Saturday, January 14, 2012

Who are the winners and losers in Pacific fisheries?

From: IslandBusiness by: Toss Gascoigne

Pacific nations are under a good deal of pressure to sustain their fish resources and maintain a vital source of food. Now climate change poses a fresh challenge.
A new book, Vulnerability of Tropical Pacific Fisheries and Aquaculture to Climate Change, claims there will be winners and losers from climate change and the way Pacific governments react and adapt is vital.
The book, published by the Secretariat of the Pacific Community (SPC), was launched at the Conference of the Pacific Community in Noumea in November by James Batley, Deputy Director-General of the Australian Agency for International Development (AusAID).
At 900 pages long, the book incorporates the contributions of 88 scientists from 36 institutions and according to Dr Jimmie Rodgers, Director-General of SPC, it is ‘the most comprehensive and up-to-date analysis yet on the likely impacts of climate change on Pacific fisheries and aquaculture and the ecosystems that underpin these activities’.
Lead editor Dr Johann Bell, a Principal Fisheries Scientist at SPC, said the book contains an analysis of the effects of projected changes to surface climate and the ocean on fish habitats, fish stocks and aquaculture.
The book also has a chapter on the implications for economic development, government revenue, food security and livelihoods, and another on adaptations and policies to reduce the threats and capitalise on the opportunities.
Dr Bell said the writing team has prepared a summary for each Pacific Islands country and territory that sets out ways fishing communities and enterprises are expected to be affected, and lists the most appropriate local adaptations and supporting policies.
The effects on fisheries fall into five main areas:
• Changes in the distribution and abundance of tuna
Alterations in ocean temperatures and currents and the nutrients at the base of the food webs in the open ocean (made up of plankton, small fish, squid, etc.) are expected to affect the distribution and abundance of tuna species.
Skipjack, yellowfin and bigeye tuna are likely to move further east. This has implications for how much fish is caught around each Pacific nation, and the supply of fish to canneries in Papua New Guinea, Solomon Islands and Fiji.
It will also affect the amount of government revenue that some of the smaller nations receive from access fees paid by distant-water fishing nations. Countries such as Kiribati, Nauru and Tuvalu, whose governments already depend heavily on these fees, are expected to benefit. More tuna in their exclusive economic zones (EEZs) is likely to result in more licence fees.
Decline in coastal fisheries and coral reefs
Because many species of coastal fish in the tropical Pacific are already living very close to their upper temperature limits, they will have to move to cooler waters as sea surface temperatures rise. Even where coastal fish species can tolerate the rises in sea temperature, many of them will struggle because the coral reefs they depend on will be degraded by ocean acidification and increased bleaching due to higher water temperatures.
Overall, the production of reef-associated fish in the tropical Pacific could decline by 20% by 2050 and by up to 50% by 2100 if high emissions of carbon dioxide continue.
According to Dr Bell, ‘the losers include people who need to continue to depend on coastal fisheries. They will have to find additional sources of food. Higher sea surface temperatures, ocean acidification, and loss of important habitats like coral reefs, seagrass beds, mangroves and intertidal flats are expected to have a dramatic impact on the fish and shellfish that support many coastal communities.’
Increases in freshwater fisheries production
Higher projected rainfall in the tropics will increase the area of fish habitat on the floodplains of large rivers in Papua New Guinea. Increased air temperatures are also expected to have positive effects on the growth rates of many freshwater fish.
Effects on aquaculture
The long-term effects of climate change on aquaculture are likely to be mixed.
Higher water temperatures, sea-level rise, ocean acidification, reduced salinity and increased disease risk could eventually affect the growth and survival of shrimp, pearl oysters, seaweed and ornamental species cultured for the aquarium trade.
On the other hand, increased rainfall and higher air temperatures should increase the number of places where freshwater fish can be grown in ponds, and the growth rates of these fish.
• Increased operating costs
The possibility that cyclones could be stronger increases the risk of damage to shore-based facilities (wharfs, jetties), domestic tuna fishing fleets and processing plants. Fleets operating within the cyclone belt may need to be upgraded. Rising sea levels may eventually make many existing wharfs and shore-based facilities unusable.
Dr Brian Dawson, Senior Climate Change Adviser with SPC, said scientists have a reasonably good idea about where climate change is heading, and what the potential impacts will be, but it may not turn out exactly as expected, so Pacific Islands countries and territories will need to adjust to circumstances.
“There’s a range of adaptations that can substantially reduce the risks and costs, but they need to be tailored to the circumstances. Adaptation is a flexible concept, not a static one.”
He said planning for change is vital, because fish is the single biggest source of animal protein in the Pacific diet. The smaller atoll countries are particularly dependent on fish to meet their daily protein requirements. Exports of fish products, particularly tuna, also provide a large income flow. Anything that reduces those export incomes is going to undermine the ability of Pacific Islands countries and territories to meet their development aspirations.
“The important thing is that there are opportunities for reducing the risks and our vulnerability. Some of these are: managing the coastal zone to protect fish habitats, looking at how to include a greater proportion of tuna into Pacific diets to fill the gap between the fish required for good nutrition and the catches available from coral reefs, and developing freshwater pond aquaculture,” he said.
The average annual consumption of fish by coastal rural populations in the tropical Pacific ranges from 30 to 100 kg per person. Even in urban centres, fish consumption usually greatly exceeds the global average of 16-18 kg per person per year.
Dr Bell said that scientists are seriously concerned about the capacity of coastal fisheries to supply the fish needed for food security.
“Another 115,000 tonnes of fish will be needed to help provide good nutrition for the expanding population of the region by 2030. That’s an increase of 47%,” he said.
Dr Rodgers added, “The reality is that there will be countries in the Pacific with bigger populations and fewer fish to eat. We ignore the book at our peril because it comes up with sound scientific analyses, hard-hitting key messages and policy options. It gives Pacific leaders the opportunity to look 20 years ahead and plan for the future.”

