Archive for the ‘Adapting to climate change’ Category

The Ever Rising Seas

Tuesday, February 23rd, 2016

Since 1970 more than 90% of the extra heat trapped by the Earth as the climate warms has been absorbed by the oceans. The oceans respond more much more steadily than the terrestrial surface climate: they give us the real, underlying picture of the warming of the planet.

We have known for a long time that as the sea warms, sea levels rise – partly from melting ice sheets and glaciers, partly from thermal expansion, and partly for other reasons. People living in coastal regions know too this all too well they experience tidal flooding increasingly often.

Global mean sea level rise from 1970 until now has been at about 2.8 mm per year, but this graph hides the huge regional variation that exists. (noaa.gov)

Global sea level rise from 1970 until now has been at about 2.8 mm per year, but this graph hides the huge regional variation that exists.(noaa.gov)

We also know that sea levels are rising at surprisingly different rates around the globe. We’re starting to understand why.

A new study, using remarkable satellite radar altimetry and satellite gravimetry data starting in 2002, teases apart the various drivers of sea level. And it contains surprises.

In addition to thermal expansion (the ‘steric’ component), and meltwater from Greenland, Antarctica and land based glaciers, other contributors to sea level changes are hydrology (involving the water cycle of evaporation, precipitation and run-off), glacial isostatic adjustments (GIA), and a component called ocean bottom pressure (OBP)

Ocean bottom pressure refers to the weight of all the water on the bottom, ocean’s version of atmospheric pressure. It varies with tides, currents, winds, and water entering and leaving basins, and it changes over oceanic regions both seasonally and annually. It is difficult to incorporate into the picture, but the satellite gravimetry makes it possible, and it is an important driver.

The various contributing components to the rise of sea levels from 2002-2014. The lines are offset for clarity: the critical information lies in their slopes (pnas.org)

The various contributing components to the rise of sea levels from 2002-2014. The lines are offset for clarity: the critical information lies in their slopes (pnas.org)

The overall view? From 2002 to 2014, ocean levels rose globally by an average of 2.74 mm/yr (the steepest, thicker grey line). Of that, 1.38 mm was the result of the thermal expansion of the warming water (the top orange line), and 1.37 mm the result of melting glaciers and ice sheets (the green, light blue and darker blue lines). Other contributors such as OBP and GIA appear on average to be variable and less important, while hydrology (the bottom green line), slopes downward, indicating a loss of water from the oceans to the land due to more rainfall, floods, groundwater loss, irrigation, and reservoirs, and so less runoff back into the oceans.

But those are global means, of little help for warning or advising coastal regions of what’s ahead.

This new study goes a lot further. It shows us not only how great is the regional variation in sea level rise, but also how much the various drivers vary in their contribution. The biggest surprise is that thermal expansion, the steric component, is about twice as great as previous estimates: sea levels are rising faster than we had thought.

The relative contribution of the drivers of sea level change can be depicted in pie charts. The same colors indicate the various contributors: steric=orange, meltwater=2 blues and light green, Glacial Isostatic Adjustment (GIA)=purple, ocean bottom pressure (OBP)= light brown, hydrology=dark green. (pnas.org)

The relative contribution of the drivers of sea level change can be depicted in pie charts. The same colors indicate the various contributors: steric=orange, meltwater=2 blues and light green, Glacial Isostatic Adjustment (GIA)=purple, ocean bottom pressure (OBP)= light brown, hydrology=dark green. (pnas.org)

The variation around the world is striking, to say the least. Look at the Philippines with mean sea level rise of a whopping 14.7 mm/yr, and Indonesia with 8.2 mm/yr. Thermal expansion of the warming water is the overwhelming contributor.

Components of sea level rise around Asian coasts The boxed number on each pie chart is the mean sea level rise, mm/year.(pnas.org)

Components of sea level rise around Asian coasts. The boxed number on each pie chart is the mean sea level rise, mm/yr.(pnas.org)

The Northwest Atlantic (eg the east coast of the US) is the other region with the most rapidly rising sea level at 9.1 mm/yr) where glacial isostatic adjustments (GIA) still play a strong role: the land continues to subside from the elastic rebound following its release from glaciation. In contrast, along the west coast of the Americas and unlike most of the rest of the world, the sea level isn’t changing in any significant way.

Contributers to sea levels around the Americas. (pnas.org)

Contributers to sea levels around the Americas. (pnas.org)

Obviously seasonal, annual and decadal variation in winds and currents play a critical role in modifying steric and OBP contributions, but the data appear to be robust and the general picture is likely to hold: the global average rise in seal level is accelerating, the steric component is greater than we expected, and global variation in rates of sea level rise are remarkable.

It is this last statement that is perhaps most important for the coastal countries of the world to absorb. Rising sea levels are already affecting some regions far more quickly than others.

What can we do about this? We cannot at this stage reverse the rise, and we probably won’t not be able to slow it for a very long time. warming sea water will continue to expand, polar ice sheets and glaciers will continue to melt.

What’s left is for us to adapt as intelligently as we can, pulling back from our current threatened shorelines.

Current hotel construction on Clearwater Beach, Tampa Bay, west coast of Florida (tampabay.com)

Current hotel construction on Clearwater Beach, Tampa Bay, west coast of Florida (tampabay.com)

Or we can continue to be really short-sighted, greedy and ignorant.

