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1.
《Climate Policy》2013,13(1):77-88
Abstract

The UK climate change programme has introduced a range of instruments to foster investment in low carbon technologies and markets. We estimate the total value of these interventions, in terms of the redirection of financial flows and directly foregone tax income, to be about £1.3 billion per year (c. Euro or US$ 2 billion per year), as from 2002 to 2003 when the renewable obligation certificates (ROCs) first take effect. About 20% of this consists of direct expenditure, the remaining 80% is in the form of indirect expenditures contained within sectors (ROCs, the energy efficiency commitments), and foregone tax revenues. Most of the energy-efficiency investment is estimated to recoup expenditure within normal life-cycles and may thus be considered profitable; the profitability of the supply-side interventions is predicated mostly upon expected cost reductions associated with the build up of the associated industries.  相似文献   

2.
Nordhaus (1991), Cline (1992), Fankhauser (1992), and Titus (1992) have published comprehensive estimates of annual climate change damages to the United States in about 2060 that vary from $55 billion to $111 billion ($1990). The estimates are comprehensive because they address market and nonmarket impacts. They based their estimates on different assumptions about the rates of climate change and sea level rise, rates of return on investment, and changes in population and income. In addition, many of the damage estimates, although reported for a 2.5–3.0 °C warming, were based on studies that assumed higher rates of warming. Thus, these studies may have overestimated damages associated with a 2.5–3.0 °C warming. In this paper, the results of these studies were standardized for a 2.5 °C warming, a 50-cm sea level rise, 1990 income and population, and a 4% real rate of return on investments. After standardization, the total damage estimates range from $42.3 billion to $52.8 billion, slightly less than 1% of United States GNP in 1990. Yet, within individual sectors, such as agriculture and electricity, standardized damages differ by more than an order of magnitude. In addition, a significant amount of speculation underlies the damage estimates. Thus, the small range of total standardized damages and apparent agreement about the magnitude of such damages should be interpreted with caution.  相似文献   

3.
Climate change may cause most harm to countries that have historically contributed the least to greenhouse gas emissions and land-use change. This paper identifies consequentialist and non-consequentialist ethical principles to guide a fair international burden-sharing scheme of climate change adaptation costs. We use these ethical principles to derive political principles – historical responsibility and capacity to pay – that can be applied in assigning a share of the financial burden to individual countries. We then propose a hybrid ‘common but differentiated responsibilities and respective capabilities’ approach as a promising starting point for international negotiations on the design of burden-sharing schemes. A numerical assessment of seven scenarios shows that the countries of Annex I of the United Nations Framework Convention on Climate Change would bear the bulk of the costs of adaptation, but contributions differ substantially subject to the choice of a capacity to pay indicator. The contributions are less sensitive to choices related to responsibility calculations, apart from those associated with land-use-related emissions. Assuming costs of climate adaptation of USD 100 billion per year, the total financial contribution by the Annex I countries would be in the range of USD 65–70 billion per year. Expressed as a per capita basis, this gives a range of USD 43–82 per capita per year.  相似文献   

4.
《Climate Policy》2001,1(3):309-326
Carbon dioxide emissions from UK energy use have fallen by more than 20% over the last 30 years, and carbon intensity — carbon emissions per unit of GDP — has halved. These reductions have been achieved by a combination of decarbonisation of the energy system and substantial improvements in energy efficiency. Use of natural gas in power generation has been a big factor in recent years, but energy efficiency improvements in households and particularly industry have been more important over a longer period. Government policies designed primarily to address climate change have not been important contributors, until recently.Future reductions in emissions will require more proactive policies. However, they are possible without any economic difficulties, notably by adopting cost-effective energy efficiency measures, using new renewable energy sources and reducing dependence on private cars. These policies will improve economic efficiency. The new UK Climate Change Programme includes policies that combine regulation, investment, fiscal measures and other economic instruments. By working with the grain of other social, environmental and economic policies, they can achieve far more than a carbon tax alone, set at any politically acceptable level. Modelling the costs of emission reductions using a carbon tax as the only instrument would not only massively over-estimate costs, it would bear little resemblance to real world politics.The paper demonstrates that a more diverse set of policy instruments is likely to be an effective and politically acceptable approach in a mature industrial economy. It is concluded that the UK’s Kyoto target of a 12.5% reduction in greenhouse gas emissions is not challenging. The UK Government’s target of reducing carbon dioxide emissions by 20% between 1990 and 2010 is also achievable. By 2010 per capita emissions from the UK will be well below 2.5 tC per year. Claims that some countries, notably the USA, could not reduce per capita emissions below 6 tC per year seem inconsistent with this experience.  相似文献   

