Using a Game to Engage Stakeholders in Extreme Event Attribution Science

The impacts of weather and climate-related disasters are increasing,and climate change can exacerbate many disasters.Effectively communicating climate risk and integrating science into policy requires scientists and stakeholders to work together.But dialogue between scientists and policymakers can be challenging given the inherently multidimensional nature of the issues at stake when managing climate risks.Building on the growing use of serious games to create dialogue between stakeholders,we present a new game for policymakers called Climate Attribution Under Loss and Damage:Risking,Observing,Negotiating(CAULDRON).CAULDRON aims to communicate understanding of the science attributing extreme events to climate change in a memorable and compelling way,and create space for dialogue around policy decisions addressing changing risks and loss and damage from climate change.We describe the process of developing CAULDRON,and draw on observations of players and their feedback to demonstrate its potential to facilitate the interpretation of probabilistic climate information and the understanding of its relevance to informing policy.Scientists looking to engage with stakeholders can learn valuable lessons in adopting similar innovative approaches.The suitability of games depends on the policy context but,if used appropriately,experiential learning can drive coproduced understanding and meaningful dialogue.

Contribution of Global Warming and Atmospheric Circulation to the Hottest Spring in Eastern China in 2018

The spring of 2018 was the hottest on record since 1951 over eastern China based on station observations,being 2.5°C higher than the 1961−90 mean and with more than 900 stations reaching the record spring mean temperature.This event exerted serious impacts in the region on agriculture,plant phenology,electricity transmission systems,and human health.In this paper,the contributions of human-induced climate change and anomalous anticyclonic circulation to this event are investigated using the newly homogenized observations and updated Met Office Hadley Centre system for attribution of extreme events,as well as CanESM2(Second Generation Canadian Earth System Model)simulations.Results indicate that both anthropogenic influences and anomalous anticyclonic circulation played significant roles in increasing the probability of the 2018 hottest spring.Quantitative estimates of the probability ratio show that anthropogenic forcing may have increased the chance of this event by ten-fold,while the anomalous circulation increased it by approximately two-fold.The persistent anomalous anticyclonic circulation located on the north side of China blocked the air with lower temperature from high latitudes into eastern China.Without anthropogenic forcing or without the anomalous circulation in northern China,the occurrence probability of the extreme warm spring is significantly reduced.

Effects of anthropogenic forcing and atmospheric circulation on the record-breaking welt bulb heat event over southern China in September 2021

In September 2021,southern China witnessed an extreme high-temperature and high-humidity event.The average regional wet bulb globe temperature(WBGT)anomaly(relative to 1961-1990 mean)in 110.0°-120.0°E,27.5°-32.5°N region was the highest on record at 3.28°C and exceeded three times the observed standard deviation.To investigate the underlying causes,we examine the effects of anthropogenic forcings and anomalous circulation patterns on this event using the multi-model ensembles from the Coupled Model Intercomparison Project Phase 6.Results indicate that 2021-like events would happen extremely rarely without anthropogenic warming(would not occur in counterfactual world simulations)and have become a 1-in-16-year event in the factual world.For the threshold of the second most extreme year,the occurrence probability of extreme WBGT events increases approximately 50 times due to the impact of anthropogenic forcings.The effect of anthropogenic warming under similar atmosphere circulation increases the probability of extreme WBGT events by 13-60 times,and that of corresponding circulation patterns under the same anthropogenic warming increases the probability by 1.3-1.8 times.