The deadlock in climate policy and the science of extreme event attribution

Climate. It is among the most discussed topics of our days: from international policy making to public demonstrations, media outlets, and even elevator small talk. There is no lack of controversy and strong opinions when climate change is on the table, but that is not exactly surprising. When concrete actions must be taken, responsibility must be assigned; and it seems to be human nature that such discussions must be hard and tiring. Naturally, even more so when people's livelihoods are affected. We may never finish discussing to what extent human action has affected our planet’s climate system, what actions need to be taken and by whom. As importantly, we could spend days debating why our governments seem stuck in the drafting of effective measures to mitigate and fight back climate change (or even recognize it, in some cases). Though the divisive issues of responsibility and effective actions are essential, they are not the focus of this humble essay. Not exactly at least; I would like to take the topic closer to home.

The science being developed over climate systems is amazing! There is a staggering amount of physical phenomena and chemical reactions interacting over an immense range of spatial and temporal scales. There is so much diversity in the people involved as well: from the finest theoretical physicists and mathematicians, to the most ingineous meteorologists, spatial scientists and computer scientists, employing the most powerful computers ever built. But this is also not my motivation today.

My objective today is to raise the debate on a sensitive topic in-between: the responsibility we hold as researchers in both the social and political debate of the ever more pressing debate that are climate actions. In particular, the challenges we need to tackle towards the development of effective policies.

Good quality and solid research is essential to inform and guide effective actions, be they local, national or global in scale. On the other hand, we need to constantly reach to our communities so that people can take their positions on the matter with well educated opinions. This is not only a fundamental social responsibility, but also essential to actually drive governments and civil institutions to take necessary policies and measures. The scientific community has been working ever harder on both ends of this debate.

We have seen, all types of communities cry out for action and rise up in protest against the inadequacy of the policies made by our leaders. This is probably the issue that most united our young generation, across geographic and social barriers. This green wave has been reshaping the practices of companies and creating new markets, as people tend more and more to prioritize products that are environmentally friendly. And yet, this is far from enough.

Below, we see the probability distributions for anomalies in the summer mean temperatures, projected over the next decades for different scenarios. The vertical line marks the average anomaly recorded during the famous 2003 European heat wave. Even if the most ambitions measures had been taken, we still would need to get used to such extreme conditions. 

Not only heatwaves, other extreme weather conditions and natural disasters such as floods and snow storms are becoming more frequent and intense. After facing such a disaster, someone will always raise the question “was this event influenced by climate change?”. Let us break it down to its core assumptions:

  • How do we characterize an event as extreme? (e.g. location, duration, likelihood, social impact...)

  • What does “influenced by”? (how are the above metrics conditioned of affected?)

  • How do we characterize climate change? (comparison between past, present and future)

These three points summarize the core of the research field that is called Extreme Event Attribution, which searches for robust causal and probabilistic relations between these extreme events and the changes between current climate conditions, its recorded past and our future predictions. These relations are instrumental in defining policies for prevention, damage control and in the payment of reparations. 

Only by understanding to which extent human actions affect the variability and frequency of extreme events, can we realistically assign responsibility and take concrete steps towards breaking the deadlock that has plagued our previous attempts at achieving a global compromise towards the protection of our climate and our environment.