Mangroves help protect coastal areas against sea level rise

Blue & Green Tomorrow: Mangrove forests could play a crucial role in protecting coastal areas from sea level rise caused by climate change, according to new research involving the University of Southampton. A joint study between researchers at the University of Southampton along with colleagues from the Universities of Auckland and Waikato in New Zealand used leading-edge mathematical simulations to study how mangrove forests respond to elevated sea levels.

Taking New Zealand mangrove data as the basis of a new modelling system, the team were able to predict what will happen to different types of estuaries and river deltas when sea levels rise. They found areas without mangroves are likely to widen from erosion and more water will encroach inwards, whereas mangrove regions prevent this effect – which is likely due to soil building up around their mesh-like roots and acting to reduce energy from waves and tidal currents.

Coastal estuaries and recesses in coastlines that form bays receive the run-off from erosion on steep catchments, which give them the tendency to fill in over time. As they infill, the movement of the tidal currents over the shallow areas create networks of sandbanks and channels. The sand banks grow upward to keep pace with water-level changes, while the channels get deeper to efficiently drain the excess water out to sea.

The researchers’ latest work shows that mangroves can facilitate this process, by adding leaf and root structures into the accumulating sediment, which increase the elevation while enhancing the trapping of new sediment arriving from the catchment.

Dr Barend van Maanen from the University of Southampton explains: “As a mangrove forest begins to develop, the creation of a network of channels is relatively fast. Tidal currents, sediment transport and mangroves significantly modify the estuarine environment, creating a dense channel network. Within the mangrove forest, these channels become shallower through organic matter from the trees, reduced sediment resuspensions (caused by the mangroves) and sediment trapping (also caused by the mangroves) and the sea bed begins to rise, with bed elevation increasing a few millimetres per year until the area is no longer inundated by the tide.”...

Mangroves in Zanzibar, shot by Fanny Schertzer, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Typhoon Nangka continues on course towards Japan: AIR analysis

The Insurance Journal: Catastrophe modeling firm AIR Worldwide has released an analysis of Typhoon Nangka, which is currently a Category 3 storm “with a central pressure of 950 mb and maximum 10-minute sustained wind speeds of 80 knots (~106 mph 1-minute sustained). The storm is located approximately 1,250 km (775 miles) from Iwakuni, Japan, Nangka, and is moving northward at 15 km/h (9 mph).

“Once the intensity of a Category 4 Super Typhoon, Nangka has weakened and maintained its current intensity for the last 72 hours,” said Dr. Anna Trevino, scientist at AIR Worldwide. “It is located in a favorable environment with very little vertical wind shear and warm sea surface temperatures, but nearby dry air is being wrapped into the center, preventing further convective growth and intensification.

 “High pressure to the northeast is steering Nangka toward Japan, and the typhoon is forecast to make landfall as a Category 2 or weak Category 3 storm between the isla
nds of Kyushu and Shikoku Thursday (local time) and rapidly weaken. Because landfall is not for at least 48 hours, there is uncertainty in the intensity of the storm at landfall. This is the first typhoon landfall in Mainland Japan has seen in 2015, with the exception of Typhoon Noul, which quickly weakened before making landfall as an extratropical storm in May.”

According to the Japan Meteorological Agency (JMA), Nangka is expected to slightly strengthen over warm ocean waters during the next two days before landfall, causing rough seas, anticipated to impact shipping....

Typhoon Nangka on July 13, 2015, via NASA

Greenland darkening to continue

A press release from City College of News York: Darkening of the Greenland Ice Sheet is projected to continue as a consequence of continued climate warming, Dr. Marco Tedesco, a City College of New York scientist, said at the European Geosciences Union (EGU) General Assembly in Vienna today.

Tedesco told a press conference in the Austrian capital that the projection is based on a model that only accounts for the effects of warming on snow grain size and melting.

An associate professor in City College’s Division of Science and head of its Cryospheric Processes Laboratory that he founded, Tedesco is an authority on the Greenland Ice Sheet where he has conducted annual research.

