In international climate talks, compensation for damage caused by the warming of the earth is a major concern. Which nations should get money? Which extreme weather events are influenced by the climate change?
Last year, most nations signed an agreement establishing a “loss-and-damage” fund. The fund will allow developed countries, which are responsible for disproportionately high greenhouse gas emissions, to give money to the most vulnerable nations who are dealing with climate change.
A portion of the fund will be used to help countries in developing regions recover from extreme weather events. It could be used, for example, to rebuild homes and hospitals after floods or to provide emergency cash transfers and food after a storm.
Some experts have suggested that the science of “event-attribution” could determine how funds are allocated. The event attribution method is used to identify the causes of extreme weather and, in particular, whether climate change caused by humans played a role.
As our paper explains, the attribution of events is not a reliable way to calculate compensations for nations that are vulnerable to climate change. A new strategy is required.
Food aid is provided to those affected by the floods that hit Pakistan in 2011. Rehan Khan/EPA
What is event attribution?
Extreme weather is complex, and many factors cause it. The science behind severe weather event attribution is primarily concerned with working out which factors contributed to the events.
A recent study, for example, found that the extreme rainfall that caused New Zealand’s flooding in February was up to 30 percent more intense because of human influence on climate systems.
The science of attribution is advancing rapidly. The focus is increasingly on extreme rainfall events, which were difficult to study in the past. It’s not yet possible to estimate costs and impacts in a way that is consistent and reliable.
The science of event attribution is based on both observations and simulations of climate models.
Most often, climate models are simulated with and without the effect of greenhouse gas emissions caused by humans. Scientists can estimate the impact of climate change on extreme events by comparing the two types.
Climate models simulate processes primarily in the ocean and atmosphere. The models do not directly affect damage from extreme weather events, such as the number of people who die in a heatwave.
Climate models simulate processes primarily in the atmosphere and ocean. Shutterstock
In order to accurately simulate the effects of an extreme event, we must know how much damage was caused by weather elements such as temperature or rainfall. In some cases, this can be determined. It requires high-quality data, like hospital admissions. This is not available everywhere.
Climate models also do not simulate some extreme events, such as severe thunderstorms or high winds. This is because extreme events tend to be sporadic, and they are often spread out over a small area. They are harder to model, for example than a heatwave, which affects a wide area.
If “loss-and-damage” funding decisions were based too heavily on event attribution, then a country with a low income that was hit by a severe heatwave could receive more assistance than a nation affected by high winds or storms relative to damage caused.
Even worse, the event attribution method is still unable to accurately estimate how climate changes cause damage in association with “composite” extreme events.
Compound events are when more than one extreme event happens simultaneously in adjacent regions or succession in the same area. Examples of compound events include a heatwave followed by a drought or a rise in sea level that makes the damage caused by a tsunami worse.
Read more: ‘Teaching our children from books, not the sea’: how climate change is eroding human rights in Vanuatu.
A drought followed by a heatwave is a ‘compound event.’ Alan Porrit/AAP
How do we move forward?
Climate change “loss and damages” cannot be calculated using event attribution.
Our paper proposes that “loss-and-damage” funds be used in conjunction with foreign aid to help low-income countries recover after extreme events, where climate change caused by humans may have been a factor.
In addition, we present four recommendations on how to use event attribution in the future for estimating “loss and damages.” They are:
Help developing countries use event attribution methods. To date, event attribution is largely conducted in wealthy countries’ regions.
Address other types of extreme events. Tornadoes, hailstorms, and lightning are beyond the capabilities of climate models that are used to attribute events because they are complex and localized. It is important to try new techniques for examining these events.
More studies on the impacts and costs associated with extreme events. Few studies have attempted to attribute the costs of extreme weather events to climate change. More efforts are required, particularly in low-income countries.
Combining event attribution and other knowledge. Scientists and experts in aid, policy, and decision-making should collaborate to develop a strategy that will allow them to use event attribution data. A better understanding of the needs and limitations of event-attribution science can lead to more useful research.