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But figuring out how to lower your carbon footprint is more complicated. That’s why several mobile tracking apps help people figure out which actions create the most emissions and how to avoid them.

Researchers have found that how their actions contribute to climate change, but can do better with more information. Apps are one way to learn more about emissions and build better habits.

So, I downloaded three popular ones. Here's how it went.

Calculating my own carbon footprint

Two of the apps started by calculating my personal footprint. And I’ll be honest. I thought I was going to look pretty good. I was wrong.

I take my climate impact seriously. I only eat meat on weekends, and it’s almost always like chicken and turkey. I share my car (a plug-in hybrid) with my spouse, and we both work from home. I , I buy in bulk and I bring plastic containers to the restaurant for leftovers, so I produce very little trash. I mean, that’s a pretty standup environmental citizen, right?

Earth Hero and Pawprint both told me I emit around 17 tons (15 metric tons) of pollution every year. Earth Hero estimates the average American emits nearly 22 tons (20 metric tons), so I was below that. But my footprint is still three times higher than the average person globally.

The biggest culprits were the energy spent heating and cooling my along with twice-yearly flights I take to see my family 2,000 miles (3,200 kilometers) away.

So, armed with guilt and panic-induced enthusiasm, I set out to reduce my impact, with the help of the apps.

The lifestyle recording apps

Earth Hero and Pawprint both started with a survey about eating, travel and spending that yielded the carbon footprint calculation. (I compared it with the , and the results lined up.)

Then I scrolled through actions that could reduce my footprint. Pawprint assigns values to each action with the help of a climate impact consulting group. Earth Hero says it relies on volunteer scientists to research values for each action based on scientific data. Most of Earth Hero's actions came with points to “level up,� but actions that can't be easily quantified (like, “join a green team at work,�) didn't impact my score.

Some were easy (wash clothes in cold water) and some were ambitious (install rooftop solar energy). Earth Hero allowed me to mark ones that went on my list of goals. Pawprint incentivized doing small actions repeatedly to build my list of habits, which reduced my calculated footprint.

Pawprint gave me “Pawpoints� that I could redeem for investments into climate causes. Earth Hero’s actions reduced my emissions score and leveled up my profile, which appealed to my competitive nature.

Earth Hero CEO Ben Gerhold said the average person who signs up for the app — which has 150,000 users — reduces their calculated annual emissions score by one ton.

I kept this up for two weeks. As my enthusiasm waned, so did my participation. The self reporting made for a personalized experience and set of goals, but I didn't want to keep opening Pawprint every time I skipped a shower or ate a vegan meal. I stopped opening Earth Hero too, because after the easy stuff, I was left with pretty lofty goals, such as installing a water heater. That is on my list, but it's not a quick task.

The passive one that monitors spending

The third app I downloaded, called Commons, didn't require the same daily commitment.

The app, which monitors credit cards, generated weekly reports on what I'm buying. It didn't require ongoing inputs.

After getting over nervousness about sharing credit card data, I was flooded with insights. It listed every purchase in reverse chronological order and provided a rough estimate of its carbon impact, encouraging less spending in general and more sustainable purchases.

I got rewards when I bought from a sustainable brand, which I could then redeem for gift cards. The weekly report gave me kudos for spending less on gas and for no-purchase streaks for brands that it has given poor climate ratings.

It also encourages spending goals. This month's challenge, for example, is to buy secondhand, and I get extra rewards if I, with the 1,800 others who accepted the challenge, collectively reach our target.

Their calculations can be based on broad formulas. For example, my grocery bill is based how much I bought and not what I bought, so the $10 I spent on tofu counted the same as if I'd bought beef.

Beyond the carbon tracking

Commons' founder, Sanchali Pal, acknowledged the carbon footprint measurements are blunt. She said monitoring purchases is meant to get users to vote with their dollars and have a larger collective impact.

“A few individuals offsetting their footprint is great, but it’s not going to shift systems,� she said. “This idea of being able to send the signal to companies to shift their behavior was a lot more powerful.�

Many of the actions in Earth Hero's app were also about collective action. I'd get points if I wrote to my political representative or signed a petition. Gerhold said those kinds of actions are going to have a "bigger ripple effect and just go beyond a niche app.�

After using the apps, I don't have a dramatically lower carbon footprint score to report, partly because life changes take longer than two weeks.

Still, I’m inspired to see how small I can make my footprint. I did book a more climate-friendly Christmas trip to see my family with a mixed plane and train itinerary, rather than flying the whole way. I am also planning home energy upgrades.

Might as well keep chipping away and see how far I get.

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