If you're using runtime languages on the backed (node, python) then you're already failing the environment. An efficient compiled language can perform the same functions much more efficiently.
Not necessarily. If you make a living running a typical CRUD software-as-a-service offering, your code may really just be glue mapping HTTP requests to database requests. There, your choice of language doesn't count for much; your code isn't doing heavy lifting, the DBMS is.
It's quite possible your hardware requirements could be lower by writing in Python and tuning your database, rather than spending the same time writing non-performance-critical code in C++.
Frameworks like Tornado, for Python, are able to quite efficiently handle highly concurrent workloads, despite using a single-threaded, interpreted, language.
For computationally intensive code, then sure, a language like Python will need far more hardware horsepower to get the job done than C++ would.
This post is about an optimized environment for C++ services though - not node or python services.
Unlike some other methods for reducing carbon emissions, which require subsidies to be competitive, massively reducing server infrastructure footprint often improves the absolute economics through radical reductions in OpEx/CapEx for data intensive businesses.
That said, if your goal is reducing expenditures, reducing your carbon footprint is a great cherry on top.
1- Yes, optimizing for lowering this consumption by an app-developer can definitely be an ill-advised endeavor economically (you're saving 0.1-10% of your cost.. by adding a huge investment of time, possibly larger than the application development itself) 2- Optimizing across all deployments, can definitely move the needle, in a very significant way, against the effort required, since you're automatically deployed on 1000-1M places.
It's the same reason library developers (especially system/langugage/heavily-used-libraries) have a very good reason economically (and therefore ecologically as well) to optimize. Competition here is a huge benefit to everyone, including the environment.
If you want to see what real computing energy looks like, look at Bitcoin.