Tag Archives: Climate


Satellites to Monitor UN Forest Protection Goals

VTT.deforestation.homepageClimate change negotiators agreed Sunday to monitor deforestation and to pay developing countries for keeping carbon trapped in forests. To measure just how much forest those countries are conserving, the United Nations Collaborative Program on Reducing Emissions from Deforestation and Forest Degradation in Developing Countries (REDD+, to its friends) will rely on a complex system of satellite measurements and field checks. The agreement is a victory for advocates in the research and conservation communities. Yet they face a lot of work implementing the program.

Many countries and agencies already have experience conducting their own long-term monitoring, but the programs often differ in their goals and methods. That makes their data hard to compare. For example Brazil spent US $1.4 billion on a satellite system a decade ago for monitoring the Amazon, but some researchers accused it of being more of a drug-smuggling interdiction tool than a forestry tool. And the U.S. National Oceanic and Atmospheric Administration (NOAA ) has been monitoring wildfire-driven deforestation since the 1980s, but that is not suited to monitoring illegal logging because the two forms of deforestation occur on different timescales. Earlier this year, Nature published a commentary by researchers and satellite builders calling for a single international standard for forest-monitoring data.

A Finnish-led team has been working on a more technical forestry problem: how to combine the various bands of data satellites can collect. Optical data, such as that provided by the Landsat system, are common, but do not penetrate the clouds that often cover tropical forests. The team found that they could boost their ability to estimate forest cover and degradation by including radar data, they reported earlier this year in IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. The project, called ReCover, collected satellite data in multiple bands from forests at five study sites and compared satellite-based interpretations to measurements of forest cover and quality on the ground. Their first-pass analyses achieved from 75 to 91 percent accuracy in forest classification, depending on the method, but combining methods should help them improve.

First published on IEEE Spectrum’s Tech Talk blog: [html] [pdf]

New Agreement Casts Spotlight on Efforts to Inventory Black Carbon

Researchers are about to take a big step toward better understanding a tiny air pollutant. A U.N. expert panel earlier this month agreed on a technical road map that will guide the first multinational effort to create a standardized emissions inventory of black carbon, a kind of microscopic soot particle. Scientists say that black carbon emissions play an important but poorly understood role in both global climate change and air pollution.

“The increased emphasis on complete reporting across the countries … is clearly an important step forward,” says atmospheric scientist Chris Dore, chair of the U.N. task force, which helps implement the 1979 Geneva Convention on Long-range Transboundary Air Pollution. Fifty-one nations, including the United States and members of the European Union, abide by the convention.

The move reflects growing concern about black carbon particles, which are produced by burning an array of fuels, including oil, wood, crop residues, and even garbage. Health researchers consider airborne soot particles smaller than 2.5 micrometers a major health threat, causing lung disease and premature death. And climate scientists say that black carbon is a key player in global warming because it can absorb solar radiation and accelerate ice melting.

Efforts to calculate black carbon’s full impact, however, suffer from incomplete emissions data. A January study in the Journal of Geophysical Research: Atmospheres, for instance, concluded that existing climate models underestimate black carbon’s climate-changing contribution by up to a factor of three as a result of data gaps in key regions. Existing inventories, such as those created by measuring emissions from smokestacks and tailpipes, contain large uncertainties, says atmospheric physicist Philip Stier of the University of Oxford in the United Kingdom. In part, that’s because they are often designed to show only that a nation is complying with air pollution rules and don’t include soot sources such as forest and cooking fires, or particles that settle on roadways and are lofted into the air by passing cars. “Black carbon is a poorly defined substance,” Stier says. “It’s always measured in a slightly different way, [which] doesn’t always refer to the same material.”

The new road map—unveiled on 20 May after a meeting of the United Nations Economic Commission for Europe’s Task Force on Emission Inventories and Projections in Istanbul, Turkey—aims to put nations on the same page. The voluntary plan calls for nations to start measuring black carbon emissions from an array of sources, including transportation, the energy industry, and agriculture. Nations will add the data to annual emissions reports and dig into existing data to calculate past emissions going back to the year 2000. The plan also requests emissions projections out to 2050.

Dore expects a U.N. steering body to approve the plan later this year, and nations will begin reporting in 2015, although a few could start in 2014. Some nations may go beyond the guidelines to collect additional data, including measures of black carbon sources not covered by the road map. The voluntary guidelines could one day become mandatory, following a path taken by other pollutants covered by the convention.

The inclusion of black carbon emissions in the annual reports is “really important,” says aerosol scientist Catherine Liousse of the Midi-Pyrenees Observatory in Toulouse, France. It will encourage nations that now don’t measure such emissions to start and enable better comparisons of existing inventories by promoting standard methods.

