Highlights of 2010 - Environmental Research Letters - IOPscience

Highlights of 2010 - Environmental Research Letters - IOPscience
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Highlights of 2010
This year we celebrate the fifth anniversary of the launch of
Environmental Research Letters
(ERL). During the past five years the quality and volume of submissions to ERL has continued to steadily increase as the journal becomes more visible to new communities. This is not only reflected in the diversity of the content published but also in the journal's ISI impact factor which has continued to see an impressive climb and now stands at 3.342. This is a remarkable rise to prominence, and makes ERL a true 'go-to' publication.
This year's collection of highlights provides a showcase of our best and most high impact research published in the last year. We hope that this collection will encourage you to submit your next piece of research to ERL.
2010 also saw the publication and launch of focus issues on a wide range of topics such as climatic and environmental change in Northern Eurasia, climate change on the Tibetan Plateau, anticipated changes in the global atmospheric water cycle and on the Deepwater Horizon oil spill.
By publishing work in an open-access journal, authors are guaranteeing themselves global visibility with no barrier to readers accessing their work. This makes ERL ideal for research that has interest and implications for those outside academia, where subscriptions to journals are not available. I would like to thank everyone who has published, read, and refereed for ERL for their hard work and support. I hope you can all continue to work with the journal through 2011 and beyond, and that you choose to submit your next article to ERL.
Editor-in-Chief
Professor Daniel Kammen
You can download the
Highlights of 2010 PDF
, or you can access the full articles below. The
2008
and
2009
collections are also available. For a print copy, please contact the
Environmental Research Letters
team at
erl@iop.org
Contents
Focus issues
Perspectives
Letters
Focus issues
Anticipated changes in the global atmospheric water cycle
Editors
Richard P Allan and Beate G Liepert
Deepwater Horizon Oil Spill
Editors
Ian McDonald, Dan Kammen and Maohong Fan
Perspectives
Open access
Snow matters in the polar regions
John Sodeau 2010
Environ. Res. Lett.
011001
View article
, Snow matters in the polar regions
PDF
, Snow matters in the polar regions
Antarctica is not quite as chemically pristine as might sometimes be thought
(Jones
et al
2008). For example, as elsewhere, reduced sulfur species
such as dimethylsulfide (DMS) are emitted from biogenic marine sources at the
poles (Read
et al
2008). Somewhat less well known is that inland (as
opposed to coastal) field campaigns have also detected, within the Antarctic
boundary layer (ABL), emissions containing unexpectedly high levels of diverse,
oxidizing chemicals such as NO
, nitrate ions, formaldehyde, ozone and
hydrogen peroxide (Honrath
et al
1999, Hutterli
et al
2004, Sumner
and Shepson 1999). And then there are the halogen-containing compounds (Simpson
et al
2007).
The transformation of DMS to sulfate aerosols capable of acting as cloud
condensation nuclei often proceeds via one main oxidized product of DMS, namely
methanesulfonic acid (MSA). Two specific reactions have been well studied to
date in this regard, namely DMS plus either OH or NO
radicals.
Corresponding reactions with halogen radicals, which also contribute to the
oxidizing capacity of our atmosphere, have generally been considered to be of
less importance. The reason for this view is that even though the reactivity of
bromine- and iodine-containing radicals is much greater than that of OH, the
halogens were thought to be relatively scarce in the polar atmosphere. However
both BrO (and IO) have been detected in the Antarctic CHABLIS campaign, as
discussed in depth in the
Atmospheric Chemistry and Physics
special issue
of 2008, see Jones
et al
(2008). It was subsequently shown that
calculated MSA production from the DMS/BrO reaction may be about an order of
magnitude greater than when the OH radical was the oxidizing reactant.
The recent analytical measurements by Antony
et al
(2010) of MSA, Br
and NO
found in snow along the Ingrid Christensen Coast of East
Antarctica are important in the above field context. Hence it would appear that
the concentrations of these ions in ice-cap sites are up to 30 times greater
than those found in ice-free areas.
The main question to ask is: how might the bromine have become released to
the atmosphere? Many ideas have, in fact, been put forward over the last few
years as to how such polar ocean–troposphere exchanges can take place. Much of
the interest was driven by the so-called 'sudden' ozone depletion episodes first
detected in Arctic air during the 1990s alongside simultaneous bromine
'explosions' which were monitored by ground-based instrumentation and satellite
(as the radical BrO) over sea-ice covered by snowpack (Hausmann and Platt 1994,
Schonhardt
et al
2008). The likely precursors suggested, to date, have
been sea-salt, frost-flowers and anthropogenic contents rather than organo-
bromine matter (Simpson
et al
2007). Associated processing routes
including the formation of HOBr, the need for acidity, the involvement of
trihalide ions and the potential role of freezing processes and the quasi-liquid
layer have all been discussed in this context (Abbatt 1994, Neshyba
et al
2009, O'Driscoll
et al
2006). Computational work has also led to
suggestions that preferential surface dispersion of the more highly polarizable
halides (iodide and bromide ions) may lead to their direct interfacial reaction
with atmospheric ozone leading to BrO or IO formation (Jungwirth and Winter
2008).
The involvement of snow micro-algae in the production of halo-compounds such
as CHBr
and CH
Br
in Antarctica cannot, of
course, be ignored following the measurement of these compounds by Sturges and
co-workers over 15 years ago (Sturges
et al
1993). And the measurement of
high levels of nutrient discussed in the recent work by Antony
et al
(2010) in the ice-cap areas do provide a basis for understanding why micro-
algae growth in snow might be promoted. However the question still comes back
to: how are these halo-compounds processed to produce 'active' species like BrO
radicals, HOBr, Br atoms, Br
gas or interhalogens such as BrCl? The
relatively long history of this topic was surveyed extensively in 2007 and the
answer is probably not related to the photolysis of the halogeno-carbons
although the transformation processes are still not completely understood
(Simpson
et al
2007). This topic along with the potential involvement of
both iodine and chlorine species is decidedly 'hot' in the intriguing world of
polar cryochemistry.
The Antony
et al
(2010) paper is actually entitled 'Is cloud seeding
in coastal Antarctica linked to bromine and nitrate variability in snow?'.
Although the nitrate ions were discussed in terms of being a simple nutrient in
the study, the photochemistry of nitrate ions in snow has actually become an
important focus of research in the laboratory. A further review by Grannas
et
al
(2007) is recommended in this respect. But important questions remain
regarding the fate of the NO and NO
molecules produced in the
primary photolytic channels, especially if concentrated into ice 'micropockets'
(Hellebust
et al
2007). Furthermore the impacts of newly discovered
reactions such as HO
/NO to directly produce nitric acid, at the
expense of NO
, have not yet been quantified in the polar ABL
context (Cariolle
et al
2008). Then there is peroxyacetylnitrate (PAN;
Mills
et al
2007) and other organo-nitrates and their possible
interactions with mercury and the halides . . .
Clearly, Antarctica is not chemically pristine and snow–ice interfaces
in both the laboratory and the field have become a very challenging medium for
exploring new and unexpected chemistry relevant to our atmosphere.
References
Abbatt J P D 1994 Heterogeneous reaction of HOBr with HBr and HCl on ice surfaces at 228 K
Geophys. Res. Lett.
