Category Archives: General

AGU Fall Meeting 2016: Polar bear numbers set to drop by one-third

by Liz Kalaugher

It’s highly likely that the world’s polar bear population, currently 26,000 strong, will decrease by a third within the next 35-40 years. That’s according to Kristin Laidre of the University of Washington, US, speaking at a press conference at the AGU Fall Meeting in San Francisco.

This finding supports the listing of polar bears as vulnerable by the International Union for Conservation of Nature (IUCN) Red List, which requires projection of species population numbers after three generations. Laidre and colleagues found that the average age of a female polar bear with dependent cubs is 11.5 years so 35 years corresponds to roughly three generations.

Polar bears use ice for traveling, hunting, mating and, in some cases, for their maternity dens. From 1979 to 2015, Arctic sea ice shrank at an average rate of 53,100 square km per year.

“When we look forward several decades, climate models predict such profound loss of Arctic sea ice that there’s little doubt this will negatively affect polar bears throughout much of their range, because of their critical dependence on sea ice,” said Laidre in a press release.

There are 19 sub-populations of polar bears around the Arctic Circle, living in 4 eco-regions. Some of these populations have never been studied whilst the number of animals in others have only been counted one or two times. Two or three populations have been studied on an annual basis, Laidre explained.

Some regions of the Arctic, such as the Chukchi Sea, are highly ecologically productive. Even though sea ice cover here has decreased, polar bears in the area are in better condition than they were 20 years ago; there could be a time lag before the full effects of the ice loss kick in. In other areas, like western Hudson Bay, polar bear survival and reproduction have declined as sea ice availability has dropped.

Laidre, Eric Regehr of the US Fish and Wildlife Service, and colleagues made their predictions by analysing sea ice extent from satellite observations and projecting this forward by 35 years. They evaluated three different relationships of polar bear numbers to sea ice – a decline proportional to the sea ice loss, and two changes based on previous data – before taking a median value across all three scenarios.

This revealed that the probability of a more than 30% reduction in polar bear numbers in the next 35-40 years is 0.71. The probability of a decrease in headcount of more than half was just 0.07.

Laidre and colleagues reported their findings in Biology Letters and The Cryosphere.

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Must vineyard managers choose between bees or worms?

By Liz Kalaugher

Given the option, would you help bees or worms? That’s the choice indicated by initial results presented at the European Geosciences Union General Assembly in Vienna this week by Sophie Kratschmer of the University of Natural Research and Life Sciences in Vienna.

As part of the VineDivers project, Kratschmer found that, contrary to expectations, solitary bees in vineyards in eastern Austria thrived when there was less management of the vegetation between rows of vines. This higher diversity was a surprise as disturbed ground tends to contain more flowers, a food source for bees. Since solitary bees nest underground, however, they may not appreciate tillage. The team did find a link between flower coverage and the number of wild bee species.

Earthworms, in contrast, were more diverse when there was ploughing of the earth between the vines, probably, according to Kratschmer, because it boosts the carbon content and makes the soil less compact. Plant diversity and biomass weren’t affected by the management intensity.

Both bees and worms are useful for viniculture, with bees providing pollination while earthworms help form soil and cycle nutrients.

Fortunately, when it comes to selecting management regimes for vineyards, the findings may not boil down to a difficult choice between bees and worms. Next Kratschmer will investigate a “medium” management intensity, intermediate between the low and high regimes in this study, which may work for both types of animal.

The wider VineDivers project will pool results from France, Romania and Spain and also use GIS analysis to find out the role of landscape diversity.

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Small modular nuclear – is small beautiful?

By Dave Elliott

A new report ‘The role for nuclear within a low carbon energy system’ from the Energy Technologies Institute, claims that the UK could have 50GW of nuclear power plants by 2050, including Small Modular Reactors (SMRs). Although it says, due to basic economies of construction and operational scale, ‘large reactors are best suited for baseload electricity production’, it notes that, based on using existing sites, there is ‘an upper capacity limit in England and Wales to 2050 from site availability of around 35 GWe’, and it could be less (e.g. if CCS plants need some of the sites). However, there could be more room for small nuclear plants (under 300kW) on new sites, at least 21GW and in theory up to 63GW.

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What a waste: an end of year lament

By Dave Elliott

In a post-Xmas pre-new year Scrooge-type austerity mood, I worry about the money we are wasting on energy. If you look at Sankey diagrams of energy flows from primary resources to final end use, you will see that for many countries around half the raw energy input is wasted in the conversion process, most of it being rejected into the atmosphere as heat, for example from steam-based fossil and nuclear generation systems.

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Are reticent climate researchers ‘failing humanity’?

By James Dacey in San Francisco.

Droves of delegates poured into the Moscone Center in San Francisco today for day one of AGU Fall 2015 – the largest Earth and space-science meeting in the world, with a whopping 24,000 delegates expected over the week. Having arrived from the UK on Saturday night, the jet-lag has kicked in with a vengeance today, so a couple of the conference coffees were definitely in order this morning. I’m just taking a break now after an interesting session about communicating climate change, and whether those researchers who don’t engage in the public debate are “failing humanity”.

