Humans are changing the weather worldwide, with rising temperatures and declining snowpack in the Pacific Northwest. The challenge of forecasting how such climate change impacts ecosystems motivates our research at Mount Rainier National Park. We monitor plant growth, survival and reproduction across the large climatic gradients this iconic mountain provides, and combine these data with models to predict how and how fast forests and alpine meadows will respond to changing climates. Such information is critical to understanding how ecosystem services provided by Pacific Northwestern mountains (e.g. carbon sequestration, biodiversity, timber, water supply) will be impacted by climate change.