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AAAS Meeting: February 2009 Archives

Sea level rise flies high

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Last year Stefan Rahmstorf of the University of Potsdam, Germany, wrote a paper over the weekend. Later the simple relationship he developed between sea-level rise and temperature change appeared in Science. This year he has surpassed himself by doing the calculations for his talk at the AAAS Meeting on the plane on the way over. While they still need checking, the sums appear to indicate that sea level rise will be substantially higher than predicted in the IPCC fourth assessment report.

"What surprised me was that even for low emissions scenarios such as B1 the best estimate for sea level rise is one metre by 2100," said Rahmstorf. "Sea level rise may well exceed one metre by 2100 if emissions continue unabated."

For the worst case scenario, the new calculation predicts sea level rise of 1.80 metres by 2100.

Rahmstorf developed the latest version of his semi-empirical equation after Martin Vermeer suggested he add a fast response term; the pair have used the relationship to predict sea level rise under the different IPCC emissions scenarios. Their paper is currently in preparation but Rahmstorf says the calculation "seems to work quite well".

"These statistical approaches are a warning for us to be cautious on what sea-level rise might be," said John Church of CSIRO, Australia. "We do need to account for what these extremes might be in our planning. We don't know enough about ice sheet physics to put an upper bound on the amount of rise and the rate of rise."

Rahmstorf agreed that the physics of the ice sheets is important. "The empirical relationship might change over time, the physics won't," he said. "Physical modelling is preferable but we have to admit that we are not there yet and we don't understand the physics well enough."

Keeping the IPCC on track

"You all kept saying something wrong," was Stephen Schneider of Stanford University's verdict on the sea level rise session at the AAAS Annual Meeting. "That the IPCC underpredicted sea level."

Schneider was involved in working group II of the IPCC fourth assessment report, which said it had medium confidence there was a risk of metres of sea level rise in several centuries. That's in contrast to working group I, which predicted 18-59 cm of sea level rise by 2100 and did not include contributions from ice sheet dynamics because of the uncertainties in the science.

According to Schneider, the disparity arose because the two working groups had different philosophies. While working group I had a "fear of a false positive" and did not want to cry wolf on sea level rise, working group II was scared of a false negative and wanted to stress the seriousness of the situation.

It's vital that the working groups interact in advance of the fifth assessment report to ensure they are making the same assumptions about science and what science means, he said. That should avoid a repeat of the fourth assessment report where "a train-wreck was avoided at the last minute".

 

Lawyer versus climate scientist

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Yesterday the AAAS Meeting saw the re-enactment of a scene John Grisham would be proud of. Ken Alex of the State of California Attorney General Office cross-examined climate scientist Myles Allen of Oxford University, UK, in a mock trial to try and discredit Allen's work. The aim was to show what might happen if someone decided to sue a coal company or power station for harm caused by climate change.

Allen was on the stand because he has researched the attribution of phenomena such as the floods that hit Oxford in 2000 to climate change. In that case he and colleagues used a twin ensemble approach to show that climate change had doubled the risk of flooding.

"Climate science has never really been subjected to the kind of scrutiny that it would be if it ever came to court," said Allen. "I'm not even pretending [my research] is trial-ready at this stage."

While many scientists say its naïve to blame climate change for an individual weather event, Allen reckons that's like a banker saying that it's naïve to blame poor risk management for a catastrophic loss. "It's just plain wrong," he said. "If you do something that increases the risk of an event you can be blamed for it occurring."

The experience provided an insight into how the uncertainty levels inherent to climate science could appear to a jury. Alex explained how he'd question all the assumptions used in the climate models Allen employed in his research and try to attack them as a house of cards.

"What does this mean for scientists?" asked Alex. "Your distaste for lawyers will increase. Your efforts are subject to attack and distortion."

  • If you'd like to donate time from your personal computer to Allen's research, which uses distributed computing, head to http://attribution.cpdn.org.