Friday, January 13, 2012

Planned retreat: Getting out of the way of the sea

By Denis Devine, From: Newsworks

A bulldozer moves sand on a beach in Belmar, N.J., in April 2010. New Jersey's coastline has benefited from hundreds of millions of federal dollars spent on rebuilding its beaches, but what happens when the money runs out? (AP Photo/Mel Evans, File)

First in a series

In a region that loves its summers at the Shore, a lot of phrases become familiar: beach tag, salt-water taffy, tear down. Here's one you may not know, but may begin to hear as storms and rising ocean levels continue to batter the coast: "planned retreat."  And its cousin: "rolling easements."

Both terms need some explaining, but they just might be our only hope of keeping the beaches we know and love every summer. And 2012 is a year that these terms will begin to seep into the vocabulary of our shore-loving region.

What terms will be big in 2012? Give us suggestions below.

"We have to ask ourselves, do we really want to hold back the sea everywhere that we’ve developed as sea level continues to rise, or would it make more sense to hold it back some places and not hold it back somewhere else. Well, if you’re not going to hold it back in some places, then one has to ask, how do we go about doing that?"

The man asking the questions is Jim Titus, the U.S. Environmental Protection Agency’s project manager for Sea Level Rise. He’s probably given more thought to answering these questions than anyone else over the last 30 years.
The problem is, Mother Nature apparently wants her beaches back. Big storms are battering the coast, and it seems their frequency is increasing. And the seas are rising. In 2007, the Intergovernmental Panel on Climate Change predicted, conservatively, that the world’s sea levels could rise by as much as 2 feet by 2100. Lately, those same scientists, with better data, are saying that a global sea level rise of 6 feet by then is a more likely worst-case scenario.
Humans have fought coastal erosion in the two main ways:

  • Armoring, through sea walls, big stones and concrete rip rap.
  • Replenishing, by dumping lots of dredged sand back on the beach.

Neither is working very well; neither is a long-term solution. Sea walls protect houses fine, but at the cost of the beach itself. And dumping sand gets really expensive, really fast.
A few years back, the New Jersey Department of Environmental Protection estimated that one decade of beach replenishment on the Jersey Shore, from 1998 to 2007, cost $700 million. And the best estimate for the bill for replenishing the entire Atlantic seaboard’s beaches from sea-level rise came in at $20 billion through the year 2100.
And who’s been footing this bill? Governments, federal, state and local governments, and in case you haven’t heard, they’re not exactly swimming in cash these days.

