• In deep waters

    Antarctic Bottom Water sounds like it’s frigidly cold, and it is. It’s the densest water in the ocean, made from open ocean water that’s cooled by surrounding polar ice that then sinks. As it’s replenished, the bottom water spreads northward like an icy chill and drives the ocean conveyor belt. It’s been thought that it would take centuries for warming surface waters to penetrate such depths. But new research published in the recent journal Science finds that climate change could reach these cool waters a whole lot sooner. Using computer simulation, researchers led by the Research Institute for Global Change in Japan found that the deep ocean is far more sensitive to the surface than previously thought. As surface waters warm in the Southern Ocean, the layers of Antarctic Bottom Water thin. This weakens the deep water current that transports

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  • Oceans aboard

    Rising seas –  of 2 feet, five feet, or even 7 feet –  have been a topic of much speculation. And knowing answers matter. How far should communities plan to back away from the ocean? What size dams are needed? How many people are in danger? Further complicating the science is the fact that global sea level rise isn’t actually global. The seas don’t rise uniformly everywhere. Changes in oceanic and atmospheric circulation impact regions differently, causing some places to be hit with higher watermarks than others. Take for example the Seychelles Islands and Zanzibar off the coast of Tanzania. These islands in the southwest Indian Ocean are actually experiencing sea level decrease. But in the North, along the Bay of Bengal, Sri Lanka, and Java are getting hammered as the oceans creep up 5 inches per century, higher than

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  • Drunk off fuel

    Ethanol has been widely trumpeted as a viable alternative to fossil fuels, at least until a couple years ago when a food scarcity scare had people suddenly questioning whether food and energy should be competitors for the same land. But here’s another thing that needs considering. One in three molecules of ethanol in the atmosphere is now human-added. No one has questioned the impacts of pumping so much ethanol a year into the air. Until now. Research led by Princeton University has come up with the first analysis of the sources of ethanol in the atmosphere and how it’s moving around. In a paper published last month in the journal Atmospheric Chemistry and Physics, researchers estimate that about nine million tons a year come from terrestrial plants, another five million tons from anthropogenic sources (industry and biofuels), and another half

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  • Biggest of them all

    Mention Arctic ice melt and the first image to come to mind is the northern Atlantic. Mostly Greenland. Sometimes the far reaches of Canada or Iceland. Maybe it’s because the northern Atlantic is the same ocean that researchers from major institutions dip their toes in in 100-plus degree heat waves. But way out in the Pacific, researchers at the University of Hawaii are taking a different look at the climate. In a paper published this week in the journal Science, oceanographer Axel Timmermann and colleagues explained what they found out by looking at sediment cores from the northern Pacific. As the last major ice age ended 17,500 years ago, massive north Atlantic ice sheets melted and all the added fresh water caused the collapse of the Atlantic Ocean conveyor belt. That should have plunged the northern Hemisphere into a deep

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  • Where ice meets sea

    How fast can a glacier melt? Usually the answer is attributed to the amount of warming or CO2 level rise. But researchers are also looking into the actual mechanics of glacier melt to get a handle on what’s causing ice to wear away. In a paper published recently in Nature Geoscience, Adrian Jenkins of the British Antarctic Survey and colleagues examined Pine Island Glacier, one of the two main contributors of ice loss in West Antarctica. West Antarctic holds enough water to boost global sea levels by several meters because much of the ice shelf is on solid ground. Any loss directly adds water to the ocean. And it’s happening fast. About 10 percent of the observed rise in global sea level is from West Antarctica. About twice the size of Scotland, Pine Island Glacier has accelerated thinning, the most

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  • Brave new world

    It’s mighty hard to figure out what the Earth’s early atmosphere looked like some 4 billion years ago. But we know that it was hot — up to a stifling 153 degrees Fahrenheit, enough to melt wax. This has always been a paradox. After all, the sun’s light was  30 percent dimmer back then, so there should have been glaciers covering the planet. Imagine what would happen if the Earth lost a third of its solar radiation today. Let’s just say there would be no outdoor barbecues on this Fourth of July. The “faint early Sun paradox” is revisited in the journal Nature Geoscience this month with an article by Alicia Newton summarizing the newest theories on our newborn Earth’s climate. They come down to the kinds of greenhouse gases that shrouded the planet, and were vitally important in creating

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  • Grass gone wild

    Buying carbon offsets may, indeed, be a sin tax. But there are more reasons than dubious moral rectitude to question the practice. Offsets are based on the belief that doing things like replanting forests and setting aside undeveloped land will mitigate the effects of global warming because more greenery will draw down CO2 from the atmosphere. Some research has even shown that plants do well under higher CO2 concentrations, growing faster and more lush, a kind of carbon sequestration known as “CO2 fertilization.” But a paper in the journal Nature published today paints a fuzzier picture. First of all, to make good on all the extra CO2, plants also need more Nitrogen to grow, and that may or may not be available. There’s a lot of Nitrogen floating around from human-made sources (fertilizers), so we should be good, right? Researchers

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  • Warm as the Arctic

    Far North off the coast of Greenland is Ellesmere Island, a mountainous, icy patch of earth that supports only one species of woody plant, the tiny, slow-growing Arctic Willow. The glaciers in this Canadian outpost have been rapidly disintegrating; its main Ward Hunt Ice shelf fractured a couple years ago, while another, the Markham shelf, broke off into the sea. It’s a great place to study the effects of climate change, both modern and past. Beaver Pond on Ellesmere Island is exceptionally well preserved with peat layers that contain a diverse assemblage of 4 to 5 million year old fossils from a time when the Earth was much warmer than today, and Beaver Pond teeming with life. Researchers led by the University of Colorado and Canadian Museum of Nature have studied some of these fossils to get a more precise

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  • Microbial pump

    The journal Science has devoted an entire issue to exploring the way the oceans are rapidly transforming in response to climate change and other factors. It’s worth taking a peek into this extensive sweep of research; the oceans, after all, account for 70 percent of the Earth’s surface and are the least explored part of the globe. I’ll be looking at a number of the papers published in the issue largely because of the growing sense I’ve felt from an accumulation of news stories and reports that the oceans are in big trouble. Could we see a collapse of the ocean ecosystems in our lifetimes? If we understand and treat the oceans better, could they also be savior in re-balancing the Earth’s climate? “The ocean surface is like a planet-sized set of lungs that inhale and exhale CO2,” writes Richard

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  • Catch a cold

    Climate change has made apparent the interconnectedness of Earth systems. That sometimes doesn’t match with our human experience of the vastness of the world, where we dump trash elsewhere, fish the oceans without limit, and send pollutants into the atmosphere thinking nothing will ever come back at us. Yet a study published in a recent journal of Science is a reminder of how change in one place can ripple to the far reaches of the globe. Data from as far back as 3.5 million years ago shows that when the polar ice sheets grow and recede, tropical waters far to the South get nippier and warmer as well. Models predict that the direct effects of large ice sheets would extend some 2,000 km, but not far enough to alter tropical water temperatures. “What surprised us is that the tropics seemed

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