The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission, led and developed by NASA and partner organizations, will monitor the pulse of the Earth to better understand climate change. CLARREO is a climate-focused mission that will become a key element of the climate observing system. The foundation for CLARREO is the ability to produce highly accurate and irrefutable climate records. Measurements derived from CLARREO will be used to detect climate trends and to test, validate, and improve climate prediction models. The CLARREO mission will provide accurate, credible, and tested climate records that lay the groundwork for informed decisions on mitigation and adaptation policies that address the effects of climate change on society.