He noted that a darkening of the Greenland Ice Sheet associated with increasing temperatures and enhanced melting occurred between 1996 and 2012. It was promoted by:

• Extensively and persistently increased surface snow grain size;
• The expansion and persistency of the areas of exposed bare ice and by the increased surface impurities concentration associated with the appearance of dirty ice;
• Increased impurities concentrations due to consolidation with snowmelt. 

Tedesco, however, added that his research had not found any evidence that points to either increased atmospheric deposition of impurities or to the number of fires over Eurasia and North America as being factors....

NASA photo of Greenland ice flowing around a ridge of bedrock

Friction means Antarctic glaciers more sensitive to climate change than we thought

A press release from Caltech: One of the biggest unknowns in understanding the effects of climate change today is the melting rate of glacial ice in Antarctica. Scientists agree rising atmospheric and ocean temperatures could destabilize these ice sheets, but there is uncertainty about how fast they will lose ice.

The West Antarctic Ice Sheet is of particular concern to scientists because it contains enough ice to raise global sea level by up to 16 feet, and its physical configuration makes it susceptible to melting by warm ocean water. Recent studies have suggested that the collapse of certain parts of the ice sheet is inevitable. But will that process take several decades or centuries?

Research by Caltech scientists now suggests that estimates of future rates of melt for the West Antarctic Ice Sheet—and, by extension, of future sea-level rise—have been too conservative. In a new study, published online on March 9 in the Journal of Glaciology, a team led by Victor Tsai, an assistant professor of geophysics, found that properly accounting for Coulomb friction—a type of friction generated by solid surfaces sliding against one another—in computer models significantly increases estimates of how sensitive the ice sheet is to temperature perturbations driven by climate change.

Unlike other ice sheets that are moored to land above the ocean, most of West Antarctica's ice sheet is grounded on a sloping rock bed that lies below sea level. In the past decade or so, scientists have focused on the coastal part of the ice sheet where the land ice meets the ocean, called the "grounding line," as vital for accurately determining the melting rate of ice in the southern continent.

"Our results show that the stability of the whole ice sheet and our ability to predict its future melting is extremely sensitive to what happens in a very small region right at the grounding line. It is crucial to accurately represent the physics here in numerical models," says study coauthor Andrew Thompson, an assistant professor of environmental science and engineering at Caltech....

The Thwaits Glacier in West Antarctica, from NASA

Wiggles: Inconsistencies undermine model reliability for projecting decade-to-decade warming

Science 2.0: A new study finds that most climate models may have wiggles that undermine accuracy - but they are likely underestimating the degree of decade-to-decade variability occurring in mean surface temperatures as Earth's atmosphere warms.

The models also provide inconsistent explanations of why this variability occurs in the first place and such discrepancies undermine the models' reliability for projecting the short-term pace as well as the extent of future warming, the study's authors warn.  As such, we shouldn't over-interpret recent temperature trends, no matter what blizzard his New York City and leads to exploitation of climate science to generate media pageviews.

"The inconsistencies we found among the models are a reality check showing we may not know as much as we thought we did," said lead author Patrick T. Brown, a Ph.D. student in climatology at Duke's Nicholas School of the Environment. "This doesn't mean greenhouse gases aren't causing Earth's atmosphere to warm up in the long run. It just means the road to a warmer world may be bumpier and less predictable, with more decade-to-decade temperature wiggles than expected. If you're worried about climate change in 2100, don't over-interpret short-term trends. Don't assume that the reduced rate of global warming over the last 10 years foreshadows what the climate will be like in 50 or 100 years."

To conduct their study, they analyzed 34 climate models used by the Intergovernmental Panel on Climate Change (IPCC) in its fifth and most recent assessment report, finalized last November.  The analysis found good consistency among the 34 models explaining the causes of year-to-year temperature wiggles, Brown noted. The inconsistencies existed only in terms of the model's ability to explain decade-to-decade variability, such as why global mean surface temperatures warmed quickly during the 1980s and 1990s, but have remained relatively stable since then....

Wrong kind of model -- Fashion Week in Budapest, shot from stylemagazin.hu, Wikimedia Commons

Predicting ENSO devastation

Sandhya Sekar in SciDev.net:A new computer model can help forecast the socio-economic devastation caused by rainfall and floods triggered by the El Nino-Southern Oscillation (ENSO) phenomena.  Philip Ward from VU University, Amsterdam, who with his colleagues created the ‘cascade’ modelling framework, says that it is capable of predicting the effect of ENSO on floods at the global and regional scales.

