Life in a Dol house
2018 - Week 12
Rising Sea Levels
Whether or not you agree that Climate Change is real, is a moot point and here I will not even look at the potential causes of said climate change.
And please don't call it "Global Warming", because what is warmer in one part of the word, is cooler somewhere else. Similarly, what is wetter in one place is drier in another.
Climate change is what it is.
There is an old saying amongst Meteorologists, that "Climate is what you expect, weather is what you get".
What is not in doubt is that everywhere in the world in recent years has seen changes to their established weather patterns. There is general agreement from the scientific community that the past three years have all been warmer than any previously recorded, with 15 of warmest years between 1850 and 2016, all being after the year 2000.
The World Meteorological Organisation (WMO) published figures in January this year showing that 2016 was the warmest year ever recorded with an El Niño event and 2017 was the warmest year recorded without an El Niño event taking place in the Pacific Ocean.
This, taken together with the reduction in sea ice in the Arctic, increases the temperature in the northern latitudes and the temperature increase was a cause of the recent breakdown of the Polar Vortex.
However it is not the reduction in sea ice which is causing the global sea levels to rise, rather it is the melting of the glacial ice sheet that covers Greenland.
Think about an ice cube in a glass of water. As it melts, the water level remains the same. But drop several ice cubes into the same glass and the water level rises.
Then there is Thermal Expansion. When water is heated, it expands, so as it is heated more, it expands more.
Sea level rise is real and increasing.
Being an island that is thrust upwards from the bed of the shallow Adriatic sea, you might think would isolate us from the problems.
However a major portion of the population of the Island of Hvar, and indeed all of coastal Croatia, live just a few vertical meters from the sea.
Almost every coastal town has its "Riva" or seafront promenade, like this one in Split.
My local town, Stari Grad, is no exception. Stari Grad literally means "Old Town" when translated to English, and it was 2,400 years ago that Greek explorers sailed up the Fjord, landing at the apex and established a town.
There was probably an Illiyran settlement here already but it was the Greeks who built the first substantial buildings.
Today you have only to venture onto the plain (Agar) just outside the town to see the monument to Greek organisation and surveying, the geometric squares of the field system that was established 2,000+ years ago and has been in continuous use ever since.
In Stari Grad however, there are few visible remains from the Greek period, but around the south side of the bay, the existing buildings speak to the succession of peoples who came to Hvar, settled and built.
Roman walls are clear to see, medieval fortified churches, castles built by wealthy merchants, all literally within a stones throw of the sea.
Look up the fjord towards the town from sea level and you get an idea of how much is low lying, barely above the current sea level.
The Riva starts from Obala Dr Franje Tuđmana in the east, where the sea wall curves towards the town primary school, on the north side of the harbour.
It is here that the bigger fishing boats land their catch onto the sea wall and sell their fish to the people of the town. The fishing boats rub shoulders with small dinghies and as you walk west along the Riva towards the old light house, slowly the working vessels turn to pleasure craft, then after the town hall to ocean going yachts and million Euro cruisers.
These days you can take a Google Street View virtual tour.
The large square on the corner of the Riva is called Trg Stjepana Radića, 'Trg' meaning 'Square' in Croatian.
This flat area floods regularly, but all the buildings have one or two steps up, to protect them from
Look closely as you walk along the Riva and you will see that all the doorways on your left have a metal channel on either side. Depending upon the time of year, some may have flood protection boards in place.
Look the other way and you will see that the sea is very close to the top of the walkway. On many days it is level with the top in places.
There is only a small tidal variation here, of less than half metre and the sea regularly comes over the stone walkway onto the sea front and up to stone steps of the buildings.
Several times a year, the water will reach the top of the step, which is when the flood board barricades stop water entering the buildings - except when the flood is a surprise and people have not slotted their barriers into place.
In July 2017, at around 01:00 hrs there was one of these surprise events, which flooded many of buildings in the town.
The sea water rose a meter above the top of the wall and flooded right back a hundred meters or more from the Riva.
In fact everywhere that wasn't built on higher ground. I have a friend with a lovely ground floor apartment, not far vertically from the sea, but more than 150 meters horizontally from the harbour, whose home was flooded.
I have seen a number of the small over topping events.
In January two years ago I was in my car, parked on the edge of the harbour when I realised that the sea was flooding the square, and the main road out of town, to a depth of car's axles.
Two streams which drain the Agar run along either side of the park, next to the road. The main road into Stari Grad was soon completely awash.
It didn't last long, perhaps ten or fifteen minutes. But flooding events do not need to last long to cause damage.
Then late last year as I was walking back to my car, I saw that the stream that parallels the main road was starting to spill over the road again, as water backed up from the harbour.
Not a big flood, or a long flooding event, in minutes the water had receded leaving just a wet road surface, but an over topping none the less.
Then just over a week ago in early March, there was another flooding which required the Vatrogasci (Fire and Rescue) to do some pumping out.
Over the 2016/2017 winter season, the municipal council had the harbour dredged to remove years of accumulated sand and mud and also raised the Riva on the north side of the harbour, by more than a meter, but this has not been continued all the way round.
This waterfront walkway was built to commemorate the founding of the town in 384 BC.