Invasion of the King Crabs

Friday, November 20th, 2015

We’re increasingly familiar with the idea that in the marine world as the sea gets warmer, organisms will move north (or south) to higher latitudes to escape the growing heat. Much less familiar is the idea that in some places animals from very deep water will move into more shallow areas, and create havoc with the ecosystem existing there.

Enter King Crabs. These are large, sometimes huge, made at least a little famous by Alaskan King Crabs that starred in the reality show The Deadliest Catch. Around the globe, they tend to live in very cold, deep water, preying on bottom living mollusks, echinoderms and other crustaceans by crushing them.

Alaskan King Crabs are abundant on the sea floor of the Gulf of Alaska, the target of one of the world's more risky fisheries (freerepublic.com)

Alaskan King Crabs are abundant on the sea floor of the Gulf of Alaska, the target of one of the world’s more risky fisheries (freerepublic.com)

A couple of other species live on the Continental Slope along the West Antarctic Peninsula, seaward of the more shallow Continental Shelf, mostly at depths between 2000 and 800 meters where water temperature varies from 0.4 degree C up to a balmy 1.16 degree C.

Like other King Crabs, they can tolerate very cold water, but there is a limit. They function well down to about 1 degree centigrade, but when the temperature is colder than about half a degree C, their magnesium physiology breaks down and they become paralysed and die.

Antarctic King Crab, Neolithodes yaldwini. The male is the larger one, guarding a female who he will mate with as soon as she molts (Katrien Heinman, nature.com)

Antarctic King Crab, Neolithodes yaldwini. The male is the larger one, guarding a female who he will mate with as soon as she molts (Katrien Heinman, nature.com)

Though that is certainly cold, sea temperatures on the adjacent more shallow Antarctic Continental Shelf remain even colder, a little below zero in all seasons, creating a lethal ceiling above the King Crabs deeper on the Slope.

This is all a relatively recent phenomenon. About 40 million years ago when the force of continental drift finally pushed Antarctica free from South America, the Antarctic Circumpolar Current formed, isolating the Southern Continent from the influence of more northerly warmer water, freezing the glaciers on the continental mass, and super-cooling the shallow seas on the Continental Shelf.

The Antarctic Circumpolar Current formed 40 million years ago, isolating and freezing Antarctica (globalspec.com)

The Antarctic Circumpolar Current formed 40 million years ago, isolating and freezing Antarctica (globalspec.com)

For 40 million years, King Crabs have not been able to penetrate the colder shelf waters, and nor have predatory bony fish, sharks or rays, also unable to tolerate such cold temperatures. For 40 million years, the bottom living animals, mostly suspension feeders except for some predatory starfish and worms, have become lightly skeletized, soft, in the absence of the shell-crushing predators.

They remind us of the bottom living Paleozoic community last seen before fish (and King Crabs) evolved, 350 million years ago, a rare and possibly unique ecosystem today.

The animals living on the sea floor on the Antarctic Continental Shelf are unusual, soft-bodied echinoderms, mollusks and worms, susceptible to predation by King Crabs (nature.com)

The animals living on the sea floor on the Antarctic Continental Shelf are unusual, soft-bodied echinoderms, mollusks and worms, susceptible to predation by shell-crushing King Crabs (nature.com)

But of course now things are changing. The Antarctic seas, especially around the West Antarctic Peninsula, are warming unusually quickly. Stronger winds, driven by climate warming, intensify the Antarctic Circumpolar Current, lifting warmer, denser, saltier water up from 4000 m over the lip of the Shelf and spilling into deeper canyons.

Marguerite Bay, West Antarctic Peninsula, where King Crabs have begun to appear in the deeper water canyons on the Shelf (pnas.com)

Marguerite Bay, West Antarctic Peninsula, where King Crabs have begun to appear in the deeper water canyons on the Shelf (pnas.com)

King Crabs are moving up into some of these canyons. The cold water ceiling above them on the Shelf is still there, but it is rising. Over the next decades – perhaps sooner than later – King Crabs will invade the rest of the Shelf.

The diverse deskeletized animals now living there will be then be history for they have no defenses against the King Crabs. The current fragile ecosystem will be disrupted, shifting toward something probably very similar to deep cold-water ecosystems elsewhere where King Crabs thrive.

At depths where King Crabs are common (black bars) potential prey (the other bar graphs) are greatly reduced (pnas.com)

At depths where King Crabs are common (black bars) potential prey (the other bar graphs) are greatly reduced (pnas.com)

This loss of an unusual ecosystem will be unfortunate, but there are obvious limits to our ability to be the stewards we might like to be. Clearly we have much more immediate and pressing problems to deal with. Still, we do know that there is so much that we but dimly understand about our current ecosystems, and as a result much of the change that lies ahead is simply unpredictable.

At least we can now add to the mix the idea that marine ecosystem change can come from any direction, including from below.

Enjoy your King Crabs – they look like survivors.

Enjoy your meal (clubnews.com)

Enjoy your meal (clubnews.com)

Global Bleaching of Corals. Again

Thursday, October 22nd, 2015

When water temperatures rise a degree or two, corals expel their symbiotic algae – zooxanthellae – and turn white. It happens frequently on a local scale, and the affected corals usually recover when the sea cools again.

