The warmer Arctic has triggered cooler winters and springs in North America, which has in turn weakened vegetation growth and lowered carbon uptake capacity in its ecosystems, research shows.
The team analyzed an index of sea surface temperatures from the Bering Sea and found that in years with higher than average Arctic temperatures, changes in atmospheric circulation resulted in the aforementioned anomalous climates throughout North America. In those years of intense cold and low precipitation, the team found that the unfavorable conditions adversely affected vegetation growth — including crop yields — which in turn decreased carbon uptake capacity by about 14%. In other words, although Arctic warming has increased carbon uptake in the Northern Hemisphere, this research has shown that the resulting interannual variability in Arctic temperatures can affect regions further away in North America and may counteract the initially observed increases in carbon uptake…
Jin-Soo Kim, Jong-Seong Kug, Su-Jong Jeong, Deborah N. Huntzinger, Anna M. Michalak, Christopher R. Schwalm, Yaxing Wei, Kevin Schaefer. Reduced North American terrestrial primary productivity linked to anomalous Arctic warming. Nature Geoscience, 2017; DOI: 10.1038/ngeo2986
..in the latest sign of how quickly changes are happening, new research published this week shows that the Arctic has seen more frequent bouts of warm air and longer stretches of mild weather. The new findings show that while warm snaps have occurred even as far as back as the 1890s, a massive shift is afoot in the region, which is warming twice as fast as the rest of the world…
Background temperatures have also been rising faster there. The North Pole region has warmed 2.3°F (1.3°C) per decade since 1979, a trend largely driven by climate change. Though the new study doesn’t tease out whether the increase in warm days is due directly to climate change, it’s part of a hugepileofevidence of how rising carbon pollution is altering the Arctic faster than the rest of the world….
….The winter of 2015-2016, for example, saw temperatures nearly 3.6 degrees Fahrenheit (2 degrees Celsius) warmer than the previous record high monthly winter temperature. At the end of December 2015, scientists recorded a temperature of 36 degrees Fahrenheit (2.2 degrees Celsius) in the Central Arctic, the warmest temperature ever recorded in this region from December through March.
…On average, the Atlantic side of the North Pole now has ten warming events each winter, while the Pacific Central Arctic has five such events, according to the study. More storms come in to the Arctic from the Atlantic Ocean during winter, which results in more warming events on the Atlantic side of the North Pole….
Robert M. Graham, Lana Cohen, Alek A. Petty, Linette N. Boisvert, Annette Rinke, Stephen R. Hudson, Marcel Nicolaus, Mats A. Granskog. Increasing frequency and duration of Arctic winter warming events. Geophysical Research Letters, 2017; DOI: 10.1002/2017GL073395
A chunk of floating ice that weighs more than a trillion metric tons broke away from the Antarctic Peninsula, producing one of the largest icebergs ever recorded and providing a glimpse of how the Antarctic ice sheet might ultimately start to fall apart.
….Larsen C, like two smaller ice shelves that collapsed before it, was holding back relatively little land ice, and it is not expected to contribute much to the rise of the sea. But in other parts of Antarctica, similar shelves are holding back enormous amounts of ice, and scientists fear that their future collapse could dump enough ice into the ocean to raise the sea level by many feet. How fast this could happen is unclear.
In the late 20th century, the Antarctic Peninsula, which juts out from the main body of Antarctica and points toward South America, was one of the fastest-warming places in the world. That warming had slowed or perhaps reversed slightly in the 21st century, but scientists believe the ice is still catching up to the higher temperatures….
A one trillion tonne iceberg — one of the biggest ever recorded — has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice finally completed its path through the ice…. Whilst this new iceberg will not immediately raise sea levels, if the shelf loses much more of its area, it could result in glaciers that flow off the land behind speeding up their passage towards the ocean. This non-floating ice would have an eventual impact on sea levels, but only at a very modest rate.
…The work shows that temperature rises measured over recent decades do not fully reflect the global warming already in the pipeline and that the ultimate heating of the planet could be even worse than feared.
….how much global temperatures rise for a certain level of carbon emissions is called climate sensitivity and is seen as the single most important measure of climate change. Computer models have long indicated a high level of sensitivity, up to 4.5C for a doubling of CO2 in the atmosphere.… the new work, using both models and paleoclimate data from warming periods in the Earth’s past, shows that the historical temperature measurements do not reveal the slow heating of the planet’s oceans that takes place for decades or centuries after CO2 has been added to the atmosphere.