“During El Niño years, the risk is higher than average in north-eastern India, the findings suggest,” says Ward in an interview with SciDev.Net. “On the other hand, some basins in eastern India show lower than average damage during La Niña years.”

ENSO refers to the effects of anomalous sea surface temperatures off the western coast of South America that cause climatic changes across the tropics and subtropics. Southern Oscillation refers to temperature variations on the surface of the tropical eastern Pacific Ocean (warming and cooling known as El Niño and La Niña, respectively) and in  surface  air pressure in the tropical western Pacific.

Ward’s approach, published in September in the Proceedings of the National Academy of Sciences, combines three different models that predict rainfall, water drainage patterns and also the socio-economic impacts of floods, including on GDP.

The models found abnormal flood volumes across more than a third of the earth’s surface during El Nino years when the oceans were warmer than usual, and also during La Nina years when the oceans were colder.  “Our models and results are already at a resolution of one square kilometre which we have found to be very useful for many users of the data in practical applications,” Ward tells SciDev.Net....

Sunrise over the South Pacific, NASA image from the International Space Station

Predicting superbugs' countermoves to new drugs

Intern Daily: With drug-resistant bacteria on the rise, even common infections that were easily controlled for decades - such as pneumonia or urinary tract infections - are proving trickier to treat with standard antibiotics. New drugs are desperately needed, but so are ways to maximize the effective lifespan of these drugs.

To accomplish that, Duke University researchers used software they developed to predict a constantly-evolving infectious bacterium's countermoves to one of these new drugs ahead of time, before the drug is even tested on patients.

In a study appearing in the journal Proceedings of the National Academy of Sciences, the team used their program to identify the genetic changes that will allow methicillin-resistant Staphylococcus aureus, or MRSA, to develop resistance to a class of new experimental drugs that show promise against the deadly bug.

When the researchers treated live bacteria with the new drug, two of the genetic changes actually arose, just as their algorithm predicted. "This gives us a window into the future to see what bacteria will do to evade drugs that we design before a drug is deployed," said co-author Bruce Donald, a professor of computer science and biochemistry at Duke.

Developing pre-emptive strategies while the drugs are still in the design phase will give scientists a head start on the next line of compounds that will be effective despite the germ's resistance mutations....

Some antibiotics, shot supplied by Wellcome Images, Wikimedia Commons, under the Creative Commons Attribution 4.0 International license 

Soil’s large carbon stores could be freed by increased CO2, plant growth

A press release from Princeton University: An increase in human-made carbon dioxide in the atmosphere could initiate a chain reaction between plants and microorganisms that would unsettle one of the largest carbon reservoirs on the planet — soil.

Researchers based at Princeton University report in the journal Nature Climate Change that the carbon in soil — which contains twice the amount of carbon in all plants and Earth’s atmosphere combined — could become increasin
gly volatile as people add more carbon dioxide to the atmosphere, largely because of increased plant growth. The researchers developed the first computer model to show at a global scale the complex interaction between carbon, plants and soil, which includes numerous bacteria, fungi, minerals and carbon compounds that respond in complex ways to temperature, moisture and the carbon that plants contribute to soil.

Although a greenhouse gas and pollutant, carbon dioxide also supports plant growth. As trees and other vegetation flourish in a carbon dioxide-rich future, their roots could stimulate microbial activity in soil that in turn accelerates the decomposition of soil carbon and its release into the atmosphere as carbon dioxide, the researchers found.

This effect counters current key projections regarding Earth’s future carbon cycle, particularly that greater plant growth could offset carbon dioxide emissions as flora take up more of the gas, said first author Benjamin Sulman, who conducted the modeling work as a postdoctoral researcher at the Princeton Environmental Institute. “You should not count on getting more carbon storage in the soil just because tree growth is increasing,” said Sulman, who is now a postdoctoral researcher at Indiana University.

On the other hand, microbial activity initiated by root growth could lock carbon onto mineral particles and protect it from decomposition, which would increase long-term storage of carbon in soils, the researchers report.

