15
CH
4
is a powerful greenhouse gas with an
atmospheric lifetime of approximately
12 years. CH
4
emissions caused by human
activities are one of the most significant
drivers of climate change. CH
4
directly
influences the climate system but also
has indirect impacts on human health
and ecosystems, including agricultural
production, through its role as the primary
precursor of tropospheric O
3
, a powerful
greenhouse gas and air pollutant (UNEP
& WMO 2011). O
3
air pollution has been
estimated to cause around 150,000 deaths
annually worldwide and affects the health
of many more (Lim S.
et al
. 2012).
Approximately 60% of methane is emitted
from human activities. In 2005, agriculture
(livestock rearing and rice production),
fossil fuel production and distribution, and
municipal waste and wastewater management
accounted for 93% of global anthropogenic
methane emissions. According to the
projected trends, without further mitigation
efforts, anthropogenic methane emissions
are expected to increase by about 25% by
2030 (UNEP &WMO 2011).
06
Methane
