Sometimes we do not need to be exact in order to understand what is feasible, sometimes ballpark estimates and back of the envelope calculations are sufficient.
For a set of calculations and supporting data about the climate and energy issues, look at the Without Hot Air site that has the full PDF of a book available that is full of the calculations and approximate data, allowing the ethical considerations to be addressed after we understand the physical constraints.
Introducing Climate Hawks as an alternative way of framing the conversation.
it becomes about values, about how hard to fight and how much to sacrifice to defend [the] future.
PHPUnit has the concept of Incomplete and Skipped Tests something that is missing in the Ruby TestUnit framework. Yes, technically TestUnit has flunk(), but that is not the same as TestUnit only reports failures and errors, whereas PHPUnit reports failures, errors, skipped and incompletes.
In Ruby, the idea of skipped and incomplete tests is not really supported, but since much of the Ruby world supports Test Driven Development, it is not really necessary. From what I have seen of the PHP world, Test Driven Development is not normally practiced, so it is useful to have the ability to mark tests as skipped or incomplete, and have PHPUnit report the test suite as passing, with a number of skipped or incomplete tests. It gives a visual reminder that more testing is needed, but it does not cause the test suite to report an error, so the next stage in the deployment process can continue without manual intervention (assuming that there are no failures or errors from the rest of the test suite.)