 

 

 

Fluctuating temperatures affect malaria transmission

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Climate change is already bringing malaria to altitudes that were previously too cold for the mosquitoes that transmit the disease to survive long enough to pass it on. Crucially, in such areas people haven't built up natural immunity. Now it seems that fluctuations in temperature during the day, not just the average temperature, are also important.

Malaria transmission is a fairly complex process and many of the parameters are temperature sensitive, explained Matthew Thomas of Pennsylvania State University at the AAAS Meeting. A female Anopheles mosquito must bite an infected human to pick up the malaria parasite, which takes about ten to 14 days to incubate inside the mosquito, depending on temperature. It turns out that the incubation period is also affected by temperature fluctuations, perhaps by as much as 50-100%. This is crucial because if the mosquito dies before the parasites have incubated, it won't be able to pass on the disease even though it is infected.

"At the moment we predict using daily averages, but for malaria daily fluctuations matter," said Thomas. "Daily temperature fluctuations around a warmer average lengthen the incubation time; temperature fluctuations around a cooler average shorten it. We may be overestimating the risk in warm areas and underestimating it in cooler areas."

Temperature fluctuations also affect the speed of development of mosquito larvae, which need about 10-20 days to mature in water. To increase the chances of disease transmission it takes a certain number of mosquitoes - and this number must build up rapidly. As for incubation of the parasite, temperature fluctuations around higher temperatures slow the process and variations around lower temperatures speed it up, which could mean that scientists are underestimating the risk of disease transmission in cooler locations.

Climate change could well affect both daily average temperatures and the extent of the fluctuations. To complicate the picture further, malaria parasites are highly sensitive to temperature - particularly in the first 12 hours after they have infected the mosquito - and will die if they get too hot. Although most mosquitoes feed at night some do feed earlier in the day, which could remove malaria from some areas as climate change progresses.

Thomas says it's possible that, while the areas where malaria occurs shift as a result of climate change, there may be no net change overall. But the introduction of malaria into new areas will have serious consequences as the local population will not have built up natural immunity.

Is there "weird life" on Earth?

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While biodiversity is generally in the news because it is decreasing, if Paul Davies' quest to find "weird life" on Earth is successful, biodiversity could get a major boost. Davies, a cosmologist at Arizona State University, reckons that one way to check whether life could begin on other Earth-like planets is to determine if life started on Earth itself more than once.

"How do we know life didn't form here several times over?" he asked. "There's been very little thought as to what weird life on Earth might be like." And because scientists don't know anything about the lifeforms in this potential "shadow biosphere", it's hard to know where to look or how to detect them.

It's possible that microbes have developed with an alternative biochemistry, perhaps boron-based or using arsenic in place of phosphorus. But techniques for studying microbes tend to be very specific, so a researcher will generally find only what he or she is looking for. That means lifeforms from a"second genesis" could be undiscovered, either co-existing alongside conventional organisms or in new habitats.

"Weird life could be right under our noses or even in our noses," said Davies. "The hard part is knowing where to look." He reckons it could be worth paying close attention to microbes that are hard to characterize, deep ocean vents, lakes heavily contaminated with arsenic in California, and the desert varnish found in Arizona - a coating that baffled Charles Darwin and whose organic nature is still a mystery.

 

 

 

IPCC fourth assessment was too optimistic

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Since 2000, emissions from fossil fuel combustion have grown three times faster than in the mid-late 1990s. "Emissions are now outside the whole envelope of possibilities considered in the IPCC's fourth assessment report," said Chris Field of Stanford University and the Carnegie Institution for Science at a press briefing at the AAAS Annual Meeting. "The emissions trajectory used was too optimistic - we didn't think broadly enough."

To make matters worse, nobody's certain how effective the carbon sink currently provided by the oceans and land will be in the future, or even whether they will become a source. For example, in greenhouse studies, additional carbon dioxide increased plant growth by around 50% but Field says that, while this was considered an immature topic in the fourth assessment report, we now know that nutrient and other restrictions will stop that from happening in the field.

