7 March 2016, Climate News Network, Climate query as US tornado risk rises. Scientists say the climate behaves too capriciously for them to know for sure whether global warming caused by burning fossil fuels is to blame for a growing tornado threat. Tornadoes in the US are getting worse, with the numbers in any one outbreak and the hazard of ever more frequent outbreaks both on the increase. And although climate change driven by global warming from human causes is under suspicion, nobody really knows for sure whether that is driving the pattern of change. But change is certainly happening. New research published in Nature Communications has examined the pattern of outbreaks and found that the average number of tornadoes in any one outbreak has increased since 1954, and the chance of extreme – and therefore extremely destructive – outbreaks has also increased. An outbreak is a large-scale weather event that can last for days, span huge regions and spawn multiple tornadoes. Continental America is used to these outbreaks, which is why a band of territory that spans central Texas, Illinois and Indiana, and embraces parts of Oklahoma, Kansas, Nebraska, Colorado and South Dakota, is known as Tornado Alley. Read More here
Category Archives: Impacts Observed & Projected
6 March 2016, Climate News Network, Risk level rises for North American forests. The speed at which the climate is changing is outstripping forests’ ability to adapt to drier, hotter conditions across vast swathes of the US and Canada. Drought and climate change are now threatening almost all the forests of the continental US, according to new research. Scientists from 14 laboratories and institutions warn in the journal Global Change Biology that climate is changing faster than tree populations can adapt. Existing forests, effectively and literally rooted to the spot, are experiencing conditions hotter and less reliably rainy than those in which they had evolved. “Over the last two decades, warming temperatures and variable precipitation have increased the severity of forest droughts across much of the continental United States,” says James Clark, professor of global environmental change at Duke University, North Carolina. He and colleagues synthesised hundreds of studies to arrive at a snapshot of changing conditions and a prediction of troubles ahead. Ominous predictions Other research has already delivered ominous predictions for the forests of the US southwest, but the scientists warn that other, normally leafier parts of the continent face increasing stress. Dieback, bark beetle infestation and wildfire risk may no longer be confined to the western uplands. “While eastern forests have not experienced the types of changes seen in western forests in recent decades, they too are vulnerable to drought and could experience significant changes with increased severity, frequency, or duration in drought,” the authors say. Professor Clark puts it more bluntly: “Our analysis shows virtually all US forests are now experiencing change and are vulnerable to future declines. Given the uncertainty in our understanding of how forest species and stands adapt to rapid change, it’s going to be difficult to anticipate the type of forests that will be here in 20 to 40 years.” Read More here
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
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