5.
The Indonesian seas provide a sea link between the tropical Pacific and Indian Oceans. The connection is not simple, not a single gap in a ‘wall’, but rather composed of the intricate patterns of passages and seas of varied dimensions. The velocity and temperature/salinity profiles Indonesian throughflow (ITF) are altered en route from the Pacific into the Indian Ocean by sea–air buoyancy and momentum fluxes, as well as diapycnal mixing due to topographic boundary effects and dissipation of tidal energy. The INSTANT program measured the ITF in key channels from 2004 to 2006, providing the first simultaneous view of the main ITF pathways. The along-channel speeds vary markedly with passage; the Makassar and Timor flow is relatively steady in comparison to the seasonal and intraseasonal fluctuations observed in Lombok and Ombai Straits. The flow through Lifamatola Passage is strongly bottom intensified, defining the overflow into the deep Indonesian basins to the south. The 3-year mean ITF transport recorded by INSTANT into the Indian Ocean is 15 × 106 m3/s, about 30% greater than the values of non-simultaneous measurements made prior to 2000. The INSTANT 3-year mean inflow transport is nearly 13 × 106 m3/s. The 2 × 106 m3/s difference between INSTANT measured inflow and outflow is attributed to unresolved surface layer transport in Lifamatola Passage and other channels, such as Karimata Strait. Introducing inflow within the upper 200 m to zero the water column net convergence still requires upwelling within the intervening seas, notably the Banda Sea. A layer of minimum upwelling near 600 m separates upwelling within the thermocline from a deep water upwelling pattern driven by the deep overflow in Lifamatola Passage. For a steady state condition upwelling thermocline water is off-set by a 3-year mean sea to air heat flux of 80 W/m2 (after taking into account the shoaling of thermocline isotherms between the inflow and outflow portals), which agrees with the climatic value based on bulk formulae sea–air flux calculations, as well as transport weighted temperature of the inflow and outflow water. The INSTANT data reveals interannual fluctuations, with greater upwelling and sea to air heat flux in 2006.  相似文献   

6.
Monthly averaged total volume transport of the Indonesian throughflow (ITF) estimated by 14 global ocean data assimilation (ODA) products that are decade to multi-decade long are compared among themselves and with observations from the INSTANT Program (2004–2006). The main goals of the comparisons are to examine the consistency and evaluate the skill of different ODA products in simulating ITF transport. The ensemble averaged, time-mean value of ODA estimates is 13.6 Sv (1 Sv = 106 m3/s) for the common 1993–2001 period and 13.9 Sv for the 2004–2006 INSTANT Program period. These values are close to the 15-Sv estimate derived from INSTANT observations. All but one ODA time-mean estimate fall within the range of uncertainty of the INSTANT estimate. In terms of temporal variability, the scatter among different ODA estimates averaged over time is 1.7 Sv, which is substantially smaller than the magnitude of the temporal variability simulated by the ODA systems. Therefore, the overall “signal-to-noise” ratio for the ensemble estimates is larger than one. The best consistency among the products occurs on seasonal-to-interannual time scales, with generally stronger (weaker) ITF during boreal summer (winter) and during La Nina (El Nino) events. The scatter among different products for seasonal-to-interannual time scales is approximately 1 Sv. Despite the good consistency, systematic difference is found between most ODA products and the INSTANT observations. All but the highest-resolution (18 km) ODA product show a dominant annual cycle while the INSTANT estimate and the 18-km product exhibit a strong semi-annual signal. The coarse resolution is an important factor that limits the level of agreement between ODA and INSTANT estimates. Decadal signals with periods of 10–15 years are seen. The most conspicuous and consistent decadal change is a relatively sharp increase in ITF transport during 1993–2000 associated with the strengthening tropical Pacific trade wind. Most products do not show a weakening ITF after the mid-1970s’ associated with the weakened Pacific trade wind. The scatter of ODA estimates is smaller after than before 1980, reflecting the impact of the enhanced observations after the 1980s. To assess the representativeness of using the average over a three-year period (e.g., the span of the INSTANT Program) to describe longer-term mean, we investigate the temporal variations of the three-year low-pass ODA estimates. The average variation is about 3.6 Sv, which is largely due to the increase of ITF transport from 1993 to 2000. However, the three-year average during the 2004–2006 INSTANT Program period is within 0.5 Sv of the long-term mean for the past few decades.  相似文献   

