Arctic plants may not provide predicted carbon sequestration potential

Arctic plants may not provide predicted carbon sequestration potential

SOURCE: University of Stirling DATE: July 2, 2020 SNIP: The environmental benefits of taller, shrubbier tundra plants in the Arctic may be overstated, according to new research involving the University of Stirling. Current ecosystem and climate models suggest that, as the Arctic warms, tundra ecosystems are becoming more productive, with greater photosynthesis resulting in more carbon being removed, or sequestered, from the atmosphere. However, most models do not consider the transfer and fate of this carbon below-ground, and how this can interact with soil carbon through the activities of soil microorganisms. This is critically important because the vast majority of carbon in Arctic ecosystems is found in soil and ‘permafrost’ (permanently frozen soil or sediment) in the form of organic matter produced by the incomplete decay of dead plants, animals and soil organisms in cold conditions. The new research considered the impact of a shrubbier Arctic on soil carbon stocks and the overall carbon sequestration potential of these ecosystems. Significantly, it found that some tall shrub communities stimulate recycling of carbon in soils, releasing it back into the atmosphere as carbon dioxide – meaning that more productive shrubs might not always result in greater carbon sequestration. Professor Wookey said: “While previous studies suggest that a warmer, greener Arctic may increase the rate that carbon dioxide is removed from the atmosphere, our research identified an acceleration in the rate of loss of carbon from soils, back into the atmosphere. “This may more than offset carbon sequestration and would, unexpectedly, turn these ecosystems into a net source of carbon dioxide to the atmosphere. Significantly, current ecosystem and climate models do not...
Climate crisis: North pole ‘soon to be ice free in summer’, scientists say

Climate crisis: North pole ‘soon to be ice free in summer’, scientists say

SOURCE: The Independent DATE: April 20, 2020 SNIP: The Arctic Ocean will likely be ice-free during summers before 2050, researchers say. Amid rapid global warming – with average Arctic temperatures already 2C above what they were in the pre-industrial era – the extent of the sea ice is diminishing ever faster. As the climate crisis worsens, scientists say it is now only the efficacy of protection measures which will determine for how many more years our planet will continue to have a northern ice cap year round. A major new piece of research involving 21 leading institutes and using 40 different climate models has found that whatever action is taken, we are on course to see ice-free summers in the coming decades. The research is published in the journal Geophysical Research Letters. The scientists considered the future of Arctic sea-ice cover in scenarios with high future CO2 emissions and little climate protection – as expected, Arctic sea ice disappeared quickly in summer in these simulations. But the study also found the Arctic summer sea ice also disappears “occasionally” if CO2 emissions are rapidly reduced. Dirk Notz, who leads the sea-ice research group at University of Hamburg, said: “If we reduce global emissions rapidly and substantially, and thus keep global warming below 2C relative to preindustrial levels, Arctic sea ice will nevertheless likely disappear occasionally in summer even before 2050. This really surprised...
Scientists find far higher than expected rate of underwater glacial melting

Scientists find far higher than expected rate of underwater glacial melting

SOURCE: Phys.org DATE: January 29, 2020 SNIP: Tidewater glaciers, the massive rivers of ice that end in the ocean, may be melting underwater much faster than previously thought, according to a Rutgers co-authored study that used robotic kayaks. The findings, which challenge current frameworks for analyzing ocean-glacier interactions, have implications for the rest of the world’s tidewater glaciers, whose rapid retreat is contributing to sea-level rise. The study, published in the journal Geophysical Research Letters, surveyed the ocean in front of 20-mile-long LeConte Glacier in Alaska. The seaborne robots made it possible for the first time to analyze plumes of meltwater, the water released when snow or ice melts, where glaciers meet the ocean. It is a dangerous area for ships because of ice calving—when falling slabs of ice that break from glaciers crash into the water and spawn huge waves. “With the kayaks, we found a surprising signal of melting: Layers of concentrated meltwater intruding into the ocean that reveal the critical importance of a process typically neglected when modeling or estimating melt rates,” said lead author Rebecca Jackson, a physical oceanographer and assistant professor in the Department of Marine and Coastal Sciences in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick. Two kinds of underwater melting occur near glaciers. Where freshwater discharge drains at the base of a glacier (from upstream melt on the glacier’s surface), vigorous plumes result in discharge-driven melting. Away from these discharge outlets, the glacier melts directly into the ocean waters in a regime called ambient melting. The study follows one published last year in the journal Science that measured...
Dwindling Arctic Sea Ice May Affect Tropical Weather Patterns

Dwindling Arctic Sea Ice May Affect Tropical Weather Patterns

SOURCE: Inside Climate News DATE: January 27, 2020 SNIP: The rapid decline of Arctic sea ice during the last couple of decades has spurred climate scientists to study how that meltdown influences the rest of the planet, and a new study suggests that the effects may extend deep into the tropics. The study, published Monday in the journal Proceedings of the National Academy of Sciences, detected a pattern that links sea ice decline since the late 1990s with more frequent warm cycles in the Central Pacific Ocean. The surges of ocean heating in that region can disrupt the climate, affecting drought, flood and hurricane patterns around the world. Winds are the link between the melting ice and the tropics. The researchers posit that the Arctic Ocean has warmed up so much in the last 20 years that warm, late-summer sea surface air forms powerful convective towers, rising to the stratosphere. When the air falls back toward the equatorial Pacific, it intensifies prevailing east-to-west trade winds that push warm water toward Asia and Oceana, giving birth to a Central Pacific El Niño, a geographically specific variation of the well-documented Pacific warming and cooling cycle that is a key driver of the global climate. The study found a secondary effect. The atmospheric roller coaster rebounds back north, and may weaken a weather pattern near Alaska that steers Pacific storms toward the West Coast. The new research shows that El Niños forming in the Central Pacific started becoming more frequent at the same time that Arctic sea ice extent started its precipitous decline. Jennifer Francis, a climate researcher with the Woods Hole...
The Arctic’s grand reveal

The Arctic’s grand reveal

SOURCE: University of Alaska Fairbanks DATE: December 12, 2019 SNIP: “This green line looks like the death of permafrost — it’s flatlining,” Louise Farquharson said to an audience of a few dozen scientists. Her reserved tone hid a bombshell message — by 2035 permafrost thaw may continue on its own, disregarding the processes that have kept it frozen for thousands of years. Farquharson is a research associate at the University of Alaska Fairbanks Geophysical Institute. She is an expert on permafrost, the parts of the ground that stay frozen for at least two consecutive years. Permafrost thaw causes the ground surface to sink, which leads to infrastructure damage, accelerates microbial activity and releases carbon and other gases into the atmosphere, accelerating global warming even more. Most experts suggest permafrost thaw will continue and even speed up as we go into the next century. However, calculated rates of thaw may be far lower than what will really happen. According to Farquharson, a key accelerating factor in permafrost thaw has been dramatically underestimated. “It’s the Arctic’s ‘grand reveal,’” Farquarson said. “We thought we saw what was happening, then it really stepped out from behind the curtain.” This factor is called talik, thawed zones in permafrost areas. The mixture of wet, frigid dirt is commonly associated with Arctic thermokarst lakes that form when enough ice-rich permafrost thaws to create a body of water. The talik beneath these lakes significantly contributes to the thawing process. Just as icewater melts faster than a lone cube of ice, the waterlogged ground accelerates thawing of the permafrost around it. Normally talik has been thought of as...