86 / 96
FROZEN HEAT
86
Environmental
Methane is a fossil fuel that contributes to greenhouse gases
when burned. In addition, methane is, itself, a greenhouse gas.
The presence of methane in the atmosphere was an important
factor in creating – over geologic timescales – the global atmos-
pheric and temperature conditions that have allowed humans
to flourish. In recent times, however, the scientific consensus is
that both anthropogenic methane and natural methane released
as a result of human activities have helped induce global warm-
ing (IPCC, 2007) and are a concern as the world struggles to
mitigate and adapt to climate change. Although less common
than carbon dioxide in the atmosphere (Blasing 2011), methane
is a particularly potent greenhouse gas (Lacies
et al.
1981; Hans-
en
et al.
1988), and relatively small fluctuations in atmospheric
methane concentrations can have a large greenhouse impact.
Methane release from naturally dissociating gas hydrates is
a topic of interest to those studying global climate change
(Reagan and Moridis 2008, 2009). Although research on the
subject has already been reported (Elliott
et al.
2011; Bhat-
tacharyya
et al.
2012), it is currently included in only a few cli-
mate predictions, partly because the magnitude and timing
of geologic emissions are poorly understood and therefore
difficult to build into regional-scale models. Nevertheless,
dissociation of gas hydrate deposits could, in the future, am-
plify warming, increase ocean acidification, and exacerbate
oxygen loss (Zachos
et al.
2005; Biastoch
et al.
2011). From a
global perspective, understanding the triggers and implica-
tions of methane release from destabilized gas hydrates is a
critical knowledge gap that needs to be addressed.
While environmental considerations related to gas hydrates
in nature remain an understudied topic, the environmental
issues related to gas hydrate production would, in many ways,
be quite different. Perhaps the primary difference relates to
issues of scale. For example, when considering gas hydrates
in nature, first-level issues relate to the vast amounts of gas
hydrate distributed widely around Earth, but in relatively low
concentrations. In comparison, commercial exploitation of
gas hydrates would be limited to localized, concentrated de-
posits. The surface area of a typical field development would
be less than 10 square kilometres and production would
likely last less than 25 years. However, the issue of how local-
scale exploitation of gas hydrates might interact with natu-
rally occurring processes would have to be addressed.
A unique environmental challenge facing gas production from
oceanic hydrates would be the disposal of the dissociation-origi-
nating water (Moridis and Reagan 2007a, b). This water, which
would be anoxic, relatively low in salinity, and possibly quite
cold, could have a considerable adverse effect on chemosynthet-
ic communities on the ocean floor if not released higher in the
water column. Another important challenge relates to the burial
depth of many marine gas hydrate deposits. Geohazards like
slope de-stabilization could by induced by extraction activities.
Policy
The policies that shape the future global energy system
will depend on how human societies and decision-makers
prioritize a range of objectives, including climate change
mitigation, energy security, air and water quality, and hu-
man health. The issues that will have to be addressed extend
beyond national borders and beyond short-term time scales.
They include, but are not limited to, the following:
• Environmental issues and safeguards;
• Socio-economic issues and opportunities; and
• Policy development at the national, multinational, and
international levels.
One argument that is advanced in support of developing natu-
ral gas hydrates as an energy source is that they are relatively
Photo: Geological Survey of Canada