It's not because you are unaware of any scientific base for global warming, that it doesn't exist
The basis of the effect is actually rather simple.
*Gas molecules consisting of different types of atoms (hetero-atomic) in the atmosphere get energetically excited by absorbing certain types of radiation (mostly infrared) coming from the earth's surface.
*After excitation, they lose this radiation by re-emitting it, in a random direction.
The netto effect: infrared radiation that would otherwise be unidirectionally emitted into space, partly becomes redirected back to the surface. In other words: some energy gets recycled.
This is a linear effect, per type of gas: double a certain type of hetero-atomic gas in the atmosphere and this recycling effect accounting for this molecule doubles too.
So for example carbon dioxide (CO2), methane (CH4) and hydrogen sulfide (H2S) are examples of greenhouse gases, while oxygen gas (O2) or nitrogen gas (N2) are not.
So, thermodynamically speaking, if the total energy level of the atmosphere is higher because the concentration of greenhouse gases is higher, then this leads to an increased level of chaos (entropy is the scientific term). Statistically, this means the chances increase of getting extreme weather phenomena.
So no single storm could be attributed to global warming, that is correct. But you could compare this to throwing dice. Throwing a six-sided die gives a lower chance of getting (e.g.) a five-or-higher result than throwing an eight-sided die. Even though no one will be able to tell you what the next throw is going to be for either one.
Climate sceptics play on this last fact: you cannot predict the future with a reasonable accuracy, especially when it comes to a complex system like the atmosphere. But statistics are in fact against them.