The room was packed to the rafters, no doubt down to the profile of the speakers. First up was James Hansen, the former NASA scientist who has been outspoken in his criticism of the recent COP21 climate discussions, or at least the lack of concrete proposals to cut carbon emissions. Hansen restated his beef with the deal and argued that the only workable solution is for authorities to collect a carbon fee at source, such as charging domestic mines for the weight of carbon they sell. This, he believes, is the most effective way to make renewable energy and low-carbon options more viable. Not one to pull his punches, Hansen described US Energy Secretary Ernest Moniz’s idea that China will be able to curb much of its carbon missions using carbon capture and storage (CSS) technologies as “pure unadulterated bullshit”.

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Designing smarter cities

By James Dacey in Berkeley, US.

This weekend politicians at the COP21 summit in Paris signed a landmark legal agreement to keep global temperature rises at bay by curbing carbon emissions. The tricky next question of course is: how are we actually going to do this? In this short video, civil engineer Arpad Horvath of the University of California Berkeley explains that one of the aspects will be a fundamental rethink of our urban infrastructures. Horvath believes we need to move towards “smart cities” with smaller carbon footprints at all levels – from greener individual buildings, to more sustainable transport networks.

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EGU 2015: Desert energy – two birds from one stone

by Liz Kalaugher, Vienna

The world’s deserts are in many ways ideal for solar power; the sunshine is generally plentiful. But there’s at least one snag – dust. Installing mirrors for concentrating solar power or photovoltaic panels disturbs the desert surface and increases dust generation. Coatings of dust on photovoltaic panels can reduce their efficiency by 10-40%. As a result, operators often wash mirrors and panels regularly. This consumes a lot of water, perhaps as much as the equivalent of 100 mm of rain a year, in areas where it’s in short supply. And it’s left to flow down into the sand.

Sujith Ravi of Temple University, US, detailed in the Energy and Policy session at the European Geosciences Union meeting in Vienna this morning how this water could be more than enough to support the growth of desert plants like agave and aloe. And that agave could be turned into a biofuel, enabling the co-location of two types of renewable energy in one place. Since it’s a low-growing plant, the agave never shades out the panels – it even prefers to grow in the shade itself – and it’s a low-maintenance, high-yield crop that could even decrease the amount of dust formation in the first place.

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AGU Fall Meeting 2014: Lightning never strikes twice?

by Liz Kalaugher

Normally aircraft pilots avoid thunderstorms but in spring 2014 one particularly intrepid aviator spent five days deliberately seeking out and flying directly through storms, for hours at a time. The goal? To find out more about the X-rays and gamma-rays created by lightning.

As Pavlo Kochkin of the Eindhoven University of Technology in The Netherlands explained at the AGU Fall Meeting, in experiments “not easy to repeat” the plane, donated by Airbus, headed out from Toulouse, France, earlier this year, chock-full of sensors from the ILDAS In-flight lightning strike damage assessment system. On the 30th April it made for northern Italy where it descended into a storm from a height of 4 km and spent five hours battling turbulence and enduring 20 lightning strikes whilst taking measurements all the while.

The tests confirmed that lightning is bright in X-rays, according to Kochkin, and may have witnessed a long gamma-ray glow, as well as confirming that the radiation is a property of the lightning and not related to altitude.

Kochkin stressed that people don’t need to worry about terrestrial gamma-ray flashes when they get on a plane. But if the pilot of a research craft deliberately flying through a storm suffered a direct hit from a gamma-ray, they could receive a dose of radiation equivalent to a whole-body CT scan in just a few microseconds. “It’s not necessarily great but it’s not going to kill you,” said Kochkin. Gamma-rays could also affect the plane’s electronics but “probably the aircraft will do fine”.

As Joseph Dwyer, University of New Hampshire, Durham, US, detailed, there are several sources of X- and gamma-rays inside our atmosphere. Lightning near the ground, for example, produces X-rays whilst thunderstorms glow in the gamma-ray, sometimes continuously. “This is really strange,” said Dwyer. “It’s … like a black hole or supernova would do.” But in space, or in particle accelerators, the gamma-rays are produced inside a vacuum – in the atmosphere they form under pressure. Thunderstorms also produce terrestrial gamma-ray flashes, which last a few milliseconds and can be picked up by low Earth orbit spacecraft. Around 1000 such flashes a day are detected worldwide.

Understanding these high-energy emissions could give us clues to how thunderstorms and lightning work, Dwyer said – we still don’t know how lightning starts. Since terrestrial gamma-ray flashes form around the same time as lightning, as a result of the strong electric field inside the storm cloud that may also cause lightning, “you can think of them as a probe for looking at lightning initiation.” Although, terrestrial gamma-ray flashes are tricky to study too. “It’s hard to measure inside a storm,” Dwyer said, particularly since not many spacecraft are dedicated to the task.

