Carbon footprint: Madrid (MAD) to Chicago (ORD)
Per-passenger CO₂ (economy, incl. radiative forcing) — compared with train and car alternatives.
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Quick answer: MAD → ORD carbon at a glance
Flying MAD to ORD (4,191 mi) emits about 377 kg CO₂ per passenger in economy (incl. radiative forcing). Train is ~149 kg, 4-person carpool ~423 kg, solo car ~1693 kg. The greenest option here is train at 149 kg — about 60% less than flying.
Factors: 0.09 kg/mile flight, 0.0355 train, 0.404 solo car (DEFRA/EPA).
Flying from Madrid (MAD, Spain) to Chicago (ORD, United States) — a ultra-long-haul international covering 4,191 miles (6,745 km) — emits approximately 377 kg of CO₂ per passenger in economy class. This estimate uses the factor 0.09 kg CO₂ per passenger-mile (kilometre equivalent: 0.056 kg/km), which incorporates radiative forcing — the warming effect of non-CO₂ emissions (water vapour, nitrogen oxides, soot) released at cruise altitude. Excluding radiative forcing, the pure CO₂ alone would be roughly half this number. For context: the average US resident emits about 16 tons (16,000 kg) of CO₂ per year from all activities, so this one flight equals about 2% of an American's annual carbon budget. The route's carbon intensity is low per mile (long-haul cruise is the most fuel-efficient phase of flight) — see the comparison table below for alternative-mode emissions on the same route.
On the same 4,191-mile route, the lowest-carbon alternative is Train at ~149 kg CO₂ per passenger — about 60% less than flying. By contrast, a solo driver in a typical 22-mpg car would emit 1693 kg over the same distance (about 349% more than the flight — solo driving is usually worse than flying on long routes because the car's per-vehicle emissions aren't shared across passengers). A four-person carpool drops the per-passenger footprint to 423 kg. To neutralise the climate impact of this flight, you'd need to plant about 18 tree-years (i.e. one mature tree absorbing CO₂ for 18 years, since a mature tree sequesters ~21 kg CO₂ per year according to the US EPA). That's also equivalent to about 85,682 smartphone charges on the US grid, or about 933 miles of solo driving in a typical car. The route's overall difficulty score (a separate metric combining distance and time-zone change) is 8/10.
Bars are scaled relative to the flight's per-passenger emissions (377 kg). All factors assume one passenger per seat for flight, one passenger for the solo car, four passengers sharing the carpool vehicle, and one passenger on a long-distance train. Air-rail comparison only valid where direct rail service exists on this corridor; actual rail distance may be longer than the great-circle flight path.
How this carbon footprint is calculated
TripRoute multiplies the great-circle distance between MAD and ORD (4,191 miles) by 0.09 kg CO₂ per passenger-mile to estimate the per-passenger climate impact of an economy flight. This factor is based on the UK Department for Business, Energy & Industrial Strategy (BEIS/DEFRA) greenhouse-gas conversion factors for short-haul economy air travel, scaled up to include radiative forcing — the non-CO₂ warming effects (water-vapour contrails, nitrogen oxides, soot) that approximately double the climate impact of emissions released at cruise altitude. For the train comparison we use the European long-distance rail average of 0.0355 kg CO₂ per passenger-mile (≈ 0.022 kg per passenger-km), which is lower than flying because electric trains draw from grid power that is increasingly decarbonised. The car factors come from the US EPA's typical light-duty vehicle emissions of about 8.89 kg CO₂ per gallon of gasoline, divided by a real-world average of 22 miles per gallon → 0.404 kg CO₂ per mile per vehicle; a four-person carpool divides this by four. Tree-offset and equivalent-driving conversions use the US EPA estimate that one mature tree sequesters about 21 kg of CO₂ per year. All factors are publicly published industry-standard numbers — no fabricated data.
TRIs offsetting MAD → ORD worth it?
At 377 kg of CO₂ per passenger this is a moderate-impact flight; one high-quality offset corresponds to roughly 18 tree-years. Taking a direct flight matters more than offset brand — a connection can roughly double emissions.
Figures computed with UK DEFRA + US EPA emission factors for 4,191 mi great-circle.
Madrid to Chicago — quick answers
What is the carbon footprint of flying from Madrid to Chicago?
Flying MAD (Madrid) to ORD (Chicago) — 4,191 miles (6,745 km) — emits about 377 kg of CO₂ per passenger in economy class. This includes radiative forcing from non-CO₂ emissions at altitude, which roughly doubles the climate impact compared to the CO₂ alone.
Is it greener to take the train or drive from Madrid to Chicago?
On this 4,191-mile route: train ≈ 149 kg CO₂ per passenger, 4-person carpool ≈ 423 kg, flight ≈ 377 kg, and solo car ≈ 1693 kg per passenger. The lowest-CO₂ option is train at 149 kg, roughly 60% less than flying.