The Climate-Aware Task Scheduler is a lightweight Python package designed to schedule tasks based on the estimated carbon intensity of the electricity grid at any given moment. This tool uses real-time carbon intensity data from the UK's National Grid ESO via their API to estimate the carbon intensity of the electricity grid, and schedules tasks at times when the estimated carbon intensity is lowest. This helps to reduce the carbon emissions associated with running computationally intensive tasks, making it an ideal solution for environmentally conscious developers. Currently CATS is built to work with the simple "at" scheduler, but work is underway to port it to Slurm. The source code can be found at https://github.com/GreenScheduler/cats and more information at https://greenscheduler.github.io/cats/.