When bleaching occurs, symbiotic algae are lost, the coral (this one is a brain coral) will die and crumble unless sea temperature drops and the zooxanthellae can recolonize the coral (compareinnovationtoronto.com)

When bleaching occurs, symbiotic algae are lost, the coral (this one is a brain coral) will die and crumble unless sea temperature drops and the zooxanthellae can recolonize the coral (compareinnovationtoronto.com)

Summer sea surface temperature just one degree warmer than usual, lasting for 4-6 weeks, is enough to start the bleaching – corals clearly live, and thrive, at temperatures close to those that bleach and kill them.

When much of the sea surface around the tropics remains warmer for a prolonged period, the bleaching spreads, corals die and reefs are heavily damaged. The last really major global bleaching event occurred in 1997-98, while a less extensive one occurred in 2010.

A now iconic picture of part of a reef in Samoa taken before and after the onset of the current global bleaching event (sciencealert.com)

A now iconic picture of part of a reef in Samoa taken before and after the onset of the current global bleaching event (sciencealert.com)

And now, starting before the current El Nino emerged and compounded by the huge, warm ‘Pacific Blob’, we are well into another global bleaching event. With the current El Nino now growing into something fierce, this bleaching event could last a couple of years, long enough to kill and crumble a lot of the corals.

NOAA has produced a remarkable, satellite-based interactive global coral watch website, where you can observe the conditions change over the next few months. It’s scary, but it’s fascinating.

Coral bleaching isn’t new, but the 1997-1998 event was the greatest in hundreds, perhaps thousands of years. Now we have another of the same or greater magnitude. Again most reefs will be damaged. Last time, global loss was about 10%. This time it will be as much or more. It is a devastating prognosis.

NOAA October 2015 prediction of 60% probability of coral bleaching over the next four months (coralwatch.noaa.gov)

NOAA October 2015 prediction of 60% probability of coral bleaching over the next four months (coralwatch.noaa.gov)

Some protective efforts that would reduce other sources of stress on the reefs are possible, for instance reducing both pollution and overfishing, especially of algal grazers. Closing reefs to all fishing would be best. Unlikely perhaps, but not impossible.

We can as well look for other lines of hope. For instance, corals vary latitudinally in their tolerance of thermal stress, and there appears to be a genetic basis to this variation. In tanks at the National Sea Simulator at Melbourne, biologists are growing different strains of coral species under conditions of warmer temperatures and higher acidity, hoping to select for those more tolerant of the coming conditions, planning then to seed them back on the reefs. Of course this is worth doing.

Sea surface temperatures have been higher than normal for the past year, not related to the Pacific Blob or to El Nino. Now they will remain high or higher as the El Nino heat spreads and lingers (dnlr.hawaii.gov)

Sea surface temperatures have been higher than normal for the past year, not related to the Pacific Blob or to El Nino. Now they will remain high or higher as the El Nino heat spreads and lingers (dnlr.hawaii.gov)

Yet the Great Barrier Reef covers 135,000 square miles and since 1985 half of its coral cover has been lost; little remains of Caribbean coral reefs; the coral reefs around Hawaii and elsewhere in the Pacific have never been under such stress. The future of coral reefs is really bleaker than ever.

For now, the Pacific Blob will eventually dissipate. The new El Nino will slowly play itself out. Sea temperatures will drop back at least in the direction of normal. Parts of coral reefs not too damaged should slowly recover once again.

But we are warned: sea temperatures rising because of climate change rather than El Ninos will not revert to past ‘normal’ temperatures. At best their rise can be slowed by enlightened global agreement to curtail the emission of greenhouse gases,

The current global coral bleaching event is growing as we head into December’s UN Conference on Climate Change in Paris – a conference that is perilously close to being our last chance to take significant global action. Threatened, damaged, bleaching, crumbling coral reefs are not a bad metaphor for the state of our planet’s climate to remind global politicians that no longer can we afford politics as usual.

 The very odd logo for the UN Conference on Climate Change, COP 21, Nov 30-Dec11: the whole world will be watching (unfccc.int)

The very odd logo for the UN conference on Climate Change, COP 21, Nov 30-Dec11: the whole world will be watching (unfccc.int)

They – we – really have to do it this time.

Old Dominion Leads the Way

Saturday, March 21st, 2015

Old Dominion University is in Norfolk, Virginia, a small city right on the edge of the entrance to Chesapeake Bay. It is part of a metropolitan area of almost 2 million people called Hampton Roads that also includes Newport News and Virginia Beach.

Hampton Roads is one of the two most vulnerable metropolitan areas in the US to rapid sea level rise (the other is New Orleans).

Sea level is rising at about twice the rate of the global average along the coast north of Cape Hatteras, centered on Chesapeake Bay (sciencenews.org)

Sea level is rising at about twice the rate of the global average along the coast north of Cape Hatteras, centered on Chesapeake Bay (sciencenews.org)

Hampton Roads , a complex metropolitan region at the mouth of Chesapeake Bay (hamptonroadsof.org)

Hampton Roads , a complex metropolitan region at the mouth of Chesapeake Bay (hamptonroadsof.org)

Global sea levels rise as a result of the melting land-based glaciers of Greenland and the West Antarctic Peninsula as well as the thermal expansion of warming waters – an average of 22 cm (8 in) since 1930. What makes Hampton Roads of special interest is that sea levels there are rising twice as fast as the average.