And thanks to sea-level rise and big storms, beach replenishment projects are getting more frequent and more expensive just when governments can least afford to pick up the tab.
"The first fear one has often is, ‘Oh my gosh the government is at it again, now they’re going to tell everyone to get out of the way of the sea,'" Titus says. "That’s probably actually the last thing that government is going to do. It’s more likely that governments will increasingly just decline to spend the money on holding back the sea. And to some people, a decision to not give you money hurts just as much as the government telling you you have to move, if the only reason you could stay is relying on the government to give you $100,000."
So if penny-pinching municipalities are going to have to somehow start planning a retreat from at least some parts of their shorelines, Titus can suggest some tools to help them do it strategically.
And his best idea is rolling easements, which was spelled out in a report released last summer by the EPA’s Climate Ready Estuaries Program.
You may have heard of conservation easements.
"In many places, nonprofit organizations or governments have purchased conservation easements to prevent farmers from converting these bucolic farms into housing developments," Titus explains. "Well, you could have a conservation easement that simply said on this particular piece of land, the owner cannot build a sea wall or a dike to hold back the sea."
The easement, in this case, would protect the beach, at the expense of the house or built structure it wants to replace.
And this isn’t an abstract concept for Titus: His family owns a home on Long Beach Island.
Now, the worst time to plan for what to do about eroding beaches is right after a storm, with houses destroyed and the news going crazy. But that’s exactly when most of the attention - and money - is spent. Rolling easements are the opposite of knee-jerk rebuilding along the shoreline. They’re a long-term plan for dealing with a problem we can all see coming.

Making difficult sacrifices in the short term to make things better in the long run is not exactly our species’ strong suit.
But because governments at all levels are running out of money, just at the time that the shore needs the most help, it might make planned retreat, and rolling easements, ideas you hear a lot more about in 2012. 

Thursday, January 12, 2012

How to Save Venice: Make It Float


By Scott K. Johnson, Ars Technica

Everyone knows that on a sinking ship, you want to pump water out. But what do you do with a sinking city? In this case, the plan might be to pump water in.

The city of Venice has long been valued for its unique character. Built in a lagoon along the coast of Italy, the scenic city is crisscrossed with canals. Its waterlogged nature draws a steady stream of visitors, but also makes it vulnerable to costly flooding. The region sometimes experiences unusually high tides, locally referred to as “acqua alta.” The phenomenon is caused by winds that drive water to “pile up” on the north end of the long and narrow Adriatic Sea. When that coincides with a high tide, the City of Water gets even wetter, and the water level can rise by 1-2 meters.

Two factors are exacerbating the flooding risk to the city: global sea level rise and subsidence. In short, the sea is rising and the city is sinking. Like other cities built on river deltas, the sediment beneath the city is compacting over time. In a natural setting, this compaction would be offset by the deposition of fresh sediment at the surface, but the rivers feeding the lagoon were diverted in the 1500s. As a result, the land surface is sinking, and the salt marshes are suffering for it.

The pumping of shallow groundwater in the mid-1900s also contributed to the problem. Water in the pores between grains of sediment provides pressure that bears some of the load. When pore pressure decreases, or water is removed completely, grains can be packed together more tightly by collapsing the pore spaces. As sediment is compacted, the land surface drops. While the effect was small (less than 15cm), Venice doesn’t have much wiggle room.

A remarkable system of inflatable gates that could close off the lagoon during dangerously high tides, dubbed the MOSE Project, has been in the works for a while now. Funding issues and environmental concerns have plagued the initiative, but it continues to move forward.

Recently, another idea has been discussed. Just as withdrawing groundwater can cause subsidence, injecting water can reverse it. It’s not entirely a two-way street—much of the pore space lost during compaction can’t be recovered—but increased pore pressure can begin to unpack the sediment. Injection was used successfully in Long Beach, California in the late 1950s to halt subsidence caused by oil and gas extraction as well as groundwater usage. After the land surface dropped nearly 30 feet, injection stabilized the subsidence and a slight rebound in land surface elevation (a little over 30cm) was even seen in some spots. Early research indicated that a similar amount of uplift could be achieved in Venice, which could make a big difference for a city on the edge. The precision of those predictions was limited, however, by the lack of detailed knowledge about the layers of sediment beneath the city.

