Fire amid the ice kindles global and local worries

The Anaktuvuk River fire burning in August 2007 on the North Slope of the Brooks Range in Alaska. University of Florida ecologist Michelle Mack and a team of scientists including fellow UF ecologist Ted Schuur found the fire released a significant amount of soil-bound carbon into the atmosphere. Credit: Alaska Fire Service

In 2007, the largest Arctic tundra wildfire on record released around 2.1 million tonnes of carbon to the atmosphere, adding to the levels of greenhouse gas CO2. That’s close to how much carbon tundra plant growth across the whole Arctic absorbs in one year, noted Michelle Mack at the University of Florida. With human-caused, or anthropogenic, climate change seemingly causing more fires, further CO2 release may contribute to more warming. Other consequences will also have a big local impact, Mack told Simple Climate. “Fire on this landscape will change many things, and that’s frightening for me because I do think that the increasing fires are driven by anthropogenic climate change,” she said. “That people emitting carbon from cities, factories and automobiles very far to the south are influencing this wilderness area where people still practise subsistence livelihood is disturbing to me.”

For about a decade, Mack has been a regular at the Toolik Field Station on the North Slope of the Brooks Range of mountains in far northern Alaska. After the fire started in July 2007 at Anaktuvuk River, a plume of smoke could be seen drifting through the air from the Toolik Field Station 15 miles to the southeast. “When it started it was characteristic of these tundra fires – very small – just a couple of hectares from a lightning strike,” Mack said. “Normally a fire like that would just go out and there would just be a little blackened spot. It wasn’t until August that the weather conditions were such that the fire blew up and burned a really large area. At that time you could see it from space. People in local villages like Anaktuvik Pass and other coastal villages were getting smoked out. People were miserable.”

Aerosols paint clearer warming slowdown picture

Light from a LIDAR instrument forms a beam in the sky over Boulder, Colo.. NOAA researchers and colleagues used LIDAR data to better understand recent changes in the amounts of tiny particles high in Earth's atmosphere.Credit: CIRES/NOAA

Increased amounts of tiny, airborne solid and liquid particles between 10 and 50 km above the Earth’s surface have slowed recent global warming, US scientists said Thursday. Such mixtures of particles in air, called aerosols, are already known to influence climate, including by reflecting energy from the sun back out into space. Now, Ellsworth Dutton and his colleagues from the US National Oceanic and Atmospheric Administration (NOAA) have identified previously overlooked aerosols, he told Simple Climate. “Additional aerosols that had not been previously known contributed to the planet being slightly cooler than it would have been without those aerosols over the past about a decade,” he said.

From 2002-2009, average global temperatures decreased – although, due to the short length of this period, this trend fails the key scientific test of “statistical significance”. This is despite increased amounts of the greenhouse gas CO2 being emitted by humans burning fossil fuels, which basic climate science predicts should warm the planet. Though Dutton and his colleagues were not seeking to resolve this contradiction, they were interested in how the composition of Earth’s atmosphere varies over periods of months to years. “Several sets of measurements were indicating some small but consistent changes that had not yet been analysed and evaluated,” Dutton said. “Then several of us got our information together to see what it might be telling us.”

Warming puts species at one in ten extinction risk by 2100

While Ilya Maclean and Robert Wilson found that measurements backed up predictions of climate change's impact on plants and animals, there were few studies in the tropics. Those that were investigated Mexican trees, like those shown here. Credit: Arturo Avila/Flickr

Climate change’s recent impact on Earth’s life has backed up previous assessments calling it “one of the major threats to global biodiversity”. Ilya Maclean and Robert Wilson at the University of Exeter, UK, compared predictions of warming’s effects on species since 2005 and actual measurements made in that time. Both predictions and observations gave an average extinction risk across all species by 2100 close to one in ten. “I was dismayed by the magnitude of potential extinctions that could occur, but was also relieved that we were able to show that scientific predictions were, on the whole, accurate,” Maclean told Simple Climate.

