how is carbon emission measured, when I hear 1tonne of greenhouse gas surely its not 1 tonne weight?

Answer 1

Indeed it is, and it is not as much as you think.

1 tonne of water occupies about 35 cubic feet. That's only the size of a small car.

Carbon dioxide is about 1/600 of the density of water, so 1 tonne of it will occupy about 20,000 cubic feet. Think of a house 40 feet by 60 feet, with 8-foot ceilings. It's a very ordinary size of house, some people would say even a small house, but it would hold about a tonne of carbon dioxide.

Answer 2

One tonne of Carbon dioxide is 1000 kilograms.
The weight of 1 tonne mass of carbon dioxide in the atmosphere would roughly weight 9800 Newtons.
With that much weight carbon dioxide being much heavier than air would not exist as a green house gas.The reason is that as soon as the Co2 cools off in the atmosphere ,it would just fall downto the ground which trees in forests need and absorb it.

Answer 3

You are right, but confused. Tonne is a unit of mass (1000kg), not weight. The weight of the gas will be measured in Newtons.

If we ignore Archimedes' principle, then:-
weight = m*g
weight = mass *9.81
(g=9.81m/sec^2 is the acceleration due to gravity, mass in kg)

However, weight is defined as the gravitational force experienced by a body, and if the weight of a gas is measured when immersed in air it will be less than m*g because of the buoyancy of the gas.

For example, methane is less dense than air, so it will float. 1 tonne of methane will therefore actually have a negative weight.