A forced response to twentieth century climate conditions of two Spanish forests inferred from widths and stable isotopes of tree rings

This dendroclimatological research is based on two close pine forests (Pinus sylvestris and Pinus uncinata) located at the Northern Iberian System (Spain), and three tree-ring variables (ring widths, δ ¹³C and δ ¹⁸O). The climate-tree growth system was assessed at local and regional scales using three climate datasets. Calibration of tree-ring records with climate showed a diversity of information recorded in the different variables, such as a general response to temperature and precipitation of current growing period, and an important contribution of previous year conditions understood as the use of food reserves. The analysis of the stability of climate-tree growth relationships throughout the twentieth century showed a shift of those climatic variables to which trees responded and results suggested an enhancement of reserve use on current tree growth. The results obtained in this research made clear a physiological adaptation of trees to changing climate. The results provided hints that the recent warming coupled to slight precipitation decay are forcing growth of studied trees to a higher stress status and to a higher climate-growth synchronisation. These instabilities also have implications on future dendroclimatic reconstructions performed with trees growing under changing environments.     

A multi-proxy approach for revealing recent climatic changes in the Russian Altai

For the first time we present a multi-proxy data set for the Russian Altai, consisting of Siberian larch tree-ring width (TRW), latewood density (MXD), δ¹³C and δ¹⁸O in cellulose chronologies obtained for the period 1779–2007 and cell wall thickness (CWT) for 1900–2008. All of these parameters agree well between each other in the high-frequency variability, while the low-frequency climate information shows systematic differences. The correlation analysis with temperature and precipitation data from the closest weather station and gridded data revealed that annual TRW, MXD, CWT, and δ¹³C data contain a strong summer temperature signal, while δ¹⁸O in cellulose represents a mixed summer and winter temperature and precipitation signal. The temperature and precipitation reconstructions from the Belukha ice core and Teletskoe lake sediments were used to investigate the correspondence of different independent proxies. Low frequency patterns in TRW and δ¹³C chronologies are consistent with temperature reconstructions from nearby Belukha ice core and Teletskoe lake sediments showing a pronounced warming trend in the last century. Their combination could be used for the regional temperature reconstruction. The long-term δ¹⁸O trend agrees with the precipitation reconstruction from the Teletskoe lake sediment indicating more humid conditions during the twentieth century. Therefore, these two proxies could be combined for the precipitation reconstruction.     

阿勒泰地区旅游气候指数及评价

根据阿勒泰地区1954—2008年气象资料,分析阿勒泰地区气温、风速、相对湿度等特征,利用温湿指数和风寒指数分析和评价阿勒泰地区旅游气候资源,得出阿勒泰地区4—10月为旅游适宜期,最佳旅游期为5—9月。阿勒泰地区旅游舒适气候的评价为阿勒泰旅游业的发展规划和旅游者选择最佳旅游季节提供了科学依据。     

应用区域气候参数定量预报农业年景温度

把影响农作物生长的诸多气象要素值按技术要求进行数据处理后,产生反映区域气候综合状况和要素间匹配状况的气候参数值。应用这类参数,可定量分析、评价和预报农业气候。下面就应用气候参数进行年景温度预报的方法及验证结果加以探讨。１建立区域气候参数１１参数理论...     

On the problem of adequate agroclimatic support of the Russian economy under climate change conditions

Problems of adapting available methods, forms, and approaches to agroclimatic support of the economy under climate change conditions are under consideration. Development and operation of an automated reference-information system (ARIS) of agricultural resources, assessment of the environmental bioclimatic potential, and preparation of agroclimatic Atlases (with a reference to hazardous agroclimatic events) are dealt with. The process of adaptation includes development of such system of agroclimatic support of the economy, which would adequately reflect the actual state of agroclimatic resources, bioclimatic potential of the environment, hazardous agroclimatic events, etc., at any prescribed moment, at any point. The problem is supposed to be solved with a mechanism of agricultural monitoring as one of the methods of agroclimatic support of the economy.     