Individual studies on climate’s effects on species inevitably give a limited picture as they typically only focus on a few plants or animals at one time. Similarly, scientists’ predictions of the likely impacts of climate change are often met with scepticism. Maclean and Wilson therefore sought to bring prediction and measurements across different species together to address both issues. They gathered together data from 74 studies published since 2005, comparing their findings against well-established methods of judging extinction threats. 42 of these were predicting extinctions, movements of and changes in species’ populations, while 32 had recorded details of the actual responses to recent changes.

Chinese pollution postpones temperature rises

Sulphur emissions, which contribute to acid rain that can damage soil, plants and trees like these, have also slowed temperature rise between 1998 and 2008 from the more rapid warming seen between the mid-70s and mid-90s. Credit: Wikimedia Commons

The full climate impact of China’s massive industrialisation between 1998 and 2008 has yet to be felt, thanks to its reliance on coal, US and Finland-based researchers said this week. Using this fuel for energy generation did release large volumes of the greenhouse gas CO2 that will warm the planet in the long term. However, it also emitted pollutants derived from the element sulphur that oppose this warming effect in the short term, explained Boston University’s Robert Kaufmann. “That let natural variations in that decade really predominate,” Kaufmann told Simple Climate.

These findings help answer a long-standing climate question, which stumped Kaufmann when he was speaking about global warming to the public in New Jersey in 2008. “A member of the audience said that he had heard that global temperatures hadn’t risen for about 10 years,” the researcher explained. “He asked me why not, and I must admit that I was at a loss to explain it.” Climate scientists have conceded that there has technically been no warming in this time, even though the US National Oceanographic and Atmospheric Administration (NOAA) said 2005 was then the warmest year on record. Kaufmann found that in fact there hadn’t yet been any satisfactory explanation why this had happened, partly due to the tools used by climate scientists. Most “general circulation” models (GCMs) used to simulate processes in the atmosphere and on the Earth calculate climate patterns from the laws of physics. While these are good at modelling changes in the long term, they are much less accurate over periods of just a few years, Kaufmann said.

Sea-level rise is the fastest in 2,000 years

The Outer Banks area of North Carolina, near where University of Pennsylvania’s Benjamin Horton and colleagues did their research. Although the damage here was done by erosion during a storm, it shows how vulnerable coastal locations are. Credit: University of Pennsylvania

The US Atlantic coast is now experiencing sea-level rises that are faster than at any time in the past two millennia, microfossils preserved under coastal salt marshes have shown. Both sea-level and temperature changes had been “subtle” for most of that period, University of Pennsylvania’s Benjamin Horton said, but accelerated from the late 19th century. “The research shows a consistent link between global mean surface temperature and changes in sea-level for the past millennium – that is a big step forward in our understanding,” Horton told Simple Climate.

Although modern direct measurements have shown that sea-level rise has been speeding up in recent years, scientists needed more information to fully understand how it’s linked to climate. To add to the recent records, Horton, together with Yale University’s Andrew Kemp studied two North Carolina salt marsh sites to reconstruct past sea-level. “In regions where sea-level is rising, salt marshes build upward by accumulating sediment to maintain their position,” Horton explained. “The accumulated piles of sediment are archives of relative sea-level changes.”

Kemp, Horton and their colleagues therefore drilled narrow columns of sediment from the marshes to access archives covering the last 2,100 years. However, the position of the layers of sediment alone did not provide an accurate enough measure of sea-level, as the marsh beds do not lay at exactly the same height as the sea. So, to get a high-resolution sea-level reconstruction they were able to use their knowledge of micro-organisms called foraminifera. The scientists had previously calculated a “transfer function” relationship describing how many foraminifera live in the modern salt marsh at a particular height above sea-level. “In samples from each core we counted preserved foraminifera and used the transfer function to estimate how high above sea-level each sample formed,” Horton explained.