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1.
Maxwell T. Boykoff 《Climatic change》2008,86(1-2):1-11
Eminent climate scientists have come to consensus that human influences are significant contributors to modern global climate
change. This study examines coverage of anthropogenic climate change in United States (U.S.) network television news – ABC World News Tonight, CBS Evening News and NBC Nightly News – and focuses on the application of the journalistic norm of ‘balance’ in coverage from 1995 through 2004. This study also
examines CNN WorldView, CNN Wolf Blitzer Reports and CNN NewsNight as illustrations of cable news coverage. Through quantitative content analysis, results show that 70% of U.S. television
news segments have provided ‘balanced’ coverage regarding anthropogenic contributions to climate change vis-à-vis natural
radiative forcing, and there has been a significant difference between this television coverage and scientific consensus regarding
anthropogenic climate change from 1996 through 2004. Thus, by way of the institutionalized journalistic norm of balanced reporting,
United States television news coverage has perpetrated an informational bias by significantly diverging from the consensus
view in climate science that humans contribute to climate change. Troubles in translating this consensus in climate science
have led to the appearance of amplified uncertainty and debate, also then permeating public and policy discourse. 相似文献
2.
Weather services base their operational definitions of “present” climate on past observations, using a 30-year normal period
such as 1961–1990 or 1971–2000. In a world with ongoing global warming, however, past data give a biased estimate of the actual
present-day climate. Here we propose to correct this bias with a “delta change” method, in which model-simulated climate changes
and observed global mean temperature changes are used to extrapolate past observations forward in time, to make them representative
of present or future climate conditions. In a hindcast test for the years 1991–2002, the method works well for temperature,
with a clear improvement in verification statistics compared to the case in which the hindcast is formed directly from the
observations for 1961–1990. However, no improvement is found for precipitation, for which the signal-to-noise ratio between
expected anthropogenic changes and interannual variability is much lower than for temperature. An application of the method
to the present (around the year 2007) climate suggests that, as a geographical average over land areas excluding Antarctica,
8–9 months per year and 8–9 years per decade can be expected to be warmer than the median for 1971–2000. Along with the overall
warming, a substantial increase in the frequency of warm extremes at the expense of cold extremes of monthly-to-annual temperature
is expected. 相似文献
3.
Infinite uncertainty,forgotten feedbacks,and cost-benefit analysis of climate policy 总被引:1,自引:1,他引:1
Tol (2003) questioned the applicability of expected cost-benefit analysis to global mitigation policy when he found evidence that the
uncertainty surrounding estimates of the marginal damage of climate change could be infinite even if total damages were finite.
Yohe (2003) suggested that this problem could be alleviated if international development aid were directed at eliminating the source
of the problem – climate induced negative growth rates in a few regions along a handful of troublesome scenarios. The hypothesis
about adding a second policy lever to the climate policy calculus is shown to hold, though perhaps not as robustly as originally
thought. A portfolio of international policies with at least two independent tools can avoid infinite uncertainty on the margins
and the associated implications for global mitigation policy at a reasonable price even in the relatively unlikely event that
climate change causes negative economic growth in a region or two.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
J. Räisänen 《Theoretical and Applied Climatology》1999,64(1-2):1-13
Summary The qualitative agreement of two climate models, HADCM2 and ECHAM3, on the response of surface climate to anthropogenic climate
forcing in the period 2020 – 2049 is studied. Special attention is paid to the role of internal climate variability as a source
of intermodel disagreement. After illustrating the methods in an intermodel comparison of simulated changes in June–August
mean precipitation, some global statistics are presented. Excluding surface air temperature, the four-season mean proportion
of areas in which the two models agree on the sign of the climatic response is only 53 – 60% both for increases in CO2 alone and for increases in CO2 together with direct radiative forcing by sulphate aerosols, but somewhat larger, 59 – 70% for the separate aerosol effect.
