Carbon emissions footprint broken down by mode of transport

30 January, 2022

In our increasingly connected world, we’re becoming aware that driving less can help us reduce our carbon emissions. But how can we measure exactly what kind of carbon emissions are associated with different types of travel? 

This article will walk through some common methods used to estimate an individual’s or organization’s carbon footprint, then break down those numbers into categories based on the type of travel they take. This way, you’ll be able to see where to make changes in order to lower your overall emissions.

How to calculate your personal carbon footprint

There are several ways to determine how much CO2 (the main component of greenhouse gases) someone contributes to global warming every year. One method calculates this value as follows:

First, figure out the average number of miles driven annually by all cars owned by people living within the same area. Then multiply this total annual mileage by the current national average gasoline price. For example, let’s say there were 1 million cars in Los Angeles County alone. If the U.S. national average gas prices were $3/gallon, then these cars would collectively produce 2.1 billion gallons of CO2.

Next, divide the aforementioned total by 365 days to find the average number of miles traveled daily. In LA County, this calculation would show that these cars produced roughly 636 tons of CO2 per day.

Now, add up all of your trips taken throughout the year. Finally, divide this total by the number of years since you began using cars. The result should give you your average annual emissions from owning and operating cars.

For example, let’s say one family has been driving cars for 20 years. They’ve averaged 10,000 miles driven during this time period. Multiply that number times 0.0221 ($20/gallon), which is the approximate cost of gasoline nationwide today, giving them an estimated annual personal emissions footprint of 2211 kilograms of CO2 emitted per year.

You can use tools like Google Drive or Microsoft Excel to perform this calculation yourself. Or, just sign up to our free portal and use our emissions calculator, which does most of this work automatically for you. You simply enter your yearly commute data, and it gives back an estimated annual emissions footprint. As an alternative, you could also search “estimated personal emissions” online and run similar calculations manually.

Note: These calculations may vary slightly depending on your location and commuting patterns. Also note that because many cities now offer bicycle share programs, we did not include biking here.

Transport modes and their environmental impacts 

To understand why choosing different forms of transportation can affect your carbon footprint, consider the following facts:

Personal automobiles contribute significantly to air pollution. Each year, they emit millions of tons of particulate matter (PM10). PM10 contains tiny particles that pose serious health risks when inhaled. Cars also release thousands of pounds worth of NOx and VOCs — both known carcinogens — into the atmosphere from tailpipes, brake pads, and other parts of the engine.

Public transit generally produces fewer emissions than private automobile usage. While buses still burn fossil fuels, trains and subway lines rely mostly on electricity generated at stations themselves. Because of this, they don’t typically cause significant air quality problems, nor do they require large amounts of land space dedicated solely to parking lots.

However, even though public transit may seem greener than driving a car, its emissions aren’t necessarily zero either. Most bus routes are heavily populated, meaning that passengers inside often generate additional levels of traffic noise and air conditioning demand. And while newer train technology helps minimize energy consumption, older diesel trains consume huge quantities of natural gas. 

Electricity isn’t always clean, either. Many states allow utilities companies to sell excess renewable power back to the grid at market rates. However, this means that some homes and businesses end up paying twice for the benefits of cleaner energy sources: once when buying the product and again when selling it back onto the grid. Other electric utility providers charge customers extra fees whenever they exceed certain electrical thresholds. Meanwhile, charging EVs at home requires access to expensive solar panels or battery storage systems. All together, this may discourage people from making the switch to electric altogether.

As such, calculating the true “net” carbon footprint of any given form of transportation can become quite complicated and difficult to interpret. It’s best to look at the bigger picture and focus on reducing your overall emissions rather than trying to pinpoint specific modes’ exact values.

And remember, none of these calculations account for the fact that many low-income families cannot afford reliable alternatives to cars like mass transit or car sharing.

One final caveat: Since we’re relying largely on statistics collected over the past few decades, it’s possible that new technologies or trends might emerge that alter the landscape entirely. Let’s hope not!

What’s so special about electric vehicles? 

While hybrid and fully electric cars tend to produce far fewer emissions compared to internal combustion engines, they can still create their fair share of greenhouse gases. That’s due to two factors: first, batteries contain chemicals like cobalt that mine production creates harmful waste. Second, even relatively small factories producing EV components can have outsized effects on the environment. A recent study found that lithium mining alone accounts for nearly 25 percent of worldwide eutrophication (i.e., water contamination with nutrients like phosphorus and nitrogen).

But perhaps the biggest concern surrounding electric vehicles is related to their limited range. Depending on local laws, drivers who live outside major metropolitan areas must occasionally plug in to recharge their batteries before continuing farther along their trip. This can cut short their commutes dramatically, but it doesn’t solve the problem completely.

Currently, only Tesla offers a 100-percent free ride option after enough kilometers are charged. Some other automakers, including Nissan Leaf owners, can opt to pay a monthly fee to extend their car’s range further away from chargers. Even worse, others like General Motors plan to roll out models that feature no onboard recharging capabilities whatsoever.

Some experts argue that future iterations of electric vehicles should come equipped with a built-in GPS tracker that allows riders to call for rideshares anywhere. Others believe consumers shouldn’t need to worry too much about finding charging stations — especially ones installed near places they frequent regularly.

Regardless, the next big step forward for electric cars is improving their ability to travel long distances without needing to stop to juice up.

Which car-sharing services have the least emissions per mile?

When looking at car-sharing services, the question becomes whether or not you want to offset your emissions when taking part in them. Most organizations choose to do so via corporate partnerships with third parties that specialize in carbon offsets.

These entities purchase credits that represent reduced emissions created elsewhere. When combined with the actual reduction made by participating in activities like walking, cycling, or riding public transportation, car-sharing users can claim credit towards their overall net emissions.

So how do various car-sharing service compare? According to the International Council on Clean Transportation (ICCT), Zipcar ranks among the top three car-sharers across North America that provide carbon offsets. Its members purchase offsets primarily through TerraPass Foundation for Sustainable Travel, which works directly with international projects that aim to improve sustainable lifestyles around the globe.

On top of that, Zipcar recently announced plans to start offering members discounted flights and hotels in exchange for their participation.

Breeze Bikes provides another popular choice for individuals wanting to go green while traveling. With its membership program called Breezeways, members receive discounts on hotel stays, airport lounges, restaurants, rental shops, and attractions. Memberships last between six months and five years, and the company purchases offsets for its cyclists through Greenfleet Global Solutions.

Other notable examples of environmentally friendly car-sharing companies include Car2Go, GetAround, CityCarShare, Parkopedia, Curitiba Trans, Lime, VanMoof, MyTaxi, and Ofo.

Where do you get information about local public transit options?

Tracking down information about public transportation in your city can sometimes prove challenging. Luckily, there are countless resources available online that detail everything you’d ever want to know about your community’s existing infrastructure.

Here are a couple of good starting points:

• Google Maps’ Transit tab shows real time arrival info for nearby buses, trolleys, subways, light rails, and commuter rail tracks. You can filter results according to state, line color, route length, and hours of operation.
• Amtrak’s Train Schedules page tells you the departure times and locations of Amtrak’s regional passenger carriers. Selecting Show upcoming schedules displays more detailed itineraries for journeys lasting multiple days.
• TripAdvisor lets users browse reviews for accommodations located close to mass transit stops. Simply input your desired transit point(s) into the search bar and select Next. From there, you can read comments written by travelers who took said transports to reach their destination.