When we see records being broken and unprecedented events such as this, the onus is on those who deny any connection to climate change to prove their case. Global warming has fundamentally altered the background conditions that give rise to all weather. In the strictest sense, all weather is now connected to climate change. Kevin Trenberth
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by Alex Morales, Bloomberg, May 12, 2014 Source: NASA/GSFC/SVS via Bloomberg
Although the Amundsen Sea region is only a fraction of the whole West Antarctic Ice Sheet, NASA estimates the region contains enough ice to raise global sea levels by 4 feet. Close
A glacial region of western Antarctica that’s already melting rapidly has passed “the point of no return,” according to the National Aeronautics and Space Administration.
“The collapse of this sector of West Antarctica appears to be unstoppable,” Eric Rignot, a glaciologist at NASA’s Jet Propulsion Laboratory and the University of California, Irvine said today in an e-mailed statement.
NASA estimates the glaciers, in the Amundsen Sea region, contain enough water to raise global sea levels by 4 feet (1.2 meters). United Nations researchers in September said sea levels have risen by 19 centimeters (7.5 inches) since the Industrial Revolution, and may rise an additional 26 centimeters to 98 centimeters by 2100.
“This sector will be a major contributor to sea level rise in the decades and centuries to come,” Rignot said in the statement. “A conservative estimate is it could take several centuries for all of the ice to flow into the sea.”
Rignot is lead author of a study that has been accepted for publication in the journal Geophysical Research Letters, NASA said. The team used radar observations from the two European Earth Remote Sensing satellites, ERS-1 and ERS-2, to track the movement of the “grounding lines,” the place where the floating portion of glacier meets land.
Floating Ice
They determined that the glaciers have become so thin that they are now floating in areas where they used to be grounded. As the grounding lines retreat inland, there’s more space below the ice for sea water, which accelerates melting. The researchers also found the masses of ice are flowing faster toward the sea, causing further thinning.
Scientists have homed in on the West Antarctic Ice Sheet because the level of melting detected there is greater than the far bigger and more stable Eastern portion of the continent.
Antarctica’s ice sheets hold enough water to raise sea levels by 187 feet, according to UN estimates, though that’s not likely for thousands of years.
Fire and climate change: don't expect a smooth ride
by Roger Jones, Victoria University, The Conversation, October 22, 2013 It really is time to talk about whether climate change is responsible for bushfires. AAP Image/Dan Himbrechts. With fires still burning across New South Wales, it’s time to have a look at the role climate change might have played. Are the conditions we’re seeing natural variation, or part of a long term trend? In fact, it doesn’t have to be one or the other.
Has bushfire risk increased due to climate change?
In research I did with colleagues earlier this year we looked at the Fire Danger Index calculated by the Bureau of Meteorology, and compared how it changed compared to temperature over time in Victoria. South-east Australia saw a temperature change of about 0.8 C when we compared temperatures before 1996 and after 1997. We know that it got drier after 1997, too. We then compared this data to the Forest Fire Danger Index, to see if it showed the same pattern. We analysed fire data from nine stations in Victoria and did a non-linear analysis. We found that fire danger in Victoria increased by over a third after 1996, compared to 1972-1996. The current level of fire danger is equivalent to the worst case projected for 2050, from an earlier analysis for the Climate Institute. While it’s impossible to say categorically that the situation is the same in NSW, we know that these changes are generally applicable across south-east Australia. So it’s likely to be a similar case: fire and climate change are linked.
What is “non-linear” change?
Climate science has been playing with a paradigm that long-term changes are gradual, and that short-term changes are simply natural climate variability. But there’s another hypothesis that climate change and climate variability actually combine. When you analyse long historical time series of temperature, plus climate change from modelled data, it actually goes up like a staircase. The “El Niño of the century” we saw in 1997-98 was one of these steps in the staircase. It’s physically impossible for climate change to be entirely gradual, and for natural variability to act independently of that. That’s like saying that some of the heat in the atmosphere is climate change heat, and some is variability heat, and that they behave differently. This also relates to the so-called hiatus. This hiatus is normal, and what we’d expect from a climate that evolves in a non-linear manner. The models do predict these steps, even if some people claim they don’t. Model data shows periods up to 20 years when there is little or no increase in warming.
What’s happened to temperature and rainfall in south east Australia?
Temperature can also be analysed through step changes. Before and after 1996, maximum temperatures went up 0.8 C. We can actually date the change to October 1996, when the El Niño started. Minimum temperatures have changed in a couple of periods. The first is the late 1960s to early 1970s, then again in 1996-1997. In fact, global temperatures went up in that period too, by about 0.3 C at the same time. Rainfall decreased in south-east Australia, and this decrease continued until 2009-2010. Then we got a massive negative Indian Ocean Dipole and La Niña, resulting in record rainfall and flooding. In southern Victoria it’s been quite moist since, but north of the Great Dividing Range, it’s dried out very quickly. These changes in rainfall and temperature are interrelated. It’s a combination of climate change and climate variability. The warming component, which is non-linear, is climate change.
What about the weather?
We can only blame weather conditions on climate change if they are part of a statistically significant pattern. If we see anomalously high temperatures - knowing that there is an anthropogenic component to temperature increases - then there’s definitely an anthropogenic warming component in that. Because the damages tend to be non-linear as well, it means the risk is magnified. So, the anthropogenic component of the temperature increase magnifies the impacts or the severity of the impacts.
Why are we so reluctant to talk about climate change?
This isn’t my line, but someone said on Monday, “there’s never a good time to talk about gun control.” Of course when people are hurting and in strife you’ve got to be sensitive to their needs. But after these events we have to seriously think about how we’re going to manage them in the future. We can’t consider severe fires as one-offs that happen every few decades. If they’re becoming a systemic part of our environment we have to consider this really seriously. There will be a financial cost and a human cost, and we will see it repeated, if we don’t plan ahead. Roger Jones is currently shortlisted and seeking funding from the Bushfire and Natural Hazards Cooperative Research Centre. This article was originally published at The Conversation.
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