Old Dominion University has established the Center of Sea Level Rise and the Mitigation and Adaptation Research Institute (MARI). It has chosen to be in the thick of it all.

Why such rapid sea level rise? And why there?

Partly it is because the land in that region is also sinking – the mile thick glaciers of the last glaciation did not reach so far south, but they compressed the land they did cover, forcing the land beyond them to bulge up. Since the glaciers withdrew, the land they compressed has risen again, while the bulge to their south is still falling back to its pre-glaciation state. Along with subsidence of the land from extraction of groundwater, this accounts for about half of the current rapid rise of sea level.

Sea level rise north of Cape Hatteras is about half due to recent climate change, and about half due to the land level readjustments following the retreat of the glaciers (americanroads.us

Sea level rise north of Cape Hatteras is about half due to recent climate change, and about half due to the land level readjustments following the retreat of the glaciers (americanroads.us

So Hampton Roads has immediate challenges, finding ways to adapt to the sea level rise sooner than most coastlines elsewhere. Coastal beaches and wetlands will certainly deteriorate, and the low lying parts of the coastal cities will be flooded. Norfolk is especially vulnerable. Pretty well everyone living there now knows this.

Old Dominion has taken the lead in a pilot project aimed at developing a comprehensive government and community cooperation in preparing for further sea level rise in Hampton Roads. In the past couple of weeks MARI has hosted seminars involving residents and state officials, focusing on resilience and environmental engineering and on perceptions of climate change and sea level rise, encouraging a willingness to address change.

In the past year it held a Rising to the Challenge Conference on sea level rise with strong bipartisan support from Congressional ans State politicians – in itself a rare and extraordinary event.

And everything, in the context of preparedness and resiliency, is on the table: tide gates, levees, flood walls, raised buildings and roads, marshes created to absorb storm surge, abandonment of low lying areas, elimination of subsidized flood insurance – the list is very real and very serious. The cities of Washington,D.C., Baltimore and Philadelphia all have reason to be watching closely.

Part of the US navy of 2012 at Norfolk Naval Base - which covers 4 miles of coastline and has 7 miles of piers (wikipedia.org).

Part of the US navy of 2012 at Norfolk Naval Base – which covers 4 miles of coastline and has 7 miles of piers (wikipedia.org).

And then there is the military. Nearby is the Norfolk Naval Base, the world’s largest naval base. Old Dominion has also recently hosted discussions by the military on how to prepare the naval base for the tidal flooding and extreme storm surges associated with sea level rise, while contemplateing the immense upheaval of having to move.

Meanwhile, home owners in the lowest parts of Norfolk can find no buyers for their homes, and as one pastor says
“I don’t know many churches that have to put the tide chart on their Web site so people know whether they can get to church.”

So: Go, Old Dominion. The whole world isn’t watching, but probably should be.

(iawrestle.com)

(iawrestle.com)

The Shift North in the Gulf of Maine

Wednesday, January 14th, 2015

The Big Shift North continues unabated in the Gulf of Maine.

In November 2014, cod fishing in the Gulf was banned. Some cod are still there but they are concentrating in colder, deeper water. Fishermen think this is just another conspiracy among scientists and regulators to keep their jobs, and think there are plenty of fish out there. There aren’t. Whatever cod are left from hundreds of years of overfishing and mismanagement, most have left, moving north.

A 3D view of the Gulf of Maine mostly enclosed by the fishing banks, dropping beyond them into very deep water (gomcensus.org)

A 3D view of the Gulf of Maine mostly enclosed by the fishing banks, dropping beyond them into very deep water (gomcensus.org)

That wonderfully sweet Northern Shrimp, Pandalus borealis, has also again failed to show up in the Gulf this winter in any numbers, cancelling the winter fishing season for them. They too have shifted north to colder waters.

Then there are the lobsters, living in unprecedented numbers in the Gulf of Maine – partly because their predators like cod have mostly vanished, partly because of the warmer coastal waters. Their region of greatest abundance on the Maine coast has also shifted north from the central coast to close to the Canadian border.

And Green Crabs, still considered invasive and inedible, have exploded in numbers on the shores of the Gulf which just a few decades ago was its northernmost range. They eat soft-shelled clams, decimate eel grass beds, and really need now to be harvested for something.

Meanwhile species from the warmer waters south of Cape Cod are extending north at least seasonally into the Gulf.

Juvenile Kemp’s Ridley Sea Turtles drifted north of Cape Cod in the autumn in far larger numbers than ever before – where they then still got stunned by the cooler waters of the Gulf, making the rescue effort by beach walking volunteers a far greater challenge.

Black Sea Bass, easy to fish for, excellent to eat, are increasingly common in the Gulf of Maine each summer (hookedup.net)

Black Sea Bass, easy to fish for, excellent to eat, are increasingly common in the Gulf of Maine each summer (hookedup.net)

More dramatic is the seasonal arrival of Black Sea Bass that live along the coast from the Gulf of Mexico to Cape Cod, separated into northern and southern stocks by Cape Hatteras. The fish forage along rock piles and ledges, pilings and jetties, quite easily caught by pots and by hook and line. They mature first as females, and then as they grow larger some shift to become males – they are protogynous hermaphrodites. They supported thriving commercial and recreational fisheries until they were almost fished out. Then amazingly serious regulations limiting quota, season, and sizes were enforced and the stock, especially north of Hatteras, has recovered reasonably well.

