Powerpoint template for scientific posters Swarthmore College

1
Terrestrial carbon sequestration A new
assessment of its technical and economic
potential for greenhouse-gas mitigation WM Post
III1, JE Amonette2, RA Birdsey3, JD Jastrow4, RC
Izaurralde2, G Marland1,6, BA McCarl5, SD
Wullschleger1, FB Metting2, and RL Graham1 1Oak
Ridge National Laboratory, 2Pacific Northwest
National Laboratory, 3United States Forest
Service, 4Argonne National Laboratory, 5Texas AM
University, 6International Institute for Applied
Systems Analysis




Introduction
Terrestrial C Sequestration
Economic and Social Issues


Fossil-fuel combustion and land-use change have
elevated atmospheric CO2 concentrations from 280
to over 380 ppm. The Intergovernmental Panel on
Climate Change Fourth Assessment Report (Solomon
et al., 2007) predicts that the current 3 ppm
annual increase will accelerate as the global
economy expands, increasing the risk of
climate-system impacts. There is good agreement
that photosynthetic-CO2 capture from the
atmosphere and its storage as above- and
below-ground biomass and transformation to soil
organic matter and inorganic C could be exploited
for safe and affordable greenhouse gas (GHG)
mitigation. It has been promoted as an option
large enough to make a difference in the coming
decades using proven land management methods
while realization of new technologies could
significantly enhance terrestrial approaches.
Widespread adoption in effect could buy time,
bridging to a future when new technologies and a
transformed energy infrastructure are able to
meet the climate challenge. Despite mounting
scientific support since it was first considered
for inclusion under the Kyoto Accords more than
ten years ago, terrestrial sequestration remains
largely marginalized as too little, too expensive
and hobbled by issues of permanence, leakage,
monitoring and verification. Here we review
progress on key scientific, economic and social
issues, postulate the extent to which new
technologies might significantly enhance
sequestration potential, and address remaining
research needs.
Fossil fuel cannot continue forever as our
primary source of energy and the potential for
significant climate change makes reductions in
use more urgent. Both the increasing growth rate
in fossil-fuel CO2 emissions and the potential
reduction in current natural sinks requires
considerable effort for stabilization of
atmospheric CO2 concentration over the next
century. The problem is difficult since
stabilization at any atmospheric concentration
requires not only that the net emissions level
off but also that they eventually drop to zero.
To achieve this we must turn to alternative
energy systems. However such developments for
non-CO2 emitting energy will require considerable
time for development and deployment. Application
of current CO2-reduction technologies, even if
they are not part of the eventual solution to
controlling CO2 concentrations, will buy
considerable time and reduce the amount of effort
and money required to stabilize CO2 concentration.
Pacala and Socolow (2004) argue there exists a
portfolio of technologies that can be scaled up
now using current technology. One of the most
overlooked technologies, terrestrial biological
carbon sequestration, is comprised of a variety
of methods that can collectively result in
sequestration of 80-100 PgC over the next 50
years.


The technological capability for increasing
carbon sequestration is at hand, many co-benefits
seem likely, and the potential magnitude of the
results appear promising. These manipulations,
however, will only be suitable for adoption if
they are technically feasible over large areas,
economically competitive with alternative
measures to offset greenhouse-gas emissions, and
environmentally beneficial. Initial cost
estimates appear to be low, but there are
concerns about the permanence of this sequestered
carbon. Forests can be cut down, attacked by
insects, or burned, and soils disturbed again.
Kim, McCarl, and Murray (2007) found that carbon
storage of limited duration (leasing of
volatilization) has economic value but has a
value that is less than 50 of a permanent
non-volatile offset. Provided the value of
sequestered carbon is high enough, along with the
value of other benefits (soil fertility,
watershed protection, recreation, etc.),
non-permanent carbon sequestration can be of
value in short-term CO2 reductions. Because of
the spatially distributed nature of terrestrial
sinks, monitoring/verification is a challenge
that will require development of low cost
sampling based schemes, integrating computer
simulations and remote sensing.
Pre-industrial values (1750) Anthropogenic
changes (2005)
Adapted from IPCC AR4 WGI with updated inventory
and flux data
This is approximately 20 of the estimated fossil
fuel releases and over 100 of the net land-use
emisions projected for this time period. Forest-
and wood-products management are among the
rapidly deployable, potentially major
contributors to enhancing terrestrial
sequestration. Forestry activities may be
categorized as avoiding deforestation and
degradation, reforestation and afforestation, and
improved forest management. Soil organic matter
management includes soil restoration,
agricultural, rangeland, wetland, and forest
practices to increase surface litter and soil
carbon. Soils contain several times as much
carbon as living vegetation and, due to past
reductions from plow-tillage agriculture (55 Pg C
lost), represent one of the considerable
resources for terrestrial C sequestration.
Path Forward