Whether carbon emissions from soil rise or fall, the researchers’ model depicts an intricate soil-carbon system that contrasts starkly with existing models that portray soil as a simple carbon repository, Sulman said. An oversimplified perception of the soil carbon cycle has left scientists with a glaring uncertainty as to whether soil would help mitigate future carbon dioxide levels — or make them worse, Sulman said....

The model projected changes (above) in global soil carbon as a result of root-soil interactions, with blue indicating a greater loss of soil carbon to the atmosphere. (Image by Benjamin Sulman, Princeton Environmental Institute)

Improving forecasts for rain-on-snow flooding

Hannah Hickey at University of Washington Today: Many of the worst West Coast winter floods pack a double punch. Heavy rains and melting snow wash down the mountains together to breach riverbanks, wash out roads and flood buildings. These events are unpredictable and difficult to forecast. Yet they will become more common as the planet warms and more winter precipitation falls as rain rather than snow.

...Most of the largest floods on record in the western U.S. are associated with rain falling on snow. But it’s not that the rain is melting or washing away the snow. Instead, it’s the warm, humid air surrounding the drops that is most to blame for the melting, Wayand said. Moisture in the air condenses on the cold snow just like water droplets form on a cold drink can
. The energy released when the humid air condenses is absorbed by the snow. The other main reason is that rainstorms bring warmer air, and this air blows across the snow to melt its surface. His work support previous research showing that these processes provide 60 to 90 percent of the energy for melting.

Places that experience rain-on-snow flooding are cities on rivers that begin in the mountains, such as Sacramento, California, and Centralia, Washington. In the 1997 New Year’s Day flood in Northern California, melting snow exacerbated flooding, which broke levees and caused millions of dollars in damage. The biggest recent rain-on-snow event in Washington was the 2009 flood in the Snoqualmie basin. And the Calgary flood in summer of 2013 included snow from the Canadian Rockies that caused rivers to overflow their banks.

The UW researchers developed a model by recreating the 10 worst rain-on-snow flooding events between 1980 and 2008 in three regions: the Snoqualmie basin in Washington state, the upper San Joaquin basin in central California and the East North Fork of the Feather River basin in southern California.

Their results allow them to gauge the risks for any basin and any incoming storm. The three factors that matter most, they found, are the shape of the basin, the elevation of the rain-to-snow transition before and during the storm, and the amount of tree cover. Basins most vulnerable to snowmelt are treeless basins with a lot of area within the rain-snow transition zone, where the precipitation can fall as snow and then rain....

The Centre Street Bridge in Calgary, Alberta, during the 2013 floods, shot by Ryan L. C. Quan, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

New study explains the role of oceans in global ‘warming hiatus’

A press release from the University of Southampton: New research shows that ocean heat uptake across three oceans is the likely cause of the ‘warming hiatus’ – the current decade-long slowdown in global surface warming.  Using data from a range of state-of-the-art ocean and atmosphere models, the research shows that the increased oceanic heat drawdown in the equatorial Pacific, North Atlantic and Southern Ocean basins has played a significant role in the hiatus.

The new analysis has been published in Geophysical Research Letters by Professor Sybren Drijfhout from the University of Southampton and collaborators from the National Oceanography Centre (NOC) Dr Adam Blaker, Professor Simon Josey, Dr George Nurser and Dr Bablu Sinha, together with Dr Magdalena Balmaseda from the European Centre for Medium Range Weather Forecasting (ECMWF).

Professor Drijfhout said: “This study attributes the increased oceanic heat drawdown in the equatorial Pacific, North Atlantic and Southern Ocean to specific, different mechanisms in each region. This is important as current climate models have been unable to simulate the hiatus. Our study gives clues to where the heat is drawn down and by which processes. This can serve as a benchmark for climate models on how to improve their projections of future global mean temperature.”

Previously, the drawdown of heat by the Equatorial Pacific Ocean over the hiatus period, due to cool sea-surface temperatures associated with a succession of cool-surface La Nina episodes, was thought to be sufficient to explain the hiatus.  However, this new analysis reveals that the northern North Atlantic, the Southern Ocean and Equatorial Pacific Ocean are all important regions of ocean heat uptake. Each basin contributes a roughly equal amount to explaining the hiatus, but the mechanisms of heat drawdown are different and specific in each basin.

