Principle 1: Carbon
Being green means different things to different people, that's a challenge when it comes to communication and deciding what to optimize for. For Sustainable Software Engineering, our focus is carbon, and that's why the first principle of Sustainable Software Engineering is to build applications that are carbon efficient.
What is carbon?
Greenhouse gases (GHG) act as a blanket that increases the Earth's temperature, which is a natural phenomenon. However, due to human activities, the global climate is changing much faster than animals and plants can adapt. How human society will adapt is still an open question.
There are many different GHGs. The most common is carbon dioxide (CO2). To make calculations more manageable, we normalize all GHG numbers to carbon dioxide equivalent (CO2eq). For example, one ton of methane has the same warming effect as about 25 tons of CO2, so we normalize it to 25 tons CO2eq. We may shorten even further to just carbon, which is often used to refer to all GHGs.
Net-zero carbon targets
The goal set by the UN IPCC and agreed and ratified by 195 states in the Paris Climate Agreement is to reduce carbon pollution so that the temperature increase stabilizes to a 1.5°C increase by 2100 when compared to pre-industrial levels.
The temperature increase on the Earth is dependent on the total amount of carbon we have in the atmosphere, not the rate at which we are emitting. To completely halt the rate of temperature increase, we need to stop adding carbon to the atmosphere or achieve net-zero emissions.
Net-zero means for each gram of carbon we emit we also extract one gram, so the overall mass of carbon in the atmosphere remains fixed.
To achieve this, we need to start immediately reducing our carbon emissions to a 45% reduction by 2030 and reach net-zero by 2050.
Don't waste carbon
We will always emit carbon through our activities; our goal is for each gram of carbon we emit into the atmosphere to make sure we extract the most value from it as possible.
To be carbon-efficient is to minimize the amount of carbon emitted per unit of work.
In the engineering space, the part we play in the climate solution is building applications that are carbon-efficient. Being carbon-efficient is about building applications that add the same value for you or your users, but emit less carbon.