In areas where the response is strong (at least twice the standard error associated with internal variability) in both models,
the agreement is better and the contrast between the different forcings becomes more marked. The proportion of agreement in
such areas is 57 – 75% for the response to increases in CO2 alone, 64 – 84% for the response to combined CO2 and aerosol forcing, and as high as 88 – 94% for the separate aerosol effect. The relatively good intermodel agreement for
aerosol-induced climate changes is suggested to be associated with the uneven horizontal distribution of aerosol forcing.
Received December 2, 1998 Revised May 5, 1999 相似文献
5.
Severe climate-induced water shortage and extremes in Crete 总被引:1,自引:0,他引:1
Ioannis K. Tsanis Aristeidis G. Koutroulis Ioannis N. Daliakopoulos Daniela Jacob 《Climatic change》2011,106(4):667-677
Climate change is expected to have a significant impact on the hydrologic cycle, creating changes in freshwater resources.
The Intergovernmental Panel on Climate Change (IPCC) predicts that, as a result, floods and prolonged droughts will take place
at increasingly frequent periods. The Mediterranean has been described as one of the main climate change “hot-spots”, with
recent simulations showing a collective picture of substantial drying and warming. This effect appears more pronounced during
warm periods, when the seasonal decrease of precipitation can exceed control climatology by 25–30%. Despite the decreasing
annual rainfall trend, an increase in the amount and intensity of wintertime rainfall is evident. However, the scientific
question on the quantitative impact of these signals to small scale coastal watersheds and Mediterranean islands has not been
answered. The state-of-the-art Ensembles dataset was employed to assess the impact of the changing climate on the water availability
of the island of Crete at basin scale. Here, the Ensembles precipitation and temperature data is used as input for a rainfall–runoff
model previous calibrated for the whole island with the principle of regionalization. Data analysis for the period 1970–2100
reveals an overall decreasing precipitation trend which, combined with a temperature rise, leads to substantial reduction
of water availability. Quantitative results of hydrological change provide the data required to improve knowledge and adaptation
policy to water shortages. 相似文献
6.
Future Effects of Ozone on Carbon Sequestration and Climate Change Policy Using a Global Biogeochemical Model 总被引:2,自引:2,他引:0
Exposure of plants to ozone inhibits photosynthesis and therefore reduces vegetation production and carbon sequestration.
The reduced carbon storage would then require further reductions in fossil fuel emissions to meet a given CO2 concentration target, thereby increasing the cost of meeting the target. Simulations with the Terrestrial Ecosystem Model
(TEM) for the historical period (1860–1995) show the largest damages occur in the Southeast and Midwestern regions of the
United States, eastern Europe, and eastern China. The largest reductions in carbon storage for the period 1950–1995, 41%,
occur in eastern Europe. Scenarios for the 21st century developed with the MIT Integrated Global Systems Model (IGSM) lead
to even greater negative effects on carbon storage in the future. In some regions, current land carbon sinks become carbon
sources, and this change leads to carbon sequestration decreases of up to 0.4 Pg C yr−1 due to damage in some regional ozone hot spots. With a climate policy, failing to consider the effects of ozone damage on
carbon sequestration would raise the global costs over the next century of stabilizing atmospheric concentrations of CO2 equivalents at 550 ppm by 6 to 21%. Because stabilization at 550 ppm will reduce emission of other gases that cause ozone,
these additional benefits are estimated to be between 5 and 25% of the cost of the climate policy. Tropospheric ozone effects
on terrestrial ecosystems thus produce a surprisingly large feedback in estimating climate policy costs that, heretofore,
has not been included in cost estimates. 相似文献
7.
In 2007, the CNA Military Advisory Board (MAB), an expert panel composed of 11 retired admirals and generals from the United
States, identified climate change as a “threat multiplier” for instability in some of the most volatile regions of the world.