7.
为探讨粤港澳大湾区实现碳中和及电力低碳转型过程的供应安全,构建粤港澳大湾区动态CGE模型,设计51种情景模拟各类型发电量的年均变化幅度,以全社会福利最大化为评价指标,研究煤电退役到保底容量、煤电完全退役和气电达峰容量的最优时间节点和发展速度。结果表明：2020年煤电发电量以年均降低66亿kW∙h幅度退役到2032年保底容量,再以年均降低40亿kW∙h幅度在2045年实现完全退役;气电发电量从2020年起以年均增长61亿kW∙h的幅度在2038年达到峰值,然后以年均51亿kW∙h幅度退役到2050年保底容量1323亿kW∙h;进一步依据2020—2050年本地总发电量增速不变得到非化石电力增长速度,此种煤电、气电和非化石电力发展速度组合的经济性最优。相比基准情景,优选出的电力转型组合情景可累积促进化石能源消费量降低1.1亿tce,碳排放降低2.8亿t CO2,电力部门增加值增长238亿元,其他部门增加值增长172亿元。  相似文献   

8.
Market-based policies to address fossil fuel-related externalities including climate change typically operate by raising the price of those fuels. Increases in energy prices have important consequences for a typical U.S. household that spent almost $4,000 per year on electricity, fuel oil, natural gas, and gasoline in 2005. A key question for policymakers is how these consequences vary over different regions and subpopulations across the country—especially as adjustment and compensation programs are designed to protect more vulnerable regions. To answer this question, we use non-publicly available data from the U.S. Consumer Expenditure Survey over the period 1984–2000 to estimate long-run geographic variation in household use of electricity, fuel oil, natural gas, and gasoline, as well as the associated incidence of a $10 per ton tax on carbon dioxide (ignoring behavioral response). We find substantial variation: incidence from the tax range from $97 dollars per year per household in New York County, New York to $235 per year per household in Tensas Parish, Louisiana. This variation can be explained by differences in energy use, carbon intensity of electricity generation, and electricity regulation.  相似文献   

9.
《Climate Policy》2013,13(3):309-326
Abstract

Carbon dioxide emissions from UK energy use have fallen by more than 20% over the last 30 years, and carbon intensity—carbon emissions per unit of GDP—has halved. These reductions have been achieved by a combination of decarbonisation of the energy system and substantial improvements in energy efficiency. Use of natural gas in power generation has been a big factor in recent years, but energy efficiency improvements in households and particularly industry have been more important over a longer period. Government policies designed primarily to address climate change have not been important contributors, until recently.

