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Record 1 of 16
Author(s): Katz, JI (Katz, Jonathan Isaac)
Title: Stratospheric albedo modification
Source: ENERGY & ENVIRONMENTAL SCIENCE, 3 (11): 1634-1644 2010
Abstract: The possibility of offsetting greenhouse gas warming by introducing artificial
aerosols into the stratosphere to increase the Earth's albedo has been widely discussed,
but little attention has been given to the details of its implementation. It is usually
assumed that the aerosols would be sulfuric acid droplets (hydrated sulfur trioxide), like
natural volcanic aerosols. Other materials may be more advantageous, but sophisticated
"engineered" particles probably cannot be produced in sufficient quantity. I consider a
variety of possible injection vehicles. Aircraft are unlikely to have sufficient lift
capability to the necessary altitudes, guns are inefficient, and exotic methods like
balloons and chimneys face daunting difficulties. Simple rockets are proven and
economical, and can deliver material to any desired altitude. Artificial injection begins at
a much higher aerosol (or precursor) density than a volcanic plume, raising novel issues
of chemical kinetics and particle agglomeration. Detailed experimental and theoretical
investigation are required to establish the feasibility of stratospheric aerosol
geoengineering. An appendix argues that natural, as well as anthropogenic, climate
change may pose challenges that could be met by these methods.
DOI: 10.1039/c002441d
Record 2 of 16
Author(s): Cokinos, C (Cokinos, Christopher)
Title: Prozac for the Planet : CAN GEOENGINEERING
MAKE THE CLIMATE HAPPY AGAIN?
Source: AMERICAN SCHOLAR, 79 (4): 20-33 FAL 2010
Record 3 of 16
Author(s): Moore, JC (Moore, J. C.); Jevrejeva, S (Jevrejeva, S.); Grinsted, A (Grinsted,
A.)
Title: Efficacy of geoengineering to limit 21st century
sea-level rise
Source: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE
UNITED STATES OF AMERICA, 107 (36): 15699-15703 SEP 7 2010
Abstract: Geoengineering has been proposed as a feasible way of mitigating
anthropogenic climate change, especially increasing global temperatures in the 21st
century. The two main geoengineering options are limiting incoming solar radiation, or
modifying the carbon cycle. Here we examine the impact of five geoengineering
approaches on sea level; SO2 aerosol injection into the stratosphere, mirrors in space,
afforestation, biochar, and bioenergy with carbon sequestration. Sea level responds
mainly at centennial time scales to temperature change, and has been largely driven by
anthropogenic forcing since 1850. Making use a model of sea-level rise as a function of
time-varying climate forcing factors (solar radiation, volcanism, and greenhouse gas
emissions) we find that sea-level rise by 2100 will likely be 30 cm higher than 2000
levels despite all but the most aggressive geoengineering under all except the most
stringent greenhouse gas emissions scenarios. The least risky and most desirable way of
limiting sea-level rise is bioenergy with carbon sequestration. However aerosol injection
or a space mirror system reducing insolation at an accelerating rate of 1 Wm(-2) per
decade from now to 2100 could limit or reduce sea levels. Aerosol injection delivering a
constant 4 Wm(-2) reduction in radiative forcing (similar to a 1991 Pinatubo eruption
every 18 months) could delay sea-level rise by 40-80 years. Aerosol injection appears to
fail cost-benefit analysis unless it can be maintained continuously, and damage caused by
the climate response to the aerosols is less than about 0.6% Global World Product.
DOI: 10.1073/pnas.1008153107
Record 4 of 16
Author(s): Korhonen, H (Korhonen, H.); Carslaw, KS (Carslaw, K. S.); Romakkaniemi,
S (Romakkaniemi, S.)
Title: Enhancement of marine cloud albedo via controlled
sea spray injections: a global model study of the influence
of emission rates, microphysics and transport
Source: ATMOSPHERIC CHEMISTRY AND PHYSICS, 10 (9): 4133-4143 2010
Abstract: Modification of cloud albedo by controlled emission of sea spray particles into
the atmosphere has been suggested as a possible geoengineering option to slow global
warming. Previous global studies have imposed changes in cloud drop concentration in
low level clouds to explore the radiative and climatic effects. Here, we use a global
aerosol transport model to quantify how an imposed flux of sea spray particles affects the
natural aerosol processes, the particle size distribution, and concentrations of cloud drops.
