# 1 gigaton corresponds to the number of megatons

## Climate change and its consequences

a very nice question in my opinion.

• A metric ton is equal to 1,000 kg, and a gigaton is as much as a billion metric tons of CO2.
Even if the vernacular sometimes imprecisely equates "carbon" with "greenhouse gases", it is important to understand that "1 gigatonne of carbon equals 3.67 gigatonnes of carbon dioxide".

• Atmospheric CO2 is usually expressed in ppm (parts per million). To convert this to gigatons
there are "conversion tables" from the Carbon Dioxide Information Analysis Center: According to this, 1 ppm of atmospheric CO2 is equivalent to 2.13 gigatons of carbon (carbon, not CO2).

• Now convert again: Today we have measured around 400ppm in the atmosphere as visualized by this counter ... which is equivalent to 852 gigatons of carbon (i.e. 852 billion metric tons), admittedly difficult to imagine what that means in terms of space and weight.

Maybe you can compare that to human breathing?
Here are a few "numbers" and I juggled them a little (I converted them to gigatons):

• Content of carbon dioxide (CO2) in dry air at sea level: 0.038%
• Content of CO2 in the air exhaled by humans: 4%
• Average CO2 emissions of a person (at rest) per year: 315 kg = 0.315 metric ton (>> 1 Gt per year see next bullet point)
• The amount of CO2 emitted by 82 million Germans (at rest) per year: approx. 26 million tons = 0.026 gigatonne >> 1 Gt would be consumed by 3,153 people in the same period (1 year, at rest) pushed out
• Production of CO2 through exhalation by all of humanity (at rest) per year: approx. 2050 million tons >> 2.05 Gt per year
• Production of CO2 through exhalation of all human beings and animals (at rest) per year: approx. 4100 million tons >> 4.1 Gt per year
• Average CO2 emissions of a VW brand car / km: 161 gr. = 0.000161 metric ton (I didn't check whether that was before or after the exhaust gas fraud became known) (number of kilometers for 1 Gt see next bullet point)
• Average CO2 emissions of a Volkswagen brand car per year when driving 20,000 km: 3220 kg = 3.22 metric ton >> 1 Gt would result from driving 6.21 billion km => The circumference of the earth at the equator is 40,075 kilometers, i.e. driving 155,000 times around the world. In 2013 there were around 4.08 million people in the German-speaking population aged 14 and over who drove more than 20,000 kilometers in their car per year (see this statistic). That means that together they have driven far more than 81.6 billion km (that would be 20,000 km per person). This in turn corresponds mathematically approximately 13 Gt with a Volkswagen.
• CO2 emissions of all cars in Germany per year: approx. 100 million tons >> 1 Gt per year --- hm, that contradicts the above statistic enormously ... or is it because the Germans don't drive a Volkswagen? ;-) probably yes ... how valid are these numbers ...? Or the statistics from Statista may go beyond the borders of Germany ... Perhaps you will find something about it?
• Worldwide CO2 emissions (including industry, cars, etc.) in 2007: 30.9 billion tons >> 30.9 Gt in 2007 alone

When you think about what went up in the last 10 years ...

This here and this overview at Guardian give an impression of the main causative industries / activities.

Does that make it a little easier? What are your thoughts on that? Did you find any other comparison data?