In this context, it means exactly the same thing. However, in other contexts it can have a slightly different nuance, as you guessed. "Should" suggests that something needs to be done in the future, but not necessarily that there is any problem or guilt with it not being done now: "We should clean the house tomorrow." This does not necessarily imply that NOT cleaning the house today is a failing. "Should be+ing" potentially implies slightly more that something should be being done RIGHT NOW (that there is some sort of current failing): "We should be cleaning the house instead of watching movies." A similar meaning could be created by saying "We should clean the house instead of watching movies", but there is possibly a greater level of "guilt" or pressure involved in the "should be cleaning" example. Though as you can see from my example sentences, extra meanings can also be created by context ("tomorrow", "instead of...") which probably give more of an idea of the meaning than the choice of "should" versus "should be + ing" In the case of "We should be taking better care of the planet", they probably did intend the guilt/blame meaning to come through - it's not that we should take better care of the planet tomorrow if something goes wrong, but that we are currently failing by NOT taking better care of it. I hope this helps! :)