In 1974, just a couple years after the launch of the first Landsat satellite, scientists noticed something odd in the Weddell Sea near Antarctica. There was a large ice-free area, called a polynya, in the middle of the ice pack. The polynya, which covered an area as large as New Zealand, reappeared in the winters of 1975 and 1976 but has not been seen since.

Scientists interpreted the polynya’s disappearance as a sign that its formation was a naturally rare event. But researchers reporting in Nature Climate Change disagree, saying that the polynya’s appearance used to be far more common and that climate change is now suppressing its formation.

What’s more, the polynya’s absence could have implications for the vast conveyor belt of ocean currents that move heat around the globe.

Satellite imagery allowed scientists to find an ice-free area in the Weddell Sea (upper left quadrant) in the Antarctic winters of 1974 through 1976. (Credit: Claire Parkinson (NASA GSFC))

Surface seawater around the poles tends to be relatively fresh due to precipitation and the fact that sea ice melts into it, which makes it very cold. As a result, below the surface is a layer of slightly warmer and more saline water not infiltrated by melting ice and precipitation. This higher salinity makes it denser than water at the surface. Read more

Planners ignore microclimates at their peril: mistakes can mean frozen crops, lower house values and camper vans blown off the highway.

Microclimates are exactly that: phenomena measured on scales of inches to miles. The wind can be gusting to gale force near a ridgetop while only gentle breezes blow in the valley below. A simple garden wall may enable a plant to thrive where it otherwise would have been hard-pressed to survive. Read more

New findings from NASA’s Mars Reconnaissance Orbiter (MRO) provide the strongest evidence yet that liquid water flows intermittently on present-day Mars.

Dark, narrow streaks on Martian slopes such as these at Hale Crater are inferred to be formed by seasonal flow of water on contemporary Mars. The streaks are roughly the length of a football field.

Using an imaging spectrometer on MRO, researchers detected signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet. These darkish streaks appear to ebb and flow over time. They darken and appear to flow down steep slopes during warm seasons, and then fade in cooler seasons. They appear in several locations on Mars when temperatures are above minus 10 degrees Fahrenheit (minus 23 Celsius), and disappear at colder times. Read more

Researchers from Lund University in Sweden have discovered that our drinking water is to a large extent purified by millions of “good bacteria” found in water pipes and purification plants. So far, the knowledge about them has been practically non-existent, but this new research is about to change that.

A glass of water contains millions of bacteria, say researchers.

A glass of clean drinking water actually contains ten million bacteria! But that is as it should be — clean tap water always contains harmless bacteria. These bacteria and other microbes grow in the drinking water treatment plant and on the inside of our water pipes, which can be seen in the form of a thin, sticky coating — a so-called biofilm. All surfaces from the raw water intake to the tap are covered in this biofilm.

Findings by researchers in Applied Microbiology and Water Resources Engineering show that the diversity of species of bacteria in water pipes is huge, and that bacteria may play a larger role than previously thought. Among other things, the researchers suspect that a large part of water purification takes place in the pipes and not only in water purification plants. Read more

Graphene is going to change the world — or so we’ve been told.

Since its discovery a decade ago, scientists and tech gurus have hailed graphene as the wonder material that could replace silicon in electronics, increase the efficiency of batteries, the durability and conductivity of touch screens and pave the way for cheap thermal electric energy, among many other things.

In a new paper published in Science, researchers at the Harvard and Raytheon BBN Technology have advanced our understanding of graphene’s basic properties, observing for the first time electrons in a metal behaving like a fluid.

It’s one atom thick, stronger than steel, harder than diamond and one of the most conductive materials on earth.

But, several challenges must be overcome before graphene products are brought to market. Scientists are still trying to understand the basic physics of this unique material. Also, it’s very challenging to make and even harder to make without impurities.

In a new paper published in Science, researchers at the Harvard and Raytheon BBN Technology have advanced our understanding of graphene’s basic properties, observing for the first time electrons in a metal behaving like a fluid.

In order to make this observation, the team improved methods to create ultra-clean graphene and developed a new way measure its thermal conductivity. This research could lead to novel thermoelectric devices as well as provide a model system to explore exotic phenomena like black holes and high-energy plasmas.

This research was led by Philip Kim, professor of physics and applied physics in John A. Paulson School of Engineering and Applied Sciences (SEAS). Read more