We assume that the proposed fleet of vessels emits sea spray particles with a wind speeddependent flux into four regions of persistent stratocumulus cloud off the western coasts
of continents. The model results show that fractional changes in cloud drop number
concentration (CDNC) vary substantially between the four regions because of differences
in wind speed (which affects the spray efficiency of the vessels), transport and particle
deposition rates, and because of variations in aerosols from natural and anthropogenic
sources. Using spray emission rates comparable to those implied by previous studies we
find that the predicted CDNC changes are very small (maximum 20%) and in one of the
four regions even negative. The weak or negative effect is because the added particles
suppress the in-cloud supersaturation and prevent existing aerosol particles from forming
cloud drops. A scenario with five times higher emissions (considerably higher than
previously assumed) increases CDNC on average by 45-163%, but median
concentrations are still below the 375 cm(-3) assumed in previous studies. An inadvertent
effect of the spray emissions is that sulphur dioxide concentrations are suppressed by 12% in the seeded regions and sulphuric acid vapour by 64-68% due to chemical reactions
on the additional salt particles. The impact of this suppression on existing aerosol is
negligible in the model, but should be investigated further in the real environment so that
inadvertent impacts can be excluded.
DOI: 10.5194/acp-10-4133-2010
Record 5 of 16
Author(s): Greene, CH (Greene, Charles H.); Baker, DJ (Baker, D. James); Miller, DH
(Miller, Daniel H.)
Title: A Very Inconvenient Truth
Source: OCEANOGRAPHY, 23 (1): 214-218 Sp. Iss. SI MAR 2010
Abstract: Studies conducted after those that contributed to the Intergovernmental Panel
on Climate Change (IPCC) Fourth Assessment Report (FAR) suggest that human society
may be facing a very inconvenient truth-that emission reduction efforts alone are unlikely
to stabilize greenhouse gas concentrations at levels low enough to prevent dangerous
anthropogenic interference with the climate system. Here, we discuss reasons why the
IPCC process is prone to underestimating the threats of global climate change. We then
review some of the critical policy-relevant scientific findings that have emerged since the
release of the IPCC FAR. Finally, we discuss how these new findings fundamentally
transform the debate on efforts needed to prevent dangerous changes to our climate
system. It now appears that to avoid such changes, society will likely need to adopt a
mixed strategy of reducing greenhouse gas emissions and employing geoengineering
approaches that extract carbon dioxide from the atmosphere and/or reduce the level of
incoming solar radiation reaching Earth's surface.
Record 6 of 16
Author(s): MacMynowski, DG (MacMynowski, Douglas G.)
Title: Can we control El Nino?
Source: ENVIRONMENTAL RESEARCH LETTERS, 4 (4): Art. No. 045111 OCTDEC 2009
Abstract: The question of whether it is possible to intentionally modify the El
Nino/Southern oscillation (ENSO) cycle is explored as a case study in the dynamics of
climate intervention beyond simple temperature adjustment. A plausible control strategy
is described, including an estimate of the energy it would require to implement. The
intent here is not to suggest that we should do so, but rather that the scale of the required
intervention is such that we could intentionally influence ENSO. Simulations use the
Cane-Zebiak intermediate complexity model, and demonstrate that depending on the
parameter regime, a feedback strategy that dynamically deflects less than 1% of the
sunlight over the Nino-3 region of the eastern tropical Pacific could be used to reduce the
probability of extreme ENSO events (T > 2 degrees C) to near zero, or conversely to
enhance the cycle.
Article Number: 045111
DOI: 10.1088/1748-9326/4/4/045111
Record 7 of 16
Author(s): Strong, AL (Strong, Aaron L.); Cullen, JJ (Cullen, John J.); Chisholm, SW
(Chisholm, Sallie W.)
