and Switzerland's Aletsch Glacier.

Last year, we wrote about a real climate science debate taking place between researchers who look at tree ring records of past climate. Penn State climate scientist Michael Mann, well-known for his work on the “hockey stick” climate reconstructions, published a paper arguing that some trees may have failed to grow for a year following major volcanic eruptions. “Skipping” a ring could shift the whole record from that tree by a year, introducing subtle errors into the compilations that are used to reconstruct past climate.

In support of that possibility, the paper analyzed mismatches between the cooling following eruptions in tree ring compilations and climate model simulations of the predicted cooling. The cooling in the tree ring records was often less, and they found that the difference could be caused by ring-skipping.

Some researchers in the tree ring community were less than enthused with the suggestion that they had failed to catch an issue like this, given the care taken to reliably compile these tree-ring histories. They criticized the earlier paper by Mann, Jose Fuentes, and Scott Rutherford, arguing that there was little positive evidence for the rings going missing during eruptions. Now, a group of researchers has published some new data in the journal Nature Climate Change that they think defends the integrity of tree ring records.

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Greenland may lose more ice than expected

Coastline near Greenland's Petermann Glacier.

A pair of reports in the last couple weeks has delivered bad news for future ice loss in Antarctica. One described the possibility of committing ourselves to several meters of sea level rise if ice in the Wilkes Basin were to become destabilized. The other concluded that we likely have already committed ourselves to over a meter of long-term sea level rise from a portion of the West Antarctic Ice Sheet. In both cases, the ice loss tipping points are a result of the shape of the valleys in which the glaciers sit, which deepen as you move inland, reaching below sea level.

That configuration has long been known to exist below the West Antarctic Ice Sheet, but it wasn't thought of as a factor in Greenland. Now, a new study from some of those same researchers has revealed that Greenland, too, has a number of deep valleys that dip below sea level. That means Greenland is susceptible to larger, more rapid losses of ice than previously thought.

The topography of the land beneath an ice sheet exerts a large amount of control over the flow of the ice, yet it’s largely hidden from view. Glaciologists have long been using airborne radar surveys to determine ice depth in much the same way that sonar can measure water depth below a ship.

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Direct evidence of cooling after the dinosaur-killing asteroid impact

“The bigger they are, the harder they fall” might have applied to some individual behemoths during the hey-day of the dinosaurs, but it also held true for the rock from space that did them in.

As best we can make out, a 10 kilometer wide asteroid struck the Earth along the coast of the Yucatán Peninsula back then and produced a shockwave and fireball of unfathomable scale. As tsunamis swept across the Gulf of Mexico and wildfires raged, huge amounts of sulfur (from rock vaporized by the impact) and soot were lifted into the air, blocking sunlight from reaching the surface. With the fires followed by cold and greatly diminished photosynthesis (sunlight might have dropped by 80 percent), ecosystems collapsed.

To make things worse, when the skies cleared after a few years to a decade, the sulfur may have acidified the surface ocean. The long-lived greenhouse gases that came from the vaporized rock took over, producing sustained warming for millennia at least. Oh, and incredibly massive volcanic eruptions on the Indian subcontinent were already messing with Earth’s climate before the impact. It was a cruel pendulum of extremes.

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Groundwater depletion leading to more earthquakes along San Andreas fault

A GPS station in the Sierra Nevada.

Poets and songwriters sometimes pledge to move mountains for their beloved to prove their devotion. If any of them also farmed California’s San Joaquin Valley, they may have actually followed through on their promise. What’s more, they may have helped affect earthquakes along the San Andreas Fault while they were at it.

The dry but agriculturally productive San Joaquin Valley is a poster child for groundwater depletion. As groundwater levels have dropped, so has the ground surface. Groundwater between grains of sediment actually provides pressure that counteracts some of the overlying weight. Remove the water, and the sediment will compact, lowering the elevation of the surface. Between 1926 and 1970, the land surface in the valley subsided by as much as 30 feet.

But that’s not the only impact of drawing down groundwater levels. A new study led by Western Washington University’s Colin Amos focuses on the solid rock beneath all that sediment to see how it is responding to being relieved of the burden of that huge weight of water.

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Across Antarctic, other glaciers hold back 4 meters of sea level rise

A glacier isn’t the kind of thing you’d expect to get away from you. After all, only the world’s fastest-flowing glaciers can match a snail’s pace. But we know it’s possible for glaciers to have tipping points that, once crossed, result in an unstoppable change. Once unstable, they can lose a lot of ice before finding another stable configuration.

Looking back through the history of the Antarctic ice sheets, we know that they have been susceptible to warming in the past. The West Antarctic Ice Sheet is especially vulnerable because a great deal of the continent beneath it is below sea level. If the ice shrinks back from the higher elevation areas, the entire ice sheet can collapse, as it may have done several times in the last million years. Some of the West Antarctic glaciers that prevent this collapse have behaved dynamically in the recent past—and, as we saw this week, there's evidence that we may be committed to seeing a repeat performance.

The amount of ice present there today could raise global sea level roughly several meters if it all melted. But across the continent, the East Antarctic Ice Sheet is much larger, holding the equivalent of 55 meters of sea level rise as ice. Fortunately, it's perched securely above sea level. Researchers are less concerned with the potential for tipping points there. There are, however, exceptions. Some East Antarctic glaciers have melted back considerably in the past. The key is to figure out how much ice they can lose and how fast they can lose it.

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