Black Sea Bass were overfished but have now recovered enough to support a sustainable commercial fishery. Recreational fishing rates are at about the same level as commercial (nefsc.noaa.gov)

Black Sea Bass were overfished but have now recovered enough to support a sustainable commercial fishery. Recreational fishing rates are at about the same level as commercial (nefsc.noaa.gov)

Now Black Sea Bass have become common enough in summer in the Gulf of Maine as far as mid-coast Maine for fishing to be regulated there as well. They eat anything they can from the seafloor, including small juvenile lobsters, but enthused recreational fishing will probably prevent them from becoming a major lobster predator.

And of course the list goes on – starfish, Blue Crabs, algae, puffins – species shift north within and out of the Gulf, following the colder water, and they shift north into the Gulf, following the warmer water. A major reorganization of the entire ecosystem is well underway.

Where is all this heading? The community may not stabilize until sometime after ocean temperatures stabilize, if that ever happens.

Sea surface temperature of the gulf of Maine has been warming gradually over the past decades, but has warmed even faster since 2004 (seascapemodeling.org)

Sea surface temperature of the gulf of Maine has been warming gradually over the past decades, but has warmed even faster since 2004 (seascapemodeling.org)

We know the Gulf of Maine is warming faster, now at about 2 degrees per decade, than almost anyplace else besides the polar regions, so the rate of change in the community is unusually rapid. But it does let us think about the kinds of global changes we will expect to face everywhere else.

At the least we can recognize that complex, unpredictable community shifts are occurring and will continue to occur, and that we need now to plan for the changes. We will have to adapt our regulatory practices for managing species of both commercial and recreational interest, finding ways to respond rapidly.

For what the Gulf of Maine is telling us is that we must expect everything to change. Soon.

The New Seawall of China

Sunday, December 7th, 2014

By now probably everyone who lives near a coast knows that coastal wetlands can protect us from some of the devastating impact of the wave surge and flooding associated with this new generation of super-storms – like Katrina, Xythia, Sandy, and Haiyan of the last few years.

Typhoon Hagupit blew across the Philippines in early December 2014. Because Typhoon Haiyan did such immense damage in the Philippines in 2013, everyone was much more prepared for Hagupit (nytimes.com)

Typhoon Hagupit blew across the Philippines in early December 2014. Because Typhoon Haiyan did such immense damage in 2013, everyone was much more prepared for Hagupit (nytimes.com)

Three kinds of responses to the threats of super-storms seem to exist. One is to retreat from the edge of the sea, and let the coastal wetlands (or barrier islands) absorb the wave surge and flooding – the wisest response but still the least likely since moving people, let alone communities or cities, can be close to impossible.

A much more common response is to adapt and prepare. Bangladesh is a famous example, for most of the country’s habitable region is the flat coastal delta of the Ganges River and there is no space for the dense coastal population to retreat to. So not only is mangrove reforestation well underway but many farmers are also planting rice that is more tolerant of higher salinity and temperature, others are growing hydroponic floating crops, and many cyclone shelters have been built. The hope is to absorb the wave surge, adapt to the flooding, and keep people alive. Some also propose migration to Canada, a more long-term solution.

The Ganges floodplain of Bangladesh is subsiding as sea level rises, and the only option available is to prepare and adapt (nature.com)

The Ganges floodplain of Bangladesh is subsiding as sea level rises, and the only option available is to prepare and adapt (nature.com)

In fact 50 of the least developed countries, including Bangladesh, now receive assistance in making similar preparations from the Global Environmental Facility’s (GEF’s) Adaptation Program, an apparently independent organization that still somehow retains association with the UN and the World Bank.

The third response is to do nothing. This is certainly the response most of us are most familiar with. Lack of funds, lack of political will or leadership, lack of community action, unfounded optimism, denial that anything serious has happened or might happen – all play their part. But such delusions are diminishing as more and more communities are directly affected by the powerful storms.

And then there’s China.

China has taken a fourth route: it has built and continues to build the longest seawall in the world, about the length of of its other more famous Great Wall.

The wall encloses coastal wetlands, making it possible to replace them with industrial, agricultural and urban development. With each passing decade the rate of wetland loss has increased, and there is no end in sight.

China's seawall extends along much of the mainland coast (red on map in upper right; The Great Wall is in yellow for comparison). The amount of wetland lost has increased in each of the past three decades (red on the graph at the center bottom) and is projected to be greater than ever in the next decade (white on the graph) (nytimes.com)

China’s seawall extends along much of the mainland coast (red on map in upper right; The Great Wall is in yellow for comparison). The amount of wetland lost has increased in each of the past three decades (red on the graph at the center bottom) and is projected to be greater than ever in the next decade (white on the graph) (nytimes.com)

This is astonishing. Wetlands not only provide a protective buffer against the damaging effects of storm surge and flooding. They also are a sink for pollutants and CO2, a nursery for fish of commercial interest, and habitats for a remarkable biodiversity, including large numbers of waterfowl.

China’s reasons for eliminating wetlands are obvious enough. The huge coastal population continues to grow, new coastal land available for development is extremely valuable, the government is obsessed by GDP growth, the conservation ethic is still embryonic, and wetlands have long been considered wasted space.

