Modern weather forecasts and climate projections rely on complex computer models that simulate how the atmosphere, land and oceans interact. Developing these systems relies on sustained international collaboration, shared infrastructure and long‑term scientific investment. 

The Unified Model Partnership was formally established in 2014, building on several years of earlier collaboration among Unified Model users, and was led by the UK Met Office. It was established to jointly develop and maintain a common modelling framework for weather and climate prediction. New Zealand was a founding member alongside the United Kingdom, New Zealand, Australia, India and Singapore, with additional associate partners joining over time. 

Members of the Momentum Partnership from all over the world gathered in India this year for a workshop and series of discussions. Photo: Earth Sciences NZ

By contributing science, expertise and computing effort, partners ensured that improvements made in one part of the system could be shared and used globally. This collaboration later evolved into what is now known as the Momentum Partnership. 

The Momentum framework brings together atmosphere, ocean, land and sea‑ice components, allowing the same core science to support day‑to‑day weather forecasts, seasonal outlooks and long‑term climate projections. 

New Zealand’s contributions have focused on improving model performance in the Southern Hemisphere, where sparse observations, complex terrain and strong ocean influences present unique challenges. This work strengthened forecasts for New Zealand and improved global understanding of Southern Hemisphere weather and climate. 

Today, the Momentum Partnership underpins forecasting systems used around the world, demonstrating the enduring value of shared science and international cooperation.