Josie Aruhasi

My research focuses on understanding how the climate system responds to external forcing and how internal climate variability shapes regional climate change. I use large ensemble climate model simulations, observations, and statistical inference to investigate historical climate mechanisms and to develop constraints on future projections and climate predictability.

I have developed an observation-based linear pattern-scaling framework that separates externally forced signals from internal variability in observed regional climate change. This approach enables like-for-like comparisons between models and observations, helps address persistent regional attribution challenges, and provides interpretable constraints for regional climate projections.

By deriving human-forced warming patterns directly from observations, this framework provides an additional line of evidence beyond model-derived forced responses. It is especially useful in regions where observations and climate models diverge, as such discrepancies may reveal missing mechanisms, model biases, or nonlinear climate responses. With the increasing availability of km-scale simulations, my work aims to connect observed regional climate signals with process-based model understanding and decision-relevant climate assessment.