What does it take to make a wellspring of biodiversity like the Amazon rainforest? A huge mountain range, a blast of heat, and a little time.
A pair of studies in this week’s edition of Science attempt to sort through tropical natural history and reach the root causes of Amazonia’s embarrassment of biological riches. The first, led by palaeoecologist Carina Hoorn, points to the influence of the Andes Mountains, the spine of South America that runs up its western coast. Sometime between about 35 and 65 million years ago, colliding tectonic plates sent the Andes bulging up. According to the researchers, the birth of a mountain range set of an ecological chain reaction.
The rising mountains that resulted from the uplift blocked humid air from the Atlantic, eventually increasing rainfall along the eastern flank of what became the Andes that eroded nutrient-loaded soils off the mountains. The Andes also kept water from draining into the Pacific, helping form vast wetlands about 23 million years ago that were home to a wide range of mollusks and reptiles. [LiveScience]
When the Environmental Protection Agency issued new rules in April attempting to crack down on mountaintop removal coal mining, you knew it was only a matter of time before the major push-back arrived. With elections looming and politicians looking to score some points at home, that time is now.
Joe Manchin, the Democratic governor of coal-rich West Virginia, says his state will sue the EPA and ask a U.S. District Court to throw out the agency’s strict new guidelines. For Mr. Manchin, the timing is certainly good:
Mr. Manchin is running for the U.S. Senate seat, formerly held by the late Democratic Sen. Robert Byrd, against Republican businessman John Raese, who has pulled ahead in some polls. The EPA’s policies on mining and climate change are controversial in West Virginia, where coal mining is a major industry supporting thousands of jobs. [Wall Street Journal]
The glaciers that form atop mountains can act like a saw or sandpaper, wearing away material as they slide and preventing the peaks from ascending too high. Until now, that’s been the consensus notion of how glaciers shape mountains. But whatever your tool shop metaphor of choice might be, neither saws nor sanders work if the glaciers don’t move. That might explain what’s happening in the far reaches of southern South America, where, scientists led by Stuart Thomson report in Nature, glaciers are not wearing down the Andes Mountains but are actually protecting them from erosion.
In the more temperate part of the range, from 38˚ to 49˚ south latitude, the glacial grinder has shaved off as much as 1000 meters from the mountains’ peaks, flattened their slopes, and smoothed their surfaces. But farther south, between 49˚ and 56˚ latitude, the mountains have been spared: The peaks are higher—some nearly 4000 meters—and the ridges are much more rugged. [ScienceNOW]
A brutal Mount Everest storm might have doomed legendary climber George Mallory. How do we know? Because it’s there—in his team’s meteorological records.
Mallory was the man who, according to legend at least, responded to a question about why he’d want to climb Everest with the immortal reply, “Because it’s there.” But he and his partner, Andrew Irvine, never returned from their 1924 attempt to summit the world’s highest peak. Their lost expedition spurred decades of curiosity about their fate, a curiosity that only intensified when explorers found Mallory’s body in 1999.
For a paper published in the journal Weather, scientists have scoured the meteorological measurements taken at the expedition’s base camp at 16,500 feet and recorded in the logs. Despite the fact that those logs were brought back to Britain in 1926, the researchers argue that they haven’t been part of the discussion of Mallory’s downfall, even though the answer could be right there on the decades-old pages.
The researchers analysed barometric pressure measurements and found that during the Mallory and Irvine summit attempt, there was a pressure drop at Everest base camp of approximately 18 millibars (mbar). Lead author GW Kent Moore, from the University of Toronto, Canada, described this as “quite a large drop”. He said: “We concluded that Mallory and Irvine most likely encountered a very intense storm as they made their way towards the summit” [BBC News].
Global warming typically takes the rap for melting glaciers, but in the case of the Himalayan mountain range’s dwindling ice, it could have a co-conspirator: soot. Today, at the American Geophysical Union’s annual meeting, scientists said that the black carbon spewed out as industrial pollution from the heavily populated areas nearby could be a much larger contributor to glacier melt than previously thought.
First, NASA’s William Lau says, atmospheric circulation leaves a layer of soot at the base of the Himalayas, and that soot then combines with dust and forms an opaque cloud that absorbs energy. As this layer heats up in the Himalayan foothills, it rises and enhances the seasonal northward flow of humid monsoon winds, forcing moisture and hot air up the slopes of the majestic mountain range. As these particles rise on the warm, overturning air masses, they produce more rain over northern India, which further warms the atmosphere and fuels this “heat pump” that draws even more warm air to the region [LiveScience].