21
665–8
Antony R
et al
2010 Is cloud seeding in coastal Antarctica linked to bromine and nitrate variability in snow?
Environ. Res. Lett.
014009
Cariolle D
et al
2008 Impact of the new HNO
-forming channel of the HO
+ NO reaction on tropospheric HNO
, NO
, HO
and ozone
Atmos. Chem. Phys.
4061–8
Grannas A M
et al
2007 An overview of snow photochemistry: evidence, mechanisms and impacts
Atmos. Chem. Phys.
4329–73
Hausmann M and Platt U 1994 Spectroscopic measurement of bromine oxide and ozone in the high Arctic during polar sunrise experiment 1992
J. Geophys. Res. Atmos.
99
25399–413
Hellebust S
et al
2007 Potential role of the nitroacidium ion on HONO emissions from the snowpack
J. Phys. Chem.
111
1167–71
Honrath R
et al
1999 Evidence of NO
production within or upon ice particles in the Greenland snowpack
Geophys. Res. Lett.
26
695–8
Hutterli M A
et al
2004 Formaldehyde and hydrogen peroxide in air, snow and interstitial air at South Pole
Atmos. Environ.
38
5439–50
Jones A E
et al
2008 Chemistry of the Antarctic boundary layer and the interface with snow: an overview of the CHABLIS campaign
Atmos. Chem. Phys.
3789–803
Jungwirth P and Winter B 2008 Ions at aqueous interfaces: from water surface to hydrated proteins
Ann. Rev. Phys. Chem.
59
343–66
Mills G P
et al
2007 Seasonal variation of peroxyacetylnitrate (PAN) in coastal Antarctica measured with a new instrument for the detection of sub-part per trillion mixing ratios of PAN
Atmos. Chem. Phys.
4589–99
Neshyba S
et al
2009 Molecular dynamics study of ice-vapor interactions via the quasi-liquid layer
J. Phys. Chem.
113
4597–604
O'Driscoll P
et al
2006 Freezing halide ion solutions and the release of interhalogens to the atmosphere
J. Phys. Chem.
110
4615–8
Read K A
et al
2008 DMS and MSA measurements in the Antarctic boundary layer: impact of BrO on MSA production
Atmos. Chem. Phys.
2985–97
Schonhardt A
et al
2008 Observations of iodine monoxide columns from satellite
Atmos. Chem. Phys.
637–53
Simpson W R
et al
2007 Halogens and their role in polar boundary-layer ozone depletion
Atmos. Chem. Phys.
4375–418
Sturges W T
et al
1993 Spring measurements of tropospheric bromine at Barrow, Alaska
Geophys. Res. Lett.
20
201–4
Sumner A L and Shepson P B 1999 Snowpack production of formaldehyde and its effect on the Arctic troposphere
Nature
398
230–3
Open access
Low solar activity is blamed for winter chill over Europe
Rasmus E Benestad 2010
Environ. Res. Lett.
021001
View article
, Low solar activity is blamed for winter chill over Europe
PDF
, Low solar activity is blamed for winter chill over Europe
Throughout recent centuries, there have been a large number of studies of the
relationship between solar activity and various aspects of climate, and yet this
question is still not entirely settled. In a recent study, Lockwood
et al
(2010) argue that the occurrence of persistent wintertime blocking events
(periods with persistent high sea level pressure over a certain region) over the
eastern Atlantic, and hence chilly winters over northern Europe, are linked to
low solar activity. Is this then a breakthrough in our understanding of our
climate?
The Wolf sunspot number, which dates back to Galileo's invention of the
telescope in the 17th century, represents one of our longest geophysical data
records. Galileo was also involved in building the first barometers and
thermometers around that period. Hence, the 17th century represents the start of
instrumental measurements of weather and climate, and there are indeed
historical records of speculations or studies on the link between changes in the
sun and conditions on Earth dating from that time (Helland-Hansen and Nansen
1920).
One notorious problem with many previous studies was that relationships
established over the calibration interval subsequently broke down. There was a
period in the mid-20th century when little work was done on solar activity and
climate, but solar activity was considered a real forcing factor before 1920.
With the advent of frontal theory, orbital forcing theory, and stronger
awareness of the implications of enhanced greenhouse gas concentrations, the
support for solar forcing seemed to have diminished in the climatology community
by the mid-20th century (Monin 1972). But non-stationary relationships, the
chaotic character of climate, weak effects, and lack of a physical understanding
behind such a link, can also explain the low support for solar forcing at that
time.
For a long time, it was not established whether more sunspots meant a
brighter or dimmer sun (the answer is brighter), and then the direct effect from
changes in the solar brightness (0.1%) was estimated to be too low to explain
the temperature changes on Earth. The solar influence on changes in the global
mean temperature has so far been found to be weak (Lean 2010, Benestad and
Schmidt 2009). The important difference between recent and early studies is,
however, that the latter lacked a theoretical framework based on physical
mechanisms.
Now we understand that stratospheric conditions vary, and are affected by
chemical reactions as well as the absorption of UV light. Furthermore, we know
that such variations affect temperature profiles, wave propagations, and winds
(Schindell
et al
2001). Lean (2010) and Haigh (2003) provide nice reviews
of recent progress on solar-terrestrial relationships, although questions
regarding the quality of the oldest solar data records are still unanswered
(Benestad 2005). All these studies still rely on empirical data analysis.
Much of the focus of the recent work has been on climate variation on global
scales. The recent paper by Lockwood
et al
(2010) represents current
progress, albeit that they emphasize that the relationship they identify has a
regional rather than global character. Indeed, they stress that a change in the
global mean temperature should not be confused with regional and seasonal means.
The physical picture they provide is plausible, yet empirical relationships
between solar activity and any of the indices describing the north Atlantic
oscillation, the Arctic oscillation or the polar vortex are regarded as
weak.
My impression is nevertheless that the explanation provided by the Lockwood
et al
(2010) study reflects real aspects of our climate, especially if
the effect is asymmetric. They argue that solar-induced changes in the
stratosphere in turn affect the occurrence of persistent wintertime
blocking. But one comprehensive, definite, consistent, and convincing
documentation of the entire chain causality is still not in place, due to
the lack of long-term high-quality observations from remote sensing
platforms. It is nevertheless well known that the temperature in northern
Europe is strongly affected by atmospheric circulation. Crooks and Gray
(2005) have identified a solar response in a number of atmospheric
variables, and Labitske (1987), Labitske and Loon (1988) and Salby and
Callagan (2000) provide convincing analyses suggesting that the zonal winds
in the stratosphere are influenced by solar activity. Furthermore, Baldwin
and Dunkerton (2001) provide a tentative link between the stratosphere and
the troposphere. The results of Lockwood
et al
(2010) fit in with
earlier work (Barriopedro
et al
2008) and provide further evidence to
support the current thinking on solar-terrestrial links. Thus, it is an
example of incremental scientific progress rather than a breakthrough or a
paradigm shift.
References
Baldwin M P and Dunkerton T J 2001 Stratospheric harbingers of anomalous weather regimes
Science
294
581–4
Barriopedro D, Garcia-Herrera R and Huth R 2008 Solar modulation of Northern Hemisphere winter blocking
J. Geophys. Res.
113
D14118
Benestad R E 2005 A review of the solar cycle length estimates
Geophys. Res. Lett.