Future reductions in emissions will require more proactive policies. However, they are possible without any economic difficulties, notably by adopting cost-effective energy efficiency measures, using new renewable energy sources and reducing dependence on private cars. These policies will improve economic efficiency. The new UK Climate Change Programme includes policies that combine regulation, investment, fiscal measures and other economic instruments. By working with the grain of other social, environmental and economic policies, they can achieve far more than a carbon tax alone, set at any politically acceptable level. Modelling the costs of emission reductions using a carbon tax as the only instrument would not only massively over-estimate costs, it would bear little resemblance to real world politics.

The paper demonstrates that a more diverse set of policy instruments is likely to be an effective and politically acceptable approach in a mature industrial economy. It is concluded that the UK's Kyoto target of a 12.5% reduction in greenhouse gas emissions is not challenging. The UK Government's target of reducing carbon dioxide emissions by 20% between 1990 and 2010 is also achievable. By 2010 per capita emissions from the UK will be well below 2.5 tC per year. Claims that some countries, notably the USA, could not reduce per capita emissions below 6 tC per year seem inconsistent with this experience.  相似文献   

10.
Dew and rain water collection in the Dalmatian Coast, Croatia   总被引：1，自引：0，他引：1  
Passive dew harvesting and rainwater collection requires a very small financial investment but can exploit a free, clean (outside urban/industrial zones) and inexhaustible source of water. This study investigates the relative contributions of dew and rain water in the Mediterranean Dalmatian coast and islands of Croatia, with emphasis on the dry summer season. In addition, we evaluate the utility of transforming abandoned roof rain collectors (“impluviums”) to collect dew water too. Two sites were chosen, an exposed open site on the coast favourable to dew formation (Zadar) and a less favourable site in a cirque of mountains in Komiža (Vis Island). Between July 1, 2003 and October 31, 2006, dew was collected two or three times per day on a 1 m2 inclined (30°) test dew condenser, together with standard meteorological data (air temperature and relative humidity, cloud cover, windspeed and direction). Maximum yields were 0.41 mm in Zadar and 0.6 mm in Komiža. The mean yearly cumulative dew yields were found to be 20 mm (Zadar) and 9.3 mm (Komiža). Because of its physical setting, Komiža represents a poor location for dew collection. However, during the dry season (May to October), monthly cumulative dew water yield can represent up to 38% of water collected by rainfall. In both July 2003 and 2006, dew water represented about 120% of the monthly cumulative rain water. Refurbishing the abandoned impluviums to permit dew collection could then provide useful supplementary water, especially during the dry season. As an example, the 1300 m2 impluvium at Podšpilje near Komiža could provide, in addition to rain water, 14,000 L dew water per year.  相似文献   

11.
Transaction costs of the Kyoto Mechanisms   总被引：2，自引：0，他引：2  
Transaction costs will reduce the attractiveness of the Kyoto Mechanisms compared to domestic abatement options. Especially the project-based mechanisms Clean Development Mechanism (CDM) and Joint Implementation (JI) are likely to entail considerable costs of baseline development, verification and certification. The Activities Implemented Jointly (AIJ) pilot phase and the Prototype Carbon Fund (PCF) programme give indications about the level of these costs. Under current estimates of world market prices for greenhouse gas emission permits, projects with annual emission reductions of less than 50,000 t CO2 equivalent are unlikely to be viable; for micro projects transaction costs can reach several hundred € per t CO2 equivalent. Thus, the Marrakech Accord rule to have special rules for small scale CDM projects makes sense, even if the thresholds chosen advantage certain project types; projects below 1000 t CO2 equivalent per year should get further exemptions. An alternative solution with no risk for the environmental credibility of the projects would be to subsidise baseline setting and charge lower, subsidised fees for small projects for the different steps of the CDM/second track JI project cycle.  相似文献   