A new paper, published in Water Resources Research, adds that information and uses it to show that the idea really could work in Venice. Without boreholes around the city to provide observations of the stratigraphy, researchers have relied on data gathered by seismic surveys. Like the familiar sonar systems used by submarines, seismic surveys require a (much more powerful) signal to be generated so its return can be analyzed as it bounces off sediment in the subsurface. That’s been difficult to pull off around Venice, though, as the lagoon is too shallow for large boats to be used. And, attempts to use potent air and water guns as seismic signal sources caused problems by kicking up large amounts of sediment.

Back in the 1980s, though, oil and gas companies hadn’t yet been banned from using explosives in settings like this. The Italian National Research Council acquired a large amount of old, raw seismic data from an Italian oil company, and the researchers were able to use it to construct a high-quality, three-dimensional model of the stratigraphy below Venice. This allowed them to confirm the presence of a continuous layer of impermeable clay below which injected water could increase pore pressure, rather than simply bubble up to the surface. It also allowed them to determine the thickness and extent of the various layers proposed to be used for the injection.

The group simulated the effects of 12 injection wells in a ring around the city. The results showed that, after 10 years of continuous seawater injection (a total of almost 150 million cubic meters of water), the city could be lifted 25-30 centimeters. That would greatly cut down on the frequency with which the MOSE floodgate system would have to be activated each year. That, in turn, decreases operational and maintenance costs, and reduces the ecological impact of the system. In addition, the uplift around the city would benefit the slowly-drowning salt marshes in the lagoon.

The study also shows that by varying the pumping rates at each of the 12 wells, a very uniform uplift can be maintained across the city. If some areas of the city rise faster than others, buildings could be damaged—a result that would be counterproductive to the entire enterprise. With careful management, the researchers say that the difference in uplift between two points 100 meters apart would be less than 1 millimeter.

While it may initially sound far-fetched, this could become part of Venice’s plan to mitigate flooding issues, which will only worsen in coming decades. Battling “acqua alta” would be much easier if the city had the high ground.

Image: Daveybot/Flickr

Source: Ars Technica

Citation: “A new hydrogeologic model to predict anthropogenic uplift of Venice.” By P. Teatini, N. Castelletto, M. Ferronato, G. Gambolati and L. Tosi. Water Resources Research, Vol. 47, W12507, Pg. 17, Dec. 7, 2011. DOI:10.1029/2011WR010900

Tuesday, January 10, 2012

Cebu City faces multiple climate change threats – WWF-BPI study

By: Earl Victor Rosero, From: GMA News

Only 21 of the many storms that hit the country from 1990 to 2010 affected Cebu City and more than half of those came in November and December, but other climate change effects threaten the Philippines' second-largest business capital and among them are landslides, flooding, saltwater intrusion, and sea level rise, according to a recently released study.
The World Wide Fund for Nature (WWF) – Philippines and the Bank of the Philippine Islands took a close look at the climate factors that influence life in Cebu City and three other cities.
Their study noted that while ”the city reports that it sits 18 meters above sea level (ASL), several districts of the old city are barely 1 to 2 meters ASL. This includes the neighboring island of Mactan where the province’s only commercial airport is located.”
“Saltwater intrusion, due to excessive groundwater extraction, has long been a problem here.  Relatively recent studies indicate that saltwater intrusion has been reported 5 kilometers inshore,” the climate change study added.
Zoning violations put people at risk
WWF Philippines and BPI also learned that non-compliance with land use standards allow the building of homes in areas where there should be none.
“Only 28 % of Cebu City’s land area falls within the range acceptable for human settlement or cultivation.  It is a matter of concern, therefore, that about 64% of city lands are classified by the national government as alienable and disposable,” the study said.
One-fourth of Cebu City’s barangays have a “high threat” level for landslides while another 16 percent of the villages face moderate landslide risk.
“Flooding is a high threat for 6 barangays and a moderate threat for 18 barangays of Cebu City.  This represents 8% and 22% of all barangays, respectively,” the study also said.
WWF Philippines and BPI also point out that “23 of the city’s 80 barangays are totally or partially located in four watershed areas” and some of them are located within “critical watersheds and other protected areas of the city, such as the Central Cebu Protected Landscape (CCPL).”
The study warned of business disruption because “it is already evident that Cebu City’s climate patterns indicate high inter-annual variability, with extreme weather events at both ends of the wet-dry spectrum.”
It challenged Cebu city’s leaders and communities to invest in “climate smart infrastructure and technology” and to rethink its development priorities lest it be  “caught in a ‘climate sandwich’ as saltwater intrusion advances further, sea levels rise and more intense typhoons lash the coastline with storm surge." — GMA News