(CNA MAB National security and the threat of climate change
2007)The Department of Defense reached a similar conclusion in last year’s Quadrennial Defense Review–a legislatively mandated
analysis of the Defense Department’s strategy and priorities. This document frames the long-term course for policy decision-making
at the highest levels. The reports demonstrate that climate change and energy are now mainstream elements of national security
planning, and can be assessed within the frameworks used to evaluate other threats, risks, and responses. However, the exact
magnitude of the threat posed by climate change is difficult to calibrate in part because the language used by scientists
to predict uncertainty and the confidence levels of judgments is not sufficiently clear. The defense community has a vast
amount of experience exploring and dealing with uncertainty. Scientists trying to better describe the effects of climate change
may be able to draw lessons from the defense community’s approach to uncertainty including how to better communicate findings
to wide audiences including policy-makers. 相似文献
8.
Alpine ecosystems in permafrost region are extremely sensitive to climate change. The headwater regions of Yangtze River and
Yellow River of the Qinghai-Tibet plateau permafrost area were selected. Spatial-temporal shifts in the extent and distribution
of tundra ecosystems were investigated for the period 1967–2000 by landscape ecological method and aerial photographs for
1967, and satellite remote sensing data (the Landsat’s TM) for 1986 and 2000. The relationships were analyzed between climate
change and the distribution area variation of tundra ecosystems and between the permafrost change and tundra ecosystems. The
responding model of tundra ecosystem to the combined effects of climate and permafrost changes was established by using statistic
regression method, and the contribution of climate changes and permafrost variation to the degradation of tundra ecosystems
was estimated. The regional climate exhibited a tendency towards significant warming and desiccation with the air temperature
increased by 0.4–0.67°C/10a and relative stable precipitation over the last 45 years. Owing to the climate continuous warming,
the intensity of surface heat source (HI) increased at the average of 0.45 W/m2 per year, the difference of surface soil temperature and air temperature (DT) increased at the range of 4.1°C–4.5°C, and
the 20-cm depth soil temperature within the active layer increased at the range of 1.1°C–1.4°C. The alpine meadow and alpine
swamp meadow were more sensitive to permafrost changes than alpine steppe. The area of alpine swamp meadow decreased by 13.6–28.9%,
while the alpine meadow area decreased by 13.5–21.3% from 1967 to 2000. The contributions of climate change to the degradation
of the alpine meadow and alpine swamp was 58–68% and 59–65% between 1967 and 2000. The synergic effects of climate change
and permafrost variation were the major drivers for the observed degradation in tundra ecosystems of the Qinghai-Tibet plateau. 相似文献
9.
Summary Tropical North African climate variability is investigated using a Sahel rainfall index and streamflow of the Nile River in
the 20th century. The mechanisms that govern tropical North Africa climate are diagnosed from NCEP reanalysis data in the period 1958–1998:
spatially – using composite and correlation analysis, and temporally – using wavelet co-spectral analysis. The Sahelian climate
is characterised by a decadal rhythm, whilst the mountainous eastern and equatorial regions exhibit interannual cycles. ENSO-modulated
zonal circulations over the Atlantic/Pacific sector are important for decadal variations, and create a climatic polarity between
South America and tropical North Africa as revealed through upper-level velocity potential and convection patterns. A more
localised N–S shift in convection between the Sahel and Guinea coast is associated with the African Easterly Jet. 相似文献
10.
Introduction to the TAC special issue: The RegCNET network 总被引:2,自引:0,他引:2
F. Giorgi J. S. Pal X. Bi L. Sloan N. Elguindi F. Solmon 《Theoretical and Applied Climatology》2006,86(1-4):1-4
Summary Fostering climate research in economically developing nations (EDNs) is especially important because the welfare and economies
of these nations are particularly dependent on climate and its variability. A critical factor that undermines the advancement
of research in EDNs is that many EDN scientists are confronted with scientific isolation and lack of exposure to state-of-the-art
research methodologies. One of the means to ameliorate this problem is to build “south–south” (i.e. EDN–EDN) and “north–south”
(i.e. EDN–EAN, or economically advanced nations) research partnerships, which become more effective when they are based on
collaborative projects where the participants share their respective expertise. This is the central paradigm underlying the
formation of the REGional Climate research NETwork, or RegCNET. 相似文献
11.
