The sun, Earth’s primary energy source, plays a crucial role in climate oscillations. Understanding its influence on climate is essential for accurate predictions. Senior Researcher at the Instituto de Astrofísica de Andalucía, Bernd Funke and his team are furnishing climate modelling with boosted fidelity of solar radiative forcing data. These data are pivotal for generating large ensembles, namely sets of climate model simulations that explore different possible future scenarios.
‘I’m excited to be part of EXPECT. It’s an immense effort and for me it’s really an opportunity to be part of a multidisciplinary team covering all important aspects from both the methodological and observational sides,’ says Bernd Funke.
At the heart of Earth’s climate system lies the Sun, the ultimate source of nearly all energy. The Sun’s brightness isn’t constant: it fluctuates over an 11-year cycle. ‘Solar activity is changing over time: this has some slight implications also on the Earth’s climate,’ says Bernd Funke.
Climate models account for how variations in solar activity can influence surface temperatures atmospheric circulation, and other climate factors. The influence of these fluctuations on Earth’s climate are referred to as solar forcing in climate models. Understanding how solar radiance variability and particle fluxes interact with Earth’s atmosphere is central to Dr Funke’s research. ‘In this context,’ he explains, ‘I’m focusing on reconstructing these variations to refine climate models.’
What is solar forcing more precisely?
Solar forcing refers to the influence of changes in solar radiation (i.e., the amount of energy the Sun emits) and particle fluxes on the Earth’s climate. This can include variations in the Sun’s output over time, such as during the solar cycle or longer-term changes in solar intensity. Solar forcing is subset of radiative forcing, which includes all factors affecting the Earth’s energy balance.
Since climate models are sensitive to even the smallest variations in solar activity, triangulation of data and methodologies enables to better understand the mechanisms at play.
How is this linked to EXPECT?
EXPECT is a unique chance to explore regional climate variability and extremes while optimising data availability. Reliable and high-quality data is essential for creating climate models that run efficiently.
In EXPECT, individual research units investigate different types of forcings – both natural and anthropogenic forcings (e.g., volcanic eruptions, solar variability, tropospheric aerosols, land use and greenhouse gases) – to understand how they interact with one another within the climate system.
‘A core activity in the project is to run climate simulations for generating large ensembles, which are then used to better understand the impact of individual climate forcers on surface climate and surface climate extremes,’ says Dr Funke.
What is your institution’s role in the project?
Forcing data preparation is essential to support the EXPECT project.
At the Instituto de Astrofísica de Andalucía, Dr Funke has dedicated his research to the atmospheric region extending from the upper troposphere to the lower thermosphere. His goal is to shed light on how solar variability impacts these high-altitude layers and how that affects surface climate.
‘Our contribution is in terms of providing the forcing data and in evaluating the quality of that data by introducing it in climate model simulations and comparing it to observations. A core activity in EXPECT is to run climate simulations for generating large ensembles, which are then used to better understand the impact of individual climate forcers on surface climate and surface climate extremes,’ says Dr Funke.
Dr Funke is also a Member of the Climate Forcing Task Group for the Coupled Model Intercomparison Project, now in its latest stage (CMIP7).
How does CMIP tie into the EXPECT project?
CMIP is an international, collaborative effort, aimed at deepening understanding of climate changes across past, present and future timeframes. Since its inception in 1995, CMIP has been spearheading a global model intercomparison within the climate science community. By leveraging a multi-model approach, the project evaluates and refines climate models, enhancing the accuracy of simulations, as well as providing clearer insights into climate patterns.
As Dr Funke explains, ‘a huge degree of coordination within climate forcing data providers is required. All these coordination sites are covered by the cooperation with the CMIP7 Climate Forcing Task Team. It’s important to have model data from different models to avoid biases introduced by specific model architectures,’ highlighting the relevance of CMIP.
For the EXPECT project, CMIP presents a valuable opportunity to tap into solar forcing datasets that are regularly revised and refreshed. In fact, one of CMIP’s standout feature is its robust global infrastructure, which not only aggregates crucial data but also ensures open access for a rapidly growing global research community.
What milestones do you hope to achieve with your research?
‘Model simulations have to run into the future and that is no easy task,’ points out Dr Funke. Among the goals that the Instituto de Astrofísica de Andalucía is committed to achieving is the establishment of a consistent method for regularly delivering forcing data, as these become available. To do so, the automatisation of the process of generation of this forcing data should be another key output.
EXPECT as a testbed for enhanced climate modelling
Future forcing scenarios rely on a probabilistic approach, as natural forcings like solar and volcanic activity remain unpredictable.
‘We are trying to generate forcing ensembles which can be used in a statistical way to provide uncertainty estimates in future climate simulation and prediction experiments in order to be sure to better constrain the uncertainty of what’s caused by natural variability in these simulations,’ explains Dr Funke.
Key challenges include understanding interactions between forcings, accurately capturing mechanisms in models, and distinguishing signals from internal variability, compounded by the need for higher-resolution simulations.
This is where EXPECT excels: generating large-scale simulations to tackle these uncertainties head-on. With its focus on stochastic ensemble scenarios, EXPECT is uniquely positioned to offer more realistic projections of natural forcing uncertainties, advancing the understanding of the climate system.
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