Question

5. Proportion of nitrous oxide has increased from 270 ppm to ___ ppm

Answer 1

Explanation:

NOAA's Annual Greenhouse Gas Index, which tracks the warming influence of long-lived greenhouse gases, has increased by 41 percent from 1990 to 2017, up 1 percent from 2016 -- with most of that attributable to rising carbon dioxide levels, according to NOAA climate scientists.

The global average surface temperature has increased since 1861 and is due, in large part, to an 85 parts-per-million (ppm) increase in carbon dioxide and a 1-ppm increase in methane concentration.