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Mark Roelfsema Hanna Fekete Niklas Höhne Michel den Elzen Nicklas Forsell Takeshi Kuramochi 《Climate Policy》2018,18(9):1103-1113
This article shows the potential impact on global GHG emissions in 2030, if all countries were to implement sectoral climate policies similar to successful examples already implemented elsewhere. This assessment was represented in the IMAGE and GLOBIOM/G4M models by replicating the impact of successful national policies at the sector level in all world regions. The first step was to select successful policies in nine policy areas. In the second step, the impact on the energy and land-use systems or GHG emissions was identified and translated into model parameters, assuming that it would be possible to translate the impacts of the policies to other countries. As a result, projected annual GHG emission levels would be about 50 GtCO2e by 2030 (2% above 2010 levels), compared to the 60 GtCO2e in the ‘current policies’ scenario. Most reductions are achieved in the electricity sector through expanding renewable energy, followed by the reduction of fluorinated gases, reducing venting and flaring in oil and gas production, and improving industry efficiency. Materializing the calculated mitigation potential might not be as straightforward given different country priorities, policy preferences and circumstances.
Key policy insights
Considerable emissions reductions globally would be possible, if a selection of successful policies were replicated and implemented in all countries worldwide.
This would significantly reduce, but not close, the emissions gap with a 2°C pathway.
From the selection of successful policies evaluated in this study, those implemented in the sector ‘electricity supply’ have the highest impact on global emissions compared to the ‘current policies’ scenario.
Replicating the impact of these policies worldwide could lead to emission and energy trends in the renewable electricity, passenger transport, industry (including fluorinated gases) and buildings sector, that are close to those in a 2°C scenario.
Using successful policies and translating these to policy impact per sector is a more reality-based alternative to most mitigation pathways, which need to make theoretical assumptions on policy cost-effectiveness.
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The middle Pleistocene transition: characteristics, mechanisms, and implications for long-term changes in atmospheric pCO2 总被引：1，自引：0，他引：1
Peter U. Clark David Archer David Pollard Joel D. Blum Jose A. Rial Victor Brovkin Alan C. Mix Nicklas G. Pisias Martin Roy 《Quaternary Science Reviews》2006,25(23-24):3150
The emergence of low-frequency, high-amplitude, quasi-periodic (100-kyr) glacial variability during the middle Pleistocene in the absence of any significant change in orbital forcing indicates a fundamental change internal to the climate system. This middle Pleistocene transition (MPT) began 1250 ka and was complete by 700 ka. Its onset was accompanied by decreases in sea surface temperatures (SSTs) in the North Atlantic and tropical-ocean upwelling regions and by an increase in African and Asian aridity and monsoonal intensity. During the MPT, long-term average ice volume gradually increased by 50 m sea-level equivalent, whereas low-frequency ice-volume variability experienced a 100-kyr lull centered on 1000 ka followed by its reappearance 900 ka, although as a broad band of power rather than a narrow, persistent 100-kyr cycle. Additional changes at 900 ka indicate this to be an important time during the MPT, beginning with an 80-kyr event of extreme SST cooling followed by the partial recovery and subsequent stabilization of long-term North Atlantic and tropical ocean SSTs, increasing Southern Ocean SST variability primarily associated with warmer interglacials, the loss of permanent subpolar sea-ice cover, and the emergence of low-frequency variability in Pacific SSTs and global deep-ocean circulation. Since 900 ka, ice sheets have been the only component of the climate system to exhibit consistent low-frequency variability. With the exception of a near-universal organization of low-frequency power associated with marine isotope stages 11 and 12, all other components show an inconsistent distribution of power in frequency-time space, suggesting a highly nonlinear system response to orbital and ice-sheet forcing.Most hypotheses for the origin of the MPT invoke a response to a long-term cooling, possibly induced by decreasing atmospheric pCO2. None of these hypotheses, however, accounts for the geological constraint that the earliest Northern Hemisphere ice sheets covered a similar or larger area than those that followed the MPT. Given that the MPT was associated with an increase in ice volume, this constraint requires that post-MPT ice sheets were substantially thicker than pre-MPT ice sheets, indicating a change in subglacial conditions that influence ice dynamics. We review evidence in support of the hypothesis that such an increase in ice thickness occurred as crystalline Precambrian Shield bedrock became exposed by glacial erosion of a thick mantle of regolith. This exposure of a high-friction substrate caused thicker ice sheets, with an attendant change in their response to the orbital forcing. Marine carbon isotope data indicate a rapid transfer of organic carbon to inorganic carbon in the ocean system during the MPT. If this carbon came from terrigenous sources, an increase in atmospheric pCO2 would be likely, which is inconsistent with evidence for widespread cooling, Apparently rapid carbon transfer from terrestrial sources is difficult to reconcile with gradual erosion of regolith. A more likely source of organic carbon and nutrients (which would mitigate pCO2 rise) is from shelf and upper slope marine sediments, which were fully exposed for the first time in millions of years in response to thickening ice sheets and falling sealevels during the MPT. Modeling indicates that regolith erosion and resulting exposure of crystalline bedrock would cause an increase in long-term silicate weathering rates, in good agreement with marine Sr and Os isotopic records. We use a carbon cycle model to show that a post-MPT increase in silicate weathering rates would lower atmospheric pCO2 by 7–12 ppm, suggesting that the attendant cooling may have been an important feedback in causing the MPT. 相似文献
3.
