There are many ways Software Engineers can contribute to reducing the carbon footprint of an application. During the design process, we can opt for choices which are more energy efficient and think about ways to minimize resource consumption without compromising functionality. A while ago, I worked with a team at Microsoft during a one-week Hackathon to consider replacing regular VMs with Spot Virtual Machines for different workloads. Spot VMs utilize unused capacity in existing data center infrastructure and usually cost just a fraction of on-demand virtual machines. By taking advantage of existing infrastructure, leveraging Spot VMs reduces the need for more hardware to run in data centers and ultimately reduces future energy consumption.
You can read about it here: How Spot Virtual Machines can reduce Carbon Footprint