Researchers, meanwhile, are working to develop better methods for getting a broader picture of black carbon in the atmosphere. One $3 million study sent a Gulfstream jet with air-sampling instruments on undulating flights—from 150 meters to 13,500 meters—in five study areas around the world over several years. Other researchers are mounting low-cost black carbon detectors on ultralight aircraft and drones. Their goal is to better understand the role black carbon is playing in different parts of the atmosphere: While climate researchers may care more about soot interactions with frozen water droplets, for instance, health researchers want to compare how different-sized particles affect the lungs.

First published by Science Magazine [html] [pdf]

Screen Shot 2013-05-27 at 11.46.29 AM

Lone pilot’s Arctic mission to map dark side of carbon

Screen Shot 2013-05-27 at 11.46.29 AMThe sky north of Ellesmere Island had just cleared when Matevz Lenarcic, flying alone in a Pipistrel Virus airplane at around 3,600m (10,000ft), got a call on his satellite phone. His friend following the weather on a computer in Slovenia had spotted heavy clouds and snow closing in on Lenarcic’s destination, an airfield near Resolute Bay, in the Canadian Arctic.

Lenarcic, a Slovenian pilot and adventurer, had departed Longyearbyen, Norway, early that morning. When he reached the North Pole, he tipped the ultralight plane’s wings over and circled the Pole in a whimsical, if brief, round-the-world flight. Two hours later, shivering despite the immersion suit he wore, Lenarcic faced a more serious decision: race the storm to Resolute Bay or divert to Eureka, a nearby weather station with no facilities for protecting his plane after landing.

On the passenger seat beside him, he carried precious cargo – an experimental Aethalometer, a device that measures black carbon, or soot, in the air. Black carbon is a common contaminant, found in emissions from diesel engines and burning farm fields. Researchers say it is the second largest human contribution to climate change after carbon dioxide.

Flying above the Arctic Ocean may seem an unlikely way to look for humanity’s footprints. But soot travels thousands of miles on winds, and the hundreds of cargo ships that ply the Arctic Ocean every year also inject it straight into the atmosphere. Soot has a stronger effect in the Arctic than in more temperate regions.

Clean Arctic sea ice can reflect as much as 90% of the sunlight that hits it. But a thin layer of soot makes the surface darker and less reflective. The Arctic has been losing sea ice since Nasa began tracking it in 1978, and it has been doing so much faster than climate models predict. Last year Arctic ice shrank by 18% compared to the previous record low of 2007, according to the official US monitoring organisation, the National Snow and Ice Data Center in Boulder, Colorado. Climate scientists have believed for some time that soot is accelerating Arctic sea ice melt.

Most soot monitoring is done from ground stations in populated areas and aerial data on polar soot are rare and scientifically valuable. “In the Arctic in particular the role of black carbon is potentially very, very important,” says atmospheric scientist Drew Shindell of Nasa’s Goddard Institute for Space Studies in New York, “What’s really important is understanding how the black carbon interacts with clouds in the Arctic.”

No-fuss approach

To address the data gap, Nasa launched a sensor-laden Gulfstream jet on a handful of soot-collecting missions. But these missions cost almost $500,000 a year. As a result, some researchers are now dabbling with aerosol-monitoring drones. Then there is Lenarcic’s no-fuss, experimental approach in a small private aircraft. “I would like to show how useful they are and that we could get huge benefits from them for just a fraction of the cost this kind of project normally requires,” he says.

The black, brick-sized Aethalometer by his side feeds on air from a tube outside the airplane. Incoming particles pass through a filter under the steady gaze of an optical beam, which measures the colour of the filter, revealing the size, colour and density of the captured particles. The analysis can even distinguish between particles from forest fires, diesel engines, wood stoves and cargo ships. By repeating the process around the world, Lenarcic hopes to collect a global overview of the story of soot.

The work lends scientific meaning to Lenarcic’s regular routine. He makes a living doing more mundane aerial surveys in Slovenia, punctuated with far-flung adventures in his plane. In 2011, he was planning a solo, round-the-world flight in pursuit of material for a photography book, when atmospheric scientist Grisa Mocnik asked him to test a prototype of the airborne Aethalometer. It was a good opportunity to show how small-time inventors and pilots can help to tackle a global problem.

On that flight too, in transit between the Cook Islands and New Zealand, a friend called to warn him of clouds on his route. There were no nearby airports. “Sometimes you have to go through because you cannot go back,” Lenarcic later recalled. The moist, tropical clouds tossed the Virus and frightened Lenarcic, but he collected the data, which Mocnik and colleagues at the Slovenian company Aerosol, which makes the instrument, are preparing for publication. However the itinerary lacked Arctic soot, so Lenarcic set his course north in April. This time, facing the prospect of icy clouds choking the engine’s air intake, Lenarcic pulled back the throttle on the cockpit floor and descended towards Eureka.

