Climate variability and change
Illustrative research question: How do internal variability and different forcings influence Earth system trends, climate sensitivity, and feedback mechanisms?
Climate variability and climate change describe different aspects of the Earth's climate behavior over time. Climate variability refers to natural fluctuations in climate over short to long timescales, driven by internal processes like ocean-atmosphere interactions (e.g., El Niño-Southern Oscillation, ENSO). These variations influence regional and global weather conditions, including changes in precipitation, temperature, and extreme events. Variability can also shape long-term climate trajectories through interactions between short-term fluctuations and spatial warming patterns (“pattern effect”) that influence feedback mechanisms. In contrast, climate change describes long-term shifts in the climate mean state, primarily caused by anthropogenic greenhouse gases (forcing agents). These changes manifest as rising global temperatures, shifting precipitation patterns, melting glaciers, and more frequent and intense extreme events. A major goal of climate science is to disentangle the influence of forcings and internal variability on the observed changes in the climate system in recent decades. Due to the short observational record, we use large ensemble climate models to study these effects.
People: Erich, Gergana, Patricia, Reto, Robin, Woon Mi
Selected publications:
Gyuleva, G., Knutti, R., & Sippel, S. (2025). Combination of internal variability and forced response reconciles observed 2023–2024 warming. Geophysical Research Letters, 52, e2025GL115270. external page https://doi.org/10.1029/2025GL115270
Mauritsen, T., Tsushima, Y., Meyssignac, B., Loeb, N. G., Hakuba, M., Pilewskie, P., et al. (2025). Earth's energy imbalance more than doubled in recent decades. AGU Advances, 6, e2024AV001636. external page https://doi.org/10.1029/2024AV001636
Sippel, S., Kent, E.C., Meinshausen, N. et al. Early-twentieth-century cold bias in ocean surface temperature observations. Nature 635, 618–624 (2024). external page https://doi.org/10.1038/s41586-024-08230-1
de Vries, I., Schillinger, M., Fischer, E. et al. Precipitation disaster hotspots depend on historical climate variability. Nat Commun 17, 16 (2026). external page https://doi.org/10.1038/s41467-025-66601-2