Dear Umbra, There's a Hot Air Balloon Festival going on in the Hudson Valley right now and I'm watching balloons out my window wishing I had the nerve to go up in one, while also wondering how bad they are for the environment. This isn't just mild curiosity; you could literally make or break my future relationship with hot air ballooning. It's funny how my fear of heights would actually diminish if riding in hot air balloons were shown to be beneficial to the environment! For now I'll just take pictures. MelissaPoughkeepsie, N.Y. Dearest Melissa, Hot air balloons work on …

Dear Umbra, You are my only hope! I need help with trophies. Not trophy boyfriends or bass fishing trophies, but a large collection of wood and metal trophies that I have accrued due to a high school career rife with geeky accomplishment. My mom, who has graciously housed these trophies up 'til now, has finally wised up. Instead of looking upon the trophies and dreaming that her daughter will one day be a neurosurgeon, she now understands that the trophies are just gathering dust while I gallivant about the world, not performing any neurosurgery at all. She wants to throw …

Dear Umbra, I shudder at the triviality of the question, but so far nobody I've asked has been able to provide a satisfying answer. So here it is: Is chewing gum biodegradable? Can I spit it on the compost instead of sticking it under the chair? Would green stalks sprout from the gum-spot-riddled sidewalks if we didn't trod them down? I hope you can finally reveal the secret of what is the core of the matter, besides spearmint and sweetener. BirgitFrankfurt, Germany Dearest Birgit, Shudder only in repulsion. I can indeed reveal the secret: The answers to your questions are …

Dear Umbra, After many years of idealistic holdout, I have finally decided to own a cell phone; changes in my lifestyle have made the benefits too heavy to be outweighed by the detrimental effects. However, I would like to minimize the impact of my decision (brain tumors notwithstanding), so I am searching for the most long-lasting, recyclable, Earth-friendly cell phone I can find. Does such a thing exist? Where can I get one? Is "Earth-friendly cell phone" a contradiction in terms? DanSeattle, Wash. Dearest Dan, Your letter filled me with bittersweet camaraderie. I, too, am soon to enter the world …

Dearest Readers, How I enjoy your letters! I'm sorry I'm unable to answer them all; lest you fear that they vanish into the void, I assure you they do not. I read each and every one of them down here in Stacklandia. I must in particular thank those of you who write in to correct, amend, or expand on issues I address in my columns. Almost without exception, those perspicacious readers who venture to mention my errors (linguistic, scientific, or moral) do so in the most delicate and sensitive manner, doing Ms. Manners proud and leaving her fellow advice columnist …

Hi Umbra, I'm wondering if you have any numbers comparing the fuel efficiency of flying versus driving the average car for the same distance. Also, how does carbon dioxide production compare for the same trip? SteveLoomis, Calif. Dearest Steve, Flight blight? Here's what I can find so far, courtesy of the Rocky Mountain Institute in beautiful Snowmass, Colo. Single-occupancy automobiles produce 0.91 pounds of carbon dioxide per mile. (You can do the long division to figure out the per-person impact if more people are traveling.) Commercial aircrafts, meanwhile, produce 0.57 pounds of CO2 per person per mile. However, planes emit …

Dear Umbra, I was thinking of buying a scooter with the idea that (in addition to being fun) I would be using a more fuel-efficient means of transportation on days when the weather was good. Then I got the edition of the Daily Grist telling me how dirty motorcycles are. Now I'm worried: Are scooters the same? I'm talking about a Vespa-type thing. Please tell me that's not as polluting as a Harley! Thanks (even if the answer isn't what I want to hear!), PatriciaAudubon, Penn. Dearest Patricia, The answer is not what you want to hear. To continue our …

Dear Umbra, I recently read a claim that "motorcycles produce far more pollution per mile than your typical car, truck, or SUV." Is that true? I've got a friend who's currently making her (bad-ass) way across country on a Harley -- 60 mpg, baby -- and we are both curious about the environmental impacts compared with a car. BillyBrooklyn, N.Y. Dearest Billy, Bad news for your friend and her bad behind. If she's getting 60 miles per gallon, that's about three times better than the average car these days, and certainly far better than the 1984 Nissan Rustbucket that I …

Dear Umbra, We have a six-year-old daughter, a three-year-old daughter, and -- surprise! (well, not completely) -- a new baby girl due in the next two months. Our fuel-efficient car cannot fit two car seats and a booster across the back seat, and according to Washington state law ("six-years-old and 60 pounds"), my petite six-year-old will remain in her booster for some time. I've been looking into minivans but am discouraged by their poor mileage. Through much Internet research, I've determined that Toyota makes a hybrid minivan (Estima) and that it will be a cold day in a warm place …

Dear Umbra, I want to quit smoking. As if the risks to my health weren't enough, could you help out by twisting that knife of guilt into my tree-hugging heart and give me some environmental reasons to stop supporting the tobacco industry? Cough, wheeze, ElaineSaint John, New Brunswick, Canada Dearest Elaine, I don't care whether you smoke or not. In fact, I think anti-smoking hype is often thinly disguised class warfare and would be best put to use as a template to create, say, anti-SUV hype or anti-pesticide-laden-suburban-lawn hype. Still, I hear your pain, and if you want me to …