And it also isn’t as if China lacks some reasonable laws protecting vulnerable wetlands – it just doesn’t enforce them. Economic growth trumps everything. Limiting growth may be the hardest adaptation we need to make on our warming planet.

In any case, against all reason China continues to radically reduced protection for people, property and habitats in its coastal wetlands.

In our new and scary 21st Century world, this is more than odd. It is a disaster.

What Coral Reefs Can Teach Us

Tuesday, September 30th, 2014

On many coral reefs, the living corals have died, the reef has turned to rubble, and diverse algae have overgrown the rubble. So far, about 80% of coral cover on Caribbean reefs has been lost, and about 50% has been lost on the reefs in the tropical Pacific. Ecologists call this shift in ecosystem structure a phase shift, or ‘regime change’.

This global coral reef disaster is not a new and sudden response to some new stress. The shift to algae has been coming for 3 or 4 decades, and the stresses responsible include overfishing of both predators and herbivores, pollution, demolition, hurricanes, diseases of both corals and sea urchins, along with ocean warming and coral bleaching. Sea level rise and ocean acidification pose ever greater threats in the decades ahead.

Surviving coral reefs around Indonesia are still fished illegally with dynamite (solcomhouse.com)

Surviving coral reefs around Indonesia are still fished illegally with dynamite (solcomhouse.com)

If we could stop the fishing, the pollution, and the habitat destruction, as we do in no-take Marine Protected Areas, and assuming for the moment that the ocean is not going to get too warm, too high, or too acidic too quickly, what kind of coral reef recovery is then possible?

If herbivores like parrot fish and sea urchins return to a reef, they can clear the algae off pieces of the substrate, and coral larvae have a chance to colonize. Whether they succeed depends on many factors: light, current, predators, competition, chance, and even the ‘taste’ of the reef. But recovery is at least possible.

To help coral reefs recovery, corals are grown for a year or two and then transplanted to a damaged reef (digitaljournal.com)

To help coral reefs recovery, corals are grown for a year or two and then transplanted to a damaged reef (digitaljournal.com)

Of course we cannot pretend that climate change will not devastate coral reefs, no matter how resilient they might be now. Even under ideal conditions, recovery would take decades, and time is something we don’t have much of.

But coral reefs may still have a lot to teach us. We know now that shifts from one stable phase to another stable phase of an ecosystem can take decades, and is likely to be the result of accumulating and interacting stresses. Such a shift may start without our recognizing it for decades, and once we finally recognize it, there may then be little we can do about it. As the climate warms, we are likely to see this play out repeatedly in both marine and terrestrial ecosystems.

Can it also occur at a planetary scale, shifting us from a cool and dry planet to a hothouse planet? It has happened before. Perhaps it has already started, a result of accumulating stresses that we have caused, passing a tipping point we have not noticed.

Or perhaps we have not reached that point, and we can recover some of what we have lost, like no-take zones in MPAs. Perhaps we can still slow the process enough so that the outcome is one we and most of our co-existing species can tolerate as we too explore the limits of our resilience.

Coral reefs as we remember them (plaza.ufl.edu)

Coral reefs as we remember them (plaza.ufl.edu)

Eemian Evidence

Sunday, December 8th, 2013

So what do we really know?

We’re deep in an Ice Age, the third that has occurred in the past half billion years. In between Ice Ages, the Earth has been very warm, in its ‘hot-house’ phase, with high sea levels and free of glaciers and ice caps.

The Ice Ages that preceded ours occurred 290 and 440 million years ago. Note that the time scale is more compressed on the left(acer-acre.ca)

The Ice Ages that preceded ours occurred 290 and 440 million years ago. Note that the time scale is more compressed on the left(acer-acre.ca)

Our Ice Age began 2.6 million years ago, caused at least in part by the drift of Antarctica to cover the southern polar region, and the northern continents closing off much of the Arctic Ocean. Without cold polar water easily mixing with warm tropical water, polar ice caps and glaciers formed and grew, and the global average temperature dropped from about 22 degrees C to about 12 degrees C.

plate_history_lge classroomatsea.net

The continents drift endlessly, slowly, on 12 plates driven by convection currents in the magma below the Earth’s crust (classroomatsea.net)

During our Ice Age glacial and interglacial periods have cycled regularly. We’re in an interglacial period now, but even the interglacial periods are cool – the ice caps just retreat, they don’t completely melt, for cold polar water is still trapped in the Arctic and around Antarctica.

In our current Ice Age, glacial and interglacial periods cycle with remarkable regularity (atala.fr)

In our current Ice Age, glacial and interglacial periods cycle with remarkable regularity (atala.fr)

Our interglacial period, which we’ve named the Holocene Interglacial, started about 12,000 years ago. Probably not merely coincidentally, while we as a species have evolved over the whole time of this Ice Age, our explosion into whatever it is we are now began with the onset of the Holocene Interglacial.

Antarctic temperatures and atmospheric CO2 and Methane levels over the past four cylces of glacial and interglacial periods (eoearth.org)

Antarctic temperatures and atmospheric CO2 and Methane levels over the past four cylces of glacial and interglacial periods (eoearth.org)

We have also learned much from the analysis the last interglacial, the Eemian Interglacial, which began 130,000 years ago and lasted for about 20 thousand years. An ice core drilled into the northern Greenland ice sheet reached down to bedrock through 2.5km of ice, and back 250,000 years. The drilling took three years, the analysis another year, and the results were published in Nature last January.