Understanding public complacency about climate change: adults’ mental models of climate change violate conservation of matter 总被引:1,自引:2,他引:1
Public attitudes about climate change reveal a contradiction. Surveys show most Americans believe climate change poses serious
risks but also that reductions in greenhouse gas (GHG) emissions sufficient to stabilize atmospheric GHG concentrations can
be deferred until there is greater evidence that climate change is harmful. US policymakers likewise argue it is prudent to
wait and see whether climate change will cause substantial economic harm before undertaking policies to reduce emissions.
Such wait-and-see policies erroneously presume climate change can be reversed quickly should harm become evident, underestimating
substantial delays in the climate’s response to anthropogenic forcing. We report experiments with highly educated adults –
graduate students at MIT – showing widespread misunderstanding of the fundamental stock and flow relationships, including
mass balance principles, that lead to long response delays. GHG emissions are now about twice the rate of GHG removal from
the atmosphere. GHG concentrations will therefore continue to rise even if emissions fall, stabilizing only when emissions
equal removal. In contrast, most subjects believe atmospheric GHG concentrations can be stabilized while emissions into the
atmosphere continuously exceed the removal of GHGs from it. These beliefs – analogous to arguing a bathtub filled faster than
it drains will never overflow – support wait-and-see policies but violate conservation of matter. Low public support for mitigation
policies may arise from misconceptions of climate dynamics rather than high discount rates or uncertainty about the impact
of climate change. Implications for education and communication between scientists and nonscientists (the public and policymakers)
are discussed. 相似文献
12.
L. D. Danny Harvey 《Climatic change》2007,82(1-2):1-25
Article 2 of the United Nations Framework Convention on Climate Change (UNFCCC) calls for stabilization of greenhouse gas
(GHG) concentrations at levels that prevent dangerous anthropogenic interference (DAI) in the climate system. However, some
of the recent policy literature has focused on dangerous climatic change (DCC) rather than on DAI. DAI is a set of increases
in GHGs concentrations that has a non-negligible possibility of provoking changes in climate that in turn have a non-negligible
possibility of causing unacceptable harm, including harm to one or more of ecosystems, food production systems, and sustainable
socio-economic systems, whereas DCC is a change of climate that has actually occurred or is assumed to occur and that has
a non-negligible possibility of causing unacceptable harm. If the goal of climate policy is to prevent DAI, then the determination
of allowable GHG concentrations requires three inputs: the probability distribution function (pdf) for climate sensitivity,
the pdf for the temperature change at which significant harm occurs, and the allowed probability (“risk”) of incurring harm
previously deemed to be unacceptable. If the goal of climate policy is to prevent DCC, then one must know what the correct
climate sensitivity is (along with the harm pdf and risk tolerance) in order to determine allowable GHG concentrations. DAI
from elevated atmospheric CO2 also arises through its impact on ocean chemistry as the ocean absorbs CO2. The primary chemical impact is a reduction in the degree of supersaturation of ocean water with respect to calcium carbonate,
the structural building material for coral and for calcareous phytoplankton at the base of the marine food chain. Here, the
probability of significant harm (in particular, impacts violating the subsidiary conditions in Article 2 of the UNFCCC) is
computed as a function of the ratio of total GHG radiative forcing to the radiative forcing for a CO2 doubling, using two alternative pdfs for climate sensitivity and three alternative pdfs for the harm temperature threshold.
The allowable radiative forcing ratio depends on the probability of significant harm that is tolerated, and can be translated
into allowable CO2 concentrations given some assumption concerning the future change in total non-CO2 GHG radiative forcing. If future non-CO2 GHG forcing is reduced to half of the present non-CO2 GHG forcing, then the allowable CO2 concentration is 290–430 ppmv for a 10% risk tolerance (depending on the chosen pdfs) and 300–500 ppmv for a 25% risk tolerance
(assuming a pre-industrial CO2 concentration of 280 ppmv). For future non-CO2 GHG forcing frozen at the present value, and for a 10% risk threshold, the allowable CO2 concentration is 257–384 ppmv. The implications of these results are that (1) emissions of GHGs need to be reduced as quickly
as possible, not in order to comply with the UNFCCC, but in order to minimize the extent and duration of non-compliance; (2)
we do not have the luxury of trading off reductions in emissions of non-CO2 GHGs against smaller reductions in CO2 emissions, and (3) preparations should begin soon for the creation of negative CO2 emissions through the sequestration of biomass carbon. 相似文献
13.
