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Choosing how to live in a way that truly helps our overburdened planet can be difficult. Researchers at DTU have calculated the impact of a wide range of everyday activities to help consumers lighten their impact on the environment.

The average Dane lives far beyond what our planet can tolerate: , we would need more than four planets to support our demands on nature. But changing to a truly sustainable life that is aligned with what the planet can support is difficult–even if you really want to.

"One problem is that it's hard for people to distinguish between what is better for the environment and what is good enough. If you get a three out of 10, it's better than a two out of 10, but it's still a bad grade. So, the question is: When can we say that the grade is good enough?" asks Ph.D. at DTU Teddy Serrano.

To help answer this question, he and five colleagues have conducted a study that provides consumers with an insight into how the choices we make within the areas of food, consumables, housing and mobility can help sufficiently mitigate the pressure on the environment.

To do this, they first estimated an acceptable annual footprint per person within six environmental categories if Danes are to live in ways that the planet can sustain. They then worked out how much of this annual impact allowance would be used up by making various choices within the four areas (see box below).

"It's like when we buy a food product and the label not only tells us how much protein and sugar and so on it contains, but also how much of it you can eat if you want to stay healthy. We are trying to do the same by providing information on what an action represents in terms of its impact on the planet," Serrano explains.

Significant exceedances

The study shows that several activities by themselves may exceed the entire yearly budget for one or more of the categories.

Eating an average omnivorous diet e.g., could overshoot three categories by itself: Functional biodiversity (384%), climate change (101%) and land occupation (149%). It also shows that a vegetarian or vegan diet has a significantly lower impact and can e.g., bring the diet to 33% and 22% of the annual climate change budget respectively.

How we choose to get around is also linked to vast differences in impact. If you—like the average motorist in the study—drive 28 km daily throughout the year and you have a standard-sized gasoline or diesel car e.g., you will have used up the entire climate change budget for that year (129% and 110% respectively). Shifting to a small electric vehicle (EV) would bring it down to 50%. On the flip side, the impact on resource use is much greater for an EV due to its battery.

In stark contrast, leaving your gasoline car at home and hopping on an e-bike for your daily 22 km commute to work sees a drop in climate budget consumption from 62% to 5%.

Helping hand

"Our study draws attention to the fact that we need to make major shifts in our current lifestyles if we want to bring our impact on the environment down to sustainable levels," Serrano says.

However, while working on the study, the researchers found that some of the lifestyle changes that many consumers may perceive as important in fact matter very little in the grand scheme of things. Therefore, they are hoping their study will help consumers make more well-informed, impactful choices.

"We want to help by showing where it really matters," Serrano stresses.

He elaborates that consumers wanting to live within their environmental budget can focus on the "4-P rule" to go for big impact, namely:

• Planes (a return trip from Copenhagen to New York e.g., uses up approx. 75% of the yearly budget for climate change)
• Places (the smaller the better because fewer building materials are needed for construction and fewer square meters require less heating)
• Plates (as outlined previously opting for plant-based foods makes a big difference)
• Pedals (making the bike our first choice for daily mobility will free up lots of room to maneuver)

You can read the entire study in a in Sustainable Production and Consumption titled "Communicating the environmental impacts of individual actions in the context of Planetary Boundaries."

The calculations are also presented in the book Er mit liv bæredygtigt? (Is my life sustainable—available in Danish only), written by DTU Professor Morten Sommer, who is co-author of the scientific paper.

About the study

In total, the study assesses the impacts of 23 common activities (such as eating, heating your home, buying clothes or traveling on holiday) across six environmental categories that were inspired by the Planetary Boundaries framework. They are:

• functional biodiversity
• climate change
• land occupation
• marine eutrophication (i.e., when a body of water is negatively affected by increased levels of nutrients)
• resource use
• water consumption.

The impacts of the different options within the various activities are calculated over their entire life cycle. When assessing the impact of driving a gasoline car to work e.g., it includes the environmental costs linked to producing and scrapping the car as well as the emissions it produces and its wear and tear on the roads.

The reference year taken is 2050 and uses the UN's forecasts for the world population. This provides consumers with a projection of how their lifestyles would need to evolve in the coming 25 years.

The calculations do not, however, take into account any technological advances that may have been achieved by then which may have lowered the impact of various activities.