14 March 2016, The Guardian, February breaks global temperature records by ‘shocking’ amount Warnings of climate emergency after surface temperatures 1.35C warmer than average temperature for the month. February smashed a century of global temperature records by “stunning” margin, according to data released by NASA. The unprecedented leap led scientists, usually wary of highlighting a single month’s temperature, to label the new record a “shocker” and warn of a “climate emergency”. The NASA data shows the average global surface temperature in February was 1.35C warmer than the average temperature for the month between 1951-1980, a far bigger margin than ever seen before. The previous record, set just one month earlier in January, was 1.15C above the long-term average for that month. “Nasa dropped a bombshell of a climate report,” said Jeff Masters and Bob Henson, who analysed the data on the Weather Underground website. “February dispensed with the one-month-old record by a full 0.21C – an extraordinary margin to beat a monthly world temperature record by.” “This result is a true shocker, and yet another reminder of the incessant long-term rise in global temperature resulting from human-produced greenhouse gases,” said Masters and Henson. “We are now hurtling at a frightening pace toward the globally agreed maximum of 2C warming over pre-industrial levels.” Read More here
Category Archives: Ecosystem Stress
14 March 2016, The Conversation, Tipping point: how we predict when Antarctica’s melting ice sheets will flood the seas. Antarctica is already feeling the heat of climate change, with rapid melting and retreat of glaciers over recent decades. Ice mass loss from Antarctica and Greenland contributes about 20% to the current rate of global sea level rise. This ice loss is projected to increase over the coming century. A recent article on The Conversation raised the concept of “climate tipping points”: thresholds in the climate system that, once breached, lead to substantial and irreversible change. Such a climate tipping point may occur as a result of the increasingly rapid decline of the Antarctic ice sheets, leading to a rapid rise in sea levels. But what is this threshold? And when will we reach it? What does the tipping point look like? The Antarctic ice sheet is a large mass of ice, up to 4 km thick in some places, and is grounded on bedrock. Ice generally flows from the interior of the continent towards the margins, speeding up as it goes. Where the ice sheet meets the ocean, large sections of connected ice – ice shelves – begin to float. These eventually melt from the base or calve off as icebergs. The whole sheet is replenished by accumulating snowfall. Floating ice shelves act like a cork in a wine bottle, slowing down the ice sheet as it flows towards the oceans. If ice shelves are removed from the system, the ice sheet will rapidly accelerate towards the ocean, bringing about further ice mass loss. A tipping point occurs if too much of the ice shelf is lost. In some glaciers, this may spark irreversible retreat. Read More here
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