COP27: âTranslation between change in weather and damages is not linearâ
Down To Earth talks to Friederike Otto, climate scientist at Imperial College London about the science of weather attribution
The fact that southern Madagascar is so vulnerable to droughts and famines has a lot to do with its colonial heritage, rather than climate change. Photo: @IFRCAfrica / Twitter
Attribution science has grown leaps and bounds to trace the link between climate change and weather events. But this link does not extend to estimating loss and damages, Friederike Otto, climate scientist at Grantham Institute of Climate Change and the Environment, Imperial College London, tells Akshit Sangomla. Excerpts:
Akshit Sangomla: How has weather attribution grown as a scientific discipline?
Friederike Otto: Weather attribution science has come a long way in the last five years. There are emerging best practice methodologies now.
Through that we now know, without having to do a new study, that every heatwave has been made more likely and more intense because of climate change.
We also know that in most cases of heavy rainfall events there is a role of climate change, though that is smaller than in heatwaves.
For droughts there are some hotspots where we do see the fingerprints of climate change. These are southern Africa, the Mediterranean region and parts of South America.
There are also many droughts that cause huge damage and food insecurity even though they do not have a climate change signal. Highlighting that vulnerability and exposure plays a crucial role.
AS: What are some open questions in weather attribution science?
FO: There are certain types of events for which attribution studies are still difficult to do. These are mainly events happening on small scales like flash floods or glacial lake outburst floods.
When it is 40°C in Delhi, some place 30 km away will also have very high temperatures. You do not need 100 weather stations within Delhi and the surroundings to have a good representation of the temperatures.
When it comes to heavy rainfall, which is not monsoon rainfall, it often changes within a few kilometres.
So to know what is happening you need a much denser network of weather stations, which in most parts of the world, we do not have.
Also, to simulate such an event properly, you would need very high resolution climate models that are expensive to run.
Even though recent Intergovernmental Panel on Climate Change models we use are a lot better than they were just 10 years ago, for small-scale events, they are just not good enough.
AS: How do attribution studies fix responsibility on polluters?
FO: With attribution studies, we see how emissions from individual companies or countries lead to changes in global mean temperature, how that in turn leads to changes in weather and additional losses and damages.
AS: The US accounts for 25 per cent of historical emissions. So for a heatwave made more likely by climate change, would it pay 25 per cent of compensation?
FO: From a scientific point of view, you can say that they [the US] are responsible for 25 per cent of the emissions so they are responsible for 25 per cent of the increase in the heatwave. But the translation between the change in the weather and the damages is not linear.
Say there is 50 per cent increase in the intensity of rainfall that might lead to 700 per cent increase in flooding. This may be because some thresholds got breached. I think it would be a much better starting point to apportion historic responsibility than to go to the damages.
AS: But would such a translation be possible in the future?
FO: I am not sure you necessarily want to do that from a loss and damage point of view because lots of other dimensions play a role as well. There are events like the drought in Madagascar two years ago, which led to famine. That is an event where climate change does not play a role.
The fact that southern Madagascar is so vulnerable to these types of events has a lot to do with its colonial heritage. So if we just translate loss and damage for only events with a strong climate change signal it would not lead to the fairest way of compensation.
The better and also simpler way of apportioning loss and damage would be to not do it to every weather event that in principle could be influenced by climate change.
Say, there is a loss and damage fund that can be used to help increase climate resilience, and to this end the global north countries pay according to their historic emissions.
This was first published in the 1-15 November, 2022 edition of Down To Earth
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