Title: Ocean Fertilization Science, Policy, and Commerce
Source: OCEANOGRAPHY, 22 (3): 236-261 Sp. Iss. SI SEP 2009
Abstract: Over the past 20 years there has been growing interest in the concept of
fertilizing the ocean with iron to abate global warming. This interest was catalyzed by
basic scientific experiments showing that iron limits primary production in certain
regions of the ocean. The approach-considered a form of "geoengineering"-is to induce
phytoplankton blooms through iron addition, with the goal of producing organic particles
that sink to the deep ocean, sequestering carbon from the atmosphere. With the
controversy surrounding the most recent scientific iron fertilization experiment in the
Southern Ocean (LOHAFEX) and the ongoing discussion about restrictions on largescale iron fertilization activities by the London Convention, the debate about the potential
use of iron fertilization for geoengineering has never been more public or more
pronounced. To help inform this debate, we present a synoptic view of the two-decade
history of iron fertilization, from scientific experiments to commercial enterprises
designed to trade credits for ocean fertilization on a developing carbon market.
Throughout these two decades there has been a repeated cycle: Scientific experiments are
followed by media and commercial interest and this triggers calls for caution and the
need for more experiments. Over the years, some scientists have repeatedly pointed out
that the idea is both unproven and potentially ecologically disruptive, and models have
consistently shown that at the limit, the approach could not substantially change the
trajectory of global warming. Yet, interest and investment in ocean fertilization as a
climate mitigation strategy have only grown and intensified, fueling media reports that
have misconstrued scientific results, and conflated scientific experimentation with
geoengineering. We suggest that it is time to break this two-decade cycle, and argue that
we know enough about ocean fertilization to say that it should not be considered further
as a means to mitigate climate change. But, ocean fertilization research should not be
halted: if used appropriately and applied to testable hypotheses, it is a powerful research
tool for understanding the responses of ocean ecosystems in the context of climate
change.
Record 8 of 16
Author(s): Lovelock, J (Lovelock, James)
Title: A geophysiologist's thoughts on geoengineering
Source: PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY AMATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, 366 (1882): 38833890 NOV 13 2008
Abstract: The Earth is now recognized as a self-regulating system that includes a
reactive biosphere; the system maintains a long-term steady-state climate and surface
chemical composition favourable for life. We are perturbing the steady state by changing
the land surface from mainly forests to farm land and by adding greenhouse gases and
aerosol pollutants to the air. We appear to have exceeded the natural capacity to counter
our perturbation and consequently the system is changing to a new and as yet unknown
but probably adverse state. I suggest here that we regard the Earth as a physiological
system and consider amelioration techniques, geoengineering, as comparable to
nineteenth century medicine.
DOI: 10.1098/rsta.2008.0135
Record 9 of 16
Author(s): Rasch, PJ (Rasch, Philip J.); Tilmes, S (Tilmes, Simone); Turco, RP (Turco,
Richard P.); Robock, A (Robock, Alan); Oman, L (Oman, Luke); Chen, CC (Chen, ChihChieh (Jack)); Stenchikov, GL (Stenchikov, Georgiy L.); Garcia, RR (Garcia, Rolando
R.)
Title: An overview of geoengineering of climate using stratospheric
sulphate aerosols
Source: PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY AMATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, 366 (1882): 40074037 NOV 13 2008
Abstract: We provide an overview of geoengineering by stratospheric sulphate aerosols.
The state of understanding about this topic as of early 2008 is reviewed, summarizing the
past 30 years of work in the area, highlighting some very recent studies using climate
models, and discussing methods used to deliver sulphur species to the stratosphere. The
studies reviewed here suggest that sulphate aerosols can counteract the globally averaged
temperature increase associated with increasing greenhouse gases, and reduce changes to
some other components of the Earth system. There are likely to be remaining regional
climate changes after geoengineering, with some regions experiencing significant
changes in temperature or precipitation. The aerosols also serve as surfaces for
heterogeneous chemistry resulting in increased ozone depletion. The delivery of sulphur
species to the stratosphere in a way that will produce particles of the right size is shown
to be a complex and potentially very difficult task. Two simple delivery scenarios are
explored, but similar exercises will be needed for other suggested delivery mechanisms.
While the introduction of the geoengineering source of sulphate aerosol will perturb the
sulphur cycle of the stratosphere signicantly, it is a small perturbation to the total
(stratosphere and troposphere) sulphur cycle. The geoengineering source would thus be a
small contributor to the total global source of 'acid rain' that could be compensated for
through improved pollution control of anthropogenic tropospheric sources. Some areas of
research remain unexplored. Although ozone may be depleted, with a consequent
increase to solar ultraviolet-B (UVB) energy reaching the surface and a potential impact
on health and biological populations, the aerosols will also scatter and attenuate this part
of the energy spectrum, and this may compensate the UVB enhancement associated with
ozone depletion. The aerosol will also change the ratio of diffuse to direct energy
reaching the surface, and this may influence ecosystems. The impact of geoengineering
on these components of the Earth system has not yet been studied. Representations for
the formation, evolution and removal of aerosol and distribution of particle size are still
very crude, and more work will be needed to gain confidence in our understanding of the
deliberate production of this class of aerosols and their role in the climate system.
