In conversation with Dr Buwen Dong: Excess warming in Europe
In recent weeks the record for the world’s hottest day was broken twice, and in the UK the number of “very hot days” of 30°C or more has tripled over the last few decades.
Researchers at the National Centre for Atmospheric Science (NCAS) are monitoring concentrations of greenhouse gases, using climate models to look forwards in time, and tracking the impacts of global warming in different regions around the world.
We spoke to Dr Buwen Dong, one of our NCAS scientists based at the University of Reading, who has dedicated their career to understanding, detecting, and predicting climate change. Buwen’s current research looks to explain excess warming in Europe during summer and winter.
We spoke to Buwen about why this research is important, what methods he is using, the challenges, and the initial findings.
Can you tell us about your current research topic?
Europe has warmed three times as fast as the global mean temperatures, in both winter and summer during the past few decades – and this rapid warming is associated with increases of weather and climate extremes. For example, there have been more intense and longer-lasting extreme heatwaves in summer, more extreme rainfall events, and a greater risk of flooding in winter. However, the reasons why we are observing faster warming in Europe remain poorly understood across the climate science community.
My research aims to find out how and why there is faster warming over Europe, relative to the average amount of warming around the world. I’m focusing on understanding the drivers and processes leading to excess warming across Europe, in both summer and winter, over recent decades. I’m studying climate data collected between 1979 and 2022, and using multiple computer model simulations to investigate the main contributions to European warming. I’m also really interested in working out how atmospheric circulation plays a role.
What inspired you to pursue this research, and why is it important?
The rapid warming over Europe in summer has led to the region being identified as a heatwave hotspot. With climate change, Europe is experiencing longer-lasting intense heatwaves – sometimes coupled with droughts too. In winter, the faster pace of warming for Europe is associated with extreme rainfall. Linked with increased surface runoff of stormwater that cannot soak into the ground, this extreme rainfall is elevating the risk of flooding for the UK and other countries across Europe. All of these have impacts on agriculture, human health, economy, and ecosystems.
Climate scientists don’t currently have a comprehensive understanding of what is causing the faster European warming we are observing, and so I am motivated to figure out the different factors that are governing the temperature change. It is vitally important, so that effective strategies for building resilience to climate change can be developed.
In view of the changes in climate extremes and their impacts, it is imperative that this kind of research continues in the future. This work will also have applications for understanding warming in other regions around the world.
What techniques are you using in your research, and what are your findings so far?
We use observational and reanalysis data sets and use multiple different computer model simulations and compare their results to investigate the contributions to excess European warming. Our method is significantly simpler to some alternative existing methods, and our findings are novel.
Over the period 1979-2022, European surface air temperatures warmed around three times as fast as the global mean temperatures in both winter and summer. We define “excess” European warming as the difference between the rate of European regional warming and the rate of global warming and we have been investigating the causes.
With our method, we have been able to estimate that about 40% (in winter) and 29% (in summer) of excess European warming is “dynamical”. That means that it is linked to changes in atmospheric circulation.
We show that the rate of European warming simulated in our models compares well with the observations, but excess European warming is underestimated – particularly in winter.
Our models suggest greenhouse gases, such as carbon dioxide and methane, are the largest contributor to the excess warming in winter. Whereas the declines of anthropogenic aerosols during the recent decades make the largest contribution in summer. Anthropogenic aerosols are very small solid or liquid chemical particles suspended in the air, produced by fossil fuel combustion and biomass burning.
Our results also indicate that in the future there could be a substantially reduced rate of excess European warming in summer. However, our models are not yet simulating trends in atmospheric circulation well enough to say this for certain.
How does this research fit into your overall career as a climate scientist?
As a research scientist, working at the National Centre for Atmospheric Science now for nearly 20 years, my career goals have been to characterise and understand the nature and causes of regional climate changes and climate extremes. This research topic fits in with my area of expertise, particularly when it comes to assessing the impact of circulation changes on regional climate and climate extremes, and to quantifying the role of different factors on climate in mid-latitudes of the northern hemisphere.