Deench

Everything for Everyone

Survey of 12,000 studies finds strong agreement on climate change

Over half of Americans believe that there’s considerable disagreement among climate scientists about human-caused climate change—perhaps because they've heard that from industry advocacy campaigns and politicians. With so much controversy in the media many assume that the same controversy must exist in the scientific community.

In most situations people agree that it’s sensible to go with the majority of relevant experts whether that's in accepting that protons are real or a given medical treatment is effective. Those decisions depend critically on an accurate understanding of expert consensus.

Several attempts have been made to shine a light on expert opinions relating to global warming. One such study surveyed about 1,000 active climate scientists, finding that 97 percent of them accepted the evidence for the consensus position that anthropogenic greenhouse gas emissions are largely responsible for the warming observed over the last century.

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Birds and the feather did not evolve together

Illustration of Microraptor, which is thought to have had iridescent feathers.
Mick Ellison/AMNH

“Which came first, the chicken or the egg?” Evolutionarily speaking, it’s a yawn of a conundrum. We know it was the egg, which evolved (with shell to enable a terrestrial lifestyle) some 300 million years ago, long before a chicken first clucked across a patch of open ground.

In between the origin of the egg and the domestication of the chicken, however, there are plenty of other interesting features to consider. Take the feather. There were hints of a revolution 150 years ago when part-dinosaur, part-bird archaeopteryx was discovered. Recently, discoveries in China have pulled back the curtain to reveal a varied cast of feathered dinosaurs, and we've found it wasn't just the direct ancestors of birds that were sporting down coats.

These discoveries have made the question of evolutionary origins even more interesting. At one point, you could have wondered whether feathers—which are basically made of the same stuff as scales— arose directly to aid flight or had been co-opted for the purpose from some other function. The prevalence of feathers and feather-like structures in flightless organisms points to the latter. So when did they first appear, and what were these other functions?

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Remains of a supernova fall to Earth

Spectral analysis indicates that silica is present in this supernova remnant, Cassiopeia A.
NASA/JPL-Caltech/ O. Krause (Steward Observatory)

Asteroids are old. Really, really old. They formed at the same time as the planets, so when their pieces fall to Earth, they deliver 4.56 billion-year-old mementos that allow us to touch the birth of the Solar System. But some small bits in those meteorites are even older, if you’re limber enough for a little more mind-bendingly deep time.

Some mineral grains that ended up in the Solar System formed in other stars. Most that have been found so far formed in certain types of red giant stars. As these stars age and run out of fuel, they swell in size. In the diffuse envelope around the star, elements can interact and cool enough to form very tiny particles—cosmic dust. Some of those particles were present in the nebula that gave birth to our Solar System, and they have survived to the present day.

Other grains appear to have a different origin—the collapse of a high mass star in a supernova. The grains we’ve found have varied chemically (some made of carbon, some of silicate or oxide minerals) but recently discovered grains from two different meteorites add a new composition to the list—SiO2. This isn’t just stamp-collecting for the fun of it—silica had been predicted to form in supernovae, but none had ever been found.

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Exploring public concerns about geoengineering the climate

Manage the symptoms or go after the root cause? In a way, those are the choices available to deal with climate change. If the task of weaning ourselves off fossil fuels (and reining in deforestation) is too unappealing, a potentially more palatable alternative is geoengineering—intentionally manipulating the climate system. With the large-scale removal of CO2 from the atmosphere currently beyond our grasp, shading the planet with reflective aerosols might be the most effective tool in our kit.

That’s no free lunch, of course. Some aerosols have direct, negative effects on human health, and a hiccup in the system would induce drastic climatic changes. Aerosols cover up the warming effect of greenhouse gases, but they don’t stay in the atmosphere very long. Stop replenishing the aerosols and the planet could very quickly feel the full force of that “hidden” warming. The vulnerability of such a system to international disagreements, war, and even terrorist attacks is obvious.

If all this makes you a little nervous about the idea, you’re not alone. Geoengineering research has been controversial. A perspective in Nature Climate Change describes an effort to engage the public to understand common concerns ahead of one such research project in the UK—the Stratospheric Particle Injection for Climate Engineering (SPICE) project.

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Robotics forecast: cool with a chance of lost humanity

You might expect a book titled Robot Futures and written by a robotics researcher to be a whiz-bang prophecy of technologies that are the best thing since sliced bread. Soon we’ll be living to 200 while traveling from vacation to vacation in our flying cars while robots handle all the parts of our jobs that we hated anyway, right? Maybe, but this book isn't the place to find it. There’s plenty of speculation in it (I mean, we are talking about the future here) but it’s decidedly more pragmatic and sober than that.

The book’s author, Illah Nourbakhsh, runs the Community Robotics, Education, and Technology Empowerment (CREATE) Lab at Carnegie Mellon University which “explores socially meaningful innovation and deployment of robotic technologies.” (He’s also one of the developers of the GigaPan imaging tools we highlighted recently.) The book, accompanied by Nourbakhsh’s blog of the same name, focuses on what he calls the “human side effects” of future technologies—the unexpected ways they could affect us socially and as a society.

Each chapter of the book—which progresses from the likely-seeming near future to an increasingly speculative and distant one— begins with a short, fictional story that illustrates the type of issues that could accompany a given technology. The rest of the chapter then beaks down those issues.

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NOVA series tours Earth history, Aussie style

Host Richard Smith with the modern stromatolites of Shark Bay.
Chris Taylor

It’s the geologist’s refrain: rocks tell stories. Geologists don’t (usually) get excited about a chunk of sandstone just because it’s sandy. It’s the secrets it holds—secrets about a world in the past that we can never visit, even as we stand on its consequences.