...Dr Sinha concluded: “The deeper understanding gained in this study of the processes and regions responsible for variations in oceanic heat drawdown and retention will improve the accuracy of future climate projections.”

Fish at an oil platform, Gulf of Mexico, photo by US Bureau of Ocean Energy Management

Researchers develop new model to study epidemics

A press release from New York University: For decades, scientists have been perfecting models of how contagions spread, but newly published research takes the first steps into building a model that includes the loop linking individual human behavior and the behavior of the epidemic itself.

The first results of the highly complex modeling led by researchers at the New York University Polytechnic School of Engineering were recently spotlighted as “brilliant research” by the American Physical Society.

Eventually, the team hopes the model will more accurately predict who should be vaccinated and isolated first and what travel restrictions will be most effective in preventing different epidemics. The speed of mass communication and modern travel requires changes to most current models. Even underdeveloped countries now have electronic devices that quickly spread the word about diseases and airplanes can carry the infected everywhere nearly as quickly, explained Alessandro Rizzo, visiting professor of mechanical engineering and a leader of the research effort. Modeling thus must be improved by accounting for contagions that spread mor
e slowly than travelers and ones that spread more quickly.

The new model also takes into consideration the differing rates at which the infected and those who merely fear infection react and thereby spread disease. For example, prior work by other researchers indicates that symptomatic people will often self-isolate and—not surprisingly—that the actions of the infected are more relevant to the spread of an epidemic than those of healthy individuals who are avoiding a contagious area. But in some kinds of epidemics, ill people who are asymptomatic behave as if they are healthy, selfishly infecting others. The new model seeks to account for these individual reactions and more.  The research team expects that a fully tested and working model is several years away...

1918 image of a Spanish flu mask in New South Wales

Researchers create more accurate model for greenhouse gases from peatlands

A press release from Argonne National Laboratory: Scientists at the U.S. Department of Energy’s Argonne National Laboratory have created a new model to more accurately describe the greenhouse gases likely to be released from Arctic peatlands as they warm. Their findings, based on modeling how oxygen filters through soil, suggest that previous models probably underestimated methane emissions and overrepresented carbon dioxide emissions from these regions.

Peatlands, common in the Arctic, are wetlands filled with dead and decaying organic matter. ...Cold temperatures keep the carbon locked in the soil. As the ground warms, however, microbes come to life and begin to decompose all that organic matter, which releases carbon into the atmosphere. Unfortunately, the extreme northern regions of the world are where warming has accelerated the most quickly—and it’s expected to pick up in the future. Scientists are concerned that Arctic warming could spiral quickly into a self-reinforcing cycle that dumps an enormous amount of carbon into the atmosphere.

...Up until now, researchers had been using a simple model that assumed water was the primary divider; soil above the water table would produce microbes that made CO2, and microbes below would produce methane. “But experiments had been showing that there could be significant limits on oxygen availability above the water ta
ble, and this would affect what form of carbon microbes release,” Fan said.

The size and characteristics of soil particles matter. If the oxygen gets trapped in air bubbles and consumed by other microbes or can’t filter down through soil, soil microbes will produce methane even if they’re above the water table. “So we set out to make a model that would take these findings into account,” Fan said.

The team used experimental data from peatland taken near Fairbanks, Alaska and plugged it into their model. The results showed their new model was much more accurate and suggested that more methane is produced and proportionally less CO2—than predicted by older water table-based models. “Revising this calculation will substantially affect current greenhouse gas production models in the Arctic,” Fan said....

Looks like a bulldozer sinking into thawing muskeg in Alaska, shot by Wyoherminator, public domain

Changing Antarctic waters could trigger steep rise in sea levels

A press release from the ARC Centre for Excellence for Climate Science (Australia): Current changes in the ocean around Antarctica are disturbingly close to conditions 14,000 years ago that new research shows may have led to the rapid melting of Antarctic ice and an abrupt 3-4 metre rise in global sea level.

The research published in Nature Communications found that in the past, when ocean temperatures around Antarctica became more layered - with a warm layer of water below a cold surface layer -  ice sheets and glaciers melted much faster than when the cool and warm layers mixed more easily. This defined layering of temperatures is exactly what is happening now around the Antarctic.