Multiproxy reconstructions of climate for three sites in the Canadian High Arctic using Cassiope tetragona

We developed calibration models and reconstructed climate for sites in the central and eastern Canadian High Arctic using dendroclimatological and stable isotope analysis techniques on the dwarf-shrub, Cassiope tetragona. Our results may suggest complex temporal and spatial patterns of climate change in the region over the past century. For sites on Bathurst and Devon Islands, we reconstructed fall mean and June–July mean temperature using multiple linear regression analysis that explained 54?% and 40?% of the variance, respectively. The predictor variables included annual growth, annual production of leaves, flower buds and annual δ13C values for the Bathurst Island model, and annual growth and δ13C values for the Devon Island model. Both models revealed warmer than average temperatures throughout the mid-20th century, followed by a cooling trend from the early 1960s and mid-1970s at the Devon and Bathurst Island sites, respectively. Temperatures remained cool until the early 1980s and then increased until 1998/1999 at both sites. Our models are supported by other paleoclimate proxies and the instrumental record from the Canadian Arctic. For sites on Axel Heiberg and Bathurst Islands, we developed models using multivariate regresssion for February and March total precipitation that explained 44?% and 42?% of the variance, respectively. The Axel Heiberg Island model included annual production of flowers and flower buds, as well as annual δ13C values as predictor variables, while the Bathurst Island model only included the annual production of flower buds as a predictor. Both models showed lower than average precipitation from the early to mid-1900s, followed by increasing precipitation from the late 1980s to 1998/1999. Our precipitation models, supported by instrumental and proxy data, suggest a trend of increasing late-winter/early spring precipitation in the late 20th century. The lack of a single detectable climate signal across the study sites suggests local climate, topography, genetic variation and/or ecological conditions may dictate, in part, site responses and result in a heterogeneous climatescape over space and time. Yet, like other arctic paleoclimate proxies, chronology error and temporal discrepancies may complicate our interpretations. However, comparisons with other arctic proxies and the meteorological record suggest our models have also registered a regional climate signal.     

Transient simulations,empirical reconstructions and forcing mechanisms for the Mid-holocene hydrological climate in southern Patagonia

This study investigates the atmospheric circulation in transient climate simulations with a coupled atmosphere–ocean general circulation model (GCM) for the mid-Holocene (MH) period 7–4.5 ka BP driven with combinations of orbital, solar and greenhouse gas forcings. The focus is on southern South America. Statistical downscaling models are derived from observational data and applied to the simulations to estimate precipitation in south-eastern Patagonia during the MH. These estimates are compared with lake level estimates for Laguna Potrok Aike (LPA) from sediments. Relative to pre-industrial conditions (i.e. 1550–1850), which show extraordinarily high lake levels, the proxy-based reconstructed lake levels during the MH are lower. The downscaled simulated circulation differences indicate higher LPA precipitation during the MH from March to August, higher annual means, and reduced precipitation from September to February. Thus the reconstructed lower LPA lake levels can not be explained solely by the simulated precipitation changes. Possible reasons for this discrepancy are discussed. Based on proxy data from southern South America hypotheses have also been proposed on the latitudinal position of the southern hemispheric westerlies (SHWs). In agreement with some of these hypotheses our simulations show an increased seasonal cycle of the latitudinal position of the SHWs during the MH, which can be explained by the orbital forcing. The simulations also show stronger SHWs over southern Patagonia during austral summer and weaker SHWs during winter. The downscaling model associates weaker SHWs with increased precipitation in the LPA region. However, this relationship is only moderate, and therefore the downscaling model does not support the assumption of a strong link between mean SHWs and precipitation over south-eastern Patagonia, which is the basis of many proxy-based hypotheses about the SHWs.     

Securing the climate benefits of stable forests

Stable forests – those not already significantly disturbed nor facing predictable near-future risks of anthropogenic disturbance – may play a large role in the climate solution, due to their carbon sequestration and storage capabilities. Their importance is recognized by the Paris Agreement, but stable forests have received comparatively little attention through existing forest protection mechanisms and finance. Instead, emphasis has been placed on targeting locations where deforestation and forest degradation are happening actively. Yet stopping deforestation and forest degradation does not guarantee durable success, especially outside the geographic scope of targeted efforts. As a result, today’s stable forests may be at risk without additional efforts to secure their long-term conservation.