The glaciers that shine at the top of Mount Kilimanjaro, the highest peak in Africa, could vanish entirely within 15 years, according to a somber new report. Says glaciologist Lonnie Thompson: “Of the ice cover present in 1912 … 85% has disappeared and 26% of that present in 2000 is now gone” [USA Today]. The mountaintop glaciers are both shrinking around the edges and growing thinner, Thompson’s team found. If the current rate of ice loss continues, the mountain could be ice free as early as 2022.
Thompson says his team has fresh evidence that global warming is to blame. As similar changes are occurring on other mountains in Africa, South America, and in the Himalayas, Thompson says that global climate change, not local weather effects, must be responsible for the receding ice. “The fact that so many glaciers throughout the tropics and subtropics are showing similar responses suggests an underlying common cause,” Thompson said [AP].
Scientists once thought that the intensity of the movement of the Earth’s tectonic plates determined how high a mountain could soar. But new research shows that it’s actually the efficiency with which colder climates erode mountains that limits their height, according to a recent study published in Nature.
The force of the tectonic plates pushing upwards, along with the strength of the Earth’s crust underneath the mountain and the force of erosion, all factor into a mountain’s height. All of the world’s highest ranges have strong underlying crust, but until now it wasn’t clear whether the world’s tallest peaks were dominated by strong uplift or minimal erosion. Using satellite images… researchers mapped all the major mountain ranges between 60° north and 60° south, plotting their land surface area against elevation [New Scientist]. They used a computer model to explore the effects of glacial erosion on these mountain ranges, and also looked at how each range’s latitude compared with its average snowline, or the point at which no significant amount of ice or snow accumulates on a mountain.
The ancient civilization known as the Incan empire, which at its peak reached a population of 8 million people spread throughout South America, may owe its success at least in part to a warming climate, according to a study in the journal Climate of the Past. A rise in temperatures would have melted glaciers and allowed crops to grow further into the Andes mountains, fostering agricultural growth.
The study found that between 1100 and 1533 AD, temperatures increased several degrees, making it possible for the Incas to use new mountain land for agriculture. It also expanded the swath of land the empire occupied which, at its peak, spanned from the middle of Chile to the border shared by Ecuador and Colombia. This climate information came from an analysis of deeply buried sediment samples in the region the Incans once occupied. The researchers examined pollen and seeds buried in layers of mud on the floor of Lake Marcacocha in the Cuzco region of the Peruvian Andes. Similar to the rings in the trunk of a tree, each layer of sediment represents a fixed period of time. In the case of Lake Marcacocha, the researchers were able to analyze a 1,200-year-old sediment record [Discovery News].
In chunks of rock quarried from a Russian mountain range, physicists have found perfect “quasicrystals,” a type of material that researchers previously thought could only be created in a lab. Quasicrystals display ordered arrangements and symmetries but are not periodic—that is, they are not defined by a single unit cell (such as a cube) that simply repeats itself in three dimensions [Scientific American]. Instead, quasicrystals have two different geometric structures that alternate, and that are organized in ways which create complex patterns and symmetries. When such a pattern is laid out in two-dimensions, the resulting design is often called Penrose tiling.
Quasicrystals were first created in the lab in 1984, and physicist Paul Steinhardt, a coauthor of the current study, says the hunt for naturally occurring quasicrystals began about 10 years ago. “The latest issue surrounding quasicrystals has been could nature ever make them? … When we make them in the lab we try very hard to make perfect quasicrystals, but nature has no such goal” [Discovery News]. The researchers put out a call to mineralogists around the world, asking them to send in likely rock samples for testing.
A radar survey conducted between 2004 and 2008 by Japanese, Chinese, and British scientists reveals how the ice on Antarctica grew, and what the land looks like beneath the ice. At the center of the continent, a nearly two-mile-thick slab of ice has clung to Antarctica’s rocky surface for 14 million years; this is the first time scientists have gotten a virtual glimpse beneath the sheet’s surface.
The topography beneath the ice is mountainous, with peaks and valleys like the European Alps, according the study published Nature. Scientists say that 34 million years ago, small glaciers expanded from the mountaintops and shifted to carve out the terrain. To collect the data, scientists drove huge trains of caterpillar tractors in tight lines over Dome A, a plateau of ice at the heart of Antarctica. The tractors carried radars that pinged down through the ice and sent back profiles of the frozen rock landscape below [New Scientist]. Scientists knew the velocity of the radar’s radio waves, so they calculated the depth of the ice by timing how long it took the waves to hit the rock and come back to the surface.