May–July Standardized Precipitation Index (SPI) for the land area of most of Turkey and some adjoining regions are reconstructed
from tree rings for the period 1251–1998. The reconstruction was developed from principal components analysis (PCA) of four
Juniperus excelsa chronologies from southwestern and south-central Turkey and is based on reliable and replicable statistical relationships
between climate and tree ring growth. The SPI reconstruction shows climate variability on both interannual and interdecadal
time scales. The longest period of consecutive drought years in the reconstruction (SPI threshold ≤−1) is 2 yr. These occur
in 1607–1608, 1675–1676, and 1907–1908. There are five wet events (SPI threshold ≥+1) of two consecutive years each (1330–1331,
1428–1429, 1503–1504, 1629–1630, and 1913–1914). A 5-yr moving average of the reconstructed SPI shows that two sustained drought
periods occurred from the mid to late 1300s and the early to mid 1900s. Both episodes are characterized by low variability. 相似文献
14.
Here we present a multi-proxy paleolimnological record from a closed-basin lake (Ebinur Lake) in northwestern China to investigate
climate change in this arid region during the last 1,500 years. The 120-cm long sediment core was dated by AMS radiocarbon
and 210Pb methods. The fine-grained clay sediments contain 3–17% organic matter (OM) and 9–31% carbonate, and are interrupted by
multiple sand and silt layers. These sand/silt layers, having consistently low OM, were found at 700–800, 1000–1100, 1300–1400,
and 1700–1750 a.d., with a time spacing of 300–400 years. We interpret that the low OM sand/silt layers were deposited during higher lake levels
caused by increased river inflow from the surrounding mountains during wet climate intervals. This interpretation is supported
by concurrent decreases in δ
18O and δ
13C of bulk carbonate and in carbonate content. Wet climate intervals at 700–800 a.d. and at 1700–1750 a.d. also correlate with elevated snow accumulation and low δ
18O from Guliya ice core on the NW Tibetan Plateau, both regions strongly influenced by the westerlies. This approximate 400-year
periodicity of wet–dry climate oscillations appear to correlate with solar activity as shown by atmosphere 14C concentration and with paleo-moisture records in interior North America. Our results suggest that solar activities might
have played a significant role in driving wet–dry climate oscillations at centennial scales in the interior of Eurasian continent. 相似文献
15.
X-C Zhang 《Climatic change》2007,84(3-4):337-363
Spatial downscaling of climate change scenarios can be a significant source of uncertainty in simulating climatic impacts
on soil erosion, hydrology, and crop production. The objective of this study is to compare responses of simulated soil erosion,
surface hydrology, and wheat and maize yields to two (implicit and explicit) spatial downscaling methods used to downscale
the A2a, B2a, and GGa1 climate change scenarios projected by the Hadley Centre’s global climate model (HadCM3). The explicit
method, in contrast to the implicit method, explicitly considers spatial differences of climate scenarios and variability
during downscaling. Monthly projections of precipitation and temperature during 1950–2039 were used in the implicit and explicit
spatial downscaling. A stochastic weather generator (CLIGEN) was then used to disaggregate monthly values to daily weather
series following the spatial downscaling. The Water Erosion Prediction Project (WEPP) model was run for a wheat–wheat–maize
rotation under conventional tillage at the 8.7 and 17.6% slopes in southern Loess Plateau of China. Both explicit and implicit
methods projected general increases in annual precipitation and temperature during 2010–2039 at the Changwu station. However,
relative climate changes downscaled by the explicit method, as compared to the implicit method, appeared more dynamic or variable.
