Volcanic Activity and Rising Seas: Grindavík Navigates Between a Rock and a Hard Place
Translation: Judy Fong
October this year started with a lot of seismic activity on the Reykjanes peninsula. With the most activity occurring at the start of November, volcanologists warned of a high likelihood of an eruption near Grindavík or even within the town itself. When this article was written, the eruption still had not happened, but the earthquake damage was already significant. Roads and water pipes have burst apart and cracks have appeared in walls and floors of many buildings. Moreover, the residents of Grindavik, a little over 4,000 people, had to evacuate from their homes.
There has been extensive media coverage of these events but the public should also be reminded that volcanic activity is not the only danger faced by the community of Grindavík in the long term. After a storm in January 2022, a tidal flood in Grindavik caused significant damage. The harbour filled up with seawater which then flowed over the piers and soon a large part of the neighbouring area was flooded. An electrical box was also flooded and with that the power went out around the harbour and at the Search and Rescue building, which had to switch to a backup power supply. Buildings filled with seawater and a 40-foot container drifted away. There was some damage to the fish freezing factory and employees sought safe harbour on the upper floor as the ground floor was immersed under one metre of water. The search and rescue team and fire brigades spent all day pumping seawater out of buildings and helping employees save valuables such as fresh and processed fish.
Events of this kind are unfortunately likely to reoccur in the future due to the rising sea levels worldwide, as a result of climate change, but Grindavík is especially impacted by this since the land in and around the town has been sinking, unlike that which is happening in many other areas of Iceland where the land is rising.
In the fourth summary report from the Scientific Council for Climate Change, it was stated that if the land subsidence in Grindavík continues at the same pace as in recent years, it could be as much as 105 centimetres by the year 2150. At the same time, rising sea levels due to climate change could reach 4.5 metres according to the worst case scenario (the best case scenario, on the other hand, shows a sea level rise of “only” 50 centimetres). Thus, the land sinkage and the rising sea levels could result in a combined difference of 5.5 metres between the sea and Grindavík. The consequences could be disastrous since the oldest part of the town is only 3 to 5 metres above sea level.
Exactly how much increase there will be is at this point extremely uncertain. The magnitude depends on whether humanity will prove successful at reducing greenhouse gas emissions and the impact of warming on the West Antarctic Ice Sheet (WAIS). Scientists have been considerably worried about the instability of WAIS and some have estimated that global warming could lead to the collapse of WAIS which would by itself raise sea levels by 3.3 metres, in addition to the rise due to melting glaciers and ice sheets as well as thermal expansion of sea water. Much uncertainty reigns over whether and when such a possibility will materialise and IPCC has said there is insufficient knowledge of this process to estimate the current likelihood.
Average temperature change of Antarctica (°C per decade) from 1957 to 2006. To the left is the WAIS of Antarctica which scientists consider especially concerning. Credit: Veðurstofa Íslands.
It is however clear that the future of the Grindavík community is extremely uncertain: the town is between a rock and a hard place.
Communities on the southeast coast should on the other hand witness a significant land rise in that region, perhaps in part compensating for the rising sea levels. Höfn in Hornafjörður could rise by up to two metres by 2150 if the current land rise continues unchanged, which is a record increase, but still might not be enough to compensate for the rising sea levels if the worst scenario materialises. Land rise, which happens near large glaciers, is a localised consequence of global warming. The decreased glacial mass causes the land nearby to rise dramatically.
Speed of vertical change (land rise/sinkage in mm/yr) according to the measurement stations of Landmælingar Íslands (Surveyors of Iceland) from 2004-2022. Credit: 4th summary report of the Scientific Council on Climate Change
The Reykjavík metropolitan area does not have the advantage of being located close to a large glacier and therefore, land rise in the capital should be little to none. The Scientific Council has estimated that land in and around Reykjavík could rise about 6 centimetres by 2150 while sea level could rise by 40 centimetres at least and by up to 4.5 metres in the worst-case scenario. Downtown Reykjavík is only 1 to 6 metres above sea level (Hafnarstræti 2.5 m., Austurstræti 3 m., Alþingi 5 m. above sea level). The future of downtown Reykjavík is thus not much brighter than Grindavík’s, even though it might be spared by seismic and volcanic activity.