"Every new piece of information I see makes the scary side look scarier," added Field. "The situation is more complicated than we thought in AR4 - we have higher emissions and a less friendly natural system. We will have to avoid more carbon emissions than we thought - either start earlier or make more aggressive cuts."

A number of delegates were concerned that the lengthy IPCC report process could delay policymakers from taking action. "The challenge is that we can either be fast or we can be good," said Field, who is one of the leaders of the fifth IPCC assessment report, due for publication in 2013/14. With an eye to more "policy-relevant timescales", the IPCC will release between two and five special reports that take 12-18 months to produce before this. The first will be on renewable energy; scientists will decide at a meeting in Turkey next month whether to go ahead with a special report on climate extremes and adaptation to those extremes.

In line with the general mood at the conference, Field was optimistic about the new US administration and climate change mitigation. "There is lots of talk that we may see the US re-emerge as a leader on this important issue," he said. "I hope it does."
 

Moving from fourth to fifth

So how will the fifth assessment compare science-wise? During  AR4, eighteen research groups contributed mainly physical climate models with century timescales, detailed Ronald Stouffer of the Geophysical Fluid Dynamics Laboratory in Princeton, US. In contrast AR5 will see 25 groups contribute a mix of earth system models and global climate models with decadal to century timescales. Earth system models "close the carbon cycle" by looking at the effect of biological changes on climate; typically they contain details of atmospheric chemistry, ocean ecology and biogeochemistry, plant ecology and land use.

According to Stouffer, some of the modelling challenges that remained at the end of the fourth assessment report include clouds and aerosols, oceanic heat uptake, regional climate information, land ice modelling, and the carbon cycle. As well as tackling some of these challenges, the fifth assessment will also include emerging frontiers of research such as decadal prediction, and the feedback between climate and air pollution.

 

Drs Doom and Gloom change their tune

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Nancy Knowlton of the Smithsonian National Museum of Natural History and her husband Jeremy Jackson of Scripps Institution of Oceanography say they've become known as Drs Doom and Gloom on the conference circuit. Given that they both research coral reefs it's no surprise that good news is a bit thin on the ground, but now they've decided to try and promote some of the few success stories through a session Knowlton's chairing at the AAAS Meeting. "We really just refused to write ever more refined obituaries for nature," said Knowlton. "There is actually good news there."

For example, the Northern Line islands in the Pacific fall into a marine protected area. Pollution is virtually non-existent, there is a large shark population and the coral is relatively healthy. Even though coral bleaching has occurred several times as a result of rising ocean temperatures, around half the reef is currently covered with living coral, which is about double the average figure. It seems that being in a protected area, and the consequent shielding from pollution and overfishing, increases an ecosystem's resilience to climate change.

 "Effective local protection can buy time for corals," said Jackson. "Protection from overfishing really makes an enormous difference. Marine protected areas clearly work but they only work if they are large and truly protect against fishing."

Andrew Rosenberg of the
University of New Hampshire, meanwhile, spoke about the recovery of fish stocks off New England following the imposition of catch limits. "In the mid-90s the haddock fisheries nearly collapsed," he explained. "A limit of 400 pounds a day was put on in 1994 and they could barely catch it." Today trip limits have been removed and the haddock stock has recovered. Rosenberg also sang the praises of marine protected areas; he says that catch limits and protected areas are more effective in combination.

 

 

Gore calls for scientists to take up politics

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Al Gore last night called for climate scientists' help: "if I could I would motivate you to leave this city after this meeting and get involved in politics. We need you." According to the Nobel prize winner, scientists can no longer in good conscience accept "this division between the work you do and the civilization in which you live." He did, however, recommend that researchers keep their day jobs.

Speaking to a packed conference room, Gore detailed how he believes the US is facing three crises - a credit crisis, a world security crisis brought on at least in part by the need for oil, and a climate crisis. "All three crises have a common thread," he said, "our absurd overdependence on fossil-based fuels." And Gore reckons the solution for all three is a one-off investment to shift to an infrastructure based on "fuels that are free" such as wind, solar and geothermal. This should help boost the economy and create jobs, reduce dependence on oil supplies from abroad, and cut carbon emissions.

