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The high mountain regions of Asia contain more glacial ice than anywhere on the planet outside of the polar regions. Because of the large population living in the Indus watershed region who are reliant on melt from these glaciers for fresh water, understanding the factors that affect glacial melt along with the impacts of climate change on the region is important for managing these natural resources. While there are multiple climate data products (e.g., reanalysis and global climate models) available to study the impact of climate change on this region, each product will have a different amount of skill in projecting a given climate variable, such as precipitation. In this research, we develop a spatially varying mixture model to compare the distribution of precipitation in the High Mountain Asia region as produced by climate models with the corresponding distribution from in situ observations from the Asian Precipitation—Highly Resolved Observational Data Integration Towards Evaluation (APHRODITE) data product. Parameter estimation is carried out via a computationally efficient Markov chain Monte Carlo algorithm. Each of the estimated climate distributions from each climate data product is then validated against APHRODITE using a spatially varying Kullback–Leibler divergence measure. Supplementary materials accompanying this paper appear online. [ABSTRACT FROM AUTHOR]

In this paper, a systematic literature review was conducted to synthesize understanding on farmers' perception on climate change. Farmers' perception of climate change is conceptualized as comprising of three dimensions—first, as farmers' "awareness"; second, "conceptual understanding"; and third, the "experience" of climate change. The review included 162 papers published during the period January 2000 to July 2019. The highest number of studies was conducted in Africa, followed by Asia. A large majority of farmers report being aware of climate change. However, only a few studies elicit the difference between climate variability and climate change from farmers. A negligible number of studies attempt to identify the role of agricultural activities in greenhouse gas emissions and climate change. Furthermore, authors compare farmers' perception with meteorological evidence, which is more aligned in terms of change in "temperature" rather than "precipitation." The insights from the review provide guidance on conceptualization and operationalization of the variable "farmers' perception of climate change" for future studies. [ABSTRACT FROM AUTHOR]

The initial collision between Indian and Asian continents marked the starting point for transformation of land-sea thermal contrast, uplift of the Tibet-Himalaya orogen, and climate change in Asia. In this paper, we review the published literatures from the past 30 years in order to draw consensus on the processes of initial collision and suturing that took place between the Indian and Asian plates. Following a comparison of the different methods that have been used to constrain the initial timing of collision, we propose that the tectono-sedimentary response in the peripheral foreland basin provides the most sensitive index of this event, and that paleomagnetism presents independent evidence as an alternative, reliable, and quantitative research method. In contrast to previous studies that have suggested collision between India and Asia started in Pakistan between ca. 55 Ma and 50 Ma and progressively closed eastwards, more recent researches have indicated that this major event first occurred in the center of the Yarlung Tsangpo suture zone (YTSZ) between ca. 65 Ma and 63 Ma and then spreading both eastwards and westwards. While continental collision is a complicated process, including the processes of deformation, sedimentation, metamorphism, and magmatism, different researchers have tended to define the nature of this event based on their own understanding, an intuitive bias that has meant that its initial timing has remained controversial for decades. Here, we recommend the use of reconstructions of each geological event within the orogenic evolution sequence as this will allow interpretation of collision timing on the basis of multidisciplinary methods. [ABSTRACT FROM AUTHOR]

Seasonal prediction of the East Asian summer monsoon (EASM) strength is probably one of the most challenging and crucial issues for climate prediction over East Asia. In this paper, a statistical method called partial-least square (PLS) regression is utilized to uncover principal sea surface temperature (SST) modes in the winter preceding the EASM. Results show that the SST pattern of the first PLS mode is associated with the turnabout of warming (or cooling) phase of a mega-El Niño/Southern Oscillation (mega-ENSO) (a leading mode of interannual-to-interdecadal variations of global SST), whereas that of the second PLS mode leads the warming/cooling mega-ENSO by about 1 year, signaling precursory conditions for mega-ENSO. These indicate that mega-ENSO may provide a critical predictability source for the EASM strength. Based on a 40-year training period (1958-1997), a PLS prediction model is constructed using the two leading PLS modes and 3-month-lead hindcasts are performed for the validation period of 1998-2013. A promising skill is obtained, which is comparable to the ensemble mean of versions 3 and 4 of the Canadian Community Atmosphere Model (CanCM3/4) hindcasts from the newly developed North American Multi-model Ensemble Prediction System regarding the interannual variations of the EASM strength. How to improve dynamical model simulation of the EASM is also examined through comparing the CanCM3/4 hindcast (1982-2010) with the 106-year historical run (1900-2005) by the Second Generation Canadian Earth System Model (CanESM2). CanCM3/4 exhibits a high skill in the EASM hindcast period 1982-2010 during which it also has a better performance in capturing the relationship between the EASM and mega-ENSO. By contrast, the simulation skill of CanESM2 is quite low and it is unable to reproduce the linkage between the EASM and mega-ENSO. All these results emphasize importance of mega-ENSO in seasonal prediction and dynamical model simulation of the EASM. [ABSTRACT FROM AUTHOR]

