Human-generated aerosols from northern hemisphere may affect rainfall patterns in Australia

Washington, August 27 (ANI): Australian scientists, using a climate model, have suggested that human-generated aerosols from the northern hemisphere may have contributed to increased rainfall in north-western and central Australia, and decreased rainfall in parts of southern Australia.

According to lead researcher, Dr Leon Rotstayn, Principal Research Scientist at the Centre for Australian Weather and Climate Research, a partnership between CSIRO and the Bureau of Meteorology, “Perhaps surprisingly, inclusion of northern hemisphere aerosols may be important for accurate modelling of Australian climate change.”Aerosols come from many different sources.

Sulphur is released when we burn coal and oil. More dust, also an aerosol, circulates in the atmosphere when land is cleared, burned or overgrazed.

Some aerosols occur naturally like sea spray and volcanic emissions, but NASA estimates ten percent of the total aerosols in the atmosphere are caused by people.

Most of this ten percent is in the northern hemisphere.
European researchers, attending the international ‘Water in a changing climate’ science conference in Melbourne from August 24-28, will discuss a new forecasting service that will identify in unprecedented detail where these aerosols are coming from and where they are going.

The new service, part of Europe’s Global Monitoring for Environment and Security (GMES) initiative, will give global information on how pollutants move around the world across oceans and continents, and will refine estimates of their sources and sinks.

According to Dr Adrian Simmons from the European Centre for Medium-Range Weather Forecasts, which is coordinating the multi-institution initiative, “The service will give much more detailed forecast information on air quality over Europe and provide the basis for better health advice across Europe and beyond”.

The service has clear implications for environmental policy and legislation. (ANI)

Melting minerals found to be source of Tanzanian volcano’s carbon-based lavas

Washington, May 7 (ANI): Scientists studying the world’s most unusual volcano in Tanzania have discovered the reason behind its unique carbon-based lavas, attributing them to an extremely small degree of partial melting of typical minerals in the earth’s upper mantle.

Although carbon-based lavas, known as carbonatites, are found throughout history, the Oldoinyo Lengai volcano, located in the East African Rift in northern Tanzania, is the only place on Earth where they are actively erupting.

The lava expelled from the volcano is highly unusual in that it contains almost no silica and greater than 50 percent carbonate minerals.

Typically, lavas contain high levels of silica, which increases their melting point to above 900 degree Celsius.

The lavas of Oldoinyo Lengai volcano erupt as a liquid at approximately 540 degrees C. This low silica content gives rise to the extremely fluid lavas, which resembles motor oil when they flow.

“Since the volcano was under magma pressure during the eruption, we were able to collect pristine samples of the volcanic gases, with minimal air contamination,” said Tobias Fischer, volcanologist at the University of New Mexico.

The pristine samples collected during a 2005 eruption offered the scientists a deeper look at the processes taking place in the earth’s upper mantle.

The geochemical analyses revealed that magma from the upper mantle below both the oceans and continents is a uniform and well-mixed reservoir of “typical” volcanic gases such as carbon dioxide, nitrogen, argon and helium.

The lava expelled from the volcano is highly unusual in that it contains almost no silica and greater than 50 percent carbonate minerals.

Typically, lavas contain high levels of silica, which increases their melting point to above 900 degrees C.

The lavas of Oldoinyo Lengai volcano are comprised of carbonatites, which erupts as a liquid at approximately 540 degrees C.

This low silica content gives rise to the extremely fluid lavas, which resembles motor oil when they flow.

“These finding are significant because it shows that these extremely bizarre lavas and their parent magmas, nephelinites, were produced by melting of a typical upper mantle mineral assemblage without an extreme carbon content in the magma source,” said geochemist Bernard Marty at the Centre de Recherches Petrographiques et Geochimiques in Nancy, France.

“Rather, in order to make carbonatite lavas, all you need is a very low melt fraction of 0.3 percent or less,” he added. (ANI)

Earthshine reflects Earth’s oceans and continents from Moon’s dark side

Melbourne, April 8 (ANI): In a new research, scientists have shown for the first time that the difference in reflection of light from the Earth’s land masses and oceans can be seen on the dark side of the moon, a phenomenon known as earthshine.

