GeoTalk: Dr Pedro Jiménez Guerrero

GeoTalk, featuring short interviews with geoscientists about their research, continues this month with a Q&A with Dr Pedro Jiménez Guerrero (University of Murcia) focusing on air pollution and climate change. If you’d like to suggest a scientist for an interview, please contact Bárbara Ferreira.

Pedro Jiménez Guerrero at the time he received the Outstanding Young Researcher Award of the Spanish Royal Academy of Engineering. (Credit: Ana I. Domenech)

First, could you introduce yourself and let us know a bit about your research topic(s)? 

I was born in Murcia, Spain in 1978. I got my Ph.D. in Environmental Engineering at the Technical University of Catalonia in 2005 (Doctoral Prize to the Best Thesis in Environmental Science and Sustainability), being a visiting researcher at the University of California UCI (USA) and the Max Planck Institute for Chemistry (Germany). After that, I was a post-doc at the Goddard Institute for Space Studies, NASA (USA), the Earth Sciences Department of the Barcelona Supercomputing Center (Spain) and the University of California UCLA (USA). Two years ago, I took a position at the University of Murcia as a researcher and senior lecturer. Recently I received the Outstanding Young Researcher Award of the Spanish Royal Academy of Engineering.

My main research topics cover the analysis of the magnitude and extension of the potential impacts of climate change at a regional scale and their impacts on future air pollution. Some pollutants, such as ozone and aerosols, are recognized as important climate agents affecting the radiative forcing, but are also the most important contributors to poor urban and regional air quality over Europe. Therefore, my research focuses on the effects of climate change on air quality (and vice-versa) analyzed under the wider framework of chemistry-climate interactions. Just by modeling systems that comprehensively simulate the climate system (with special emphasis on the interactions atmosphere-ocean-chemistry), it becomes possible to explore changes in future climate caused by the increase of the emissions of anthropogenic greenhouse gases and the concentration of atmospheric pollutants.

Regarding the relation between climate and air pollution, could you explain in what ways can climate change impact air quality?

Climate change alone may influence future air quality through modifications of gas-phase chemistry, transport, removal, and natural emissions. This influence is particularly important in the context of the intercontinental and transboundary transport and in hemispheric air pollution. Conversely, air pollutants can affect climate in different ways. Apart from typical greenhouse gases (CO2, methane), other chemical tracers, such as ozone, can absorb infrared terrestrial radiation, while aerosols reflect and absorb solar radiation. Both these processes exert a direct radiative forcing on the climate system (the so-called ‘direct effect’), with associated semi-direct effects due to the changes in the atmospheric structure. In addition, we can find an ‘indirect effect’ since aerosols act as cloud condensation nuclei, thereby modifying the microphysical and optical properties of clouds, affecting the climate.

What can be done to improve future air quality in a warming world? Do scientists have a role to play in this process, or does the reduction of air pollution rest only on decision-makers?

Scientists must play a role in the strategies aimed at reducing air pollution. According to recent studies of the European Environmental Agency, air pollution is the environmental factor with the greatest impact on health in Europe and is responsible for the largest burden of environment-related diseases. Recent estimates indicate that 20 million Europeans suffer from respiratory problems every day. So, the challenges posed by anthropogenic climate change and its influence on air quality call for a proper assessment of these impacts. In this sense, scientists must help decision-makers to establish the magnitude and extent of potential impacts of climate change on air quality and to advice major government authorities about the best strategies to abate air pollution and to define the most appropriate mitigation measures with the most current and complete information as possible (based on their knowledge and their research).

In an interview with ABC last year, you mentioned that “climate scientists would be nothing without supercomputers”. Why is that so? How have supercomputers contributed to improve our knowledge of the Earth system?

The dependence of climate scientist on high-performance computing relies on very different factors. There is a need for high resolution, quality and comprehensive climate information over long periods. Modern high-resolution full transient simulations (covering several decades or even centuries), as those proposed in the CORDEX initiative of the World Climate Research Program, demand important computing resources. On the other hand, considerable uncertainty affecting climate simulations still exists. For instance, diverse regional climate models produce different results even when driven by the same boundary conditions provided by a global model. Another source of uncertainty is the definition of emission scenarios, or the inherent internal variability. Moreover, the interactive coupling of complex climate models and full chemistry schemes is computationally demanding. Therefore, ensemble approaches (multi-model or intra-model approaches) demanding huge computational resources are commonly conducted to further improve our understanding of the behavior of climate models and ultimately reduce this uncertainty. Hence, there is a clear need for high-performance computing if we want to improve our knowledge of the Earth system.

Last but not the least, can you tell us a bit about your future research plans?

My research plan in the long term includes the study of the feedbacks between climate change and air pollution in the next decades over Europe, the Western Mediterranean, and the Iberian Peninsula. These possible impacts include potential excesses of critical levels causing changes in the patterns of extreme events, high levels of air pollutants, modifications in the kinetics and atmospheric chemistry, feedbacks (both positive and negative) with the regional climate systems, etc. For that purpose, the methodology I’m working on includes the development of an integrated framework of regional climate models applied with very high resolution, taking into account the interactions between atmospheric, oceanic, and chemistry transport processes.

One of my most pressing current objectives is the quantification of the different sources of uncertainty inherent to air quality modeling from a climatic perspective, including the frequency distribution of extreme events (e.g. exceeding the thresholds for the protection of human health or ecosystems). Also, I plan to study several topics, from the influence of the selection of the physics and chemistry of the models in the forecast of climatic impacts on air quality to the definition of the chemical weather types associated to air pollution. I am currently working on a paper studying the influence of North Atlantic Oscillation (NAO) on the atmospheric dynamics affecting the patterns of air quality over the European continent.

Bárbara Ferreira was the Media and Communications Manager of the European Geosciences Union from 2011 to 2019. Bárbara has also worked as a science writer specialising in astrophysics and space sciences, producing articles for the European Space Agency and others on a freelance basis. She has a PhD in astrophysics from the University of Cambridge.

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