Consumers can be creatures of habit, comfortable shopping at their favorite stores in the usual way. So there is sure to be some grumbling come July 1 when Oahu’s ban of a common and popular type of plastic bag finally takes effect.

The complaining is likely to be short-lived, though, once Honolulu shoppers adjust and adopt habits that the most environmentally inclined consumers have sworn by for years, such as toting along sturdy cloth bags for their groceries and other purchases.

Retailers, too, have had plenty of time to implement feasible solutions, and some already have, ahead of deadline. After all, the Honolulu City Council first passed this law three years ago; businesses that procrastinated cannot justifiably claim that they lacked notice.

Once Oahu residents and visitors expand the lens beyond their own shopping preferences, they will recognize what promises to be one of the most immediate improvements fueled by the bag ban: a decrease in unsightly litter because there are fewer plastic bags blowing around, getting caught in chain-link fences, fouling parks and beaches and posing health threats to precious marine life.

Oahu is the last of the major Hawaiian islands to prohibit most commercial uses of the inexpensive, lightweight plastic bag commonly used to bag groceries. Positive outcomes on Maui, Kauai and the Big Island — all of which report less plastic litter — portend more positives than negatives for Oahu too, despite the naysayers who predict higher grocery prices, more shoplifting and more paper rubbish in the ban’s wake.

There were similarly dire predictions on the outer islands, advocates there recall — predictions that did not come true. Former Maui County Councilman Mike Molina recalled opponents warning that merchants would go out of business if the county banned the use of plastic grocery bags, as it did 41⁄2 years ago.

"The sky was falling and it was the end of humanity. But it wasn’t the end of the world. And now Maui is a lot cleaner," Molina, now an executive assistant to Mayor Alan Arakawa, told Honolulu Star-Advertiser reporter Timothy Hurley.

If Oahu does not see similar measurable results, it will mean that the law needs tweaking to make the ban stricter, to close some of the loopholes advocates worry will encourage businesses to skirt the intent of the law. The ultimate idea is to reduce the use of plastic bags, period, not to replace thin, cheap plastic bags with thicker, more expensive ones.

Under the new law, most businesses, including grocery stores, will be prohibited from giving out non-compostable plastic bags and nonrecyclable paper bags to their customers at the point of sale for carrying purchases; there are many exceptions, such as for dry cleaners and takeout restaurants.

At grocery stores, acceptable checkout bags will be compostable plastic bags, recyclable paper bags and "reusable bags," defined as multiple-use, handled bags made of washable fabric or other durable material, including plastic that is at least 2.25 mils (0.00225 inch) thick.

It’s the compostable and the thicker plastic bags that have some environmentalists understandably worried. Compostable bags don’t break down in water and the county does not have a composting facility for them; they will be disposed of as regular trash. The thicker plastic bags pose their own risks to marine life and the environment and seem less likely to be reused as often as a cloth bag. Compromises designed to make the ban more palatable threaten to weaken its environmental impact.

The plastic bag ban will work best if Oahu businesses embrace it wholeheartedly, as businesses on the neighbor islands have. Those who credit customers who bring their own carrying bags and resist the urge to impose a bag fee for anything other than a sturdy reusable bag will do their customers and the environment much good. Paper or plastic is an option at most grocery stores now, without an additional fee being charged, and recyclable paper will remain an option once the plastic ban takes effect. So we hope the fears about rising costs for businesses are overblown.

The bottom line is that Hawaii’s reputation as a tropical paradise demands that we all do what we can to keep the islands clean and beautiful. A change in shopping habits is not too much to ask.