32
L15714
Benestad R E and Schmidt G A 2009 Solar trends and global warming
J. Geophys. Res. Atmos.
114
D14101
Crook S A and Gray L J 2005 Characterization of the 11-year solar signal using a multiple regression analysis of the ERA-40 dataset
J. Climate
18
996–1014
Haigh J D 2003 The effects of solar variability on the Earth's climate
Phil. Trans. R. Soc. Lond. A
361
95–111
Helland-Hansen B and Nansen F 1920 Temperature variations in the North Atlantic ocean and in the atmosphere
Smithsonian Miscellaneous Collections
70
(4) 408 pp
Labitzke K 1987 Sunspots, the QBO, and the stratospheric temperature in the North polar region
Geophys. Res. Lett.
14
535–7
Labitzke K and van Loon H 1988 Association between the 11-year solar cycle, the QBO, and the atmosphere, I. The troposphere and stratosphere on the northern hemisphere winter
J. Atmos. Terr. Phys.
50
197–206
Lean J L 2010 Cycles and trends in solar irradiance and climate
WIREs Climate Change
111–22
Lockwood M, Harrison R G, Woollings T and Solanki S K 2010 Are cold winters in Europe associated with low solar activity?
Environ. Res. Lett.
024001
Monin A S 1972
Weather Forecasting as a Problem in Physics
(Cambridge, MA: MIT Press) (Engl. translation from Russian)
Salby M and Callagan P 2000 Connection between the solar cycle and the QBO: the missing link
J. Climate
13
328–38
Shindell D T, Schmidt G A, Mann M E, Rind D and Waple A 2001 Solar forcing of regional climate change during the Maunder minimum
Science
294
2149–52
Open access
Technical fixes and climate change: optimizing for risks and consequences
Philip J Rasch 2010
Environ. Res. Lett.
031001
View article
, Technical fixes and climate change: optimizing for risks and consequences
PDF
, Technical fixes and climate change: optimizing for risks and consequences
Scientists and society in general are becoming increasingly concerned about the
risks of climate change from the emission of greenhouse gases (IPCC 2007). Yet
emissions continue to increase (Raupach
et al
2007), and achieving reductions soon
enough to avoid large and undesirable impacts requires a near-revolutionary
global transformation of energy and transportation systems (Hoffert
et al
1998). The size of the transformation and lack of an effective societal response
have motivated some to explore other quite controversial strategies to mitigate
some of the planetary consequences of these emissions.
These strategies have come to be known as geoengineering: 'the deliberate
manipulation of the planetary environment to counteract anthropogenic climate
change' (Keith 2000). Concern about society's inability to reduce emissions has
driven a resurgence in interest in geoengineering, particularly following the
call for more research in Crutzen (2006). Two classes of geoengineering
solutions have developed: (1) methods to draw CO
out of the atmosphere and
sequester it in a relatively benign form; and (2) methods that change the energy
flux entering or leaving the planet without modifying CO
concentrations by,
for example, changing the planetary albedo. Only the latter methods are considered
here.
Summaries of many of the methods, scientific questions, and issues of testing
and implementation are discussed in Launder and Thompson (2009) and Royal
Society (2009). The increased attention indicates that geoengineering is not a
panacea and all strategies considered will have risks and consequences (e.g.
Robock 2008, Trenberth and Dai 2007).
Recent studies involving comprehensive Earth system models can provide insight
into subtle interactions between components of the climate system. For example
Rasch
et al
(2009) found that geoengineering by changing boundary clouds will
not simultaneously 'correct' global averaged surface temperature, precipitation,
and sea ice to present-day values. There is a tradeoff between cooling the
planet and consequences to the hydrologic cycle and sea ice cover in the Arctic.
Ban-Weiss and Caldeira (2010) have taken another step in this exploration. They
have treated geoengineering as an optimization problem and searched for an
optimal solution by varying one aspect of a geoengineering methodology, imposing
differences in the spatial location of the geoengineering—contrasting changes
concentrated in polar regions with spatially uniform aerosol distributions (i.e.
shielding the poles to protect the sea ice may have a different impact on the
planet than shielding an equatorial region). They measured the impact by looking
at the root mean square difference between the geoengineered world and
present-day precipitation and temperature (as opposed to the global averaged changes in
the Rasch
et al
study). They found that broad fixed location geoengineering
is quite a crude mechanism for control of temperature and precipitation.
Differences between uniform and optimal geoengineering distributions are quite
modest, and the tradeoffs found in earlier studies are also found here.
Solutions that minimize differences from present-day temperatures are not the
best solutions in terms of differences in present-day precipitation.
The study is simple and idealized. The measures of desirability of climate to
optimize for can be made more comprehensive, including other variables or
measures, for example, of transient variability (seasonal, diurnal variability,
or frequency of extreme events), and it is easy to identify ways to make the
geoengineering strategy much more complex. The study is thought provoking,
delivers clear and useful messages, outlines a methodology and helps to clarify
ways to think about geoengineering consequences.
References
Ban-Weiss G A and Caldeira K 2010 Geoengineering as an optimization problem
Environ. Res. Lett.
034009
Crutzen P J 2006 Albedo enhancement by stratospheric sulfur injections: a contribution to resolve a policy dilemma?
Clim. Change
77
211–20
Hoffert M I, Caldeira K, Jain A K, Haites E F, Harvey L D, Potter S D, Schlesinger M E, Schneider S H, Watts R G, Wigley T M L and Wuebbles D J 1998 Energy implications of future stabilization of atmospheric CO
content
Nature
395
881–4
IPCC 2007 Summary for policymakers
Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change
ed S Solomon, D Qin, M Manning, Z Chen, M Marquis, K B Averyt, M Tignor and H L Miller (Cambridge: Cambridge University Press) chapter 0, pp 1–18
Keith D W 2000 Geoengineering the climate: history and prospect
Ann. Rev. Energy Environ.
25
245–84
Launder B and Thompson M 2009 A review of stratospheric sulfate aerosols for geoengineering
Geo-Engineering Climate Change: Environmental Necessity or Pandoras Box?
(Cambridge: Cambridge University Press) 332 pp
Rasch P J, Chen C-C and Latham J L 2009 Geo-engineering by cloud seeding: influence on sea-ice and the climate system
Environ. Res. Lett.
045112
Raupach M R, Marland G, Ciais Ph, Le Quere C, Canadel J G, Klepper G and Field C B 2007 Global and regional drivers of accelerating CO
emissions
Proc. Natl Acad. Sci.
104
10288–93
Robock A 2008 Twenty reasons why geoengineering might be a bad idea
Bull. Atomic Scientists
64
14–8
Royal Society 2009
Geoengineering the Climate: Science, Governance, and Uncertainty
(London: The Royal Society) ISBN: 978-0-85403-773-5
Trenberth K E and Dai A 2007 Effects of Mount Pinatubo volcanic eruption on the hydrological cycle as an analog of geoengineering
Geophys. Res. Lett.
34
L15702
Open access
How committed are we to monitoring human impacts in Antarctica?
Kevin A Hughes 2010
Environ. Res. Lett.
041001
View article
, How committed are we to monitoring human impacts in Antarctica?
PDF
, How committed are we to monitoring human impacts in Antarctica?
Under the Antarctic Treaty System, environmental monitoring is a legal
obligation for signatory nations and an essential tool for managers attempting
to minimize local human impacts, but is it given the importance it merits?