"This is a moment in our history that is completely without precedent," said Gore. "There is an old African proverb, if you want to go quickly go alone, if you want to go far go together. We have to go far quickly."

 

 

Penguins "vote with their feet"

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It looks like changing ocean conditions are leading Magellanic penguins from the Punta Tombo reserve in Argentina to move their colonies north, onto privately-owned land where they are no longer protected from predators.

"I think of penguins as our ocean sentinels - they tell us a lot about what's happening in the ocean and also on land," said Dee Boersma of the University of Washington, US.

 "Penguins are telling us there are already problems. The good news is they're voting with their feet and trying to colonize new places."

It seems the penguins are following the hake, squid and anchovies they prey on, which have shifted north due to changing ocean conditions. For once, overfishing doesn't appear to be a factor - the area is one of the few that hasn't been overexploited, although this may change in the future.

According to Boersma the penguins are typically having to swim 25 miles further from their nest to find food for their partner left behind incubating the egg. "It's like if you buy a house in the suburbs of Chicago and your job gets shifted to Des Moines," said Boersma. "The cost of living for the penguin is rising."

Boersma says that the penguins are racing their own physiology - one member of a breeding pair sits on the eggs fasting while the other heads out to find food, swimming back with fish for its partner in its stomach, which it inevitably starts to digest en route.

The penguins are also starting to breed three days later on average, because they are finding it harder to find food in their winter feeding grounds to the north before they return south to breed. If a female Magellanic penguin does not find enough food to be in good breeding condition, she will skip a year of reproduction. At Punta Tomba penguin numbers have declined by more than 20% since 1997, from 300,000 breeding pairs to just 200,000.

 What's more, twelve of the currently known 19 penguin species are in trouble. "The real elephant in the room is human numbers and consumption," said Boersma. "It took 100,000 generations for Earth to reach one billion people, now we can add a billion in three generations. We have to have control over our consumption if we are to have penguins."

 

     

 

 

 

AAAS: From Darwin to Obama

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This year's American Association for the Advancement of Science (AAAS) Annual Meeting has the all-encompassing subtitle "Our planet and its life: origins and futures". As AAAS president James McCarthy put it, "it's been fun but my advice to any future AAAS president is to pick a theme with just one word".

McCarthy explained how scientists from different disciplines have been joining together to link up our understanding of the Earth's systems. In the past it was rare for physical oceanographers to communicate with biological oceanographers, for example, but nowadays there's much more insight into how biology influences climate.

Appropriately enough for a theme that encompasses the origins of life, the conference kicks off on the 200th anniversary of the birthday of Charles Darwin, founder of the theory of evolution. The mid- to late- 1800s, when Darwin's ideas appeared, also saw the development of new technologies such as the internal combustion engine and oil extraction and refinement.

"We were beginning, although no-one knew it at the time, technologies that today we look to as having significantly altered the environment of this planet, especially with regards to climate change," said McCarthy. "We have choices to make and the choices we make today will have a profound effect a few decades out. Organisms that have co-evolved with other species to a particular climate regime now have to adapt."

Today is also the birthday of US president Abraham Lincoln, which prompted a lot of questions for McCarthy at this morning's press briefing about the latest US government administration. "Obama has recruited scientific talent of extraordinary calibre," he said. "In energy and environment it would be hard to find better people. I am very optimistic." And McCarthy remains optimistic despite the fact that there will be "distractions, such as the economy". He reckons that Obama is "not simply saying let's invest in climate change research, he's saying let's look at the broader picture, the employment problem - how renewable energy can create new jobs and improve energy security".

 

 

Coming soon: AAAS Meeting!

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Environmentalresearchweb will be blogging live from the American Association for the Advancement of Science (AAAS) Annual Meeting (February 12th - 16th), bringing you all the latest news and views on environmental science.

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