The mid-Pliocene warm period was the most recent geological period in Earth's history that featured long-term warming. Both geological evidence and model results indicate that East Asian summer winds (EASWs) strengthened in monsoonal China, and that East Asian winter winds (EAWWs) weakened in northern monsoonal China during this period, as compared to the pre-industrial period. However, the corresponding mechanisms are still unclear. In this paper, the results of a set of numerical simulations are reported to analyze the effects of changed boundary conditions on the mid-Pliocene East Asian monsoon climate, based on PRISM3 (Pliocene Research Interpretation and Synoptic Mapping) palaeoenvironmental reconstruction. The model results showed that the combined changes of sea surface temperatures, atmospheric CO concentration, and ice sheet extent were necessary to generate an overall warm climate on a large scale, and that these factors exerted the greatest effects on the strengthening of EASWs in monsoonal China. The orographic change produced significant local warming and had the greatest effect on the weakening of EAWWs in northern monsoonal China in the mid-Pliocene. Thus, these two factors both had important but different effects on the monsoon change. In comparison, the effects of vegetational change on the strengthened EASWs and weakened EAWWs were relatively weak. The changed monsoon winds can be explained by a reorganization of the meridional temperature gradient and zonal thermal contrast. Moreover, the effect of orbital parameters cannot be ignored. Results showed that changes in orbital parameters could have markedly affected the EASWs and EAWWs, and caused significant short-term oscillations in the mid-Pliocene monsoon climate in East Asia. [ABSTRACT FROM AUTHOR]

A large intraseasonal variation in geopotential height over the Central Asia region, where the Asian subtropical jet is located, occurs between May and June, and the most dominant variation has a wave-like distribution. This variation in geopotential height influences precipitation across South and Southeast Asia. In this paper, we use composite analysis to determine the causes of this intraseasonal variation over Central Asia. The wave train propagates from the northern Atlantic Ocean to Central Asia over a period of a week, and generates an anomaly in geopotential height over the region. The tropical disturbance, which is similar to the Madden-Julian oscillation, appears a few days before the maximum of the anticyclonic anomaly over Central Asia, and is accompanied by active convection over the Indian Ocean and suppressed convection over Central America. Results of numerical experiments using a linear baroclinic model show that the active convection over the northern Indian Ocean causes the anticyclonic anomaly over Central Asia. The wave train that extends from the northern Atlantic Ocean to Central Asia is generated by negative thermal forcing over Central America, and the phase distribution of this wave train is similar to that observed in the composite analysis. Central Asia is the region where the effects of the tropics and middle latitudes overlap, and it is an important connection point between the Asian monsoon and middle latitudes. [ABSTRACT FROM AUTHOR]

Geological climatic records and model simulations on the Asian summer monsoon climate change induced by insolation forcing of the Earth's precession are systematically reviewed in this paper. The presentation of the questions on the mechanism of the Asian monsoon evolution at the precession band, currently existing debates and future research directions are discussed. Since the early 1980s, more and more observed evidence and simulated results, especially the absolute-dated stalagmite records and orbital-scale transient model runs in the last few years, have indicated that the quasi-20ka period in the Quaternary monsoon climate change is caused by precession. However, debates still exist on the dynamic mechanism how precession affects the Asian monsoon. The "zero phase" hypothesis says that the Asian monsoon is merely controlled by summer insolation in the Northern Hemisphere (NH) while the "latent heat" hypothesis emphasizes the dominant effect of latent heat transport from the Southern Hemisphere (SH) besides the role of the northern insolation. The two hypotheses have separately been supported by some evidence. Although we are cognizant of the importance of northern solar radiation and the remote effect of southern insolation, it has still a long way to go before comprehensively understanding the evolutionary mechanism of the Asian monsoon. In view of the problems existing in present researches of monsoon-dominated climate change at the precession scale, we propose that studies on the environmental significance of geological monsoon proxies, feedback processes in the long-term transient simulations and intercomparisons between observations and modeling results should be strengthened in the future. [ABSTRACT FROM AUTHOR]

Biological monitoring of solar UV radiation using spore dosimeters has been undertaken since the year 1999 at more than 20 sites in Asia, Europe and South America. The monthly-cumulative data to the end of the year 2004 have been presented before. In this paper, successive data to the end of the year 2007 are compiled and the trends and correlation analyses with yearly and monthly average amounts of columnar ozone are presented. Mean yearly doses at 10 northern and 6 southern hemisphere sites exhibited exponential latitudinal gradients with similar slopes indicating a doubling of the dose with the decline of about 14 degrees. Among 12 sites where continual data for more than 6 years were available, increasing trends in yearly UV doses were observed at 11 sites. At one European (Brussels), two tropical Asian (Padang and Denpasar), and two South American (São Martinho and Punta Arenas) sites, decreasing trends of ozone amounts were noted, whereas at the remaining 6 sites (five sites in Japan and Thessaloniki), increasing trends of the UV doses were observed without notable changes, or with an increase at one site (Kiyotake), of the average ozone amounts. At one site (Taipei), the UV doses and the ozone amounts stayed constant. In the monsoon areas, climatic variations and changes, particularly in the extent of cloudiness and frequency of rainfall in summer months, might have been largely responsible for the trends of the UV doses. However, even at these sites, the decreases in the ozone amounts in summer months were frequently observed and might have contributed to the increasing trends of the UV doses. Since each region and locality is unique in climatic and atmospheric conditions, it is not easy to generalize the global trends. However, at many sites involved in this monitoring project, the increases in the biological UV doses during this period seemed to be linked to the decreases in the ozone amounts. [ABSTRACT FROM AUTHOR]