you're making a logical error. The CO2 is cumulative. So in case of replacing an inefficient laptop with a more efficient one: manufacturing: 300kg use 4 years

you're making a logical error. The CO2 is cumulative. So in case of replacing an inefficient laptop with a more efficient one: manufacturing: 300kg use 4 years: 400kg manufacturing new laptop: 300kg new laptop 4 years: 300kg That's 2 laptops, 8 years of use: 1300kg only using the inefficient laptop: manufacturing: 300kg 4 years of use: 400kg 4 years of use: 400kg one inefficient laptop after 8 years: 1100kg. Even if both examples would have the same co2 output, it would still be more environmental to keep using the inefficient laptop, because the act of buying stuff and throwing away old stuff carries costs too. An obvious example is that if people would replace their laptops twice as often, then the world would need twice the amount of laptop factories, twice the amount of resources, twice the amount of laptop recycling stations, twice the amount of space in landfills for laptops, etc. Maintaining and reusing old hardware is good for the environment