Ignoring for a moment that its educators and proponents believe "foundational science" to be somewhat immaterial and unnecessary of "regard," this field might have potential if they stuck to this (all emphases added):

In an effort to promote durable living on a finite planet, environmental psychology develops, and empirically validates, practical intervention strategies regardless of where the foundational science resides.

...and went deeper than common sense, like:

Environmental psychologists Rachel Kaplan and Stephen Kaplan suggest that the difference between reasonable and infuriatingly unreasonable behavior may be partly explained by the environments in which people find themselves.

...and:

Being confused or incompetent does not bring out the best in people thus restoring and maintaining mental vitality and proficiency is essential to supporting reasonable behavior.

...because there is a fair amount of this:

After all, to deal with the urgent environmental problems being faced, people may be called upon to make far-reaching changes away from the status quo, toward an unfamiliar life pattern, some promoted by abstract scientific arguments alone.

...and this:

Citizen and environmental experts alike should constantly tinker with new institutional forms, metaphors, norms and principles.

...used to help "sell" foregone conclusions through manipulation when "unjust" people aren't "reasonable":

As we contemplate the changes that will be needed to address the many environmental issues being faced (e.g., climate disruption, energy descent, environmental injustice, soil depletion), it is heartening that the reasonable person model supports the notions that humans seek meaningfulness more than novelty, that they benefit more from developing a sense of competence, clarity and mental vitality than from pursuing convenience or hedonic pleasure, and that the mind is better adapted to exploring, problem solving and sense making than it is to affluence.

But this field obviously has more to do with political science, which is not a science. The potential this field has anything to do with understanding the science of psychology goes out the window with statements like:

Although our current analytical tools can help make sense of the past (e.g., how did we get to this state of climate disruption and energy descent) and the present (e.g., what is the nature of our environmental predicament) and can extrapolate recent trends into the future, they cannot determine which paths into the future will prove more useful. For this we must adopt an adaptive, experimental approach. Our problem solving must seek a plurality of solutions, not the one right solution or the magic elixir. Emerging plans, policies and procedures should be viewed as hypotheses in constant need of reality testing. Or, as author and community organizer Pat Murphy puts it, we need to "make a lot of mistakes quickly"(quoted in Cobb 2009). The quickly part of this suggestion comes from the concern that climate disruption and energy constraints are happening at a frequency and intensity thought to be, until recently, many decades away...

An approach to behavior change under conditions of urgency, great environmental uncertainty and grave stakes, yet with a need for place-based sensitivity, might start with small steps. As anthropologist and political scientist James Scott advises with respect to interventions for economic development, "Prefer wherever possible to take a small step, stand back, observe, and then plan the next small move." (Scott 1998: 345). Scott’s suggestion follows, in part, the small-experiment approach to environmental problem-solving outlined by Irvine and Kaplan (2001; see also Kaplan, Kaplan & Ryan 1998). Small experiments is a framework for supporting problem-solving that is based on the innate inclinations that are at the core of the reasonable person model, particularly the building and sharing of mental models.

And as if that wasn't obvious enough to expose the field's underlying nature (pun intended):

Some people may argue that the small experiment framework is a renamed version of the experimenting society proposed by Campbell (1981). The experimenting society suggests that social programs should be designed and implemented as experiments with a built-in evaluation process. However, in Campbell’s version the evaluation is a formal process, one conducted by social scientists using meticulous, expertly designed trials followed by rigorous statistical analyses. Furthermore, the results are intended for use by governmental policy makers and, perhaps, for later publication.

The small experiments approach uses the concept of an experiment in a much less restricted sense. The analysis involved in such experiments is less formal and more compatible with immediate needs and local capabilities. Online accounts, reports by participants or visits by interested individuals would be appropriate additions to whatever formal record keeping is employed. The more expert-based framing of an experiment used by Campbell make his approach less likely to be tried by, and the results less accessible to, non-experts.

The small experiment framework is a quick and simple way to promote behavior change that is compatible with what environmental psychology has learned about human nature. Such an approach can enable people to build mental models that allow them to view the urgent and serious environmental issues they face in terms of challenge and possibility rather than inevitability and despair.

Politically, environmentalism is a racket, has a great deal of junk science, and is known for a significant amount of fraudulent and manipulated data. Psychology has a reputation for more than its share of junk science. Bringing the two together is ripe for corruption. Nothing wrong with using science and empirical data to try to convince people that cleaning up the environment, moving away from fossil fuels, etc. are good things and bring about current and future benefits, but this strikes me as another effort by Al Gore and Co. trying to manipulate people through psychology. This isn't learning about how the brain works or alleviating mental diseases. This is about how to make propaganda more effective. We also must be watchful of what occurs in the field lest we forget that the top professional organization for psychologists sanctioned torture.