Monday, January 09, 2012

Stronger but fewer cyclones for Australia says CSIRO scientist

From: indymedia

New research by CSIRO scientists is showing a trend for fewer tropical cyclones forming off the Western Australian coast, but those that do form may become more intense and potentially destructive. The results apply across the Australian region according to CSIRO in an interview with Dr Debbie Abbs from CSIRO Marine and Atmospheric Research.

Dr Debbie Abbs said there could be a 50 percent reduction in the number of storms in the second half of this century - from 2051-2090 - compared to the period from 1971-2000. The climate model developed by Dr Abbs' team also indicates a distinct shift towards more destructive storms. "Despite a decrease in the number of tropical cyclones, there is a greater risk that a tropical cyclone that forms will be more severe in future," Dr Abbs said. "Even a small increase in cyclone intensity is concerning because of the threat to life, property, industry and agriculture," said Dr Abbs in a CSIRO media release.

The research work is being done on behalf of the Indian Ocean Climate Initiative (IOCI) which is a strategic research partnership between the WA government, CSIRO and the Bureau of Meteorology.

Tropical cyclone formation is a complex process which scientists are continuing to study, with global long term trends in cyclone frequency still difficult to determine from natural variability. Sea surface temperatures, wind shear, temperature and humidity of the atmosphere all contribute to cyclone formation and behaviour.

It was once thought that elevated sea surface temperatures alone would increase cyclone frequency, but this has proved not to be the case. "In the early days of climate research we thought that increase in sea surface temperatures would result in more tropical cyclones. However in the world that we live in today cyclones are due to more than just high sea surface temperatures." said Dr Debbie Abbs from CSIRO Marine and Atmospheric Research.

"If we get changes in either the wind shear or in the temperature and humidity characteristics of the atmosphere, then that will affect the ability of the atmosphere to form tropical cyclones, and we find that is happening, but the relative contributions are still under investigation. Some of our climate models say that it's the shear is the most important, and other climate models say it's the temperature and humidity characteristics that are the most important." said Dr Abbs.

The results apply not only to western Australia but the whole Australian region according to Dr Abbs. "Our modelling shows a very consistent picture of decreases in cyclone occurrence across the Australian continent as a whole."

The cyclones that do form are likely to be larger and of greater intensity, said Dr Abbs, "There's a greater likelihood, or greater risk, that the cyclones that do form will form in the category three, four and five level. To say that they'll be Cyclone Yasi is pushing it a little bit too far, but there's a greater risk that they will be at that level."

The destructive potential of cyclones will increase with a change in the size of tropical cyclones according to the research, "We're finding larger cyclones, and that's cause for concern because it's the size of cyclones that affects the destruction from waves and storm surge." said Dr Abbs.

Caption: Storm surge graph for Cyclone Grant in 1999 at Exmouth,
Western Australia. Copyright BOM.

Low lying Pacific Island nations are particularly vulnerable to Storm surge and extreme sea levels generated by cyclones. A December 2011 paper by Kevin Walsh, Kathleen McInnes and John McBride - Climate change impacts on tropical cyclones and extreme sea levels in the South Pacific -- A regional assessment (abstract) published in Global and Planetary Change, reviews the current understanding of the effect of tropical cyclones and climate change on extreme sea levels in the South Pacific region.

