Climate ranking of Norwegian municipalities

We present here  NORADAPT 's first comprehensive climate ranking of all Norwegian municipalities. NORADAPT have gathered data on expected climate and societal changes, and compared these data with actions the municipalities are taking to adapt to climate change. This gives a picture of the total climate risk for Norwegian municipalities in the future.

The ranking consists of 12 indicators: four indicators for different ways a municipality is prone to climate hazards, four indicators for different ways a municipality is vulnerable to climate change and four indicators for different ways a municipality is adapting to climate change.

The scatter plot below shows a summary of the climate ranking. We have combined the indicators for proneness to climate hazards and vulnerability into what we call 'exposedness'. This is the x-axis for the scatter plot below. The municipalities' adaptation is shown along the y-axis. Each circle in the scatter plot is a municipality and they are placed in one of four squares formed by the average values for exposedness and adaptation. The colours indicating different municipalities in the scatter plot corresponds with the colouring of the municipalities in the map:

• Top left quadrant (green): These are municipalities that have made greater than average efforts to adapt to climate change but are exposed less than average.
• Top right quadrant (yellow): These are municipalities that have made greater than average efforts to adapt to climate change, but that also are more than average exposed.
• Bottom left quadrant (grey): These are municipalities that have made less than average efforts to adapt to climate change but are also less than average exposed.
• Bottom right quadrant (red): These are municipalities that have made less than average efforts to adapt to climate change but are more than average exposed.

One observation of the distribution of municipalities in the scatter plot is that there is no correlation between how exposed Norwegian municipalities are and how much effort they put into climate change adaptation. If this were the case, we would have seen a collection of municipalities in squares I (top left) and IV (bottom right) or in squares II (top right) and III (bottom left).

For more info, click the arrow on the right hand side.

Here are some main conclusions based on the six slides above:

For climate impact, we use four indicators: Rot index, Flood risk, Storm surge, and Days with snow cover exceeding 30 cm.

Many of the indicators for susceptibility to climate hazards have been obtained from the Norwegian Climate Service Center. The Climate Service Center creates indices showing a 30-year average for the mid- century (2031-2060) or the end of century (2071-2100) relative to the reference period 1971-2000. The authorities recommend a 'worst-case' approach for the choice of emission scenario and time horizon, i.e., choosing the 'worst' alternative as a precautionary measure. We therefore use RCP 8.5 and the time horizon 2071-2100 for the climate impact indicators (look  here  for an explanation on RCP 8.5).

The rot index is a measure of how exposed wooden buildings are to rot. For the reference period (1971-2000), the rot index ranges from 1 - 73. The  Norwegian Meteorological Institute  uses this index and divides it into three categories for low, medium and high risk of rot damage (look  here  for details):

• low rot risk (index values up to and including 24)
• medium rot risk (index values from 25 to 48)
• high rot risk (index values above 48)

Maps for rot risk are available from the Norwegian Climate Service Center and by using these for the reference period, as well as for the period 2071 – 2100,  we have calculated the average rot risk for Norwegian municipalities based on the IPCC's scenario RCP 8.5. Below, you can see the rot risk in the reference period and what it may be in the future.

For the reference period, several municipalities have a low rot risk on average, but based on the RCP 8.5 scenario, all municipalities will on average have medium or high risk of rot in the period 2071- 2100. The range of values is changed from 1 to 73 (for the reference period) to 10 to 108 for the period 2071 - 2100 in accordance with RCP 8.5. By taking the difference between the future and current rot index, we get the map on the left below. This is calculated with a resolution of 1x1 km.  By taking the average for the cells within each municipality, we get the map on the right below.

The  Norwegian Water Resources and Energy Directorate (NVE)  have carried out flood zone mapping for more than 150 river sections but have prioritized the major watercourses close to existing buildings. As of January 2023, flood risk maps are available for 138 out of 356 municipalities in Norway. The flood zone with a recurrence interval of 200 years is the most frequently mapped flood zone (mapped for 127 municipalities). The fact that just under 40% of municipalities have flood zone mapping makes it difficult to assess the flood risk in many municipalities.

We have calculated the indicator by measuring the increase in area covered by the future flood zone in relation to the current flood zone. We consider the municipalities with the largest percentage increase in flood-exposed area to be the most prone to flooding.

One of the effects of climate change and a warming planet is sea level rise. The reason for this is that the ocean expands as it gets warmer, and melting ice sheets add more water to the oceans. In Norway, we long thought that rising sea levels would not affect us much since the country also experience land uplift, but as knowledge about sea level rise resulting from climate change has increased, we know that the Norwegian coast also will be affected. However, there are geographical differences in expected sea level rise.