We synthesize the gaps in existing policy efforts that could address the climate-related benefits derived from stable forests, noting several barriers to action, such as uncertainty around the level of climate services that stable forests provide and difficulties describing the real level of threat posed. We argue that resource and finance allocation for stable forests should be incorporated into countries’ and donors’ comprehensive portfolios aimed at tackling deforestation and forest degradation as well as resulting emissions. A holistic and forward-looking approach will be particularly important, given that success in tackling deforestation and forest degradation where it is currently happening will need to be sustained in the long term.

Key policy insights

• Climate policies, finance, and implementation have tended to focus on areas of recent forest loss and near-term threats of anthropogenic disturbance, resulting in an imbalance of effort that fails to adequately address stable forests.

• In some contexts, policy measuresintended to secure the climate-related benefits of stable forests have competed poorly against more urgent threats. Policymakers and finance mechanisms should view stable forests as a complementary element within a holistic, long-term approach to resource management.

• International mechanisms and national frameworks should be adjusted and resourced to promote the long-term sustainability and permanence of stable forests.

• Beyond additional resources, the climate benefits of stable forests may be best secured by pro-actively designing implementing policies that recognize the rights and interests of stakeholders who are affected by land management decisions.

     

Spatial and temporal variation of rainwater stable isotopes in Egypt and the east Mediterranean

Summary ?By analyzing normalized variables, it was found that the latitudinal secular variations of the rainwater deuterium fractionation ratio δ²H, oxygen fractionation ratio δ¹⁸O, vapor pressure, and surface temperature were almost non-linear, occurred in parallel, and decreased with latitude. The rate of depletion around the equator is asymmetric and smaller to the south of 45° S than to the north of 45° N. In the east Mediterranean, the rate of change of δ¹⁸O with height was found to be −.2‰ per 100 m and that of δ²H is comparable with the dry lapse rate in the atmosphere. Analysis of the annual time series of δ²H at Alexandria has indicated that variations show sinusoidal waveform with a major cycle of two years that accounts for 68% of the total variance. Although the quasi-biannual cycle in the atmosphere has small amplitude in the lower layers of the atmosphere at East Mediterranean latitudes, the major cycle in annual series of δ²H or δ¹⁸O may be linked to the quasi-biannual oscillation in the atmosphere. It was also found that the first three Empirical Orthogonal Functions (EOF) account for 72% of the seasonal variation of δ²H and share 68% of the seasonal variation of δ¹⁸O. Share of variances of monthly EOF in the months of the year indicate that the main underlying factors that cause fractionation processes for δ²H and δ¹⁸O are similar across the east Mediterranean especially in late winter and early spring. Received May 13, 2002; revised July 8, 2002; accepted August 6, 2002     

Measuring and modeling Russian newspaper coverage of climate change

As a significant emitter of greenhouse gases and a country rich in fossil fuels, Russia plays a crucial role in achieving a comprehensive solution to climate-related challenges. Yet, Russia's official position on climate change has varied considerably since the beginning of global negotiations, with the country playing everything from policy leader to laggard. While there are a number factors that shape domestic policy positions, this study offers a comprehensive investigation of newspaper coverage on climate change in Russia. How have Russian newspapers discussed the issue since the Yeltsin era? We approach this question by compiling the largest data set of Russian newspaper coverage to date, which includes 11,131 climate-related articles from 65 papers over a roughly 35 year period. After introducing a “computer assisted” approach to measure the core themes running through climate change coverage, we statistically evaluate the national- and newspaper-level factors associated with how coverage is framed, focusing attention on 23 high circulation papers over the period from 2000 to 2014. We find that national-level predictors—particularly economic conditions—are highly influential in determining whether climate change is covered and how the issue is framed, while paper-level factors such as the presence of an energy interest and ownership structure also have notable effects. Overall, this study offers a rich data set and useful methods to better understand the drivers of climate communication in Russia.     

