One of the central challenges in understanding pro-environmental behavior is measurement. Currently, most researchers (including myself) lean on self-report of behavior.
What kinds of pro-environmental behaviors might be realistically measured by researchers? For example, recycling bins have been measured at the curb for weight (time-consuming), electrical meters have been read by students (time-consuming), household water usage has been measured by partnering with a water district.... there are also laboratory tasks such as recycling, donation, and turning out the lights.
There's room here for more creativity. What other behaviors might affect conservation or public discussions of environmentalism and could be observed?