Storm surge is a weather phenomenon that occurs when low air pressure is combined with strong winds. Within meteorology, air pressure is measured in hectopascals (hPa), and according to the  Norwegian Mapping Authority , a strong low pressure of 960 hPa10 will cause the water to rise by about half a meter. Combined with strong winds pushing water towards land, the water will rise even more. If there is also a high tide (spring tide), the surge will be further amplified. Sea level rise due to climate change will also exacerbate the effects of storm surges.

To assess the impact of storm surge in Norwegian municipalities, we have used the Norwegian Mapping Authority's zones for 1000-year storm surge for the current situation and for the situation in 2090. These are the same datasets that you can study with the application “Se havnivå i kart” (View the sea level in maps).

For each municipality, we have calculated the area covered by the storm surge zone for the situation in 2090 and the current situation. We have taken the difference and ranked Norwegian municipalities based on the largest percentage increase in flooded area. You can study the results below.

Days with snow cover highlights an important gradual change in the "winter country" (and winter ecosystem) of Norway. For this indicator, we use 'days with snow depth over 30 cm' collected from the  Norwegian Climate Service Center .

We look at changes from the reference period 1971 - 2000 to 2071 - 2100 (using the development path with high emissions, RCP 8.5, explained  here ) and take the average of the cell values within the municipality for change in the number of days with snow depth.

The figure on the left shows 1 km grid cells for changes in snow cover for Sirdal and surrounding municipalities. The darker the green colour, the greater the negative value.

No grid cell will get more days with a snow depth exceeding 30 cm. On average, Norwegian municipalities will have 58 fewer days with more than 30 cm snow by 2100 if climate emissions continue as today, but the variation is large. Berlevåg could have as many as 185 fewer days with snow depths of 30 cm or more.

From the map below - click on the elements from the left panel to see how many fewer days with snow cover of 30 cm or more a collection of municipalities could have by the end of the century.

For climate vulnerability, we use four indicators: population, housing, business and mobility.

To assess the municipalities' efforts to adapt to climate change, we use four indicators from three sources:

• The Norwegian Environment Agency's grant scheme for local climate adaptation measures
• The Norwegian Directorate for Civil Protection’s (DSB) municipal survey
• Norwegian Climate Monitor (two indicators)

In the first main report from the UN Intergovernmental Panel on Climate Change (from 1990) and in the first international climate agreement (the Kyoto Protocol from 1992), emission reductions dominated, which led a number of researchers in the 1990s to point out that the need for climate change adaptation was overshadowed in the political debate by the need for emission reductions (Schipper, 2006). This situation changed during the 1990s and into the early 2000s, and the latest main report from the UN Intergovernmental Panel on Climate Change (IPCC) states that no matter how quickly society manages to reduce greenhouse gas emissions, society will have to adapt to the major and often unknown consequences of climate change.

Unfortunately, Norwegian municipalities do not have a long tradition of climate adaptation. Work on climate adaptation started in the early 2000s in Norway, and the first public report on climate change adaptation was not published until 2010:

 Adaptation to a changing climate - Society's vulnerability and need to adapt to the consequences of climate change. 

With the help of changes in laws and regulations, a major increase in knowledge production, guidance, coordination and, to some extent, the use of resources, society's capacity for climate change adaptation has been strengthened since 2010.

Nevertheless, much work remains to be done. Both the Office of the Auditor General and the government itself have pointed out that work on climate change adaptation must be strengthened in the future if Norwegian society is to remain safe in the future.

 It is difficult to assess how affected and vulnerable Norwegian municipalities are to climate change, and how well they are working to adapt to the changes. One problem is that exposure to natural hazards, vulnerability and adaptation are complex concepts that can also affect each other in different ways, and only a few indicators does not tell the whole story.

Nevertheless, the climate ranking gives us important insights into how the various dimensions of climate risk are distributed between municipalities and regions within the country. This will be a useful starting point for more complete local analyses.

One topic that has not been captured in this first version of the climate ranking of Norwegian municipalities is transboundary climate risk, i.e. the risk to which municipalities (and Norway) are exposed when other countries are affected by climate change. Examples of this include increased food prices in Norway due to a global crop failure caused by climate change. NorAdapt works to improve Norway's ability to adapt to climate change and has also started working with developing methods to make this, for many, new type of climate risk more tangible, i.a. through the project  "Making trans-border climate change risks tangible for adaptation actions" (TransAdapt) . The results from TransAdapt will shed light on trans-border climate risks and provide a basis for one or several indicators to represent this climate risk.