Antarctica is a vast frozen continent with an area around 1.5 times that of
Europe (14 000 000 km
), but the majority of its
terrestrial life is found on multiple outcrops or 'islands' of ice-free coastal
ground, with a combined area of ~6000 km
, equivalent to four times
that of Greater London (Tin
et al
2009). The biological communities of
these ice-free terrestrial habitats are dominated by a small number of
biological groups, primarily mosses, lichens, microinvertebrates and
microorganisms. They include many endemic species, while birds and marine
mammals use coastal areas as breeding sites (Chown and Convey 2007).
Figure 1.
Map of the Antarctic Treaty area (south of latitude
60°S) showing the locations of year-round and seasonal stations built on
rock or permanent ice (i.e. ice sheets or ice shelves). Data on station
locations were taken from the Council of Managers of National Antarctic Programs
website (COMNAP 2010). There is evidence to suggest that although these stations
are registered on the COMNAP list, a number of stations are not regularly
occupied or in use (see United Kingdom
et al
2006, p 9).
Since the influx of national scientific research programmes and
infrastructure that accompanied the International Geophysical Year (1957–1958),
Antarctica's habitats have been encroached upon increasingly by human
activities. Over 120 research stations have been built (~75 currently
operational) with the great majority located on ice-free coastal ground to allow
ease of access by ship. (Headland 2009, COMNAP 2010). Construction of cargo and
personnel landing and handling facilities, station buildings, airport
infrastructure, roads and fuel storage areas have, to varying degrees, destroyed
native vegetation and terrestrial fauna and displaced bird and marine mammals
from breeding sites in their immediate environment. An early history of poor
environmental management and waste disposal practices around many stations has
left a legacy of fuel-contaminated ground and abandoned waste sites in adjacent
marine and terrestrial environments (Tin
et al
2009).
Construction of research stations and other infrastructure fulfils two
national objectives: (1) supporting geopolitical aspirations of claimant nations
and (2) demonstrating a significant commitment to undertaking science in
Antarctica, which is a prerequisite for attaining consultative status at the
Antarctic Treaty Consultative Meeting. However, these objectives may not be
supported equally, with little or no science performed routinely at some
stations (United Kingdom
et al
2006). In addition, co-ordination of
science activities between nations—another aspiration under the Antarctic
Treaty—is often lacking, leading to duplication of research between
national programmes, and even that undertaken at nearby stations. In some cases,
components of national research programmes lack any international, open or
objective assessment of quality. Nevertheless, new nations continue to become
involved in Antarctic affairs, and almost inevitably seek to establish their own
infrastructure, while some established Treaty Parties continue to further expand
their existing logistic and infrastructure footprints. Despite calls for nations
to share existing infrastructure or reuse abandoned stations (ATCM 2006), new
stations continue to be constructed on pristine sites, with the Antarctic
terrestrial environment in particular coming under increased pressure.
The Protocol on Environmental Protection to the Antarctic Treaty (commonly
known as the Environmental Protocol), which came into force in 1998, sets out
common minimum standards for environmental management by all Antarctic Treaty
Parties. Under the Protocol, it is mandatory to regularly monitor the
environmental impacts caused by any new infrastructure that requires the
completion of a Comprehensive Environmental Evaluation during the planning, as
would be required for research stations or other large building projects.
Ideally, monitoring should include assessment of levels of physical disruption
of marine and terrestrial habitats, and should record levels of pollutants and
also their impacts upon the full range of biological groups within local
ecosystems. Biodiversity surveys should also be undertaken, in order that
introduced non-native species can be identified at an early stage and eradicated
(Hughes and Convey 2010).
But where can the scientific data describing national Antarctic programme
impacts be found? Some nations have a good track record of publishing
environmental monitoring data, but the large majority do not. With around 75
active stations, monitoring research should be well represented in the
scientific literature, but data for most stations are not available.
Furthermore, Antarctic Treaty signatory nations are required to supply details
of their monitoring work through the Antarctic Treaty System's Electronic
Information Exchange System (see
www.ats.aq/e/ie.htm
), yet
only three out of 28 Treaty nations did so for 2008/2009.
In their recent synthesis paper, Kennicutt
et al
(2010) describe the
results of a long-term monitoring programme at the United States' McMurdo
Station, giving us a comprehensive picture of human impacts at this location.
The high quality and breadth of this research makes it one of the best-documented
and longest-running monitoring programmes within Antarctica to date.
Yet, why is this work so exceptional, when the USA have simply fulfilled their
obligations under the Environmental Protocol? Monitoring programmes of this
standard should be undertaken for all stations and large infrastructure. Factors
preventing this may include (1) a lack of monitoring expertise or access to
sophisticated techniques, particularly by smaller or less well-funded Antarctic
programmes, and (2) the lack of importance or prestige attributed to 'routine'
monitoring or survey programmes by science funding bodies, compared to other
'forefront' science areas.
With little formal international scrutiny other than occasional station
inspections, a lack of enforcement mechanisms in place to penalize contravention
of the provisions of the Antarctic Treaty and its related legal instruments, and
a need to maintain good diplomatic relations between Antarctic Treaty Parties,
nations are under little pressure to prioritize human impact monitoring. Despite
the efforts of the Scientific Committee for Antarctic Research and COMNAP, most
Antarctic nations still act individually, with little co-ordination of
monitoring effort or use of standardized techniques. Close examination of the
Environmental Protocol even casts some doubt over whether monitoring of
infrastructure constructed before its implementation in 1998 is a formal
obligation, although many would maintain that failure to do so would be contrary
to the spirit of the Protocol.
While it can be hoped that most signatory nations take their Antarctic
environmental responsibilities seriously, recent reports of poor environmental
practice show that not all national programmes adhere fully to even the minimum
requirements of the Environmental Protocol (Braun
et al
2010). If basic
environmental practice is poor, then standards of environmental monitoring may
also be poor or non-existent. In stark contrast, researchers from Antarctic
programmes who willingly disseminate their results through the scientific
literature deserve credit as they allow other nations to learn from their
efforts. Until all Antarctic Treaty nations engage with their monitoring
obligations and develop together a co-ordinated continent-wide view of human
impacts, Antarctica's environmental values will remain under threat of continued
degradation and the principles of the Antarctic Treaty brought into
disrepute.
References
ATCM 2006
Final Report of the 29th Antarctic Treaty Consultative Meeting
paragraph 73, available online at
www.ats.aq/documents/ATCM29/fr/ATCM29_fr001_e.pdf
Braun C
et al
2010 Environmental situation and management proposals for the Fildes region (Antarctic)
Int. Polar Year Conf., 8–12 June 2010
Abstract no EA8.4-6.8, available online at
Chown S L and Convey P 2007 Spatial and temporal variability across life's hierarchies in the terrestrial Antarctic
Phil. Trans. R. Soc. B
362
2307–31
Council of Managers of National Antarctic Programs (COMNAP) 2010
Antarctic Facilities
available online at
www.comnap.aq/facilities
Headland R 2009
A Chronology of Antarctic Exploration
(London: Quaritch) p 722
Hughes K A and Convey P 2010 The protection of Antarctic terrestrial ecosystems from inter- and intra-continental transfer of non-indigenous species by human activities: a review of current systems and practices
Glob. Environ. Change
20
96–112
Kennicutt M C II, Klein A, Montagna P, Sweet S, Wade T, Palmer T, Sericano J and Denoux G 2010 Temporal and spatial patterns of anthropogenic disturbance at McMurdo Station, Antarctica
Environ. Res. Lett.