DOI: 10.1098/rsta.2008.0131
Record 10 of 16
Author(s): Lunt, DJ (Lunt, D. J.); Ridgwell, A (Ridgwell, A.); Valdes, PJ (Valdes, P. J.);
Seale, A (Seale, A.)
Title: "Sunshade World": A fully coupled GCM evaluation of the
climatic impacts of geoengineering
Source: GEOPHYSICAL RESEARCH LETTERS, 35 (12): Art. No. L12710 JUN 25
2008
Abstract: Sunshade geoengineering - the installation of reflective mirrors between the
Earth and the Sun to reduce incoming solar radiation, has been proposed as a mitigative
measure to counteract anthropogenic global warming. Although the popular conception is
that geoengineering can re-establish a 'natural' pre-industrial climate, such a scheme
would itself inevitably lead to climate change, due to the different temporal and spatial
forcing of increased CO2 compared to reduced solar radiation. We investigate the
magnitude and nature of this climate change for the first time within a fully coupled
General Circulation Model. We find significant cooling of the tropics, warming of high
latitudes and related sea ice reduction, a reduction in intensity of the hydrological cycle,
reduced ENSO variability, and an increase in Atlantic overturning. However, the changes
are small relative to those associated with an unmitigated rise in CO2 emissions. Other
problems such as ocean acidification remain unsolved by sunshade geoengineering.
Article Number: L12710
DOI: 10.1029/2008GL033674
Record 11 of 16
Author(s): Bala, G (Bala, G.); Duffy, PB (Duffy, P. B.); Taylor, KE (Taylor, K. E.)
Title: Impact of geoengineering schemes on the global
hydrological cycle
Source: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE
UNITED STATES OF AMERICA, 105 (22): 7664-7669 JUN 3 2008
Abstract: The rapidly rising CO2 level in the atmosphere has led to proposals of climate
stabilization by "geoengineering" schemes that would mitigate climate change by
intentionally reducing solar radiation incident on Earth's surface. In this article we
address the impact of these climate stabilization schemes on the global hydrological
cycle. By using equilibrium climate simulations, we show that insolation reductions
sufficient to offset global-scale temperature increases lead to a decrease in global mean
precipitation. This occurs because solar forcing is more effective in driving changes in
global mean evaporation than is CO2 forcing of a similar magnitude. In the model used
here, the hydrological sensitivity, defined as the percentage change in global mean
precipitation per degree warming, is 2.4% K-1 for solar forcing, but only 1.5% K-1 for
CO2 forcing. Although other models and the climate system itself may differ
quantitatively from this result, the conclusion can be understood based on simple
considerations of the surface energy budget and thus is likely to be robust. For the same
surface temperature change, insolation changes result in relatively larger changes in net
radiative fluxes at the surface; these are compensated by larger changes in the sum of
latent and sensible heat fluxes. Hence, the hydrological cycle is more sensitive to
temperature adjustment by changes in insolation than by changes in greenhouse gases.
This implies that an alteration in solar forcing might offset temperature changes or
hydrological changes from greenhouse warming, but could not cancel both at once.
DOI: 10.1073/pnas.0711648105
Record 12 of 16
Author(s): Trenberth, KE (Trenberth, Kevin E.); Dai, A (Dai, Aiguo)
Title: Effects of Mount Pinatubo volcanic eruption on the
hydrological cycle as an analog of geoengineering
Source: GEOPHYSICAL RESEARCH LETTERS, 34 (15): Art. No. L15702 AUG 1
2007
Abstract: The problem of global warming arises from the buildup of greenhouse gases
such as carbon dioxide from burning of fossil fuels and other human activities that
change the composition of the atmosphere and alter outgoing longwave radiation (OLR).