Wavelet methods: application to the study of the stable atmospheric boundary layer under non-stationary conditions

In this work, some wavelet methods are introduced to study the atmospheric boundary layer under stable conditions, where intermittent events and non-stationary turbulence take place. Such behavior makes classical methods, based on Fourier transform, difficult to use or even of no application.The wavelet transform is used to detect and characterize some structures in the stable atmospheric boundary layer. First, a wave-like event with a 16 min period is detected and analyzed in a wind record. The sum of some Morlet wavelets is proposed as a model for the oscillations. Afterwards, the wavelet transform is introduced to the study of non-stationary small scale turbulence. It provides the time evolution of the energy and a good location in time of the spots of turbulence. Finally, some wavelet tools are used to characterize a traveling structure, provided that it is simultaneously detected at different locations. The phase differences in the wavelet transform give the wavelength and the phase speed of the oscillations, whereas a double transform method is introduced to estimate the group velocity of the structure.     

中国建筑气候分区和采暖气候条件变化研究

利用1951-1980年和1981-2010年两个气候期的月平均气温数据,对中国大陆地区建筑气候分区进行对比,讨论建筑气候分区的变化;并基于近气候期的建筑气候分区以逐日气温为基础,讨论了1951-2018年不同分区采暖气候条件变化特征。结果表明：与1951-1980年相比,1981-2010年严寒地区范围有所缩减,南界北移;寒冷区、夏热冬冷区、夏热冬暖区北进,温和区西扩,夏热冬暖区范围增大。中国大陆采暖度日数、采暖日数、采暖日均强度分布一致,东部随纬向增加,西部随海拔增加;采暖度日数严寒地区最大,寒冷地区其次,夏热冬暖地区最小;1951-2018年,中国大陆各建筑分区的采暖度日数都呈显著减少趋势,减少速率严寒地区最大,温和地区最小;夏热冬冷地区距平百分率的波动最大,严寒地区波动最小。1998-2012年,全国各建筑气候分区采暖度日数和采暖日均强度在此期间均表现为增加,其中夏热冬暖地区增加趋势通过了0.05显著性检验。     

Assessment of forthcoming climate changes on the territory of the Russian Federation

A brief characterization of observed climatic changes in surface temperature is presented for the globe and the Russian Federation. In accordance with this characteristic, observed changes are indicative of global warming, most pronounced after the 1970s. The skill in simulating a global climate in the 20th century by modern climate models is analyzed. It is shown that climate models satisfactorily reproduce the fields of long–term means, the seasonal cycle, and tendencies of changes in some meteorological objects, whereas their interannual variability (after removal of the trend) is not virtually simulated by the models. An approach to constructing a strategic forecast of forthcoming climatic changes in the Russian Federation for the next decades is discussed, and recommendations on its using are formulated. A variant of a probabilistic strategic forecast of air temperature for the 30-year period of 2008–2037 over Russia is proposed.     

Impact of in-consistency between the climate model and its initial conditions on climate prediction

We investigated the influence of dynamical in-consistency of initial conditions on the predictive skill of decadal climate predictions. The investigation builds on the fully coupled global model “Coupled GCM for Earth Simulator” (CFES). In two separate experiments, the ocean component of the coupled model is full-field initialized with two different initial fields from either the same coupled model CFES or the GECCO2 Ocean Synthesis while the atmosphere is initialized from CFES in both cases. Differences between both experiments show that higher SST forecast skill is obtained when initializing with coupled data assimilation initial conditions (CIH) instead of those from GECCO2 (GIH), with the most significant difference in skill obtained over the tropical Pacific at lead year one. High predictive skill of SST over the tropical Pacific seen in CIH reflects the good reproduction of El Niño events at lead year one. In contrast, GIH produces additional erroneous El Niño events. The tropical Pacific skill differences between both runs can be rationalized in terms of the zonal momentum balance between the wind stress and pressure gradient force, which characterizes the upper equatorial Pacific. In GIH, the differences between the oceanic and atmospheric state at initial time leads to imbalance between the zonal wind stress and pressure gradient force over the equatorial Pacific, which leads to the additional pseudo El Niño events and explains reduced predictive skill. The balance can be reestablished if anomaly initialization strategy is applied with GECCO2 initial conditions and improved predictive skill in the tropical Pacific is observed at lead year one. However, initializing the coupled model with self-consistent initial conditions leads to the highest skill of climate prediction in the tropical Pacific by preserving the momentum balance between zonal wind stress and pressure gradient force along the equatorial Pacific.