“The reason for the layering is that global warming in parts of Antarctica is causing land-based ice to melt, adding massive amounts of freshwater to the ocean surface,” said ARC Centre of Excellence for Climate System Science researcher Prof Matthew England an author of the paper.

“At the same time as the surface is cooling, the deeper ocean is warming, which has already accelerated the decline of glaciers on Pine Island and Totten. It appears global warming is replicating conditions that, in the past, triggered significant shifts in the stability of the Antarctic ice sheet.”

The modelling shows the last time this occurred, 14,000 years ago, the Antarctic alone contributed 3-4 metres to global sea levels in just a few centuries. “Our model simulations provide a new mechanism that reconciles geological evidence of past global sea level rise,” said researcher UNSW ARC Future Fellow Dr Chris Fogwill.

“The results demonstrate that while Antarctic ice sheets are remote, they may play a far bigger role in driving past and importantly future sea level rise than we previously suspected.” The accelerating melting of land ice into the sea makes the surface of the ocean around Antarctica colder, less salty and more easily frozen, leading to extensive sea ice in some areas. It is one of the reasons ascribed to the increasing trend in sea ice around Antarctica....

A backlit iceberg off the Antarctic coast, shot by Jason Auch, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

With few data, Arctic carbon models lack consensus

A press release from NASA's Jet Propulsion Laboratory: As climate change grips the Arctic, how much carbon is leaving its thawing soil and adding to Earth's greenhouse effect? The question has long been debated by scientists. A new study conducted as part of NASA's Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) shows just how much work still needs to be done to reach a conclusion on this and other basic questions about the region where global warming is hitting hardest.

Lead author Josh Fisher of NASA's Jet Propulsion Laboratory, Pasadena, California, analyzed 40 computer models of the amounts and flows of carbon in the Alaskan Arctic and boreal ecosystems. His team found wide disagreement among the models, highlighting the urgent need for more measurements from the region.

Models represent scientists' integrated understanding of Earth processes and systems. They are used both to test that understanding, by comparing their results with real-world observations, and to gain insight into how current trends may affect our planet's future.

"We all knew there were big uncertainties in our understanding, and we wanted to quantify their extent," said Fisher. That extent proved to be greater than almost anyone expected. "The results were shocking to most people," he said.

However, pinpointing the extent and areas of uncertainty is the first step toward reducing them. Fisher noted that he has shared preliminary results with the modelers who participated in the study, and some have already used the results as an opportunity to rethink how they are representing Arctic processes in global models. Moreover, the uncertainty maps that the study produced, showing the specific Arctic regions where the disagreement is greatest, highlight key locations for field campaigns to collect data.

The study, which involved 30 co-authors from around the world, examined how well the models agreed on various factors, such as the rate of plant growth and the amount of carbon exchanged between living things and the atmosphere. They also evaluated the performance of the models against measurements of carbon at monitoring sites along the tundra of the Alaskan North Slope.

"If all the models agree with the observations, uncertainty is probably pretty low. If they wildly disagree, uncertainty is pretty high," Fisher said. "The models were all over the board."....

Tundra in the Russian Arctic on Bolshaya Muksalma Island, shot by Aleksander Kaasik, Wikimedia Commons, under the Creative Commons 3.0 license 

While the Arctic is melting the Gulf Stream remains

A press release from the University of Bergen (Norway): The melting Arctic is not the source for less saline Nordic Seas. It is the Gulf Stream that has provided less salt. A new study published Sunday in Nature Geoscience documents that the source of fresher Nordic Seas since 1950 is rooted in the saline Atlantic as opposed to Arctic freshwater that is the common inference.

This is an important finding as it shows that the Gulf Stream is not about to short circuit. A halting Gulf Stream has been a concern with ongoing climate change; its collapse was taken to the extreme in the Hollywood blockbuster “The Day After Tomorrow”, says Tor Elde
vik, professor in oceanography at the University of Bergen and the Bjerknes Centre.

The Nordic Seas have freshened substantially since 1950. This has happened at the same time as there has been observed increased river runoff and net ice melting in the Arctic. The concurrence of a less saline ocean and Arctic freshwater input has given the climate research community reason for concern.