Technologies for Enhancement
A number of potential greenhouse gas mitigation
options involve replacement of existing capital
stock (like replacing electric power plants), or
developing new technological advances (like
carbon capture and storage or hydrogen supported
transport). Such developments take time as they
are limited by factors such as time for RD
innovation, the rate of turnover in capital stock
and the availability of investment capital. There
is some immediacy in the need for action on GHG
net emission reduction as argued in the IPCC 2007
Mitigation report (Metz et al. 2007).
Sequestration involves currently implementable
technologies that can provide a valuable bridge
to the future when the other technologies become
available. A classic finding in the theory of
optimal action is that removal of constraints
always yields benefits. As such it is not at all
unexpected that findings have been generated that
inclusion of sequestration in the total portfolio
of response options decreases the cost of
attaining a given level of emissions reductions.
A number of proven management technologies and
some novel promising technologies currently exist
that can make immediate but in most cases,
short-term impacts on CO2. The main difficulties
in proceeding appear to lie in evaluating their
effectiveness and providing incentives for
implementation. These difficulties can be solved.
Forest and Wood Products Management. Avoiding
deforestation and degradation retains existing
carbon stocks that would otherwise be lost
because of a change in land use or other land
management practice that permanently reduces
carbon stocks. Afforestation increases carbon
stocks on land that was not previously forested.
Improved forest management includes many
different practices applied during the cycle of
forest growth and harvest to increase
sequestration, reduce emissions, or both and may
involve stand establishment, manipulation of
stocking by selective tree removal, removal of
competing vegetation (e.g., by prescribed fire),
controlling pests and wildfire, and timber
harvesting. Correct measurement of the effect of
these management actions on the carbon cycle
involves a complete accounting for changes in
ecosystem carbon pools and harvested wood
products, and the energy used for growing,
harvesting, and manufacturing, compared with a
defined baseline. Soil Management. Management
methods that significantly alter amount,
partitioning, and longevity of organic matter
inputs into the soil include cropping organic
intensification - soil fertility enhancement,
erosion control, irrigation, summer fallow
elimination, integrated pest management,
precision agriculture amendments - animal and
green manure, mulches, compost conservation
tillage - ridge tillage, mulch tillage,
no-tillage. Establishment of perennial vegetation
(pasture,
Climate Challenge
Carbon dioxide emissions from fossil fuel burning
rose 51 from 1973 to 2001 to a rate of 6.5
PgC/y. This average of 1.5/y year increase is
the mean and median of 40 IPCC SRES future
emissions scenarios over the next 50 years with a
mean of 15 PgC/y being estimated to be released
in 2054. Recently, however, between 1999 and
2005, the emission rate rose from 6.5 to 7.8
PgC/y, increasing at a much larger rate of
3.0/y. Not all of the emitted CO2 remains in the
atmosphere.
biofuel crops with perennial grasses such as
switchgrass and short-rotation woody crops) and
afforestation of long-used agricultural land
results in more than 0.3 Mg C/ha/y accumulation
in soil. New Technical Developments. Plant
Biotechnology The genomics era provides an
opportunity to identify genes, enzymes, and
biochemical pathways that underlie rate-limiting
steps in C acquisition, transport, and fate of
carbon in ecosystemsand agro-ecosystems. Biomass
Carbonization Converting harvestable biomass to
a more recalcitrant form of C rather than
combusting it offers a new approach to
terrestrial C sequestration and has potential
side-benefits of energy production and enhanced
soil fertility. The basic process involves two
steps. First, the biomass is carbonized by
heating under low-oxygen conditions to produce
char-like substances. Second, the carbonized
biomass is incorporated into soil to protect it
from further combustion (Lehmann, 2007). It may
also serve to improve nutrient- and
moisture-holding capacities while decomposing at
a much slower rate than unconverted
biomass. Deep-profile Sorption Amendments with
urea and phosphate fertilizers are capable of
hydrolyzing organic matter in litter and soil
surface layers and result in transport to deeper
layers where is is adsorbed. Because of low
oxygen levels and stabilization by mineral
surface, the half-life of sorbed C is estimated
at thousands of years. The lower horizons (B and
B/C) of Alfisols, Ultisols, and Oxisols have a
large capacity to absorb organic C.
Oceans and terrestrial ecosystems take up
approximately 40. The fraction that remains in
the atmosphere has remained steady since the
1950s averaging 60. There are indications that
this airborne fraction may be decreasing due to
saturation of current natural carbon sinks. Both
the increasing rate of growth in fossil-fuel CO2
emissions and the potential reduction in current
natural sinks requires that considerable effort
is required for stabilization of atmospheric CO2
concentration over the next century.
Acknowledgments Research funded by the U.S.
Department of Energys Office of Biological and
Environmental Research within the Office of
Science as part of the Carbon Sequestration in
Terrestrial Ecosystems (CSiTE) program.
References 1Solomon, S., et al. (eds.) 2007.
Climate Change 2007 The Physical Science Basis.
Contribution of Working Group I to the Fourth
Assessment Report of the Intergovernmental Panel
on Climate Change. Cambridge University Press,
Cambridge, United Kingdom and New York, NY,
USA.. 2Pacala, S., and R. Socolow. 2004.
Stabilization wedges Solving the climate problem
for the next 50 years with current technologies.
Science 305968-972. 3Lehmann, J. 2007.
Bio-energy in the black. Frontier Ecol. Environ.
5381-387. 4 Kim, M-K., B.A. McCarl, and B.C.
Murray, "Permanence Discounting for Land-Based
Carbon Sequestration," Ecological Economics,
forthcoming, 2008. 5Metz, B., et al. (eds.)
2007. Climate Change 2007 Mitigation.
Contribution of Working Group III to the Fourth
Assessment Report of the Intergovernmental Panel
on Climate Change. Cambridge University Press,
Cambridge, United Kingdom and New York, NY, USA.