Rivers recover after dam removal

More than 1,000 dams have been removed across the United States because of safety concerns, sediment buildup, inefficiency or having otherwise outlived usefulness. A paper published today in Science finds that rivers are resilient and respond relatively quickly after a dam is removed. 

“The apparent success of dam removal as a means of river restoration is reflected in the increasing number of dams coming down, more than 1,000 in the last 40 years,” said lead author of the study Jim O’Connor, geologist with the U.S. Geological Survey. “Rivers quickly erode sediment accumulated in former reservoirs and redistribute it downstream, commonly returning the river to conditions similar to those prior to impoundment.”

Declining 'large herbivore' populations may lead to an 'empty landscape'

The decline of the world's large herbivores, especially in Africa and parts of Asia, is raising the specter of an "empty landscape" in some of the most diverse ecosystems on the planet, according to a newly published study. Many populations of animals such as rhinoceroses, zebras, camels, elephants and tapirs are diminishing or threatened with extinction in grasslands, savannahs, deserts and forests, scientists say.

Photosynthesis measured on a global scale

A research team led by geoscientists from Brown University and the Marine Biological Laboratory has provided some crucial ground-truth for a method of measuring plant photosynthesis on a global scale from low-Earth orbit. The researchers have shown that chlorophyll fluorescence, a faint glow produced by plant leaves as a byproduct of photosynthesis, is a strong proxy for photosynthetic activity in the canopy of a deciduous forest. That glow can be detected by orbiting satellites and could be used to monitor global photosynthetic activity in real time.

If you sit all day at a desk, please get up and walk around now and then!

A new study suggests that engaging in low intensity activities such as standing may not be enough to offset the health hazards of sitting for long periods of time. On the bright side, adding two minutes of walking each hour to your routine just might do the trick. These findings were published in the Clinical Journal of the American Society of Nephrology (CJASN).

Numerous studies have shown that sitting for extended periods of time each day leads to increased risk for early death, as well as heart disease, diabetes and other health conditions. Considering that 80 percent of Americans fall short of completing the recommended amount of exercise, 2.5 hours of moderate activity each week, it seems unrealistic to expect that people will replace sitting with even more exercise.

What ecosystem is most at threat from human impact?

An international team of scientists has used the 23-million-year fossil record to calculate which marine animals and ecosystems are most at risk of extinction today. In a paper published in the journal Science, the researchers found those animals and ecosystems most threatened are predominantly in the tropics.

Plane de-icing agents contribute to soil and groundwater contamination at airports

Spring has arrived in Europe with mild temperatures and sunshine. Where just a few weeks ago the ground was frozen and partly covered in snow and ice, it is now thawing. This doesn't only have an impact on the flora and fauna. Thawing results in soil and the groundwater at airports being impacted by chemicals, which are contained in melt water. The reason: Airports have to use de-icing agents during the winter, which end up on unpaved areas and infiltrate into the soils during snowmelt.

Reducing impaired-driving crashes proves good for the economy too

The halving of alcohol-fuelled car crashes since the mid-1980s boosted US economic output by $20 billion, increased national income by $6.5 billion, and created 215,000 jobs in 2010, reveals an analysis of the economic impact of drink-driving, published online in the journal Injury Prevention.

In a bid to estimate the impact of alcohol-fuelled car crashes on the US economy in 2010, the researchers calculated the economic gains (and losses) resulting from the substantial fall in this type of road traffic collision since 1984-6 and the monetary costs directly incurred by employers and consumers in 2010.

Can organic farming reverse agriculture from a carbon source to a carbon sink?

More than a third of global greenhouse gases (GHGs) come from agriculture and a new theory suggest human can reverse global warming by sequestering several hundred billion tons of excess CO2 through regenerative, organic farming, ranching and land use. 

Oregon State University study links climate changes in Northern and Southern Hemispheres - with 200 year lag

A new study using evidence from a highly detailed ice core from West Antarctica shows a consistent link between abrupt temperature changes on Greenland and Antarctica during the last ice age, giving scientists a clearer picture of the link between climate in the northern and southern hemispheres.

Greenland climate during the last ice age was very unstable, the researchers say, characterized by a number of large, abrupt changes in mean annual temperature that each occurred within several decades. These so-called “Dansgaard-Oeschger events” took place every few thousand years during the last ice age. Temperature changes in Antarctica showed an opposite pattern, with Antarctica cooling when Greenland was warm, and vice versa.

Selective logging may underestimate carbon stock

Up to 64 percent of above-ground biomass in selectively logged forests may consist of dead wood left over from logging damage, argues a paper published this week in Environmental Research Letters.