When you try to find out exactly how much CO2 has been released by humans, you come across a lot of numbers. The problem with numbers, is that they tend to lose their importance when you don’t understand what they actually mean. Here, I try to put some of the numbers in context.

Measured carbon dioxide since 1700

Before the Industrial Revolution – that is when society began to develop, use and rely on technology – carbon dioxide levels in the atmosphere were at about 280ppm*.

Today, carbon dioxide concentrations in the atmosphere have increased to about 396ppm. (You can get an exact measure here). This makes for a total increase of 116ppm since 1800.

But, what we need to do is put these numbers into context. To do that, we need to look at the climate of the past. In this instance, we will be looking at ice core data.

Carbon dioxide concentrations for the last 400,000 years, as measured at Vostok Ice Core

The figure above shows the record of carbon dioxide, as measured at Vostok Ice Core, for the last 400,000 years. This data is freely available online (along with a whole bunch of other published data) if you’re interested.

In order to put the current increase in carbon dioxide into context, I chose the time of the fastest carbon dioxide rise in the past. In this case, it looks to be at about 130,000 years ago.

During this ‘rapid’ event, carbon dioxide increased from 198ppm to 287ppm (a total of 89ppm) over a period of 7,500 years.

Not only is the rate of current carbon dioxide emissions unseen in the last 400,000 years, the magnitude of the change is also incredible. If you look at the graph above, you can see that carbon dioxide has not gone above 300ppm during that time. We are now nearly at 400ppm.

I think this video from NOAA shows it best.

People ask me, ‘is climate change real?’ When you look at this data, it’s pretty hard to try and blame natural variability.

*ppm = parts per million. It is a measure of the ratio of gas molecules (in this case, carbon dioxide) to the total number of molecules of dry air. For example, 280ppm means there are 280 molecules of carbon dioxide for every 1 million molecules of dry air.