Nicklas G. Pisias 《Quaternary Research》1978,10(3):366-384
The varved sediments of the Santa Barbara Basin off southern California, offer a unique opportunity to study the changes in oceanographic conditions of this nearshore area during the last 8000 yr. Quantitative analysis of Radiolaria found in recent surface sediment samples from the eastern North Pacific allows the identification of four “assemblages” which can be related to the physical oceanography of the California Current. Two assemblages are associated with the southerly flowing California Current, one with the main stream of the current (California Current Assemblage) and the other with the offshore flow along northern California (Central Assemblage). The two other assemblages are associated with the subtropical region of the eastern North Pacific (Subtropical Assemblage) and one found mostly off the coast of Baja California (Baja Assemblage). Analysis of the Radiolaria found in the varved sediments of a core from the Santa Barbara Basin give an 8000-yr continuous record of these four assemblages. The California and Baja Assemblages show only minor fluctuations in their importance in the sediments of the Santa Barbara Basin. The California Assemblage, however, shows a steady increase during this time period. Prior to 5400 yr B.P. the Radiolaria were predominately subtropical in character, whereas after 5400 yr B.P. the Central Assemblage becomes more important. Since 5400 yr B.P. most of the changes in the radiolarian fauna consist of fluctuations in the importance of these two assemblages. Past sea-surface temperatures for the month of February were calculated using the transfer function technique of J. Imbrie and N. G. Kipp (1971, In “The Late Cenozore Glacial Ages” L. K. Turekian, Ed.), (Chap. 5, Yale Univ. Press, New Haven, Conn.). The time series of paleotemperature estimates show major changes in the average February temperature of Santa Barbara Basin waters. The range of estimated temperatures (12°C) exceeds that of the historical observations of February temperatures in the Santa Barbara Basin but does not exceed the observed range for the California Current region. The intervals from 800 to 1800 yr B.P. 3600 to 3800 yr B.P. and 5400 to the end of the record appear to have been generally warmer than today. Comparison of the Holocene record of alpine glacial advances with the radiolarian assemblage and paleotemperature time series shows that the initiations of advances was coincident with a decrease in sea-surface temperatures and an increase in the importance of the Central Assemblage in the Santa Barbara Basin. The terminations of these advances were not marked by any consistent characteristic in the Santa Barbara Basin time series. 相似文献
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Sam VanLaningham Nicklas G. Pisias Robert A. Duncan Peter D. Clift 《Earth and Planetary Science Letters》2009,277(1-2):64-72
A large sediment deposit known as the Meiji Drift, located in the northwestern Pacific Ocean, is thought to have formed from deep water exiting the Bering Sea, although no notable deep water forms there presently. We determine the terrigenous sources since 140 ka to the drift using bulk sediment 40Ar–39Ar and Nd isotopic analyses on the silt-sized (20–63 μm) terrigenous fraction from Ocean Drilling Program (ODP) Site 884 to reconstruct paleo-circulation patterns. There are large changes in both isotopic tracers, varying on glacial–interglacial cycles. During glacial intervals, bulk sediment 40Ar–39Ar ages range between 40 and 80 Ma, while Nd isotopic values range from εNd = ? 1 to + 2. During interglacial intervals, sediments become much younger and more radiogenic, with bulk sediment ages falling to 2–15 Ma and Nd isotopic values ranging between εNd = + 5 and + 9. These data and quantitative comparison to potential source rocks indicate that the young Kamchatkan and Aleutian Arcs, lying NW and NE of the Meiji Drift, contribute the majority of sediment during interglacials. Conversely, older source rocks, such as those drained by the Yukon River and northeast Russia are the dominant origin of sediments during glacials. Mixing model calculations suggest that as much as 35–45% of the sediment deposited in the Meiji Drift during glacials is from the Bering Sea. It remains unclear whether thermohaline-type circulation or focussing of Bering Sea flow lead to the glacial–interglacial sediment source changes observed here. 相似文献
5.
Summary Astrometric measurements of 18 visual double stars carried out with a CCD are given.
The present observations are a test of the propriety of the CCD technique for astrometric observations of visual double stars.
The duration of the observations was 75 minutes. The precision of the CCD measures corresponds the precision of the photographic
method, so the advantages of CCD's are the great loss of reduction work and the corresponding time saving, inclusive shortering
the observing time.
Based on observations made at E.S.O., La Silla, Chile. 相似文献
6.