…The new research, published in the journal Science Advances, has ended that. “The worrisome part is that all the models show there is an amplification of the amount of warming in the future,” he said. The situation might be even worse, as Proistosescu’s work shows climate sensitivity could be as high as 6C.
….“The models simulate a warming pattern like today’s, but indicate that strong feedbacks kick in when the Southern Ocean and Eastern Equatorial Pacific eventually warm, leading to higher overall temperatures than would simply be extrapolated from the warming seen to date,” said [co-author] Peter Huybers…“But there is no perfect analogue for the changes that are coming.”
….The most important measurement of global warming is in the oceans. In fact, “global warming” is really “ocean warming.” If you are going to measure the changing climate of the oceans, you need to have many sensors spread out across the globe that take measurements from the ocean surface to the very depths of the waters. Importantly, you need to have measurements that span decades so a long-term trend can be established.
These difficulties are tackled by oceanographers, and a significant advancement was presented in a paper just published in the journal Climate Dynamics. ….We found that regardless of whose data was used or where the data was gathered, the oceans are warming.
…In the study, we looked at the different ways that three groups make decisions about mapping, bias, and climatology. We not only asked how much the oceans are warming, but how the warming differs for various areas (ocean basins) and various depths. We found that each ocean basin has warmed significantly. Despite this fact, there are some differences amongst the three groups. For instance, in the 300-700 meter oceans depths in the Pacific and Southern oceans, significant differences are exhibited amongst the tree groups. That said, the central fact is that regardless of how you measure, who does the measurements, when or where the measurements are taken, we are warming….. it will be important that we keep high-quality temperature sensors positioned throughout the oceans so in the future we will be able to predict where our climate is headed. We say in science that a measurement not made is a measurement lost forever. And there are no more important measurements than of heating of the oceans.
Inconsistent global/basin ocean heat content (OHC) changes were found in different ocean subsurface temperature analyses, especially in recent studies related to the slowdown in global surface temperature rise. This finding challenges the reliability of the ocean subsurface temperature analyses and motivates a more comprehensive inter-comparison between the analyses. Here we compare the OHC changes in three ocean analyses (Ishii, EN4 and IAP) to investigate the uncertainty in OHC in four major ocean basins from decadal to multi-decadal scales. First, all products show an increase of OHC since 1970 in each ocean basin revealing a robust warming, although the warming rates are not identical. The geographical patterns, the key modes and the vertical structure of OHC changes are consistent among the three datasets, implying that the main OHC variabilities can be robustly represented. However, large discrepancies are found in the percentage of basinal ocean heating related to the global ocean, with the largest differences in the Pacific and Southern Ocean. Meanwhile, we find a large discrepancy of ocean heat storage in different layers, especially within 300–700 m in the Pacific and Southern Oceans. Furthermore, the near surface analysis of Ishii and IAP are consistent with sea surface temperature (SST) products, but EN4 is found to underestimate the long-term trend. Compared with ocean heat storage derived from the atmospheric budget equation, all products show consistent seasonal cycles of OHC in the upper 1500 m especially during 2008 to 2012. Overall, our analyses further the understanding of the observed OHC variations, and we recommend a careful quantification of errors in the ocean analyses.
The Earth’s rising temperature is expected to knock the global water cycle out of whack, but exactly how it will change is uncertain. Scientists, though, can look for clues as to what the future might bring in the major climate swings that have happened in the past.
A new study that does just that suggests that Earth’s rain belts could be pushed northward as the Northern Hemisphere heats up faster than the Southern Hemisphere. That shift would happen in concert with the longstanding expectation for already wet areas to see more rain and for dry ones to become more arid.
….These changes in rain distribution could have implications for future water resources, particularly in areas where water supplies are already stressed, such as the western U.S.and parts of Africa…
Biologists have shown what could be a startling drop in the amount of carbon stored in the Sierra Nevada mountains due to projected climate change and wildfire events.
….roughly half of all human-emitted carbon is absorbed by vegetation and the ocean, and is stored through natural processes — something that helps limit our actual carbon impact on the atmosphere. The problem is, as forests begin to change, due to global warming and large scale fires, the amount of forest carbon uptake will decrease, accelerating the amount of human-made carbon making its way into the atmosphere.
“Our simulations in the Sierra Nevada show that the mean amount of carbon loss from the forests under these projections could be as large as 663 teragrams,” said Hurteau. “That’s equal to about 73 percent of the total above ground carbon stock estimated in California vegetation in 2010.”
…The two factors that influence these findings are changes in climate and the likelihood of large scale forest fires. Because California is experiencing warmer and drier conditions due to global warming, certain tree species are not able to flourish across particular geographic regions like they once were. Less tree growth, means less carbon uptake in forests.
