The events that precipitate the narrative are caused by a storm surge across the whole of the western coast of the United Kingdom.
A number of events could cause this, but we do know that extreme weather events will become more common if climate change continues, at whatever rate.
We also know that the Antarctic ice cap is melting as is the ice cover on Greenland. This would cause sea level rise over time.
Research has been conducted over what is likely to happen on the coast where I am setting my story.
The type of event which would give rise to the houses on the seafront of Borth being destroyed with flooding as described in the book would most likely occur if there was a confluence of events as described below.What level of climate change is currently expected?
The reduction targets of all countries currently (February 2 2010) associated with the Copenhagen Accord leave the world heading for a global warming of over 3oC above pre-industrial levels by 2100, according to Climate Action Tracker.
Mark Lynas, author of the book ‘Six Degrees’ has envisaged what this would mean, and National Geographic magazine has made the following video about it:
I think that climate science is broadly correct despite the efforts of oil-industry funded climate change deniers to argue to the contrary.
What would this mean for the Dyfi estuary?
The following is taken from an interview that I conducted with Mike Bailey, of the CCW (Countryside Council for Wales), the site officer responsible for Cors Fochno and Ynyslas and Borth and information he supplied me with.
There have been two studies looking at the potential impacts of climate change/ sea level rise around the Dyfi.
The first commissioned by The Environment Agency (EA) & CCW focussed on Cors Fochno and included modelling work by Halcrow Ltd.
The second, commissioned by CCW and carried out by Bangor University, Centre for Applied Marine Sciences, involved estuary-wide modelling.
The findings of the two reports are in close accord, both showing that the margins of the bog (which have been impacted by peat cutting and drainage subsidence) and particularly the archaic bog reclaimed for agriculture (most severe shrinkage subsidence of the peat) are most at threat from s.l.r.
The central dome of the raised bog is higher than the margins and seems unlikely to be flooded over the next 50yrs at least.
Scenario 1 shows results of a 100yr tidal event at current sea levels
Scenario 2: shows a 10yr tidal event + 100 yr fluvial event + 0.8m rise in sea level (= c.50yrs). This represents something approaching a worst case scenario over the 50yr timescale.
In 1997 the banks of the Afon (river) Leri broke in an extreme flood event. It happened close to the road bridge, the railway bridge and the Dyfi boatyard.
Water streamed out onto the Borth bog on its north side and flooded the road. The railway line was closed.
The Greenland icesheet
I have investigated whether a chunk of the Greenland icesheet could fall into the sea large enough to create a tsunami. This is what I uncovered:
Edited from the Wikipedia entry:
The melt zone, where summer warmth turns snow and ice into slush and melt ponds of meltwater, has been expanding at an accelerating rate in recent years. When the meltwater seeps down through cracks in the sheet, it accelerates the melting and, in some areas, allow the ice to slide more easily over the bedrock below, speeding its movement to the sea. Besides contributing to global sea level rise, the process adds freshwater to the ocean, which may disturb ocean circulation and thus regional climate.
Researchers monitoring daily satellite images have discovered that a massive 11-square-mile (29-square-kilometer) piece of the Petermann glacier in northern Greenland broke away between July 10 and July 24, 2008.
The last major ice loss to Petermann occurred when the glacier lost 33 square miles (86 square kilometers) of floating ice between 2000 and 2001.
Between 2001 and 2005, a massive breakup of Sermeq Kujalleq erased 36 square miles (94 square kilometers) from the ice field and raised the awareness of worldwide of glacial response to global climate change.
Sudden loss of a chunk of ice sheet might plausibly be attributed to “coupling between surface melting and ice-sheet flow” which “provides a mechanism for rapid, large-scale, dynamic responses of ice sheets to climate warming” [Swiss camp].
Wikipedia continues: “The second mechanism is a force imbalance at the calving front* due to thinning causing a substantial non-linear response. In this case an imbalance of forces at the calving front propagates up-glacier. Thinning causes the glacier to be more buoyant, reducing frictional back forces, as the glacier becomes more afloat at the calving front. The reduced friction due to greater buoyancy allows for an increase in velocity. This is akin to letting off the emergency brake a bit.
“The reduced resistive force at the calving front is then propagated up glacier via longitudinal extension because of the backforce reduction. For ice streaming sections of large outlet glaciers (in Antarctica as well) there is always water at the base of the glacier that helps lubricate the flow. This water is, however, generally from basal processes, not surface melting.”
The article gives examples. It adds: “An examination of 32 outlet glaciers in southeast Greenland indicates that the acceleration is significant only for marine terminating outlet glaciers. That is glaciers that calve into the ocean. Further, noted that the thinning of the ice sheet is most pronounced for marine terminating outlet glaciers.”
* = The sudden release and breaking away of a mass of ice from a glacier, iceberg, ice front, ice shelf or crevasse. The ice that breaks away can be classified as an iceberg, but may also be a growler, bergy bit or a crevasse wall breakaway. Calving of Greenland’s glaciers produce 12,000 to 15,000 icebergs each year alone.”
“An examination of 32 outlet glaciers in southeast Greenland indicates that the acceleration is significant only for marine terminating outlet glaciers. That is glaciers that calve into the ocean.
“Further, it noted that the thinning of the ice sheet is most pronounced for marine terminating outlet glaciers.”
When a glacier calves, the mass of ice can produce 8 metre waves. People surf these waves apparently. But an 8 metre wave is not a tsunami.
“Since the surging nature of ice sheet motion is a relatively recent discovery, and is still a long way from being entirely understood, no models have yet made a comprehensive evaluation of the effects of climate change. However, it is clear that climate change will act to destabilise ice sheets by a number of mechanisms. “Rising sea levels will reduce the stability of ice shelves, which have a key role in reducing glacial motion. Some Antarctic ice shelves are currently thinning by tens of metres per year, and the collapse of the Larsen B shelf was preceded by thinning of just 1 metre per year.” – Ice sheet dynamics, From Wikipedia.
Ice sheet models on the web:
- Ice Sheet System Model, a multi-purpose massively-parallelized finite element framework dedicated to ice sheet systems modeling (Thermomechanical coupling, data assimilation, sensitivity analysis,…)
- Glimmer-CISM, a three-dimensional thermomechanical ice sheet model, designed to be interfaced to a range of global climate models.
- PISM (Parallel Ice Sheet Model), which includes ice shelves and ice streams.
- SICOPOLIS (SImulation COde for POLythermal Ice Sheets), a three-dimensional ice sheet model which accounts for polythermal conditions (coexistence of ice at and below the melting point in different parts of an ice sheet).
- CISM (Community Ice Sheet Model), under development as a land ice component of the Community Climate System Model (CCSM).
- Elmer, a multi-physics Finite Element code with special modules for full-stress ice dynamics analysis.