Growth of the Foot Print
A James Cook University scientist says a new map of the ecological footprint of humankind shows 97 per cent of the most species-rich places on Earth have been seriously altered.
JCU's Professor Bill Laurance has taken part in a study to map the ecological effect of people on the planet. He said the news isn't great. "The most species-rich parts of the planet – especially including the tropical rainforests – have been hit hardest. In total, around 97 percent of Earth's biologically richest real estate has been seriously altered by humans," he said.
The scientists found environmental pressures are widespread, with only a few very remote areas escaping damage. "Humans are the most voracious consumers planet Earth has ever seen. With our land-use, hunting and other exploitative activities, we are now directly impacting three-quarters of the Earth's land surface," said Professor Laurance.
Researchers combined data garnered from unprecedented advances in remote sensing with information collected via surveys on the ground. They compared data from the first survey in 1993 to the last available information set from 2009.
Professor Laurance said that 71 percent of global ecoregions saw a marked increase in their human footprints. But he said the news was not all bad.
A Dark Milky Way
Using the world's most powerful telescopes, an international team of astronomers has found a massive galaxy that consists almost entirely of dark matter.
The galaxy, Dragonfly 44, is located in the nearby Coma constellation and had been overlooked until last year because of its unusual composition: It is a diffuse "blob" about the size of the Milky Way, but with far fewer stars. "Very soon after its discovery, we realised this galaxy had to be more than meets the eye. It has so few stars that it would quickly be ripped apart unless something was holding it together," said Yale University astronomer Pieter van Dokkum, lead author of a paper in the Astrophysical Journal Letters.
Van Dokkum's team was able to get a good look at Dragonfly 44 thanks to the W.M. Keck Observatory and the Gemini North telescope, both in Hawaii. Astronomers used observations from Keck, taken over six nights, to measure the velocities of stars in the galaxy. They used the 8-metre Gemini North telescope to reveal a halo of spherical clusters of stars around the galaxy's core, similar to the halo that surrounds our Milky Way galaxy.
Star velocities are an indication of the galaxy's mass, the researchers noted. The faster the stars move, the more mass its galaxy will have. "Amazingly, the stars move at velocities that are far greater than expected for such a dim galaxy. It means that Dragonfly 44 has a huge amount of unseen mass," said co-author Roberto Abraham of the University of Toronto.
Scientists initially spotted Dragonfly 44 with the Dragonfly Telephoto Array, a telescope invented and built by van Dokkum and Abraham.