Consequently, the responses to climate change, simulated with the explicit method, seemed more dynamic and sensitive. For
a 1% increase in precipitation, percent increases in average annual runoff (soil loss) were 3–6 (4–10) times greater with
the explicit method than those with the implicit method. Differences in grain yield were also found between the two methods.
These contrasting results between the two methods indicate that spatial downscaling of climate change scenarios can be a significant
source of uncertainty, and further underscore the importance of proper spatial treatments of climate change scenarios, and
especially climate variability, prior to impact simulation. The implicit method, which applies aggregated climate changes
at the GCM grid scale directly to a target station, is more appropriate for simulating a first-order regional response of
nature resources to climate change. But for the site-specific impact assessments, especially for entities that are heavily
influenced by local conditions such as soil loss and crop yield, the explicit method must be used. 相似文献
16.
Ulrike Löptien Olga Zolina Sergey Gulev Mojib Latif Vladimir Soloviov 《Climate Dynamics》2008,31(5):507-532
Cyclone activity and life cycle are analysed in the coupled GCMs ECHAM5/OM and ECHAM4/OPYC3. First, the results for the present
climate (1978–1999) are compared with ERA-40 and NCEP/NCAR reanalyses, showing a drastic improvement in the representation
of cyclone activity in ECHAM5/OM compared to ECHAM4/OPYC3. The total number of cyclones, cyclone intensity, propagation velocity
and deepening rates are found to be much more realistic in ECHAM5/OM relative to ECHAM4/OPYC3. Then, changes in extra tropical
cyclone characteristics are compared between present day climate and future climate under the emission-scenario A1B using
ECHAM5/OM. This comparison is performed using the 20-year time slices 1978–1999, 2070–2090 and 2170–2190, which were considered
to be representative for the various climate conditions. The total number of cyclones does not undergo significant changes
in a warmer climate. However, regional changes in cyclone numbers and frequencies are evident. One example is the Mediterranean
region where the number of cyclones in summer increases almost by factor 2. Some noticeable changes are also found in cyclone
life cycle characteristics (deepening rate and propagation velocity). Cyclones in the future climate scenario tend to move
slower and their deepening rate becomes stronger, while cyclone intensity does not undergo significant change in a warmer
climate. Generally, our results do not support the hypothesis of enhanced storminess under future climate conditions. 相似文献
17.
Daniel Steiner Andreas Pauling Samuel U. Nussbaumer Atle Nesje Jürg Luterbacher Heinz Wanner Heinz J. Zumbühl 《Climatic change》2008,90(4):413-441
A nonlinear backpropagation network (BPN) has been trained with high-resolution multiproxy reconstructions of temperature
and precipitation (input data) and glacier length variations of the Alpine Lower Grindelwald Glacier, Switzerland (output
data). The model was then forced with two regional climate scenarios of temperature and precipitation derived from a probabilistic
approach: The first scenario (“no change”) assumes no changes in temperature and precipitation for the 2000–2050 period compared
to the 1970–2000 mean. In the second scenario (“combined forcing”) linear warming rates of 0.036–0.054°C per year and changing
precipitation rates between −17% and +8% compared to the 1970–2000 mean have been used for the 2000–2050 period. In the first
case the Lower Grindelwald Glacier shows a continuous retreat until the 2020s when it reaches an equilibrium followed by a
minor advance. For the second scenario a strong and continuous retreat of approximately −30 m/year since the 1990s has been
modelled. By processing the used climate parameters with a sensitivity analysis based on neural networks we investigate the
relative importance of different climate configurations for the Lower Grindelwald Glacier during four well-documented historical
advance (1590–1610, 1690–1720, 1760–1780, 1810–1820) and retreat periods (1640–1665, 1780–1810, 1860–1880, 1945–1970). It
is shown that different combinations of seasonal temperature and precipitation have led to glacier variations. In a similar
manner, we establish the significance of precipitation and temperature for the well-known early eighteenth century advance
and the twentieth century retreat of Nigardsbreen, a glacier in western Norway. We show that the maritime Nigardsbreen Glacier
is more influenced by winter and/or spring precipitation than the Lower Grindelwald Glacier. 相似文献
18.
