During the last 800,000 years, methane concentrations have always varied between 350-800 ppb. Methane: How Much Does Human Activity Contribute to The Environment. Which has increased global methane levels. Scientists just discovered that there has been about 25 to 40% under-estimation of human contribution to methane in our atmosphere. While methane lasts only a decade on average (compared to the 300 to 1,000 years that carbon dioxide remains in the atmosphere), it also absorbs much more energy. Methane is … So much so that they are now 2.5 times larger.3 4 Since the Industrial Revolution, methane levels have become much higher. In those short decades, methane warms the planet by 86 times as much as CO2, according to the Intergovernmental Panel on Climate Change. Humans are creating methane emissions a lot faster than the Earth can remove them. Researchers studying global methane levels from 2000 to 2017 have shown a dramatic spike in the amount of gas in our atmosphere. The net effect of this shorter lifespan combined with the higher energy absorption is reflected in its global warming potential. So methane warms the planet rapidly, but it dissipates from the atmosphere more quickly than carbon dioxide. Methane emitted into the atmosphere can be sorted into two categories, based on its signature of carbon-14, a rare radioactive isotope.