But it’s worth the effort. Terrestrial gamma-ray flashes are the most energetic atmospheric phenomenon on planet Earth, as Themistoklis Chronis, University of Alabama, Huntsville, US, put it. Discovered in the early 1990s, the flashes were first linked to high altitude sprites before scientists realised their association with intra-cloud lightning.

The flashes are still able to surprise today. Despite theories that only stronger storms would create the flashes, Chronis has found that even weak clouds are up to the job. He and his colleagues looked at 24 storms that produced the flashes in locations along the US Gulf Coast, the Caribbean and Guam, where NEXRAD ground radar and atmospheric sounding data were also available to provide details on storm strength. Any type of storm can generate a terrestrial gamma-ray flash, the team concluded.

The flashes all originated from the highest part of the storm, between seven and nine miles high, Chronis found. This could be because gamma rays from flashes lower down encounter so much water vapour as they travel higher into the atmosphere that they become too weak to reach NASA’s Fermi Gamma-ray Burst Monitor high above them. So there may be more terrestrial gamma-ray flashes than we think.

Now Chronis would like to look at other parts of the world and to find out whether the flashes form during the growing or decaying phase of the storm. “Lightning still holds many secrets,” he said.

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Glaciologists and primary school children pass judgement on each other

At last week’s UK Antarctic Research Symposium in Bristol, scientists were visited by a group from the local Hareclive Primary School. The students, all members of the Room 13 art project based at the school, had judged the photo competition for delegates at the Symposium and the International Glaciological Society British Branch meeting held earlier in the week.

Prize photo by Mark Brandon

Prize photo by Mark Brandon

Joint first prize went to Mark Brandon of the Open University, UK, for his picture “A blue berg waiting to calve” at Jokulsarlen, Iceland, and to Jan De Rydt of the British Antarctic Survey for “Early morning sun halo whilst measuring the ice thickness of the glacier” at Pine Island, Antarctica.

Close runner-up was Martin O’Leary from Swansea University’s photo entitled “With around two thousand inhabitants, Tasiilaq is the largest settlement on the east coast of Greenland. The lack of light pollution, along with its location on the Arctic Circle, make it an ideal place to see the northern lights. Here, researchers take pictures and enjoy the display, after a successful field season”.

Photo of early morning sun halo whilst measuring the ice thickness of the glacier at Pine Island, Antarctica.

Prize photo by Jan De Rydt

In third place was Michael Meredith, also of the British Antarctic Survey, for “The view from the library. Sometimes it’s hard to concentrate on reading about Antarctic science, when the real thing is just out the window distracting you….” taken at Bransfield House on the Antarctic Peninsula.

Each of the 16 judges assigned marks out of ten to the 32 photos entered in the competition. In turn, delegates at the UK Antarctic Research Symposium and the International Glaciological Society British Branch meeting voted for their favourite artwork created by the children, using an arguably-less-rigorous one vote per delegate system. The standard was extremely high and the top three places went to pictures of penguins.

Art work by students from Room 13 Hareclive

Room 13 artwork

The school students were inspired to create the art following a pre-conference outreach visit from Bristol University ice researchers, led by Tamsin Edwards, in which they discussed life in the Arctic and Antarctic, re-created one of explorer Shackleton’s lifeboats in the playground, and tried on polar clothing.

“Thank you for taking us seriously,” said Lily from Hareclive Primary School at the end of her speech to delegates.

 

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EGU 2014: trapped melt ponds slow sea ice growth

by Liz Kalaugher

The larger the area of melt ponds on Arctic sea ice in May and early June, the smaller the sea ice coverage will be the following September, Daniella Flocco of Reading University, UK, reported at the European Geosciences Union (EGU) meeting in Vienna. In fact, the relationship is strong enough to make a skilful forecast of September sea ice cover, as Flocco, Reading colleague Daniel Feltham and other team members recently published in Nature Climate Change. It seems that melt ponds reduce the albedo of the ice surface, leading to greater heat absorption and more melting.

Now the team has moved onto the next problem, Flocco explained, namely trapping of melt ponds in the autumn as ice freezes above them. The phenomenon is invisible from the air but the latent heat released as the trapped melt pond freezes delays thickening of the ice layer into the ocean below.

Ignoring trapped melt ponds could cause models to overestimate ice growth in the autumn by around 265 cubic km [figure updated from sq. km, see comments below] over two months, roughly one-quarter of the total ice growth predicted, Flocco has calculated.

From satellite images the researchers estimate that around 20% of melt ponds become trapped as the freeze begins. Ultimately their studies will help them calculate this figure, Flocco and Feltham told environmentalresearchweb at the EGU meeting. Typically ponds remain trapped for a few months under thin lids of ice, becoming increasingly salty; the team plans to investigate this further.

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