"The most extreme sea levels in this region are generated by tropical cyclones. The intensity of the strongest tropical cyclones is likely to increase, but many climate models project a substantial decrease in tropical cyclone numbers in this region, which may lead to an overall decrease in the total number of intense tropical cyclones.

...While storm surges from tropical cyclones give the largest sea level extremes in the parts of this region where they occur, other more frequent high sea level events can arise from swell generated by distant storms. Changes in wave climate are projected for the tropical Pacific due to anthropogenically-forced changes in atmospheric circulation. Future changes in sea level extremes will be caused by a combination of changes in mean sea level, regional sea level trends, tropical cyclone incidence and wave climate."

The CSIRO and Bureau of Meteorology issued a major new report in November 2011 on Climate change in the Pacific, scientific assessment and new research in which they say that many Pacific Island nations will experience higher temperatures, sea level rise, and changing rainfall.

There is also a trend for cyclones moving further south, so far by about one degree or 100 kilometres. "So that means that when they eventually peter out or decay it's going to be a little bit further south than we expect today." said Dr Abbs.

Larger cyclones of greater intensity will have a major impact on human structures. Adaptation regimes need to be considered to avoid disasterous impacts such as ocurred recently with Cyclone Sendong (Washi) causing torrential rain then flash flooding in the Philippines resulting in over 1500 deaths. The Guardian has reported that the torrential rain and flash flooding circumstances were predicted in 2009 as part of a UN exercise in disaster reduction planning. The Philippines government never got around to implementing a plan to reduce this hazard.

The Bureau of Meteorology also reports on Cyclone frequency and intensity:

There have been three recent studies producing projections for tropical cyclone changes in the Australian region. Two suggest that there will be no significant change in tropical cyclone numbers off the east coast of Australia to the middle of the 21st century. The third study, based on the CSIRO simulations, shows a significant decrease in tropical cyclone numbers for the Australian region especially off the coastline of Western Australia. The simulations also show more long-lived eastern Australian tropical cyclones although one study showed a decrease in long-lived cyclones off the Western Australian coast.

Each of the above studies finds a marked increase in the severe Category 3 - 5 storms. Some also reported a poleward extension of tropical cyclone tracks.

Caption: Graph showing the number of severe and non-severe
tropical cyclones from 1970 - 2005. Copyright BOM.

The work of Dr Abbs and others has been referred to The Institute of Engineers to adapt building and other civil engineering structure specifications. "The Institute of Engineers is using information related to our work to upgrade their technical specifications for wind loadings for buildings. Another part of the Institute of Engineers are revising the Australian rainfall and runoff, and that's used to design major dams, and subdivisions, gutters, and so on, drainage. They're interested in upgrading their technical specifications related to change in extreme rainfall, and for many parts of northern Australia extreme rainfall is due to tropical cyclones."

The research also feeds in to State Government and Local Government planning for storm water disposal, flood mitigation and protection of buildings from storm surge in the future.

The Intergovernmental Panel on Climate Change (IPCC) Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) released in November 2011 said there are still too many uncertainties for attribution of a single cyclonic event to human causation. "The uncertainties in the historical tropical cyclone records, the incomplete understanding of the physical mechanisms linking tropical cyclone metrics to climate change, and the degree of tropical cyclone variability provide only low confidence for the attribution of any detectable changes in tropical cyclone activity to anthropogenic influences."

The SREX predicted for Tropical cyclones that "Intensity may increase but frequency may stay the same or even decrease. Wind speeds likely to increase, although perhaps not in all ocean basins. Medium confidence in a projected poleward shift of extra-tropical storm tracks, and a reduction in the average number of extra-tropical cyclones."

Statistical modelling by Kuleshov et al from the National Climate Centre, Bureau of Meteorology published in January 2010 in the Journal of Geophysics Research found that there was no apparent trends in the total number or intensity of Tropical cyclones in the Indian Ocean, South Pacific and Australian regions. (See abstract)

However a 2010 paper in Nature Geoscience by Thomas R. Knutson et al on Tropical cyclones and climate change (abstract), found that:

"...high-resolution dynamical models consistently indicate that greenhouse warming will cause the globally averaged intensity of tropical cyclones to shift towards stronger storms, with intensity increases of 2-11% by 2100. Existing modelling studies also consistently project decreases in the globally averaged frequency of tropical cyclones, by 6-34%. Balanced against this, higher resolution modelling studies typically project substantial increases in the frequency of the most intense cyclones, and increases of the order of 20% in the precipitation rate within 100 km of the storm centre. For all cyclone parameters, projected changes for individual basins show large variations between different modelling studies."

