Lets roundup all of our technology used to detect exoplanets. Lets also pack all of our know-how as well. Lets even hypothetically take what we might develop in the foreseeable future.
Now, .... lets start a journey away from our planet. Imagine a GoogleEarth flyaway. I would think we could readily identify that our planet contains organic life from, say, Mars. So lets travel further. To Jupiter, to Saturn, to the planet exiled Pluto. Into the Kuiper Belt. How far can we get into space before Earth is no longer distinguishable as having life?? When does the signal for organic life become undetectable by our current technologies of science??
If we are to determine the presence of life on other distant planets, we only have one we can use as a model: Earth. And to identify such planets as Earthlike, containing life, we must be patient. We must let both our knowledge and technology ratchet up several notches. Maybe scores of notches, considering we may have to look deeply into space to find such ones. Either way, at least scientists are beginning to look at this question. If something Earthlike is close we will have to wait less. Is there another pale blue dot out there waiting to be found??