“Australia’s First 4 Billion Years," a four-part series that begins April 10th on NOVA, recounts the tale of Earth’s history the right way—by letting the rocks tell it. And it does so without even leaving the land down under (save a short stop in New Zealand).

That’s not a limitation, it’s a strength. It allows the program to hone in on details that many won't have heard before, rather than providing a montage of interesting events around the world—an approach that usually yields only the most familiar ones. The program builds an appreciation for the landscape, too, by allowing you to more fully explore the rich history of a region. Besides, Australia’s geology lays bare an impressive amount of geologic time. You could do much worse as far as locations go.

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About a third of US rivers contaminated with agricultural runoff

The Snake River flowing through Grand Teton National Park. Photo by Ansel Adams (courtesy of U.S. National Archives).
Ansel Adams

At least our rivers don’t light on fire anymore. Inspired by a well-publicized fire on the Cuyohoga River in 1969, the passage of the Clean Water Act in the US led to huge reductions in water pollution. Despite those positive strides, maintaining water quality requires ongoing attention. A new survey of streams and rivers, performed by the EPA, provides a greater sense of the scale of the challenge. While industrial pollution, like mercury, remains a concern, agricultural runoff, in the form of sediment and fertilizers, is now far more widespread.

Water quality monitoring is performed by states using a variety of methods, which can make it difficult to accurately compile the national picture. The US Environmental Protection Agency has started carrying out nation-wide surveys to provide consistent, standardized snapshots of water quality. Following on the heels of the 2006 Wadeable Streams Assessment, the EPA recently released a draft comprehensive survey of streams and rivers.

The legwork was carried out in 2008 and 2009 by 85 crews that visited 1,924 sites in the lower 48 states. The sites were selected at random using an algorithm that ensured a representative sample. At each site, crews evaluated the stream’s surroundings, inventoried the species present, and collected samples for chemical analysis.

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Oceans continue to warm, especially the deeps

When discussing global warming, the public eye is mostly directed to global average surface air temperatures, but that’s just one slice of the climate pie. If you haven’t noticed, the ocean is awfully big, and it holds a great deal more heat energy than the atmosphere. In fact, about 90 percent of the energy that’s been added to the climate system by human activities has gone into the ocean.

Unfortunately, it’s hard to monitor that. There are a multitude of measuring stations for surface air temperatures, but our presence in the ocean is limited. With the advent of the Argo array—a fleet of autonomous, drifting floats that measure ocean temperatures—in the early 2000s, our data improved drastically. Still, the uncertainty has historically been greater for deeper waters.

In 2010, researchers identified an imbalance in our global energy arithmetic. If we measure the energy that's being trapped by increasing greenhouse gases, some of it seems to disappear—there wasn’t enough warming in the atmosphere or shallow ocean to account for all that extra energy— and there's been a deficit since 2004. (Though a later study suggested the mismatch might be within the margin of error for the temperature estimates.)

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PBS’ follow up to Erin Brockovich left key details out

Recently, PBS NewsHour ran a two-part investigative story that must have seemed to have all the elements of a compelling piece. There was a relatively unknown but apparently widespread carcinogen and a great hook—it was tied to the story of contaminated water behind the film Erin Brockovich (and the book A Civil Action). Issues relating to public health threats demand careful and thorough reporting. Unfortunately, those qualities were at times absent from the PBS story.

The story focused on hexavalent chromium (Cr6+) in drinking water. Most chromium is trivalent, which isn’t very soluble in water. When oxidized to hexavalent chromium, however, it becomes mobile. Unlike the trivalent variety, hexavalent chromium is carcinogenic. It's much worse if inhaled, but there’s evidence that it is dangerous when ingested as well. As the NewsHour story noted, recent sampling has shown that hexavalent chromium is present in drinking water across the country. Does that mean we have a public health crisis on our hands, caused by shockingly widespread contamination? Let’s slow down and get some context.

Meet the metal

Hexavalent chromium occurs naturally. That’s a rather important fact never mentioned in the NewsHour story, which describes the water as “tainted” by industrial chemicals. Chromium, like many elements, is present in Earth’s crust. Some types of rock have more than others, but it’s actually a little bit more common than copper or zinc—the average concentration in the upper crust is something like 90 parts per million. Oxidize some of that chromium to the hexavalent state, and it can be mobilized into groundwater. If hexavalent chromium is showing up in wells nearly everywhere we look, it might be because it’s naturally present rather than a ubiquitous, human-introduced contaminant.

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How salty is that seawater? Ask the Aquarius satellite

Artist's conception of SAC-D satellite
NASA

Some 400 miles above the Earth, NASA satellites are watching you. They’re not actually interested in you or anything you do, of course—they’re just making measurements of environmental variables like temperature or cloud cover. While most people equate space agencies like NASA or the ESA with the exploration of extraterrestrial destinations, a critical part of their mission is to study our own planet from the unique orbital point of view.

The advantages are obvious: rapid coverage of large areas using the same instrument and continuous data collection. But there are challenges, too. It’s not exactly cheap to get the instrument up there, and if a component breaks, it’s game over. Then there’s the not insignificant task of finding a way to measure the thing you’re interested in from hundreds of miles away.

One of the newest members of the Earth-observing club is Aquarius (along with its friends aboard the SAC-D satellite). Launched on June 20, 2011, the satellite is a collaborative effort between the US and Argentina. Its job? To map surface ocean salinity around the globe and improve our understanding of ocean circulation and the hydrologic cycle.

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