Karl Braganza, David Jones and Yuri Kuleshov, climatologists from the Bureau of Meteorology, also state the difficulty in determining trends for cyclones in a December 2011 article on The Conversation website - Australia expecting an active cyclone season, but future cyclones still hard to predict - but conclude that climate modelling of global warming predicts a trend for fewer storms but an increase in storm intensity:

For large increases in greenhouse gases, extensive climate modeling has pointed to some consistent future changes. Future projections based on physics and using high-resolution dynamical models consistently indicate that greenhouse warming will cause the globally averaged intensity of tropical cyclones to shift towards stronger storms. The average intensity will increase with global warming.

Existing modeling studies also consistently project decreases in the globally averaged frequency of tropical cyclones. In other words, there will be fewer overall storms.

However that is balanced against the projected increases in the frequency of the most intense cyclones as global warming intensifies. This suggests a future world where tropical cyclones are less frequent, but those storms which do occur are more dangerous.

So, the long term prognosis is fewer tropical cyclones making landfall, but the ones that do are likely to be more powerful and more destructive. Climate Adaptation measures will be important to reduce the risk to people. Disaster management planning will be important along with upgrading planning and building regulations to take account of increased wind speed, flash flooding, and extreme sea level due to storm surge associated with Category 3-5 tropical cyclones. While we may be able to reduce the risk to people, agriculture will certainly suffer from the impacts of more intense cyclones with stronger winds.

More Information:
Skeptical Science - What is the link between hurricanes and global warming? (2010) - includes links to several related scientific sources and summaries.

Sunday, January 08, 2012

Sea Level Rise Drove Out Albatross

Source: Bernews

Researchers who unearthed the first fossilised breeding colony of albatrosses in Bermuda in 2003 concluded a massive jump in sea level — to more than 65 feet above its current height — drove the birds out 400,000 years ago.

No albatrosses live in Bermuda today or anywhere else in the North Atlantic.

After the Bermuda colony was discovered at the Government Quarry, Storrs Olson of the National Museum of Natural History in Washington DC told the British magazine:  ”Nature” that albatrosses would probably still be there if we hadn’t had the rise.”

Future rises, perhaps due to global warming, could take a similarly heavy toll on birds and other shore dwellers warned Mr. Olson.

All of the Bermuda birds were short-tailed albatrosses [pictured at top]. This critically endangered species is now found on only a few islands off Japan, having been all but wiped out by feather-collectors a century ago.

Elsewhere, albatrosses are under threat from accidental killings by long-line fishing.

The birds breed on islands, on open land by the sea. Their taste for wind-swept nesting sites makes them unlikely fossils. The Bermuda colony was entombed under several metres of sand in a single storm, burying adults, eggs and chicks.

“People have always wondered whether there was a North Atlantic breeding colony, and where they might have been,” ecologist Richard Phillips of the British Antarctic Survey told “Nature”.

The Bermuda colony was swamped at around the time that the West Antarctic Ice Sheet melted, causing a dramatic rise in sea level.

This would have flooded all of the good breeding sites on Bermuda, as well as those on many other islands.

A real sea change

From: Scientific American Blog

By Mathew Stutz

International diplomats met two weeks ago at the UN Durban Climate Change Conference in South Africa to discuss a greenhouse gas reduction plan—displaying no urgency to reach any meaningful agreement. Meanwhile, researchers at the American Geophysical Union annual meeting in San Francisco are reporting what many scientists have suspected for a long time but have been thus far not been able to prove convincingly—that the world’s sea level is likely to rise by at least 3 feet in the next 100 years.

