3 March 2016, Science Daily, Greenland’s ice is getting darker, increasing risk of melting. Feedback loops from melting itself are driving changes in reflectivity. Greenland’s snowy surface has been getting darker over the past two decades, absorbing more heat from the sun and increasing snow melt, a new study of satellite data shows. That trend is likely to continue, with the surface’s reflectivity, or albedo, decreasing by as much as 10 percent by the end of the century, the study says. While soot blowing in from wildfires contributes to the problem, it hasn’t been driving the change, the study finds. The real culprits are two feedback loops created by the melting itself. One of those processes isn’t visible to the human eye, but it is having a profound effect. The results, published in the European Geosciences Union journal The Cryosphere, have global implications. Fresh meltwater pouring into the ocean from Greenland raises sea level and could affect ocean ecology and circulation. “You don’t necessarily have to have a ‘dirtier’ snowpack to make it dark,” said lead author Marco Tedesco, a research professor at Columbia University’s Lamont-Doherty Earth Observatory and adjunct scientist at NASA Goddard Institute of Space Studies. “A snowpack that might look ‘clean’ to our eyes can be more effective in absorbing solar radiation than a dirty one. Overall, what matters, it is the total amount of solar energy that the surface absorbs. This is the real driver of melting.” The feedback loops work like this: During a warm summer with clear skies and lots of solar radiation pouring in, the surface starts to melt. As the top layers of fresh snow disappear, old impurities, like dust from erosion or soot that blew in years before, begin to appear, darkening the surface. A warm summer can remove enough snow to allow several years of impurities to concentrate at the surface as surrounding snow layers disappear. At the same time, as the snow melts and refreezes, the grains of snow get larger. This is because the meltwater acts like glue, sticking grains together when the surface refreezes. The larger grains create a less reflective surface that allows more solar radiation to be absorbed. The impact of grain size on albedo — the ratio between reflected and incoming solar radiation — is strong in the infrared range, where humans can’t see, but satellite instruments can detect the change. Read More here
Category Archives: Impacts Observed & Projected
1 March 2016, Science Daily, Impact of climate change on public health. Health consequences of climate change: Doctors urge action to help mitigate risks and prepare for new challenges. Climate change is already having a noticeable impact on the environment and global health. Around the world extreme weather events, increased temperatures, drought, and rising sea levels are all adversely affecting our ability to grow food, access clean water, and work safely outdoors. Soon in some areas, the transformation will be so drastic and devastating that native populations will be displaced and forced to find new homes as environmental refugees. In a review published in theAnnals of Global Health, doctors warn of the impending public health crisis brought on by climate change and call for action to help prepare the world for what is ahead. As we begin to experience an unprecedented shift in temperature, we are starting to see the immense impact climate change will have on people around the world, especially those living in low-income countries. Bearing the brunt of the damage caused by climate change, low-income nations are especially susceptible because their economies often rely solely on agriculture and most do not possess the resources to ease the risks posed by climate events. Low-income countries contribute just a tiny fraction of greenhouse gases (GHG), yet, they stand to lose the most if something is not done to curb emissions. In 2004, the United States, Canada, and Australia approached 6 metric tons (mt) of GHG per capita, while per-capita GHG emissions in low-income countries was only 0.6 mt overall. “As global temperature increases, rich countries’ economies continue to prosper, but the economic growth of poor countries is seriously impaired,” explained co-author Barry S. Levy, MD, MPH, Adjunct Professor, Department of Public Health and Community Medicine, Tufts University School of Medicine. “The consequences for economic growth in poor countries will be substantial if we continue on a ‘business-as-usual’ path of increasing carbon dioxide concentrations and rapid climate change, with poor countries’ mean annual growth rate decreasing from 3.2% to 2.6%.” Read More here
23 February 2016, The Conversation, Aboriginal fire management – part of the solution to destructive bushfires. As destructive bushfires become more common there is increasing political discussion how we manage them sustainably. Inevitably these debates raise questions of the past ecological effects of Aboriginal fire usage. There are two well-known narratives about Aboriginal fire use. One, popularised by Tim Flannery, stresses the ecologically disruptive impact of Aboriginal fire use. This storyline argues that the megafauna extinctions that immediately followed human colonisation in the ice age resulted in a ramping up of fire activity. This then led to the spread of flammable vegetation which now fuels bushfires. Another, promoted by Bill Gammage, suggests that the biodiverse landscapes that were colonised by the British were the direct product of skilful and sustained fire usage. Such broad-brush accounts give the impression that the specific details of Aboriginal fire usage are well-known and can be generalised across the entire continent. Sadly this is not the case. So rapid was the socio-ecological disruption of southern Australia that researchers have had to rely on historical sources, such as colonial texts and images, and tree rings, pollen and charcoal in lake sediments, to piece together how Aboriginal people burned the land. Such records are open to interpretation and there remains vigorous debate about the degree to which Aboriginal people shaped landscapes. Piecing together the past There are only a handful of detailed observational studies of the ecology of Aboriginal fire usage, and all from northern Australia, so there is dispute whether their findings can be extrapolated in the south. These studies demonstrate skilful use of fire that created fine-grained burn patterns, designed to promote food resources. For instance, a prime motive for burning savannas is attracting kangaroos to nutrient-rich grass that sprouts after the fire. In the desert, Aboriginal patch burning increases the habitat for sand goannas. In sum, there is mounting evidence that sustained Aboriginal fire use shaped many Australian landscapes by sharpening vegetation boundaries, maintaining open vegetation, and creating habitat for game species. Read More here
18 February 2016, The Conversation, Revealed: why some animals and plants will thrive under climate change. It’s mid-February and along Britain’s south coast gilt-head bream are drifting from the open sea into the estuaries. Meanwhile, thousands of little egrets are preparing to fly to continental Europe for breeding season, though a few hundred will remain in the UK. Across northern Europe, young wasp spiders will soon scamper out of their silky egg sacs. And this summer, countryside visitors throughout the south of England will catch sight of iridescent blue flashes as small red-eyed damselflies flit across ponds. These events all have one thing in common: they’re happening much further north than they would have as recently as 20 years ago. It’s not just a European thing. Polar bears are on the move, umbrella trees are creeping northwards through the US, and tropical birds in New Guinean mountains are retreating uphill. Southern Africa’s iconic quiver tree, which provides refridgeration in its hollowed out trunks, is itself escaping the heat and heading away from the equator. Across the world species are moving from their natural habitats. Fingers point at climate change. As areas become too hot or dry, many wildlife populations are declining. But on the flip side, some species are showing up in places that were historically too cold or wet. The story we usually hear is of terrible declines in plants and animals. The Pyrenean Frog is languishing on mountaintops on the Spanish-French border, for instance, unable to move to cooler climes. Magellanic penguin chicks are dying in storms brought on by climate change. Costa Rica’s golden toads, which are actually a rather amazing bright orange, are thought to have been driven to extinction by warmer, drier weather, among other factors. Read More here