034010
Tin T
et al
2009 Impacts of local human activities on the Antarctic environment
Antarct. Sci.
21
3–33
United Kingdom
et al
2006 Report of joint inspections under Article VII of the Antarctic Treaty and Article 14 of the Environmental Protocol
ATCM XXVIII 2006
Working paper 32, available online at
www.ats.aq/documents/ATCM28/att/ATCM28_att270_e.pdf
Open access
Working towards a community-wide understanding of satellite skin temperature observations
Cheney Shreve 2010
Environ. Res. Lett.
041002
View article
, Working towards a community-wide understanding of satellite skin temperature observations
PDF
, Working towards a community-wide understanding of satellite skin temperature observations
With more than sixty free and publicly available high-quality datasets,
including ecosystem variables, radiation budget variables, and land cover
products, the MODIS instrument and the MODIS scientific team have contributed
significantly to scientific investigations of ecosystems across the globe. The
MODIS instrument, launched in December 1999, has 36 spectral bands, a viewing
swath of 2330 km, and acquires data at 250 m, 500 m, and 1000 m spatial
resolution every one to two days. Radiation budget variables include surface
reflectance, skin temperature, emissivity, and albedo, to list a few. Ecosystem
variables include several vegetation indices and productivity measures. Land
cover characteristics encompass land cover classifications as well as model
parameters and vegetation classifications. Many of these products are
instrumental in constraining global climate models and climate change studies,
as well as monitoring events such as the recent flooding in Pakistan, the
unprecedented oil spill in the Gulf of Mexico, or phytoplankton bloom in the
Barents Sea. While product validation efforts by the MODIS scientific team are
both vigorous and continually improving, validation is unquestionably one of the
most difficult tasks when dealing with remotely derived datasets, especially at
the global scale. The quality and availability of MODIS data have led to
widespread usage in the scientific community that has further contributed to
validation and development of the MODIS products.
In their recent paper entitled 'Land surface skin temperature climatology:
benefitting from the strengths of satellite observations', Jin and Dickinson
review the scientific theory behind, and demonstrate application of, a MODIS
temperature product: surface skin temperature. Utilizing datasets from the
Global Historical Climatological Network (GHCN), daily skin and air temperature
from the Atmospheric Radiation Measurement (ARM) program, and MODIS products
(skin temperature, albedo, land cover, water vapor, cloud cover), they show that
skin temperature is clearly a different physical parameter from air temperature
and varies from air temperature in magnitude, response to atmospheric
conditions, and diurnal phase. Although the accuracy of skin temperature
skin
) algorithms has improved to within 0.5–1°C
for field measurements and clear-sky satellite observations (Becker and Li 1995,
Goetz
et al
1995, Wan and Dozier 1996), general confusion regarding the
physical definition of 'surface temperature' and how it can be used for climate
studies has persisted throughout the scientific community and limited the
applications of these data (Jin and Dickinson 2010). For example, satellite sea
surface temperature was used as evidence of global climate change instead of
skin temperature in the IPCC 2001 and 2007 reports (Jin and Dickinson 2010).
This work provides clarity in the theoretical definition of temperature
variables, demonstrates the difference between air and skin temperature, and
aids the understanding of the MODIS
skin
product, which could
be very beneficial for future climate studies.
As outlined by Jin and Dickinson, 'surface temperature' is a vague term
commonly used in reference to air temperature, aerodynamic temperature, and skin
temperature. Air temperature (
air
), or thermodynamic
temperature, is measured by an
in situ
instrument usually 1.5–2 m
above the ground. Aerodynamic temperature (
aero
) refers to
the temperature at the height of the roughness length of heat. Satellite derived
skin temperature (
skin
) is the radiometric temperature
derived from the inverse of Planck's function. While these different temperature
variables are typically correlated, they differ as a result of environmental
conditions (e.g. land cover and sky conditions; Jin and Dickinson 2010). With an
extensive network of
air
measurements, some have questioned
the benefits of using
skin
at all (Peterson
et al
1997, 1998).
skin
and
air
can vary
depending on land cover or sky conditions and variations may be large, e.g., for
sparsely vegetated areas where net radiation is largely balanced by sensible
heat flux (Hall
et al
1992, Sun and Mahrt 1995, Jin
et al
1997).
skin
can be higher than
aero
at midday and
lower at night (Sun and Mahrt 1995) and some models use
aero
to approximate surface radiative temperature (Hubband and Monteith
1986).
One of the strengths of the MODIS instrument is the simultaneous collection
of surface and atmospheric conditions. By incorporating a range of MODIS
variables in their comparison to
skin
, the authors examine
the relationship of
skin
to atmospheric and surface
conditions. Results from their global evaluation of
skin
highlight its variability on an inter-annual basis, its variation with solar
zenith angle, and diurnal variations, which are not achievable with
air
measurements. Comparison with land cover type illustrates
the seasonality of
skin
for different land covers. Comparison
with the enhanced vegetation index (EVI) suggests more vegetation reduces skin
temperature. Using the MODIS albedo, they demonstrate a clear relationship
between yearly averaged
skin
and land surface albedo. Lastly,
their examination of water vapor and cloud cover in comparison to
skin
suggests similar seasonality between these two
variables.
The MODIS
skin
product is not without uncertainty;
retrieving
skin
requires a calculation of radiative transfer
to account for atmospheric emission and molecular absorption, which is time and
resource intensive (Jin and Dickinson 2010). Additionally, surface emissivity,
instrument noise, and view angle geometry contribute to error in
skin
estimations (Jin and Dickinson 2010). The transparency
of the scientific theory underlying this work, and the clear demonstration of
the distinction between temperature measures on varying scales, demonstrates the
usefulness of
skin
despite the uncertainties. Perhaps equally
as important is the tone; in a time when the controversy surrounding climate
change is peaking and the very ethics of the scientific community are being
questioned, it is more critical than ever to be transparent in one's work and to
assist the scientific community in understanding the tools we have available to
us for investigating climate change.
References
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Letters
Open access
Radiative forcing and temperature response to changes in urban albedos and associated CO
offsets
Surabi Menon
et al
2010
Environ. Res. Lett.
014005
View article
, Radiative forcing and temperature response to changes in urban albedos and associated CO2 offsets
PDF
, Radiative forcing and temperature response to changes in urban albedos and associated CO2 offsets
The two main forcings that can counteract to some extent the positive forcings from
greenhouse gases from pre-industrial times to present day are the aerosol and related
aerosol-cloud forcings, and the radiative response to changes in surface albedo. Here, we
quantify the change in radiative forcing and land surface temperature that may
be obtained by increasing the albedos of roofs and pavements in urban areas in
temperate and tropical regions of the globe by 0.1. Using the catchment land
surface model (the land model coupled to the GEOS-5 Atmospheric General
Circulation Model), we quantify the change in the total outgoing (outgoing
shortwave+longwave) radiation and land surface temperature to a 0.1 increase in urban albedos for all
global land areas. The global average increase in the total outgoing radiation was
0.5 W m
−2
, and temperature
decreased by ∼0.008 K for an average 0.003 increase in surface albedo. These averages represent all global land
areas where data were available from the land surface model used and are for the boreal
summer (June–July–August). For the continental US the total outgoing radiation increased by
2.3 W m
−2
, and land surface temperature decreased by
∼0.03 K for an average 0.01 increase in surface albedo. Based on these forcings, the expected emitted
CO
offset for a plausible 0.25 and 0.15 increase in albedos of roofs and
pavements, respectively, for all global urban areas, was found to be
∼57 Gt CO
. A
more meaningful evaluation of the impacts of urban albedo increases on global climate and the expected
CO
offsets would require simulations which better characterize urban surfaces and represent the
full annual cycle.
