The overall atmospheric concentration of these greenhouse gases has been increasing in recent decades.

Production of this radical is not fully understood and has a large effect on atmospheric concentrations.

Its atmospheric concentration varies greatly depending on the season and conditions.

This means that atmospheric concentrations of greenhouse gases would continue to grow.

The oxygen in the air is sometimes kept a few percent less than atmospheric concentration to reduce fire danger.

At normal atmospheric concentrations this is a very slow process.

Its atmospheric concentration was between 270 and 280 parts per million in 1850.

The atmospheric concentration, however, is over 100 times lower, which shoots the cost up to $2,500/ton.

Using this data, atmospheric concentrations appear to have increased rapidly over the past 100 years and are currently higher than ever in human history.

Natural C production and hence atmospheric concentration varies only slightly over time.