The NEEM ice core was taken from the northeern part of the ice sheet where the deepest ice is 250,000 years old (neem.dk)

The NEEM ice core was taken from the northeern part of the ice sheet where the deepest ice is 250,000 years old (neem.dk)

In the Eemian Interglacial, global average temperatures were about 4 degrees C warmer than our current global average; CO2 levels rose to about 320 parts per million, sea levels rose about 6-8 meters higher than present, and the Greenland ice sheet melted from about 200m higher than present to about 130 lower than it is now. Since the Greenland ice sheet didn’t all melt during the Eemian Interglacial, the rest of the sea level increase must have come from the melting of the West Antarctic ice sheet.

Knowing all this, what can we truly predict about our future? We have clear models from the recent and from the more distant past of what the possible outcomes actually would be.

With atmospheric CO2 levels as high as they are at present, 393 ppm as of October, we can expect the global average temperature to become at least a few degrees warmer, and sea levels to rise at least a few more meters.

Average global temperature tracks CO2 levels over the past 400,000 years. Our Holocene Interglacial is on the extreme right, and our CO2 levels are striking (icecore_records-sympatico.ca)

Average global temperature tracks CO2 levels over the past 400,000 years. Our Holocene Interglacial is on the extreme right, and our CO2 levels are striking (icecore_records-sympatico.ca)

If CO2 levels continue to rise, as they are likely to do, we may force the Earth prematurely out of this Ice Age and back to its hothouse phase, over-riding the impact of continental drift in keeping the poles cold.

Obviously this is an ever changing planet, whether or not we are here to ride it out, and any sense we have that it is stable, benign or in any kind of equilibrium is shear delusion on our part.

But we have increased the pace of change, and this is going to be quite a trip. There are an awful lot of us on the planet, and if the changes happen as quickly as all the graphs from the past indicate they will, the human cost of the upheaval is going to be huge.

Of course we can adapt, but we need more time to do so without excessive misery.
We still do have the potential to limit both the extent and the pace of global warming.

Celebrating the last piece of ice core, extracted from 2.5 km below the surface of the Greenland ice sheet (neem.dk)

Celebrating the last piece of ice core, extracted from 2.5 km below the surface of the Greenland ice sheet (neem.dk)

Jellyfished

Monday, September 30th, 2013
Moon jellyfish (Aurelia aurita) form huge blooms in many of our oceans (guardian.co_.uk).

Moon jellyfish (Aurelia aurita) form huge blooms in many of our oceans (guardian.co_.uk).

Increasing jellyfish blooms are a symptom of the challenged health of our oceans. Where fish have been fished down or out, jellyfish thrive. Where oxygen levels drop too low for many organisms, jellyfish thrive. Where a community then flips from fish-dominated to jellyfish dominated, recovery is difficult to achieve.

Jellyfish blooms clog fishing nets, intake pipes of desalination and nuclear plants, cause mass mortality of salmon in coastal farms, decimate fisheries already in steep decline, and sting swimmers out of the water at beaches everywhere.

Nomura's Jellyfish are giants, up to 200 kg and 2 meters in diameter, and do much damage to fishermen's nets in the Sea of Japan (fastcompany.com).

Nomura’s Jellyfish are giants, up to 200 kg and 2 meters in diameter, and do much damage to fishermen’s nets in the Sea of Japan (fastcompany.com).

In a new book Stung!: On Jellyfish Blooms and the Future of the Ocean, Lisha-ann Gershwin documents the ravages of jellyfish blooms and the deterioration of marine ecosystems, and her final conclusion is a very cold bath: we have permanently wrecked the oceans, we can’t fix what we have done, and all we can do now is adapt to the inevitable lousy changes that have already begun.

Box jellyfish (Cubomedusae) have powerful stings, and drive swimmers out of the water, as they did in the northern Mediterranean this past summer (Selby, flickr.com)

Box jellyfish (Cubomedusae) have powerful stings, and drive swimmers out of the water, as they did in the northern Mediterranean this past summer (Selby, flickr.com)

What do we do with that? Ignore it, I think, and continue to try to mitigate the extent of the changes. The new IPCC report clearly illustrates the different outcomes of different levels of atmospheric CO2, and the long-term advantages of stabilizing those levels soon are extraordinarily clear.

But Gershwin also writes about some of the remarkable biology of jellyfish, for they are more than just graceful but dangerous animals. Perhaps the most intriguing is one of a group of small species of the genus Turritopsis, which grow to about half a centimeter in diameter and are now common in most tropical and temperate oceans.

Turritopsis dohrnii medusa, about 1/2 cm in diameter, with a bright red stomach and a ring of tentacles (turritins.com)

Turritopsis dohrnii medusa, about 1/2 cm in diameter, with a bright red stomach and a ring of tentacles (turritins.com)

Like most jelly fish, it has a two part life cycle. When jellyfish (medusae) are sexually mature, they shed eggs and sperm into the water, and then die. A fertilized egg develops into a tiny creeping planula larva that settles onto some hard substrate and then grows into a colonial hydroid or polyp that feeds on microplankton in the surrounding water. Eventually other buds on the hydroid develop into very small medusae which then escape and swim off.