12.
Tides affect transport and mixing in the Indonesian Seas, impacting the throughflow and the return flow of the global thermohaline circulation. In a previous study, barotropic and baroclinic tides were simulated for the Indonesian Seas at 5 km resolution in order to characterize the tides of the region and to identify and quantify locations of tidal mixing. Baroclinic tidal velocities exceeded barotropic velocities except in shallow regions and their variability was on smaller scales. Model results agreed reasonably with observations and are consistent with the resolution. However, only four mooring locations were available for comparison. The new International Nusantara Stratification (INSTANT) data set enables a more comprehensive comparison. With the exception of Lombok Strait, the model replicated the observed INSTANT velocity spectra, falling within the 90% confidence limits of the observed spectra, both in regions of high and low baroclinic tidal activity for the band of frequencies from 0.02 cph to 0.33 cph (periods of 50–3 h, respectively), which includes the major semidiurnal and diurnal tides and several of their first harmonics. The model overestimated the semidiurnal baroclinic tides in the narrow Lombok Strait, which is not well resolved in the model. Comparisons of vertical profiles of the major axes of the tidal ellipses at the mooring sites generally reproduced the vertical pattern, although there were exceptions, such as Lombok and Ombai Straits. Rms differences between the model estimates and hourly observations for the major axes of the tidal ellipses were typically 1–8 cm s−1 in regions of high tidal activity, 1–5 cm s−1 in regions of low tidal activity, and 1–20 cm s−1 for the semidiurnal tides in Lombok and Ombai Straits. Rms errors of 1–6 cm s−1 are typical in regions of moderate baroclinic tidal activity at this model resolution (5 km). Many of the larger rms differences result from vertical discrepancies in the depths of the internal tidal beams. The local nature of the internal tides generation and beam propagation results in large differences from small vertical shifts in the beams or generation due to topographic differences between the model topography and the actual topography. In addition, the moorings experienced severe blowdown. The blowdown adds uncertainty to the depths of the instruments and introduces errors in the observational tidal analysis in magnitude of the tidal constituents, both of which contribute to rms differences. Tidal mixing was found to occur in intense local regions with strong internal tidal shear. The local regions of mixing were typically along the bottom in steep slopes and over sills. In conclusion, the tidal model was found to reproduce the kinetic energy distribution and transfer of energy from tides to other frequencies in the Indonesian Seas and to roughly replicate the observed structure and magnitude of the tidal currents. Improvements in the tidal simulations in reproducing observations are expected with increased resolution.  相似文献   

13.
A 50-year record of the Indonesian throughflow (ITF) was obtained using the Simple Ocean Data Assimilation (SODA) dataset to calculate a timeseries of Pacific-to-Indian Ocean pressure differences, which were calibrated to transport profiles using ARLINDO (1997) and INSTANT (2004–2006) observational data. The 50 year SODA based ITF transport average is 10.4 Sv; the transport weighted temperature (TWT) is 14.6 °C and the internal energy transport (IET) is 0.53 PW. The different configurations of the ITF transport and temperature profiles result in a dissimilarity in the variability of the IET and the TWT, with the IET more closely correlated with both the depth of the 18 °C isotherm in the western equatorial Pacific and the NINO3.4 index. As with the transport, the IET increases during La Niña and decreases during El Niño. The TWT is only weakly correlated with NINO3.4, suggesting that the El Niño-Southern Oscillation signal is transmitted from the Pacific to the Indian Ocean via changes in pressure and thus in transport rather than by changes in temperature.  相似文献   

14.
ABSTRACT

China’s overseas investment flows (US$ 183 billion) and stock (US$ 4.7 trillion) reached a record peak in 2016, second only to those of the US. A major cause for concern lies in the environmental sustainability of China’s overseas investment portfolio, which is compounded by the lack of transparency of China’s main development finance arms. We intend in this paper to give an update on the magnitude of green finance in China’s overseas investment and development finance portfolio on the basis of the best available estimates, and to put these figures into a broader perspective of multilateral development banks’ commitments and practices to combat climate change. We derive practical policy recommendations that Chinese development banks could take to further align China’s overseas investment with the 2°C target of the Paris Agreement, with the first step being to revise the ‘host country standard’ principle, to ensure that Chinese development banks use the most stringent of the two environmental standards, abroad or at home.