 It has been a concern that a layer of Arctic freshwater could impede the Gulf Stream’s Arctic branch. Going back in time – into and through ice ages – such a freshwater lid has been understood to reduce ocean circulation and thus the Gulf Stream’s poleward heat transport, says Tor Eldevik.

Eldevik is co-author of the study where Mirjam Glessmer and colleagues at the Bjerknes Centre in Bergen, Norway, show that change in the Nordic Seas is at the receiving end of change in the more global climate system. The Nordic Seas are in this case not a precursor in a real world parallel to “The Day After Tomorrow”....

Because the story is from Norway: a fjord. Shot by Karamell, Wikimedia Commons, under the Creative Commons 3.0 license

Carbon stored in the world’s soils more vulnerable to climate change than expected

A press release from the University of Exeter: The response of soil microbial communities to changes in temperature increases the potential for more carbon dioxide to be released from the world's soils as global temperatures rise, scientists have revealed.

The potential for global warming to stimulate decomposition rates in soils, and thus release large quantities of carbon dioxide to the atmosphere, has long been considered to be one of the potentially most important positive feedbacks to climate change.

However, the results from more recent studies have suggested that responses within microbial communities could greatly reduce, or even eliminate, the potential for soil carbon losses under global warming.

This key idea was tested using soils collected from a thermal gradient from the Arctic to the Amazon rainforest. The results, published in Nature, show that, contrary to expectations, microbial community responses resulted in an overall increase, rather than a decrease, in the effects of temperature on rates of carbon dioxide release from soils.

Dr Kristiina Karhu of the University of Helsinki, and lead author of the paper, said: “Because soils store more than twice as much carbon than the atmosphere, changes in rates of decomposition and carbon dioxide release from soil could be very important. Our findings suggest that warming will increase the activity of soil microbes to a greater extent than was previously expected, which could have implications for future rates of climate change.”...

Some soil in the Netherlands, shot by FotoDutch , Wikimedia Commons, under the Creative Commons 3.0 license

No more pause: Warming will be non-stop from now on

Michael Slezak in New Scientist: Enjoy the pause in global warming while it lasts, because it's probably the last one we will get this century. Once temperatures start rising again, it looks like they will keep going up without a break for the rest of the century, unless we cut our greenhouse gas emissions.

The slowdown in global warming since 1997 seems to be driven by unusually powerful winds over the Pacific Ocean, which are burying heat in the water. But even if that happens again, or a volcanic eruption spews cooling particles into the air, we are unlikely to see a similar hiatus, according to two independent studies.

Masahiro Watanabe of the University of Tokyo in Japan and his colleagues have found that, over the past three decades, the natural ups and downs in temperature have had less influence on the planet's overall warmth. In the 1980s, natural variability accounted for almost half of the temperature changes seen. That fell to 38 per cent in the 1990s and just 27 per cent in the 2000s.

Instead, human-induced warming is accounting for more and more of the changes from year to year, says Watanabe. With ever-faster warming, small natural variations have less impact and are unlikely to override the human-induced warming.

"The implication is that we will get fewer hiatus periods, or hiatus periods that last for a shorter period," says Wenju Cai at the CSIRO in Melbourne, Australia, who wasn't involved in the work...

Hokusai's "The Wave"

A reanalysis of the 1931-43 Atlantic hurricane database

In Insurancenews.net, Michael Dickinson posted an interesting analysis of Atlantic hurricanes. Here's the abstract, broken up for readability: A reanalysis of the Atlantic basin tropical storm and hurricane database ("best track") for the period from 1931 to 1943 has been completed as part of the Atlantic Hurricane Database Reanalysis Project. This reassessment of the main archive for tropical cyclones of the North Atlantic Ocean, Caribbean Sea, and Gulf of Mexico was necessary to correct systematic biases and random errors in the data as well as to search for previously unrecognized systems.

Methodology for the reanalysis process for revising the track and intensity of tropical cyclone data is largely unchanged from that of the preceding couple of decades and has been detailed in a previous paper on the reanalysis. Accurate Environmental Forecasting's numerical weather prediction-based wind field model was utilized here to help determine which states were impacted by various hurricane force winds in several U.S. landfalling major hurricanes during this era.

