Flying premium from San Francisco to Los Angeles, a common trip for some Californians, could generate 101 kilograms of carbon emissions, or perhaps 142 or even 366 kilograms—depending on what source you search online.
The wide range of estimates stems from what some climate experts view as a growing problem, with Google at the center. More people are trying to factor climate change impacts into life choices such as where to vacation or what to eat. Yet scientists are still debating how to accurately estimate the impacts of many activities, including flying or producing meat. While the math gets sorted out, some industries decry emissions estimates as unfair.
Google has led the way among big tech companies in trying to inform users about their potential carbon footprint when traveling, heating their homes and, as of recently, making dinner. But airlines, cattle ranchers, and other industry groups are pushing back, saying Google’s nudges could hurt their sales. They have demanded—successfully, in the case of airlines—that the search giant rethink how it calculates and presents emissions data.
The United Nations' climate panel has begun saying individual decisions are significant, noting for instance in a report last year that taking trains and avoiding long flights could account for as much as 40 percent of the potential cut in global aviation emissions by 2050 from changes in how people choose to travel. But for consumers, getting a personal read on their carbon impact is tricky, as major studies tend to focus on global or regional averages and not personalized metrics, emissions researchers say.
Scientists and startups working on emissions estimates worry that showing shoppers varying data will leave them not only misinformed about the impact of their choices but also discouraged from trusting emissions estimates for years to come. That could hamper efforts...