Tree rings and climate for the last 680 years in Wulan area of northeastern Qinghai-Tibetan Plateau 总被引:3,自引:0,他引:3
A 680-year ring-width chronology of Sabina przewalskii Kom. was developed for Wulan area of northeastern Qinghai-Tibetan Plateau, China. Response function and correlation analyses
showed that spring precipitation (May–June) is the critical limiting factor for tree-ring growth, and temperature in prior
November may also play a role in affecting tree-ring growth. Excessive spring precipitation occurred during AD 1380s–1390s,
1410s–1420s, 1520s–1560s and 1938 to present. Dry springs occurred during AD 1430s–1510s, 1640s–1730s and 1780s–1890s most
of which generally coincided with cold intervals of the Little Ice Age (LIA) on the plateau, suggesting that the LIA climate
on the northeastern Qinghai-Tibetan Plateau might be characterized by three episodes of dry spring and cold autumn. The relatively
driest spring and probably coldest autumn occurred in AD 1710s–1720s, 1787–1797, 1815–1824, 1869–1879 and 1891–1895. The extreme
drought in AD 1787–1797 might result from little monsoon precipitation due to the failure of Asian monsoon in this period.
The tree-ring data produced in this study contribute to the spatial expansion of proxy climate records for the Qinghai-Tibetan
Plateau. 相似文献
19.
Scenarios indicate that the air temperature will increase in high latitude regions in coming decades, causing the snow covered
period to shorten, the growing season to lengthen and soil temperatures to change during the winter, spring and early summer.
To evaluate how a warmer climate is likely to alter the snow cover and soil temperature in Scots pine stands of varying ages
in northern Sweden, climate scenarios from the Swedish regional climate modelling programme SWECLIM were used to drive a Soil-Vegetation-Atmosphere
Transfer (SVAT)-model (COUP). Using the two CO2 emission scenarios A and B in the Hadley centres global climate model, HadleyA and HadleyB, SWECLIM predicts that the annual
mean air temperature and precipitation will increase at most 4.8°C and 315 mm, respectively, within a century in the study
region. The results of this analysis indicate that a warmer climate will shorten the period of persistent snow pack by 73–93 days,
increase the average soil temperature by 0.9–1.5°C at 10 cm depth, advance soil warming by 15–19 days in spring and cause
more soil freeze–thaw cycles by 31–38%. The results also predict that the large current variations in snow cover due to variations
in tree interception and topography will be enhanced in the coming century, resulting in increased spatial variability in
soil temperatures. 相似文献
20.
Lucas da Costa Santos Jefferson Vieira Jos Fabiani Denise Bender Daniel Soares Alves Pablo Ricardo Nitsche Elton Fialho dos Reis Rubens Duarte Coelho 《Theoretical and Applied Climatology》2020,140(1):55-68
The hydrological variable evapotranspiration (ET) is challenging to estimate because it cannot be measured directly in natural environments (except in small plots). The uncertainties associated with the models used for its prediction have increased under climate change conditions. We studied the influence of stomatal resistance on ET estimates using the Penman-Monteith method as projected by three general circulation models in two emission scenarios (RCP4.5 and RCP8.5) for future climates throughout the twenty-first century (2010–2039, 2040–2069, and 2070–2099). We also investigated the probable ET rate changes in relation to the current (30 years average, 1980–2009) climate conditions for the Paraná state in the southern region of Brazil. The results were regionalized to help policymakers assess climate change impacts and design adaptation measures. ET increases of up to 15% were found in future climate conditions, which may lead to a significant increase in the water demand for agricultural crops. However, we believe that plant morphophysiological changes may occur under atmospheric CO2 enrichment conditions and that a possible reduction in stomatal conductance will result in lower ET increases than those obtained with the traditional Penman-Monteith method. When considering future climate scenarios, we propose the equation be adjusted to consider stomatal resistance as a function of CO2 concentrations. 相似文献