AN ABERRATION IN THE GLOBAL CARBON CYCLE 55 MILLION YEARS AGO: IMPLICATIONS FOR CARBON CYCLE ...
Description:
Approximately 55 million years ago (Mya) at the
boundary between the Paleocene and Eocene epochs (P-E boundary), the Earth
experienced an extreme global warming event that persisted for several tens of
thousands of years, and which triggered short- and long-term changes in marine
and terrestrial ecosystems. Several lines of evidence suggest that the warming
was caused by the sudden decomposition of marine methane hydrates which
ultimately released >2000 gigatons of carbon (GtC) to the atmosphere. In
theory, a large portion of this carbon would have been absorbed by the ocean,
thereby lowering the ocean pH, and initiating a neutralization process
involving the massive dissolution of seafloor carbonate. This process would
enable the ocean to absorb and temporarily store additional carbon. Permanent
sequestration of this excess carbon, however, would occur gradually through a
number of negative feedback processes such as the burial of organic carbon. Quantitatively,
the most important feedback should be the chemical weathering of silicate
rocks, and eventual redeposition of carbonate on the seafloor. Here, I discuss
the evidence used to constrain the magnitude of changes in ocean carbon
chemistry 55 Mya, and implications for future carbon cycle feedbacks.
Author's Names: James C Zachos and Matthew C Kelly
Filesize: 25.00 Kb
Added on: 09-Aug-2005 Downloads: 95
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CLIMATE CHANGE: DESIGNING AN EFFECTIVE RESPONSE
Description:
Reversing
the atmospheric buildup of carbon dioxide (CO2) and other greenhouse
gases will require a radical transformation in the world’s economies. Such changes are difficult to plan and imply
coordination of policies on a scale not yet experienced. Not only is the task difficult, but the
problem of climate change has many attributes that historically are associated
with policy failure—namely, the perception of high immediate costs for
uncertain and highly diffuse future benefits.
This paper explores the historical experience with addressing partially
analogous global challenges. The paper
is pessimistic that societies will have much effect on their emissions
trajectories in the next few decades, implying that substantial amounts of
climate change are likely and the risk of abrupt changes in climate will also
multiply. It is optimistic about the
longer-term—the period from five decades on—when zero carbon technologies can
diffuse into widespread use through the normal turnover of energy
infrastructures.
Author's Names: D.G. Victor
Filesize: 17.33 Kb
Added on: 09-Aug-2005 Downloads: 89
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FACTORS SHAPING LONG-TERM FUTURE GLOBAL ENERGY DEMAND AND CARBON EMISSIONS
Description: This
presentation discusses the forces shaping long-term future global energy demand
and carbon emissions. The most important factors shaping future global
energy demand and carbon emissions are population and technology.
Population acts to set the scale of human activity, though there are many
subtleties that work to either temper or magnify the basic scale effect. These
factors, such as “tastes,” which temper the effect of population on energy
demand are sometimes bundled under the heading “socio-economic” factors. Their effects can be significant.
Author's Names: J.A. Edmonds
Filesize: 18.85 Kb
Added on: 28-Jul-2005 Downloads: 86
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LONG-TERM CONSEQUENCES OF CONTINUED CARBON DIOXIDE EMISSION TO THE ATMOSPHERE
Description: Continued emissions of carbon dioxide to the
atmosphere will affect climate and ocean chemistry. These consequences can be
anticipated by consideration of basic physical principles, past climates, and
calculations. Emission of 5,000 PgC (= amount of carbon in conventional fossil-fuel
resources) over a few centuries could produce radiative forcing of climate of
about 10 W m-2 which could be expected to produce global mean
warming of ~4 to 12 °C. Warming in this
range would have large biological and human consequences. It could threaten the
ice sheets and lead to a long-term sea-level rise of 70 m. Ocean pH could decrease by 0.7 units, making
the oceans more corrosive to carbonate minerals than they have been for many
millions of years. From the perspective of geology and biological evolution,
these changes would occur rapidly, overwhelming most natural processes that
would buffer CO2 changes occurring
over longer time intervals, and thus may produce changes at a rate and of a
magnitude that exceed the adaptive capacity of at least some biological
systems. To find comparable events in Earth history, we need to look back tens
of millions of years to rare catastrophic events.
Author's Names: K. Caldeira
Filesize: 21.50 Kb
Added on: 27-Jul-2005 Downloads: 275
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