Open access
Robust negative impacts of climate change on African agriculture
Wolfram Schlenker and David B Lobell 2010
Environ. Res. Lett.
014010
View article
, Robust negative impacts of climate change on African agriculture
PDF
, Robust negative impacts of climate change on African agriculture
There is widespread interest in the impacts of climate change on agriculture in
Sub-Saharan Africa (SSA), and on the most effective investments to assist adaptation to
these changes, yet the scientific basis for estimating production risks and prioritizing
investments has been quite limited. Here we show that by combining historical crop
production and weather data into a panel analysis, a robust model of yield response to
climate change emerges for several key African crops. By mid-century, the mean estimates
of aggregate production changes in SSA under our preferred model specification are − 22, − 17, − 17, − 18, and − 8%
for maize, sorghum, millet, groundnut, and cassava, respectively. In all cases except
cassava, there is a 95% probability that damages exceed 7%, and a 5% probability that
they exceed 27%. Moreover, countries with the highest average yields have the largest
projected yield losses, suggesting that well-fertilized modern seed varieties are more
susceptible to heat related losses.
Open access
A second hydrocarbon boom threatens the Peruvian Amazon: trends, projections, and policy implications
Matt Finer and Martí Orta-Martínez 2010
Environ. Res. Lett.
014012
View article
, A second hydrocarbon boom threatens the Peruvian Amazon: trends, projections, and policy implications
PDF
, A second hydrocarbon boom threatens the Peruvian Amazon: trends, projections, and policy implications
The Peruvian Amazon is home to extraordinary biological and cultural diversity, and vast
swaths of this mega-diverse region remain largely intact. Recent analysis indicates,
however, that the rapid proliferation of oil and gas exploration zones now threatens the
region’s biodiversity, indigenous peoples, and wilderness areas. To better elucidate this
dynamic situation, we analyzed official Peruvian government hydrocarbon information
and generated a quantitative analysis of the past, present, and future of oil and
gas activities in the Peruvian Amazon. We document an extensive hydrocarbon
history for the region—over 104 000 km of seismic lines and 679 exploratory and
production wells—highlighted by a major exploration boom in the early 1970s. We
show that an unprecedented 48.6% of the Peruvian Amazon has been recently
covered by oil and gas concessions, up from just 7.1% in 2003. These oil and gas
concessions overlap 17.1% of the Peruvian Amazon protected area system and
over half of all titled indigenous lands. Moreover, we found that up to 72% of the
Peruvian Amazon has been zoned for hydrocarbon activities (concessions plus
technical evaluation agreements and proposed concessions) in the past two years,
and over 84% at some point during the past 40 years. We project that the recent
rapid proliferation of hydrocarbon zones will lead to a second exploration boom,
characterized by over 20 000 km of new seismic testing and construction of over 180 new
exploratory wells in remote, intact, and sensitive forest areas. As the Peruvian
Amazon oil frontier rapidly expands, we conclude that a rigorous policy debate is
urgently needed in order to avoid the major environmental impacts associated with
the first exploration boom of the 1970s and to minimize the social conflict that
recently led to deadly encounters between indigenous protesters and government
forces.
Open access
Are cold winters in Europe associated with low solar activity?
M Lockwood
et al
2010
Environ. Res. Lett.
024001
View article
, Are cold winters in Europe associated with low solar activity?
PDF
, Are cold winters in Europe associated with low solar activity?
Solar activity during the current sunspot minimum has fallen to levels unknown
since the start of the 20th century. The Maunder minimum (about 1650–1700)
was a prolonged episode of low solar activity which coincided with more severe
winters in the United Kingdom and continental Europe. Motivated by recent
relatively cold winters in the UK, we investigate the possible connection with
solar activity. We identify regionally anomalous cold winters by detrending the
Central England temperature (CET) record using reconstructions of the northern
hemisphere mean temperature. We show that cold winter excursions from the
hemispheric trend occur more commonly in the UK during low solar activity, consistent
with the solar influence on the occurrence of persistent blocking events in the
eastern Atlantic. We stress that this is a regional and seasonal effect relating to
European winters and not a global effect. Average solar activity has declined rapidly
since 1985 and cosmogenic isotopes suggest an 8% chance of a return to Maunder
minimum conditions within the next 50 years (Lockwood 2010
Proc. R. Soc.
466
303–29): the results presented here indicate that, despite hemispheric warming, the
UK and Europe could experience more cold winters than during recent decades.
Open access
The role of pasture and soybean in deforestation of the Brazilian Amazon
Elizabeth Barona
et al
2010
Environ. Res. Lett.
024002
View article
, The role of pasture and soybean in deforestation of the Brazilian Amazon
PDF
, The role of pasture and soybean in deforestation of the Brazilian Amazon
The dynamics of deforestation in the Brazilian Amazon are complex. A growing
debate considers the extent to which deforestation is a result of the expansion
of the Brazilian soy industry. Most recent analyses suggest that deforestation
is driven by the expansion of cattle ranching, rather than soy. Soy seems to be
replacing previously deforested land and/or land previously under pasture. In this
study, we use municipality-level statistics on agricultural and deforested areas
across the Legal Amazon from 2000 to 2006 to examine the spatial patterns and
statistical relationships between deforestation and changes in pasture and soybean
areas. Our results support previous studies that showed that deforestation is
predominantly a result of pasture expansion. However, we also find support for the
hypothesis that an increase of soy in Mato Grosso has displaced pasture further north,
leading to deforestation elsewhere. Although not conclusive, our findings suggest
that the debate surrounding the drivers of Amazon deforestation is not over,
and that indirect causal links between soy and deforestation may exist that need
further exploration. Future research should examine more closely how interlinkages
between land area, prices, and policies influence the relationship between soy and
deforestation, in order to make a conclusive case for ‘displacement deforestation’.
Open access
Self-charging of the Eyjafjallajökull volcanic ash plume
R G Harrison
et al
2010
Environ. Res. Lett.
024004
View article
, Self-charging of the Eyjafjallajökull volcanic ash plume
PDF
, Self-charging of the Eyjafjallajökull volcanic ash plume
Volcanic plumes generate lightning from the electrification of plume particles. Volcanic
plume charging at over 1200 km from its source was observed from
in situ
balloon sampling
of the April 2010 Eyjafjallajökull plume over Scotland. Whilst upper and lower edge
charging of a horizontal plume is expected from fair weather atmospheric electricity, the
plume over Scotland showed sustained positive charge well beneath the upper plume edge.
At these distances from the source, the charging cannot be a remnant of the eruption
itself because of charge relaxation in the finite conductivity of atmospheric air.