The 1931-43 dataset now includes 23 new tropical cyclones, excludes five systems previously considered tropical storms, makes generally large alterations in the intensity estimates of most tropical cyclones (at various times both toward stronger and weaker intensities), and typically adjusts existing tracks with minor corrections. Average errors in intensity and track values are estimated for both open ocean conditions as well as for landfalling systems.

Finally, highlights are given for changes to the more significant hurricanes to impact the United States, Central America, and the Caribbean for this time period....

A still from John Ford's 1937 film, "The Hurricane"

Why global warming is taking a break

Fabio Benjamin at the ETH (Switzerland): ...Global warming is currently taking a break: whereas global temperatures rose drastically into the late 1990s, the global average temperature has risen only slightly since 1998 – surprising, considering scientific climate models predicted considerable warming due to rising greenhouse gas emissions. Climate sceptics used this apparent contradiction to question climate change per se – or at least the harm potential caused by greenhouse gases – as well as the validity of the climate models. Meanwhile, the majority of climate researchers continued to emphasise that the short-term ‘warming hiatus’ could largely be explained on the basis of current scientific understanding and did not contradict longer term warming.

Researchers have been looking into the possible causes of the warming hiatus over the past few years. For the first time, Reto Knutti, Professor of Climate Physics at ETH Zurich, has systematically examined all current hypotheses together with a colleague. In a study published in the latest issue of the journal Nature Geoscience, the researchers conclude that two important factors are equally responsible for the hiatus.

One of the important reasons is natural climate fluctuations, of which the weather phenomena El Niño and La Niña in the Pacific are the most important and well known. "1998 was a strong El Niño year, which is why it was so warm that year," says Knutti. In contrast, the counter-phenomenon La Niña has made the past few years cooler than they would otherwise have been.

...According to the study, the second important reason for the warming hiatus is that solar irradiance has been weaker than predicted in the past few years....Furthermore, several volcanic eruptions, such as Eyjafjallajökull in Iceland in 2010, have increased the concentration of floating particles (aerosol) in the atmosphere, which has further weakened the solar irradiance arriving at the Earth's surface.

The scientists drew their conclusions from corrective calculations of climate models. In all climate simulations, they looked for periods in which the El Niño/La Niña patterns corresponded to the measured data from the years 1997 to 2012. With a combination of over 20 periods found, they were able to arrive at a realistic estimate of the influence of El Niño and La Niña. They also retroactively applied in the model calculations the actual measured values for solar activity and aerosol concentration in the Earth's atmosphere. Model calculations corrected in this way match the measured temperature data much more closely.

...Despite the warming hiatus, Knutti is convinced there is no reason to doubt either the existing calculations for the climate activity of greenhouse gases or the latest climate models. "Short-term climate fluctuations can easily be explained. They do not alter the fact that the climate will become considerably warmer in the long term as a result of greenhouse gas emissions," says Knutti. He believes that global warming will recommence as soon as solar activity, aerosol concentrations in the atmosphere and weather phenomena such as El Niño naturally start returning to the values of previous decades....

NASA image of a sunspot

Nigeria and UNDP launch national digital flood model

AllAfrica.com via Leadership (Abuja): The Federal Ministry of Environment, in collaboration with the United Nations Development Programme, has launched a National Digital Flood Model for better forecasting and monitoring of flooding nationwide.

The Minister of Environment, Mrs Laurentia Mallam, said this at the public presentation and launch of the instrument in Abuja. Represented by Mrs Rabi Jimeta, the Permanent Secretary in the ministry, Mallam said that it would ensure effective environmental governance and prompt response to impending flood disaster.

She said that the model permits interaction between predicted hydro-metrological data and earth surface conditions such as land use and soil type. However, she said that the major challenge to the use of the model was for it to be adopted in flood management service delivery in the country.

According to her, the forum was organised forum to discuss ways to create awareness among stakeholders on the adoption of the model in flood management. The minister said the launch and public presentation of the model was organised to facilitate interaction among stakeholders on the operations and success of the Flood Early Warning System (FEWS) and the National Digital Flood Model in the monitoring and management of flood in Nigeria....