Nicklas G. Pisias 《Quaternary Research》1979,11(3):373-386
Two independent data sets are used to develop a model for reconstructing sea-surface temperature and dynamic height anomaly distributions for the California Current during the last 8000 years. The first data set, all hydrographic data available for the California Current region, was used to determine the statistical relationships between the historical record of sea-surface conditions in the Santa Barbara Basin and all one-degree-square grid points of the California Current area. Given these relationships and the second data set, an 8000-year record of sea-surface temperatures and dynamic height anomalies from the Santa Barbara Basin, past sea-surface conditions throughout the California Current can be estimated for times before historical observations. The 8000-year record of sea-surface conditions was estimated by analysis of the radiolarian fauna found in a varved sediment core from the Santa Barbara Basin (Pisias, N. G., 1978, Quaternary Research 10, 366–384). The reconstructions of sea-surface temperature and dynamic height anomalies indicate that at times of cold sea-surface conditions in the Santa Barbara Basin, the flow of the California Current was much stronger than it is today or was during the times of the warmest sea-surface conditions during the last 8000 years. The atmospheric circulation during the winter of 1950, the period of the coldest recorded sea-surface temperatures in the Santa Barbara Basin based on the historical data set, contained a strong northerly component in the winds which is consistent with the inferred increase in the California Current at times of cold sea-surface temperatures. Times of warm sea-surface temperatures in the Santa Barbara Basin are characterized by decreased southward flow of the California Current and a marked increase in northward flow into the Santa Barbara Basin itself. In the historical record, times of warm sea-surface temperatures are often associated with high precipitation in southern California. The atmospheric circulation during the winter of 1968–1969 is characterized by strong eastward flow over southern California and a northward transport of warm humid air from the tropics into the region of southern California producing the high rainfall observed. The persistence of this atmospheric circulation could produce the more zonal flow predicted for the California Current during times of warmer average conditions in the Santa Barbara Basin. 相似文献
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We compared seed banks between two contrasting anthropogenic surface disturbances (compacted, trenched) and adjacent undisturbed controls to determine whether site condition influences viable seed densities of perennial and annual Mojave Desert species. Viable seeds of perennials were rare in undisturbed areas (3–4 seeds/m2) and declined to <1 seed/m2 within disturbed sites. Annual seed densities were an order of magnitude greater than those of perennials, were one-third the undisturbed seed densities on compacted sites, but doubled on trenched sites relative to controls. On trenched sites, greater litter cover comprising the infructescences of the dominant spring annuals, and low gravel content, enhanced seed densities of both annuals and perennials. Litter cover and surface ruggedness were the best explanations for viable perennial seed densities on compacted sites, but litter cover and the presence of a common harvester ant explained annual seed densities better than any other surface characteristics that were examined. Surface disturbances can have a varied impact on the condition of the soil surface in arid lands. Nevertheless, the consistently positive relationship between ground cover of litter and viable seed density emphasizes the importance of litter as an indicator of site degradation and recovery potential in arid lands. 相似文献
9.
Larry A. Mayer Cyril Gobrecht Nicklas G. Pisias 《International Journal of Earth Sciences》1996,85(3):505-512
Recent developments in continuous core-logging techniques now permit us to recover the high-resolution time series necessary
for the detailed spectral analyses of paleoclimatic proxy records. When applied to long records recovered by scientific drilling
(5–10 Ma) they enable us to look at the long-term history and evolution of the ocean's response to orbital forcing. A serious
limitation in these studies is the need to display the complex, multidimensional spatial and temporal interactions of the
ocean-climate system in an easily comprehensible manner. We have addressed this issue by developing a series 3D visualization
tools which permit visualization of the role of the orbital parameters in determining the latitudinal variation of insolation
as well as the interactive exploration of multidimensional data sets. The ORBITS tool allows us to visualize the effect of
orbital eccentricity, precession, and tilt on the latitudinal distribution of insolation on the earth at the solstices and
the equinoxes for any time over the past 5 Ma (for Berger's orbital model) or 10 Ma (for Laskar's orbital model). The effect
of the orbital parameters on insolation can be viewed individually, in pairs, or all three together. By moving the model steadily
through time, the rate at which orbitally induced changes in insolation occur can also be visualized. To look at the ocean's
response to orbital forcing we take the long time series generated from our paleoclimatic proxies and calculate their spectrum
over a fixed, but sliding, time window. To view the complex multidimensional relationships found in these evolutionary spectral
analyses, we use another interactive 3D data exploration tool developed at the University of New Brunswick (Canada). This
tool (FLEDERMAUS) uses a six-degrees-of-freedom input device (BAT) and a series of software modules for color coding, shading,
and rendering complex data sets, to allow the user to interactively "fly" through the multidimensional data. Through the use
of color, texture, and 3D position, as many as six or seven variables can be explored in a simple and intuitive manner. With
special liquid-crystal-display glasses, the scene can be viewed in true "stereo." We use these tools to explore the relationship
between orbital forcing and the response of the benthic isotope and calcium carbonate record at ODP Site 846 (90°W and 5°S)
This analysis shows an equatorial Pacific carbonate record which has a large component of linear response to tilt, but little
linear response to precession. There is a major shift in response, from a carbonate-dominated response to an isotope (ice
volume)-dominated response at approximately 4.5 Ma, and as expected, there is a large nonlinear response at the lower frequencies
(400 and 100 kyr) during the past 800 kyr to 1 Ma
Received: 22 June 1995 / Accepted: 29 January 1996 相似文献
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