In the year 384, BC in this bay there landed
Greek sailors from the Aegean island of Paros
who founded Faros - now Stari Grad.
This waterfront was built in the year 2016, the year dedicated
to the 2,400th anniversary of the town's founding
But this raised section is not continuous, allowing the sea to run round behind it during an over topping event.
It will not take much sea level rise to turn a monthly event into a daily event here.
All that is required now, is for a low pressure system to be in the Adriatic and a westerly wind to push the bulge of water up the Fjord.
When it reaches the neck, it has nowhere else to go.
In many places along both sides of the Adriatic coast, cities have been built that are only just above the ocean level.
But we are not alone, and by no means worst off when compared to other countries.
Rising sea levels could cause Abu Dhabi's coastline to retreat by several kilometres over the next 80 years, a study has predicted.
Researchers have forecast that the climate change-induced sea level changes, and the knock-on effects on the ecology of the coastline, will cause the shoreline to retreat by between 2.26km and 3.81 km this century.
While many of the emirate's built-up areas may not be flooded because they sit on land that was elevated during the building process, other coastal regions could be significantly affecte
There are low lying areas, barely a metre above current lea levels, which house significant numbers of people and many important installations.
The lead author of the study, Dr Stephen Lokier, an associate professor at the Abu Dhabi Petroleum Institute, part of Khalifa University of Science and Technology, said measurements found that the shoreline retreat taking place was greater than expected given how fast the sea level is rising.
"When we started looking at what was happening we were genuinely surprised," he said.
Sea levels around the world are rising by about 3.2 millimetres per year, which would be expected to cause the shoreline to retreat by about 2.5 metres annually; however, the actual retreat observed is between 10 and 29 m per year.
Shoreline retreat has been increased by a process called "dynamic flooding", in which the effect of the rise in sea level is multiplied because it increases erosion by, for example, changing the mangroves and the “mats” of microorganisms that line much of the coast.
Published in the journal Geomorphology, the study warns that the retreat of the shoreline “will threaten existing coastal infrastructure”.
But it is around the Pacific and Indian Oceans where sea level rise will be felt most.
Five small island states will completely disappear, and vast swathes of coastal Bangladesh and surrounding countries will be inundated, affecting millions of the world's poorest people.
There is now better information available to scientists and researchers, than there has ever been. No longer do figures have to be manually reported from tide gauges around the world. Instead specialist constellations of satellites are continuously monitoring the level of seas and oceans around the world and highly accurate automatic gauges feed information into the system, 24 hours a day.
TOPEX/Poseidon, a joint US and European satellite programme worked until an instrument failed in 2006, but not before it was joined by the JASON series of satellites, which all fly in tandem, measuring the height of the world's oceans. JASON has measured an average increase of 2,28 mm per year, every year since 2001. But this is not uniform, in some places the sea level rise is more, and in others less.
Scientists and oceanographers have been studying the continuous data from Jason and TOPEX/Poseidon, with accurate data going back 25 years and and have calculated that the sea level isn't rising at a steady rate, it's accelerating.
If the trend continues, the total sea level rise could be twice as high by 2100, as previous projections have suggested.
The researchers say that their findings are just the beginning. The 25-year period studied so far is long enough for the acceleration to be detected, but further data will be gathered by the ongoing Jason-3 project and other altimetry satellites, as well as more advanced ground stations.
The research team involved scientists from the Cooperative Institute for Research in Environmental Sciences (CIRES), the University of Colorado Boulder, the University of South Florida, NASA Goddard Space Flight Center, Old Dominion University, and the National Center for Atmospheric Research. The study was published in the journal Proceedings of the National Academy of Sciences.
In places like Stari Grad,
and the many small inlets here on the island,
All places where people built waterfront property, some times centuries ago, the sea defences could be raised to prevent regular inundations by the sea, but not without significant local costs.
But building walls high enough to cater for the unusual combination of a flood tide, a low pressure weather system and a strong wind, as well as sea level rise, is unlikely to happen.
Sea level rise is already being felt around the world, as well as here in my world of Dol. Many people know the story of King Canute, who is reported to have tried to stop the incoming sea, although he is believed to have been demonstrating the futility of trying, not that he had supernatural powers.
As individuals there are things we can do: Use fewer resources, less plastic etc. But also I contribute to climate knowledge both passively and actively.
My weather station uploads data very five minutes, of every day to a number of meteorological organisations world wide. The data is available for researchers and I have even been awarded a "Gold Star" for being a "High quality station" with data which passes stiff quality control standards.
This is passive. I just make sure the batteries in the various sensors are replaced regularly and there is a connection to the internet (of things). But I also actively support NASA and other organisations through things like GLOBE. I'm currently studying to become a trained (accredited) observer.
I have an App on my tablet and take photographs of clouds and report atmospheric conditions, especially as satellites are passing overhead. With a new earth observing satellite which started to gather data in January, NASA wants ground observers to help calibrate it.
As satellites pass overhead several times a day, I get emails of the times and when possible take a photo of the clouds, and report what I see. This is then compared with the 'top down' view from the satellite.
The NASA Globe Cloud Protocol is all about citizen science and while there is little one individual can do about climate change, we can all add to the sum of human knowledge by providing observations for others to use.