The vast Greenland ice sheet is melting at an increasingly rapid rate—much faster than most conservative estimates made by, among other authorities, the UN’s own Intergovernmental Panel on Climate Change (IPCC). In the last decade, scientific technologies have made fast advances toward more confident and precise measurements of the complex changes in the Greenland ice sheet.

Previous estimates by the IPCC were kept low because there was so much uncertainty in the measurements. Many suspected it was melting faster, but at best could only support such claims anecdotally. This scientific uncertainty has been cast erroneously by some as evidence that the risk of glacial melting was being exaggerated. It was always a distinct possibility that the ice sheets were melting more rapidly.

What’s more worrying is the range of possibilities is growing larger. Due to the nonlinear behavior of melting ice, a slight increase in the rate of melting now would result in an enormous difference in how much ice melts over the next 100 years. You can relate this powerful effect to how much a homeowner saves from a 1-2% drop in interest rates over the life of a 30-year mortgage.

Think of it this way—if sea level is forecast to rise 1 foot, it is really a mid-range estimate between 0.5 feet and 2 feet. If the mid-range estimate is now 2 feet or even 3 feet, the possible range suddenly expands from 1.5 to 6 feet. Our coastal inhabitants and managers must be able to comprehend the scope of what such a change would mean for us.

We can look to Louisiana to see a parallel. The Louisiana coast, made up of the expansive Mississippi Delta, has been ground zero for an ongoing coastal catastrophe for decades. Due to numerous man-made alterations, the delta is sinking, that is the sea level is rising, as much as 3 feet per century (leaving some portions of New Orleans 10 feet below sea level). As a result, one football field-sized area drowns on the Mississippi Delta every hour, 15 square miles every year.

At one time Louisiana had numerous strings of sandy barrier islands along the delta, some having served as popular resorts as far back as the mid- 1800’s. Those that remain today are shifting landward and shrinking in size faster than any other barrier islands in the lower US. Hurricanes have finished off most of the Chandelier Islands, Timbalier Island, and Isles Dernieres—and the remaining ones will eventually suffer the same fate.

The Chesapeake and the Albemarle-Pamlico estuaries are the next largest coastal wetland systems in the US. If the Mississippi Delta barrier islands and wetlands give us any insight about the future of the Outer Banks and the Albemarle-Pamlico system, they don’t stand a chance facing 3 feet of sea level rise.

The Outer Banks of North Carolina differ significantly from Louisiana’s barrier islands. Louisiana never had one continuous unbroken line of islands; the Outer Banks are wider and higher in many places. We may not see a total collapse of the entire Outer Banks but it is a virtual certainty that we will see the islands migrating toward the mainland. Patch-up jobs will not suffice. Within the sounds, the marsh and swamplands will disappear in a similar fashion to the Louisiana marshes.

There is no credible reason to believe that sea level will not continue to rise indefinitely. The year 2100 is not the end of time. Will 3 feet become 6 feet or 10 feet? There is enough ice in the Greenland ice cap to raise sea level by 20 feet, and Antarctica has 10 times more ice than Greenland. Whatever happens centuries from now, the immediate future has enough potential for catastrophic change that we can’t just bury our proverbial heads in the sand and hope that we can patch up our beaches or stick our fingers in the dike.

It is time to make bold and innovative changes to our future economic and environmental planning for our coast. In the past we worried about saving a few beach houses; we must see that the news we are receiving now threatens our entire coastal economy.

Cape Hatteras, North Carolina area as seen from Apollo 9

This imagery was acquired by the NOAA Remote Sensing Division to support NOAA national security and emergency response requirements. In addition, it will be used for ongoing research efforts for testing and developing standards for airborne digital imagery.  Individual images have been combined into a larger mosaic and tiled for distribution. The approximate ground sample distance (GSD) for each pixel is 50 cm (1.64 feet). Image file size is between 1 MB and 6 MB and covers 2.5 by 2.5 kilometers (1.55 miles.). NASA JSC Digital Image Collection

Mathew StutzAbout the Author: Mathew Stutz is an assistant professor of geoscience at Meredith College in Raleigh, NC. Stutz recently conducted a global survey with researchers at Duke University that found the Earth has 657 more barrier islands than previously known. His research also examines how climate change impacts the formation and evolution of these islands.