The research, conducted by researchers from the University of Melbourne and Princeton University, indicates that the brightness of the reflected earthshine varied as the Earth rotated, revealing the difference between the intense mirror-like reflections of the ocean compared to the dimmer land.

According to Sally Langford from the University of Melbourne’s School of Physics, “In the future, astronomers hope to find planets like the Earth around other stars. However these planets will be too small to allow an image to be made of their surface.”

“We can use earthshine, together with our knowledge of the Earth’s surface to help interpret the physical make up of new planets,” she said.

This is the first study in the world to use the reflection of the Earth to measure the effect of continents and oceans on the apparent brightness of a planet.

Other studies have used a colour spectrum and infrared sensors to identify vegetation, or for climate monitoring.

The three-year study involved taking images of the Moon to measure the earth’s brightness as it rotated, allowing Langford to detect the difference in signal from land and water.

bservations of the Moon were made from Mount Macedon in Victoria, for around three days each month when the Moon was rising or setting.

The study was conducted so that in the evening, when the Moon was a waxing crescent, the reflected earthshine originated from Indian Ocean and Africa’s east coast.

In the morning, when the Moon was a waning crescent – it originated only from the Pacific Ocean.

“When we observe earthshine from the Moon in the early evening we see the bright reflection from the Indian Ocean, then as the Earth rotates the continent of Africa blocks this reflection, and the Moon becomes darker,” Langford said.

“If we find Earth sized planets and watch their brightness as they rotate, we will be able to assess properties like the existence of land and oceans,” she added. (ANI)

Venus may have had continents and oceans in its ancient past

London, Jan 14 (ANI): In a new research, scientists have claimed to detect evidence for granite highlands on Venus in data almost two decades old, which suggests that the planet may have once been far more like Earth, with oceans and continents.

According to a report in Nature News, the data includes nighttime infrared emissions coming from the surface of Venus, which was detected by NASA’s Galileo spacecraft in 1990.

Analyzing these data, an international team led by planetary scientist George Hashimoto, now at Okayama University, Japan, found that Venus’s highland regions emitted less infrared radiation than its lowlands.

One interpretation of this lower infrared emission from the highlands, according to the authors, is that they are composed largely of ‘felsic’ rocks, particularly granite.

Granite, which on Earth is found in continental crust, requires water for its formation.

“This is the first direct evidence that early in the history of the Solar System, Venus was a habitable planet with plenty of water,” said Dirk Schulze-Makuch, an astrobiologist at Washington State University in Pullman.

“The question is how long Venus remained habitable. But this gives new impetus for the search for microbial life in Venus’s lower atmosphere,” he added.

Before Galileo, researchers had believed that only radar could see through the dense clouds of sulphuric acid in Venus’s atmosphere to the surface, according to co-author Kevin Baines, a scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California.

“Detecting the surface in the infrared is a breakthrough,” he said.

The possible presence of granite also suggests that tectonic plate movement and continent formation may have occurred on Venus, as well as recycling of water and carbon between the planet’s mantle and atmosphere.

According to geophysicist Norm Sleep of Stanford University in California, the implication of continent formation is “quite significant”.

Venus might have once been almost entirely underwater, although without further geochemical data, we don’t know whether this early ocean’s temperature was 30 degree Celsius or 150 degree Celsius, he added.

“Whether tepid or boiling, any ocean on Venus would have lasted only a few hundred million years. As the Sun became hotter and brighter, the planet experienced a runaway greenhouse effect,” Sleep explained.

Nowadays, the planet is a paragon of the uninhabitable, with an atmosphere of 96 percent carbon dioxide and a surface temperature of around 460 degrees C.

“Any life on Venus that hadn’t figured out how to colonize the cloud tops a billion years after the planet’s formation would have been in big trouble,” said Sleep. (ANI)