The study also shows that wildfires will play a big role in the reduction of stored carbon. And while many of these incidents will occur naturally, Hurteau says we are, in part, to blame for their significance….
…”We’ve been putting out fires for a hundred years, causing tree density to go way up. In the absence of fire that system has a lot more carbon stored in it,” explained Hurteau. “But, when you have these large fire events the amount of carbon stored in the system drops because it kills many of the trees. Whereas, in a forest that’s been maintained by regular forest fires, which is the natural ecological state, your total carbon at any given point in time can be lower but it stays more consistent.”
…Hurteau says researchers have identified strategies for reducing some of the fire risk by actively thinning forests to manage tree density and restoring surface fires. It’s an idea that seems counterproductive until you consider how volatile these ecosystems are due to the risk of large scale fires that end up destroying hundreds of thousands of acres.
…He says it’s not only for the benefit of nature but for all of us, since healthy ecosystems lead to cleaner, better regulated water flow to communities across the western United States.
Shuang Liang, Matthew D. Hurteau, Anthony LeRoy Westerling. Potential decline in carbon carrying capacity under projected climate-wildfire interactions in the Sierra Nevada. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-02686-0
…Researchers have found that carbon particles released into the air from burning trees and other organic matter are much more likely than previously thought to travel to the upper levels of the atmosphere, where they can interfere with rays from the sun — sometimes cooling the air and at other times warming it.
“Most of the brown carbon released into the air stays in the lower atmosphere, but a fraction of it does get up into the upper atmosphere, where it has a disproportionately large effect on the planetary radiation balance — much stronger than if it was all at the surface,” said Rodney Weber, a professor in Georgia Tech’s School of Earth & Atmospheric Sciences.
…The climate is more sensitive to those particulates as their altitude increases. The researchers found that brown carbon appears much more likely than black carbon to travel through the air to the higher levels of the atmosphere where it can have a greater impact on climate….
Yuzhong Zhang, Haviland Forrister, Jiumeng Liu, Jack Dibb, Bruce Anderson, Joshua P. Schwarz, Anne E. Perring, Jose L. Jimenez, Pedro Campuzano-Jost, Yuhang Wang, Athanasios Nenes, Rodney J. Weber. Top-of-atmosphere radiative forcing affected by brown carbon in the upper troposphere. Nature Geoscience, 2017; DOI: 10.1038/NGEO2960
Warming temperatures are prompting some tree species in the Rocky Mountains to ‘migrate’ to higher elevations in order to survive. Researchers have discovered that tiny below-ground organisms play a role in this phenomenon — and could be used to encourage tree migration in order to preserve heat-sensitive species. Their work shows how these invisible biotic communities create ‘soil highways’ for young trees, meaning they could determine how quickly species march uphill, if at all.
The newfound role of the soil microbiome — the collection of microscopic bacteria, fungi and archaea that interact with plant roots — represents a turning point for research aimed at understanding and predicting where important tree species will reside in the future…
…”we need to work with the trees near the bottom of the mountain, because they are the ones that will feel the most stress from warming temperatures,” Van Nuland said. “So we have to figure out a way to coax them to move up.” The research could help scientists design specific groups of bacteria and fungi to encourage the migration of trees threatened by warming climates….
The Waggonwaybreen glacier in Svalbard. Photo: Andreas Weith
As can be seen above, the Waggonwaybreen glacier in Svalbard, Norway, has retreated substantially since 1900. Svalbard’s glaciers are not only retreating, they are also losing about two feet of their thickness each year. Glaciers around the world have retreated at unprecedented rates and some have disappeared altogether. The melting of glaciers will affect people around the world, their drinking water supplies, water needed to grow food and supply energy, as well as global sea levels.
The Intergovernmental Panel on Climate Change estimates that around the world glaciers (excluding the Greenland and Antarctic ice sheets) will decrease in volume between 15 to 55 percent by 2100 even if we are able to limit global warming to under 2˚C; they could shrink up to 85 percent if warming increases much more.
In Earth’s history, there have been at least five major ice ages, when long-term cooling of the planet resulted in the expansion of ice sheets and glaciers. Past ice ages have been naturally set off by a numerous factors, most importantly, changes in the Earth’s orbit around the sun (Milankovitch cycles) and shifting tectonic plate movements that affect wind and ocean currents. The mixture of gases in the atmosphere (such as carbon dioxide and methane) as well as solar and volcanic activity are also contributing factors. Today we are in a warm interval—an interglacial—between ice ages….