One geoengineering solution being proposed is to reduce the incoming sunshine by
emulating a volcanic eruption. In between the incoming solar radiation and the OLR is
the entire weather and climate system and the hydrological cycle. The precipitation and
streamflow records from 1950 to 2004 are examined for the effects of volcanic eruptions
from El Chichon in March 1982 and Pinatubo in June 1991, taking into account changes
from El Nino-Southern Oscillation. Following the eruption of Mount Pinatubo in June
1991 there was a substantial decrease in precipitation over land and a record decrease in
runoff and river discharge into the ocean from October 1991-September 1992. The results
suggest that major adverse effects, including drought, could arise from geoengineering
solutions.
Article Number: L15702
DOI: 10.1029/2007GL030524
Record 13 of 16
Author(s): Warren, LA; Haack, EA
Title: Microbial geoengineering: Acid rock drainage biofilms,
metals and Mn oxyhydroxides
Source: GEOCHIMICA ET COSMOCHIMICA ACTA, 68 (11): A194-A194 Suppl. S
JUN 2004
Record 14 of 16
Author(s): Buesseler, KO; Andrews, JE; Pike, SM; Charette, MA
Title: The effects of iron fertilization on carbon sequestration
in the Southern Ocean
Source: SCIENCE, 304 (5669): 414-417 APR 16 2004
Abstract: An unresolved issue in ocean and climate sciences is whether changes to the
surface ocean input of the micronutrient iron can alter the flux of carbon to the deep
ocean. During the Southern Ocean Iron Experiment, we measured an increase in the flux
of particulate carbon from the surface mixed layer, as well as changes in particle cycling
below the iron-fertilized patch. The flux of carbon was similar in magnitude to that of
natural blooms in the Southern Ocean and thus small relative to global carbon budgets
and proposed geoengineering plans to sequester atmospheric carbon dioxide in the deep
sea.
Record 15 of 16
Author(s): Govindasamy, B; Caldeira, K; Duffy, PB
Title: Geoengineering Earth's radiation balance to mitigate
climate change from a quadrupling of CO2
Source: GLOBAL AND PLANETARY CHANGE, 37 (1-2): 157-168 JUN 10 2003
Abstract: It has been suggested that climate change induced by anthropogenic CO2
could be counteracted with geoengineering schemes designed to diminish the solar
radiation incident on Earth's surface. Though the spatial and temporal pattern of radiative
forcing from greenhouse gases differs from that of sunlight, it was shown in a recent
study that these schemes would largely mitigate regional or seasonal climate change for a
doubling of the atmospheric CO2 content. Here, we examine the ability of reduced solar
luminosity to cancel the effects of quadrupling of CO2 content. In agreement with our
previous study, geoengineering schemes could markedly diminish regional and seasonal
climate change. However, there are some residual climate changes: in the geoengineered
4 x CO2 climate, a significant decrease in surface temperature and net water flux occurs
in the tropics; warming in the high latitudes is not completely compensated; the cooling
effect of greenhouse gases in the stratosphere persists and sea ice is not fully restored.
However, these residual climate changes are much smaller than the change from
quadrupling of CO2 without reducing solar input. Caution should be exercised in
interpretation because these results are from a single model with a number of simplifying
assumptions. There are also many technical, environmental and political reasons not to
implement geoengineering schemes. (C) 2003 Elsevier Science B.V. All rights reserved.
DOI: 10.1016/S0921-8181(02)00195-9
Record 16 of 16
Author(s): Govindasamy, B; Thompson, S; Duffy, PB; Caldeira, K; Delire, C
Title: Impact of geoengineering schemes on the terrestrial
biosphere
Source: GEOPHYSICAL RESEARCH LETTERS, 29 (22): Art. No. 2061 NOV 15 2002
Abstract: [1] Climate stabilization via "Geoengineering'' schemes seek to mitigate
climate change due to increased greenhouse gases by compensating reduction in solar
radiation incident on earth's surface. In this paper, we address the impact of these climate
stabilization schemes on terrestrial biosphere using equilibrium simulations from a
coupled atmosphere-terrestrial biosphere model. Climate stabilization would tend to limit
changes in vegetation distribution brought on by climate change, but would not prevent
CO2-induced changes in Net Primary Productivity (NPP) or biomass; indeed, if CO2
fertilization is significant, then a climate-stabilized world could have higher NPP than our
current world. Nevertheless, there are many reasons why geoengineering is not a
preferred option for climate stabilization.
Article Number: 2061
DOI: 10.1029/2002GL015911