# How do I calculate Per capita $\ce{CO2}$ emissions?

I need to find the per capita $\ce{CO2}$ emissions for Canada in 2010 (expressed in kg/day). I know that Canada had $\ce{CO2}$ emissions of 0.55 (Gt) and a population of 34 million in 2010.

I am just having trouble on how to calculate it per capita emissions.

I tried dividing 0.55 by 34,000,000 (I looked up my question and saw someone suggest this) but having an answer of $1.6\times10^{-8}$ doesn't really seem correct to me.

• The Canada row on en.wikipedia.org/wiki/… would confirm that 16 tonnes per annum seems about right. That's about 40 kg per day, but keep in mind that industrial and commercial emissions are included, and shared among people too. – naught101 Sep 26 '14 at 0:03

You have the right idea, but you have your units and orders of magnitude confused. You have started with knowing that Canada has 34 million people, and emits 0.55Gt - i.e. $0.55 \times 10^9$ tonnes - per year.

Now rather than just using those figures, think about the units that you have, and the units that you've been asked to give the answer in. How many kilograms are in a gigatonne? Once you have a figure for kilograms per year, how will you convert this to kilograms per day?

If Canada produced 0.55 (Gt) of $\ce{CO2}$ emissions from 34 million people in 2010, the per capita emissions is indeed $1.6\times10^{-8}$ Gt of $\ce{CO2}$ per person per year. This is equivalent to $16$ tons per person per year. However, if you want your answer expressed in kg per day, you will needed to multiply by the unit conversions.

I confirmed the value of Canadian emissions and that the units are metric tons (not US tons).

Here are the needed unit conversion ratios:

$1000$ kg / metric ton

$1$ year / $365$ days

Notice I wrote the unit conversion ratios such that the desired units are in their proper positions.

So, this yields:

$16$ tons / person / per year $\times$ $1000$ kg / ton $\times$ $1$ year / $365$ days = $44$ kg / person / day