Key policy insights

  • Chinese development banks lend, give or invest between US$ 38 billion and US$ 45 billion every year to developing countries, without either elaborating on, or integrating, the provisions of the Paris Agreement into their investment strategy.

  • Regulations and safeguards are much more stringent for China’s domestic investment than for China’s overseas investment, and this stringency gap has been widening over recent years.

  • As a step towards aligning Chinese overseas investment with the Paris Agreement, Chinese development banks could revise the ‘host country standard principle’. They could instead choose the highest among the two – recipient country or Chinese domestic – in terms of environmental stringency, consequently harmonizing overseas environmental regulation and safeguards with those that apply domestically.

  相似文献   

15.
While it has been recognized that actions reducing greenhouse gas (GHG) emissions can have significant positive and negative impacts on human health through reductions in ambient fine particulate matter (PM2.5) concentrations, these impacts are rarely taken into account when analyzing specific policies. This study presents a new framework for estimating the change in health outcomes resulting from implementation of specific carbon dioxide (CO2) reduction activities, allowing comparison of different sectors and options for climate mitigation activities. Our estimates suggest that in the year 2020, the reductions in adverse health outcomes from lessened exposure to PM2.5 would yield economic benefits in the range of $6 to $30 billion (in 2008 USD), depending on the specific activity. This equates to between $40 and $198 per metric ton of CO2 in health benefits. Specific climate interventions will vary in the health co-benefits they provide as well as in potential harms that may result from their implementation. Rigorous assessment of these health impacts is essential for guiding policy decisions as efforts to reduce GHG emissions increase in scope and intensity.  相似文献   

16.
Monthly mean total vertical column abundances of acetylene have been determined from series of infrared solar spectra recorded at the Jungfraujoch station, Switzerland, between June 1986 and April 1991. The data have been obtained by nonlinear least-squares fittings of the 5 band R19 transition of C2H2 at 776.0818 cm-1. The average of 22 monthly mean total vertical columns of C2H2 retrieved during that time interval of almost 5 years was found to be equal to (1.81±0.12)×1015 molec/cm2, which corresponds to an average mixing ratio of (0,22±0.013) ppbv (parts per billion by volume) in a troposphere extending from the altitude of the station (3.58 km), up to 10.5 km. Despite the large variability found from year to year, a least-squares sine fit to the data reveals a seasonal variation with an amplitude of about ±40% of the mean; the maximum occurs during mid-winter and the minimum in the summer. The present results are compared critically with similar in-situ data found in the literature. A sinusoidal fit to all such free troposphere measurements made in-situ between 30°N and 60°N indicates good agreement in shape and phase with the seasonal variation derived above the Jungfraujoch, but their average column abundance, 2.3×1015 molec/cm2, is about 30% higher; this difference is explained on the basis of non-upwelling meteorological conditions generally prevailing during ground-based remote solar observations.  相似文献   

17.
This study presents the first appraisal of the socio-economic impacts of river floods in the European Union in view of climate and socio-economic changes. The assessment is based on two trajectories: (a) no adaptation, where the current levels of protection are kept constant, and (b) adaptation, where the level of protection is increased to defend against future flooding events. As a basis for our analysis we use an ensemble-based pan-European flood hazard assessment for present and future conditions. Socio-economic impacts are estimated by combining flood inundation maps with information on assets exposure and vulnerability. Ensemble-based results indicate that current expected annual population affected of ca. 200,000 is projected to increase up to 360,000 due to the effects of socio-economic development and climate change. Under the no adaptation trajectory current expected annual damages of €5.5 billion/year are projected to reach €98 billion/year by the 2080s due to the combined effects of socio-economic and climate change. Under the adaptation trajectory the avoided damages (benefits) amount to €53 billion/year by the 2080s. An analysis of the potential costs of adaptation associated with the increase in protection suggests that adaptation could be highly cost-effective. There is, however, a wide range around these central numbers reflecting the variability in projected climate. Analysis at the country level shows high damages, and by association high costs of adaptation, in the United Kingdom, France, Italy, Romania, Hungary and Czech Republic. At the country level, there is an even wider range around these central values, thus, pointing to a need to consider climate uncertainty in formulating practical adaptation strategies.  相似文献   