Typical life cycle of a hydrozoan jellyfish (devbiol.com)

Typical life cycle of a hydrozoan jellyfish (devbiol.com)

All Turritopsis do this, and because they are all small as adult jellyfish, less than 1cm in bell diameter, they are also very small when they first break free of their hydroid source, less than 1mm in diam.

At least one species of Turritopsis though has remarkable further capabilities.

When starved or physically damaged, where other jellyfish would just die, the medusae of this species instead can undergo an amazing transformation. The mouth and tentacles are resorbed, and the bell shrinks into a blob-like cyst that falls to the bottom, attaches to the substrate, and grows into a hydroid or polyp colony once again, reversing the usual life cycle. And there large numbers of new medusae develop, all clones of the original damaged medusa.

Reversing the usual life cycle, Turritopsis medusa 'transdifferentiates' back into a hydroid (newtimes.pl)

Reversing the usual life cycle, Turritopsis medusa ‘transdifferentiates’ back into a hydroid (newtimes.pl)

This is truly an extraordinary event, about as close to immortality as one can get.

Not surprisingly, as our medical use of stem cells grows ever greater, we are very interested in how cells that had been specialized for one function in the medusa ‘transdifferentiate’ into quite different cells in the hydroid.

Meanwhile, Turritopsis has spread around the world’s oceans, from Spain to Japan to South Africa, probably assisted by the ballast water of transport ships. It is wonderfully adapted to survive in this changing world, and may in turn play a role in the changes.

And it is also a reminder of how extraordinary it is to be a living being on Planet Earth, whether as a jellyfish or as a curious human.

Crossota alba is another small hydrozoan medusa, one that lives in deep water and drifts around in the dark, tentacles extended, preying on the plankton that it drifts into (whoi.edu)

Crossota alba is another small hydrozoan medusa, one that lives in deep water and drifts around in the dark, tentacles extended, preying on the plankton that it drifts into (whoi.edu)

Moving Sand

Friday, September 20th, 2013

Even in a more stable world, undisturbed by the collateral damage of a warming climate, sand beaches and dunes are forever growing, shrinking, changing shape and moving as storms and waves do their familiar work.

For decades the Army Corps of Engineers has defended the sandy coastline from Cape Cod to the southern tip of Florida, dredging or pumping up offshore sand to replenish eroding beaches, and plowing up sand ridges to prevent more wave and surge damage to coastal properties.

Their current efforts in both New Jersey and Florida are much in the news.

The ten miles of Miami Beach have depended on sand replenishment since the 1970s, but nearby sources of offshore sand have now run out. Where will more sand come from? North Carolina? The Bahamas? At what cost? And can there be a Miami Beach without a beach for tourists to frolic on?

Beach replenishment restored a beach front to Miami Beach, but now what? (geology.upm.edu

Beach replenishment restored a beach front to Miami Beach, but now what? (geology.upm.edu

Meanwhile, for years the Army Corps of Engineers has been busy building sand ridges and dunes seaward of beach communities along the New Jersey coast. Where they have been prevented from building by beach-front homeowners, Hurricane Sandy did its most impressive damage. Most people who own such homes now recognize that having a dune blocking their view of the ocean is far better than having their home swept away, and have granted easements to have the remaining dunes built.

The New Jersey shore. Created 'dunes' protect parts of it, but they are only a short-term solution (nj.com)

The New Jersey shore. Created ‘dunes’ protect parts of it, but they are only a short-term solution (nj.com)

The Army Corps of Engineers, here plowing up a ridge on the NJ shore, is charged with the impossible task of defending the coastline against the sea (usatoday.com)

The Army Corps of Engineers, here plowing up a ridge on the NJ shore, is charged with the impossible task of defending the coastline against the sea (usatoday.com)

Not all agree, of course, not wanting to lose their ocean views, and feelings have run high. Since dune protection isn’t much use if there are gaps in the dunes, the State’s Supreme Court has granted communities the ability to take ocean front space by eminent domain where holdouts refuse to grant easements, and the reamining dunes will no doubt soon be built.

Sand ridges plowed up in front of shore front homes will provide only short-term protection (fema.gov).

Sand ridges plowed up in front of shore front homes will provide only short-term protection (fema.gov).

These are of course very short-term solutions. Beach replenishment is so clearly unsustainable, financially costly, and environmentally damaging, while plowing up sand ridges in front of beach-front homes does not make them dunes – they are temporary and unstable mounds of sand. These defenses will fail.

Instead, in the face of rising sea levels and increasingly intense storms, now is the time to initiate long-term responses. New Jersey’s Gov Christie understands this, and no doubt feels constrained by the stubbornness of coastal home owners. Florida’s Gov Rubio apparently does not accept the reality of climate change, so any leadership in Florida must continue to come from the county and municipal level.

Managed retreat is probably the best long-term option. The sand spits and barrier islands along the east coast should become free of human communities, left as sanctuaries and as natural buffers against the sea and climate changes that are occurring. We need their protection, and they need to be free to respond dynamically to the resculpting forces of winds and waves. Where barrier islands do not exist, communities need to retreat inland and to higher ground if it exists.

We can start this soon, with care and organized planning. If we wait, we will still have to do it, but it will be done in the face of catastrophe, the worst of circumstances.

And Miami Beach? Loss of its beaches is not its greatest problem. Miami is the US city most vulnerable to the impact of sea level rise, and it has nowhere to go.