Open access
Atmospheric carbon dioxide removal: long-term consequences and commitment
Long Cao and Ken Caldeira 2010
Environ. Res. Lett.
024011
View article
, Atmospheric carbon dioxide removal: long-term consequences and commitment
PDF
, Atmospheric carbon dioxide removal: long-term consequences and commitment
Carbon capture from ambient air has been proposed as a mitigation strategy to counteract
anthropogenic climate change. We use an Earth system model to investigate the response
of the coupled climate–carbon system to an instantaneous removal of all anthropogenic
CO
from the atmosphere. In our extreme and idealized simulations, anthropogenic
CO
emissions are halted
and all anthropogenic CO
is removed from the atmosphere at year 2050 under the IPCC A2
CO
emission scenario when the model-simulated atmospheric
CO
reaches 511 ppm and surface temperature reaches
1.8 °C
above the pre-industrial level. In our simulations a one-time removal of all anthropogenic
CO
in the atmosphere reduces surface air temperature by
0.8 °C within a few
years, but 1 °C
surface warming above pre-industrial levels lasts for several
centuries. In other words, a one-time removal of 100% excess
CO
from the
atmosphere offsets less than 50% of the warming experienced at the time of removal. To maintain atmospheric
CO
and temperature at low levels, not only does anthropogenic
CO
in the atmosphere need to be removed, but anthropogenic
CO
stored in the ocean and land needs to be removed as well when it
outgasses to the atmosphere. In our simulation to maintain atmospheric
CO
concentrations at pre-industrial levels for centuries, an additional amount of
CO
equal to the
original CO
captured would need to be removed over the subsequent 80 years.
Open access
Parking infrastructure: energy, emissions, and automobile life-cycle environmental accounting
Mikhail Chester
et al
2010
Environ. Res. Lett.
034001
View article
, Parking infrastructure: energy, emissions, and automobile life-cycle environmental accounting
PDF
, Parking infrastructure: energy, emissions, and automobile life-cycle environmental accounting
The US parking infrastructure is vast and little is known about its scale and environmental
impacts. The few parking space inventories that exist are typically regionalized and no
known environmental assessment has been performed to determine the energy and
emissions from providing this infrastructure. A better understanding of the scale of US
parking is necessary to properly value the total costs of automobile travel. Energy and
emissions from constructing and maintaining the parking infrastructure should be
considered when assessing the total human health and environmental impacts of vehicle
travel. We develop five parking space inventory scenarios and from these estimate
the range of infrastructure provided in the US to be between 105 million and
2 billion spaces. Using these estimates, a life-cycle environmental inventory is
performed to capture the energy consumption and emissions of greenhouse gases, CO,
SO
NO
, VOC (volatile organic
compounds), and PM
10
(PM: particulate matter) from raw material extraction, transport, asphalt and
concrete production, and placement (including direct, indirect, and supply chain
processes) of space construction and maintenance. The environmental assessment is
then evaluated within the life-cycle performance of sedans, SUVs (sports utility
vehicles), and pickups. Depending on the scenario and vehicle type, the inclusion
of parking within the overall life-cycle inventory increases energy consumption
from 3.1 to 4.8 MJ by 0.1–0.3 MJ and greenhouse gas emissions from 230 to 380
g CO
e by
6–23 g CO
per passenger kilometer traveled. Life-cycle automobile
SO
and
PM
10
emissions show some of the largest increases, by as much as 24% and 89% from the baseline
inventory. The environmental consequences of providing the parking spaces are discussed as
well as the uncertainty in allocating paved area between parking and roadways.
Open access
Accounting for soil carbon sequestration in national inventories: a soil scientist’s perspective
Jonathan Sanderman and Jeffrey A Baldock 2010
Environ. Res. Lett.
034003
View article
, Accounting for soil carbon sequestration in national inventories: a soil scientist’s perspective
PDF
, Accounting for soil carbon sequestration in national inventories: a soil scientist’s perspective
As nations debate whether and how best to include the agricultural sector in greenhouse
gas pollution reduction schemes, the role of soil organic carbon as a potential large carbon
sink has been thrust onto center stage. Results from most agricultural field trials indicate a
relative increase in soil carbon stocks with the adoption of various improved management
practices. However, the few available studies with time series data suggest that this relative
gain is often due to a reduction or cessation of soil carbon losses rather than an
actual increase in stocks. On the basis of this observation, we argue here that
stock change data from agricultural field trials may have limited predictive power
when the state of the soil carbon system is unknown and that current IPCC
(Intergovernmental Panel on Climate Change) accounting methodologies developed
from the trial results may not properly credit these management activities. In
particular, the use of response ratios is inconsistent with the current scientific
understanding of carbon cycling in soils and response ratios will overestimate
the net–net sequestration of soil carbon if the baseline is not at steady state.
Open access
Is physical water scarcity a new phenomenon? Global assessment of water shortage over the last two millennia
Matti Kummu
et al
2010
Environ. Res. Lett.
034006
View article
, Is physical water scarcity a new phenomenon? Global assessment of water shortage over the last two millennia
PDF
, Is physical water scarcity a new phenomenon? Global assessment of water shortage over the last two millennia
In this letter we analyse the temporal development of physical population-driven water
scarcity, i.e. water shortage, over the period 0 AD to 2005 AD. This was done using
population data derived from the HYDE dataset, and water resource availability based on
the WaterGAP model results for the period 1961–90. Changes in historical water resources
availability were simulated with the STREAM model, forced by climate output data of the
ECBilt–CLIO–VECODE climate model. The water crowding index, i.e. Falkenmark
water stress indicator, was used to identify water shortage in 284 sub-basins.
Although our results show a few areas with moderate water shortage (1000–1700
/capita/yr) around the year 1800, water shortage began in earnest at around 1900,
when 2% of the world population was under chronic water shortage
(<1000 m
/capita/yr). By 1960, this percentage had risen to 9%. From then on, the number of people under
water shortage increased rapidly to the year 2005, by which time 35% of the world
population lived in areas with chronic water shortage. In this study, the effects of changes
in population on water shortage are roughly four times more important than changes
in water availability as a result of long-term climatic change. Global trends in
adaptation measures to cope with reduced water resources per capita, such as
irrigated area, reservoir storage, groundwater abstraction, and global trade of
agricultural products, closely follow the recent increase in global water shortage.
Open access
Climate control of terrestrial carbon exchange across biomes and continents
Chuixiang Yi
et al
2010
Environ. Res. Lett.
034007
View article
, Climate control of terrestrial carbon exchange across biomes and continents
PDF
, Climate control of terrestrial carbon exchange across biomes and continents
Understanding the relationships between climate and carbon exchange by
terrestrial ecosystems is critical to predict future levels of atmospheric carbon
dioxide because of the potential accelerating effects of positive climate–carbon cycle
feedbacks. However, directly observed relationships between climate and terrestrial
CO
exchange with the atmosphere across biomes and continents are lacking. Here we present
data describing the relationships between net ecosystem exchange of carbon (NEE) and
climate factors as measured using the eddy covariance method at 125 unique sites in
various ecosystems over six continents with a total of 559 site-years. We find that NEE
observed at eddy covariance sites is (1) a strong function of mean annual temperature at
mid- and high-latitudes, (2) a strong function of dryness at mid- and low-latitudes, and
(3) a function of both temperature and dryness around the mid-latitudinal belt (45°N). The sensitivity of NEE to mean annual temperature breaks down at ∼ 16 °C
(a threshold value of mean annual temperature), above which no further increase of
CO
uptake with temperature was observed and dryness influence overrules temperature
influence.