18.
The emission targets adopted in the Kyoto Protocol1 far exceed thelikely level of emissions from Russia and Ukraine. These countries could selltheir surplus if the Protocol is followedand industrialized countries establish an international emission tradingsystem. Critics have condemned the potentialsale and dubbed the surplus hot air because it does not represent anyreduction in emissions below the level thatwould have occurred anyway. Using the most recent, comprehensive regionalscenarios2 for the emissions of carbon dioxide from the energysystem, we estimate that during the Protocol's2008–2012 budget period the surplus will range from 9 MtC (milliontons of carbon) to 900 MtC for Russia andfrom 3 MtC to 200 MtC for Ukraine. Even scenarios with high economic growthand carbon-intensive technologies donot exhaust the surplus before the budget period. In the central (middlecourse) scenario, the total carbon surplusexceeds 1000 MtC and is worth 22 to 170 billion U.S. dollars (4 to 34 billionU.S. dollars per year). This flow ofrevenues, which could exceed Russian earnings from natural gas exports($10 billion in 19973), is comparable with the projectedtotal investmentsof the Russian energy system for 2008–2012. If directed towardslow-carbon infrastructure investments (e.g., gaspipelines), surplus transfers could reinforce and partially lock-indecarbonization of the world energy system.  相似文献   

19.
We provide an assessment of surface temperature changes in mountainous areas of the world using a set of climate projections at a 0.5° resolution for two 30-year periods (2040–2069 and 2070–2099), using four Intergovernmental Panel for Climate Change (IPCC) emission scenarios and five AOGCM. Projected average temperature changes varied between +3.2 °C (+0.4 °C/per decade) and +2.1 °C (+0.26 °C/per decade) for 2055 and +5.3 °C (+0.48 °C/per decade) and +2.8 °C for 2085 (+0.25 °C/per decade). The temperature is expected to rise by a greater amount in higher northern latitude mountains than in mountains located in temperate and tropical zones. The rate of warming in mountain systems is projected to be two to three times higher than that recorded during the 20th century. The tendency for a greater projected warming in northern latitude mountain systems is consistent across scenarios and is in agreement with observed trends. In light of these projections, warming is considered likely to affect biodiversity (e.g., species extinctions, changes in the composition of assemblages), water resources (e.g., a reduction in the extent of glaciated areas and snow pack), and natural hazards (e.g., floods). Accurate estimate of the effects of climate change in mountain systems is difficult because of uncertainties associated with the climate scenarios and the existence of non-linear feedbacks between impacts.  相似文献   

20.
This paper assesses the implications of climate policy for exposure to water resources stresses. It compares a Reference scenario which leads to an increase in global mean temperature of 4 °C by the end of the 21st century with a Mitigation scenario which stabilises greenhouse gas concentrations at around 450 ppm CO2e and leads to a 2 °C increase in 2100. Associated changes in river runoff are simulated using a global hydrological model, for four spatial patterns of change in temperature and rainfall. There is a considerable difference in hydrological change between these four patterns, but the percentages of change avoided at the global scale are relatively robust. By the 2050s, the Mitigation scenario typically avoids between 16 and 30% of the change in runoff under the Reference scenario, and by 2100 it avoids between 43 and 65%. Two different measures of exposure to water resources stress are calculated, based on resources per capita and the ratio of withdrawals to resources. Using the first measure, the Mitigation scenario avoids 8-17% of the impact in 2050 and 20-31% in 2100; with the second measure, the avoided impacts are 5-21% and 15-47% respectively. However, at the same time, the Mitigation scenario also reduces the positive impacts of climate change on water scarcity in other areas. The absolute numbers and locations of people affected by climate change and climate policy vary considerably between the four climate model patterns.  相似文献   

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