Abstract:
The rapidly changing global climate since the mid-20th century is attributed to the observed
increase in anthropogenic greenhouse gas (GHG) emissions. Pakistan is ranked 12th among the
nations that are most susceptible to the extreme weather events such as heavy floods and
droughts etc. In order to implicate the impacts of enhanced greenhouse gas concentrations over
Pakistan, a spatiotemporal analysis of concentration is conducted by using satellite observations
from SCIAMACHY. The Iterative maximum a posteriori (IMAP)-DOAS algorithm is used to
retrieve column densities from Nadir observations of SCIAMACHY instrument. This study
focuses mainly on long term spatial and temporal variations in atmospheric Methane over
Pakistan during the time period of 2003–2011. Temporal analysis indicated a gradual increase of
2.67% in CH4 concentration over Pakistan during the study period (2003 - 2011). Rice cultivated
regions of Punjab and Sindh consistently showed high concentrations. Satellite observations
exhibited a constant seasonal variability in CH4 concentrations over Pakistan, being highest in
summer and lowest in winter except for the year 2010. An anomalous shift in seasonal cycle of
Methane is observed as a repercussion of the devastating nationwide floods of 2010, which
resulted in a loss of about 0.5 Million Hectares of Rice cropland.
