According to the Intergovernmental Panel on Climate
Change (IPCC) Fifth Assessment Report (IPCC, 2013), many
currently observed climate changes are unprecedented and the
existence of global warming since the 1950s is unequivocal.
Due to human activities such as fossil fuel use and land use
changes since pre-industrial times, CO2 concentrations in the
atmosphere have increased by about 40%. Also, only about half
of the total anthropogenic CO2 emissions remain in the
atmosphere ((240 ± 10) Pg C); the rest is absorbed by
land ((160 ± 90) Pg C) and the ocean ((155 ± 90) Pg C) (IPCC,
2013). Based on simulations using 11 coupled climateecarbon
cycle models, Friedlingstein et al. (2006) concluded that
climate change will reduce the efficiency of the land and the
ocean in absorbing atmospheric CO2. Furthermore, the IPCC
reported that CO2 increases and climate change have different
effects on the land's and ocean's carbon storage. CO2 increases
will lead to the increased carbon storage by the land and ocean.
Climate change will reduce the land and ocean's capacity to
absorb atmospheric CO2 due to the increasing temperatures of
both the land and ocean and increasing oceanic stratification.
The ocean, which has absorbed 27.9% of the anthropogenic
CO2 in the past 200 years (IPCC, 2013), plays a crucial role in
the global carbon cycle.
The ocean carbon cycle is determined by a series of complex
interactions involving the air-sea exchange, inorganic
carbon chemistry, ocean general circulation, and marine biological
processes (Plattner et al., 2001)