Open access
Top-down solar modulation of climate: evidence for centennial-scale change
M Lockwood
et al
2010
Environ. Res. Lett.
034008
View article
, Top-down solar modulation of climate: evidence for centennial-scale change
PDF
, Top-down solar modulation of climate: evidence for centennial-scale change
During the descent into the recent ‘exceptionally’ low solar minimum, observations have
revealed a larger change in solar UV emissions than seen at the same phase of previous
solar cycles. This is particularly true at wavelengths responsible for stratospheric ozone
production and heating. This implies that ‘top-down’ solar modulation could be a larger
factor in long-term tropospheric change than previously believed, many climate models
allowing only for the ‘bottom-up’ effect of the less-variable visible and infrared
solar emissions. We present evidence for long-term drift in solar UV irradiance,
which is not found in its commonly used proxies. In addition, we find that both
stratospheric and tropospheric winds and temperatures show stronger regional
variations with those solar indices that do show long-term trends. A top-down
climate effect that shows long-term drift (and may also be out of phase with
the bottom-up solar forcing) would change the spatial response patterns and
would mean that climate-chemistry models that have sufficient resolution in the
stratosphere would become very important for making accurate regional/seasonal
climate predictions. Our results also provide a potential explanation of persistent
palaeoclimate results showing solar influence on regional or local climate indicators.
Open access
Increased crop failure due to climate change: assessing adaptation options using models and socio-economic data for wheat in China
Andrew J Challinor
et al
2010
Environ. Res. Lett.
034012
View article
, Increased crop failure due to climate change: assessing adaptation options using models and socio-economic data for wheat in China
PDF
, Increased crop failure due to climate change: assessing adaptation options using models and socio-economic data for wheat in China
Tools for projecting crop productivity under a range of conditions, and assessing
adaptation options, are an important part of the endeavour to prioritize investment in
adaptation. We present ensemble projections of crop productivity that account for
biophysical processes, inherent uncertainty and adaptation, using spring wheat in
Northeast China as a case study. A parallel ‘vulnerability index’ approach uses
quantitative socio-economic data to account for autonomous farmer adaptation.
The simulations show crop failure rates increasing under climate change, due to increasing
extremes of both heat and water stress. Crop failure rates increase with mean temperature,
with increases in maximum failure rates being greater than those in median failure rates.
The results suggest that significant adaptation is possible through either socio-economic
measures such as greater investment, or biophysical measures such as drought or heat
tolerance in crops. The results also show that adaptation becomes increasingly necessitated
as mean temperature and the associated number of extremes rise. The results, and the
limitations of this study, also suggest directions for research for linking climate
and crop models, socio-economic analyses and crop variety trial data in order to
prioritize options such as capacity building, plant breeding and biotechnology.
Open access
Analysis of the Copenhagen Accord pledges and its global climatic impacts—a snapshot of dissonant ambitions
Joeri Rogelj
et al
2010
Environ. Res. Lett.
034013
View article
, Analysis of the Copenhagen Accord pledges and its global climatic impacts—a snapshot of dissonant ambitions
PDF
, Analysis of the Copenhagen Accord pledges and its global climatic impacts—a snapshot of dissonant ambitions
This analysis of the Copenhagen Accord evaluates emission reduction pledges by individual
countries against the Accord’s climate-related objectives. Probabilistic estimates of the climatic
consequences for a set of resulting multi-gas scenarios over the 21st century are calculated with
a reduced complexity climate model, yielding global temperature increase and atmospheric
CO
and
CO
-equivalent concentrations. Provisions for banked surplus emission allowances and credits
from land use, land-use change and forestry are assessed and are shown to have the
potential to lead to significant deterioration of the ambition levels implied by the
pledges in 2020. This analysis demonstrates that the Copenhagen Accord and
the pledges made under it represent a set of dissonant ambitions. The ambition
level of the current pledges for 2020 and the lack of commonly agreed goals for
2050 place in peril the Accord’s own ambition: to limit global warming to below
2 °C, and even
more so for 1.5 °C, which is referenced in the Accord in association with potentially strengthening the
long-term temperature goal in 2015. Due to the limited level of ambition by 2020, the
ability to limit emissions afterwards to pathways consistent with either the 2 or
1.5 °C
goal is likely to become less feasible.
Open access
Agricultural net primary production in relation to that liberated by the extinction of Pleistocene mega-herbivores: an estimate of agricultural carrying capacity?
Christopher E Doughty and Christopher B Field 2010
Environ. Res. Lett.
044001
View article
, Agricultural net primary production in relation to that liberated by the extinction of Pleistocene mega-herbivores: an estimate of agricultural carrying capacity?
PDF
, Agricultural net primary production in relation to that liberated by the extinction of Pleistocene mega-herbivores: an estimate of agricultural carrying capacity?
Mega-fauna (defined as animals > 44 kg) experienced a global extinction with 97 of 150 genera going extinct by ∼ 10 000
years ago. We estimate the net primary production (NPP) that was liberated following the
global extinction of these mega-herbivores. We then explore how humans, through
agriculture, gradually appropriated this liberated NPP, with specific calculations for 800,
1850, and 2000 AD. By 1850, most of the liberated NPP had been appropriated
by people, but NPP was still available in the Western US, South America and
Australia. NPP liberated following the extinction of the mega-herbivores was ∼ 2.5% (∼1.4 (between 1.2
and 1.6) Pg yr
− 1
of 56 Pg C yr
− 1
; Pg: petagrams) of global terrestrial NPP. Liberated NPP peaked during the
onset of agriculture and was sufficient for sustaining human agriculture until ∼ 320 (250–500) years ago.
Humans currently use ∼ 6
times more NPP than was utilized by the extinct Pleistocene mega-herbivores.
Open access
Energy intensity ratios as net energy measures of United States energy production and expenditures
C W King 2010
Environ. Res. Lett.
044006
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, Energy intensity ratios as net energy measures of United States energy production and expenditures
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, Energy intensity ratios as net energy measures of United States energy production and expenditures
In this letter I compare two measures of energy quality, energy return on energy
invested (EROI) and energy intensity ratio (EIR) for the fossil fuel consumption
and production of the United States. All other characteristics being equal, a fuel
or energy system with a higher EROI or EIR is of better quality because more
energy is provided to society. I define and calculate the EIR for oil, natural
gas, coal, and electricity as measures of the energy intensity (units of energy
divided by money) of the energy resource relative to the energy intensity of the
overall economy. EIR measures based upon various unit prices for energy (e.g.
$/Btu
of a barrel of oil) as well as total expenditures on energy supplies (e.g. total dollars spent on
petroleum) indicate net energy at different points in the supply chain of the overall energy
system. The results indicate that EIR is an easily calculated and effective proxy for EROI
for US oil, gas, coal, and electricity. The EIR correlates well with previous EROI
calculations, but adds additional information on energy resource quality within the supply
chain. Furthermore, the EIR and EROI of oil and gas as well as coal were all in decline for
two time periods within the last 40 years, and both time periods preceded economic
recessions.
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