Two months before Lenarcic’s polar flight, an international team of scientists announced that most climate models underestimate black carbon’s impact on atmospheric warming by up to a factor of three. “We think [black carbon] is a really powerful warming agent on its own,” says Shindell, “But without really understanding what it does to clouds, it’s hard to draw a more definitive conclusion.” In warm temperatures, for example, black carbon particles can seed clouds, which reflect sunlight and may cool the atmosphere. But to understand how freezing clouds behave, researchers need fresh aerial data on soot and clouds.

Researchers studying Arctic climate change say that there is little manoeuvring room for mitigating human-provoked ice melting. But they say reducing black carbon emissions may be the best short-term bet. The Arctic is responding faster to climate change than are other regions on Earth. Black carbon acts over short timescales. It sinks quickly out of the atmosphere compared to greenhouse gases such as carbon dioxide, making it a good target for reducing atmospheric warming in the short term, according to a 2012 study by Shindell and colleagues.

Data gap

International organisations are already taking note. In February, Arctic environment ministers agreed to cooperate on estimating and eventually reducing emissions of short-lived pollutants including soot. The UN Economic Commission for Europe issued its first reporting guidelines for black carbon emissions at a mid-May meeting in Istanbul. Arctic residents say regulation cannot happen fast enough. Last month the international treaty organisation Arctic Athabaskan Council petitioned the Inter-American Commission on Human Rights for help regulating Canadian black carbon emissions.

But reporting, says Mocnik, is not as good as measurement. Reporting tends to be a calculation based on official estimates of what an economy is burning. Since people do not report home woodstove burning to tax authorities or economists, for example, those estimates are often too low to be useful. Researchers will need real-world data such as those Nasa and Lenarcic are collecting. And the most cost-effective way to do that is still up in the air.

Having slowed his descent to Eureka, Lenarcic still had to land with his data intact. The plane’s shadow slowed over the snow as Lenarcic circled the airfield and aligned the plane’s nose with the runway. He drew back the throttle just enough to establish a gentle descent and waited until crossing the runway threshold before he reached up to the cockpit roof, pulled the air brake lever and committed to the landing. The Virus’ wheels met the snow-drifted runway and rolled to a stop.

“This is not a very pleasant place to stay for a long time,” he told me from the shelter of the eight-man weather station the next day. Before landing the temperature had been -18C (-0.4F). He fretted about starting the Virus’ engine again. Such deep cold can sap the starter battery and the howling winds can press sharp ice crystals deep into the engine’s tubes and wires.

But he was able to upload the data to Mocnik, who hopes to persuade his peers in the atmospheric science community that such data are useful. They are accustomed to rare injections of higher-precision data from the occasional Nasa or German jet mission, he says. “We hope to prove … that one can do really sophisticated aerosol science on a scale which does not require this huge infrastructural investment,” says Mocnik. If he can make the Aethalometer simple and robust enough, even recreational paraglider pilots might one day provide scientists with aerosol profiles, he says.

Such a widespread, consistent dataset would allow researchers to compare how black carbon travels the globe, says Shindell. It would let climate modellers test their theories against real-world data to improve their accuracy. Then it will be up to policymakers to make the changes which could improve the actual forecast, says Mocnik.

“We believe we collected quite interesting information,” Lenarcic said after his polar flight. “I could see something in the air which might have been soot.” If low cost efforts such as his can help plug the black carbon data gap, perhaps the warnings of scientists and fine words of politicians will finally be translated into action.

First published by BBC Future [html] [pdf]

See also my previous news items on Lenarcic’s 2012 round-the-world flight for Science [html] and Popular Science [html]


Cave detective hunts for clues to past sea level

A yellow splash of light from Bogdan Onac’s headlamp bounces around the dripping orange walls of a cave like a frenetic firefly. At the other end of the beam, the University of South Florida paleoclimatologist explains that the walls of this cave, on the Mediterranean island of Majorca, have collected a bathtub ring of minerals as brackish water washes in and out. “Majorca is like a Gruyère,” Onac says, its underlying limestone filled with holes just like the cheese.

Unlike most coastal cave sites around the world, Majorca sits on a stable tectonic plate and so can serve as a fixed point from which to measure the rise and fall of the sea over time. its caves became encrusted with marine minerals over the course of half a million years. High water marks remain, like graffiti from a changing climate.

A surprise in these cave walls has put Onac at the center of a debate about past sea levels. encrustations dating back 81,000 years at several of his research sites sit about a meter above present-day sea level, suggesting that’s how much higher the seas were then. This contradicts estimates of past sea levels…

See the rest of this profile, these photos, and more in Science News Prime: [html] [pdf]