Climate Change in the Himalayas

This chapter primarily provides an overview on climate and climate change with a general description on climate system its connection with geological phases and sun-earth system as a whole. Archeologists and historians have attributed many episodic changes in human civilization to the climate changes which have also been detected in the data relating to the evolution of geomorphic features in the time span of the geological periods. The first few sections deal with the evolution of science of climate change and its theoretical and observational foundation. Mechanisms taking place through the atmosphere as a result of solar radiation and anthropogenic activities are also described. Solar spectrum and the interactions with earth-atmosphere system are discussed along with the thermal structure of the atmosphere. The role of greenhouse gases (GHGs) is to give rise to the mean surface temperature of earth and its repercussions on Himalayan ecosystem, in particular, demonstrates a dynamic interplay of all forms of weather and climates interacting with a highly fragile mountain ecosystem. Science of climate and climate change has been enriched by a large galaxy of scientists from diverse disciplines coming from many countries and a few of them have been mentioned in the respective section. A holistic picture of global climate emerges out of evolutionary and interactive processes within a complex system consisting of five major components, namely, Atmosphere, Hydrosphere, Lithosphere, Cryosphere, and Biosphere. The climate change due to natural causes, in terms of Milankovitch hypothesis, a very large timescale and a very small timescale such as El-Nino is also discussed. IPCC WG1 report has provided the observed global mean land and ocean surface temperature anomalies from 1850 to 2012 that indicates the increasing trend in the global rise in temperatures as a result of increase in the anthropogenic emission of GHGs. There are a number of governmental and non-governmental organizations working with many initiatives focused on environmental issues, the role of such organization to mitigate various climate-related issues are discussed in the section devoted to it. Climate in India has always been a key factor in the socioeconomic well-being of the country; therefore, there have been a number of Indian national initiatives on climate change in the recent past in concurrence with the international agencies. A section summarizes the climate science in the context of ancient ideas and from historical perspective which gives a detailed account on the chronological development of climate science right from the time of Rigveda with the famous sentence “आदित्यात् जायते वृष्टि: | वृष्टि: धान्यम् तत: प्रजा।” to the modern observational network and the weather forecasting system. The chapter also presents the observations and data for climate change studies taken over 300 Indian stations established by India meteorological department. All-India surface temperature and rainfall anomalies are the highlights of this section. Finally, the relation between climate change and society is presented.

This chapter on Himalaya describes the geographical and ecological importance of the Himalaya with a detailed description of its weather and climate. The role of Himalaya in the establishment and maintenance of monsoon systems over South Asia is highlighted and explained. Lack of high spatial density meteorological observations continuously over a long period of time is a handicap in documenting the climate change scenario and precisely detecting the signal of change over the region. This chapter therefore describes the position of meteorological data collection over the region including the multiagency efforts of the recent years. The weather and climate study of the region is based on number of challenging scientific issues. The chapter contains a list of those for the benefit and the guidance of research works in the field. Himalaya being the best example of studying the high altitude meteorology, a brief introduction to various studies and observations relating to the altitude dependency of surface climate parameters particularly the surface temperature is also reviewed. A comprehensive analysis of available temperature data (maximum, minimum, extremes and range) is presented for the Western Himalaya from the global grid point data sources. The analysis clearly brings out the increasing trends in the temperature parameters more significantly detectable during certain seasons for the recent periods. These upward trends of temperature point out the influence of global warming which needs to be further documented and analyzed.

Himalayan region mainly consisting of fragile mountain systems is very sensitive and venerable to the climate change that possesses a serious threat to the livelihood and socioeconomic activities of the population residing in the Himalayan states, for example, cloudbursts and flash floods as a result of heavy rain are commonly observed during Indian summer monsoon season. This chapter delineates about the Himalayan weather systems, cloud and precipitation processes, and their microphysics. The various types of ice crystals synthesized in a laboratory environment are also presented to understand formation mechanism of hydrometeors inside the clouds. The Mountain topography plays an important role in modulating the large horizontal flows and influences the diurnal variability of wind locally around and along the mountain slopes. Some examples of occasional fronts observed over a central Himalayan site during different seasons are also presented here. The events discussed are based on the micrometeorological observations made over the high altitude site mentioned here. The analysis shows that frontal activities in spring and summer seasons are dominant as compared to winter and series of fronts are observed during every month from March to June of 2014. During these episodes, the cold air mass suddenly replaces the warm air with rapid fall in temperature of the order of 5–10°. The intensity of the front observed in winter is much higher than those observed in spring and summer.

This chapter presents a brief introduction to the complex but very important subject of climate modeling without going into the details of mathematical formulations and hierarchy of currently available models and their results. Models are numerical representations of the climate system based on physical, chemical, and biological properties of their components which provide future projections on global as well as regional scales. To generate acceptable future climate projections, it is essential that many plausible scenarios of greenhouse gases are designed taking into account alternate pathways of development strategy likely to be adopted by the human societies. These alternate options may have their representative concentrations of greenhouse gases and other external forcing functions. Therefore, the chapters have a very important section on emission scenarios which presents a summary of sets of alternate scenarios suggested by the scientific groups under the IPCC guidelines. Since the authenticity of the model projections is a function of the initial scenario, the chapter describes the entirely family of IPCC emission scenarios extensively used by various modeling groups. To model the large-scale circulation features and other physical parameters on global scale, the models are built on a closed system involving the entire Earth system known as General Circulation Models. For the projection of climate of a smaller subregion the models are designed over a smaller region taking into account the local factors using the boundary conditions generated by the GCMs. These can be further down scaled to represent much smaller regions. In view of the importance of regional climate, some description is provided with examples of regional climate model (RCM) experiments and the merits and demerits of global versus the regional climate models are pointed out. Lastly, the chapter provides a summary of recent studies relating to the model generated climate scenarios of the future over the Asian monsoon region. Some results of a case study for western Himalayan region are also presented.

This chapter describes the basic ingredients of climate change for the central Himalayan region mostly represented by the state of Uttarakhand in the northern part of Central Himalaya. The geographical, hydrological, and environmental significance of the region in context of changing climate scenario is presented. Surface meteorological parameters for the region using available grid point data are analyzed. The analysis demonstrates an increase in the surface temperature values during the recent decades. The state of Uttarakhand is a region of highly variable climate from south to north as well as from one part to the other coupled with a climate-sensitive fragile ecosystem. Therefore, to detect the signals of climate change it is essential that the greenhouse gas (GHG) emission status at present and its potential to grow in future is critically examined. A subjective description on major sectors with high emission potential is discussed. These include industry, power generation, transportation, agriculture, firewood, and biomass burning. The region at present is having very low level of emission from these sources; however, the potential for future increase is also discussed in a subjective manner and elaborated.

This chapter provides a brief description of glaciers in Uttarakhand Himalaya and witnessed the impact of climate changes over the past few decades. Glaciers are inhomogeneously distributed from north-west to south-east along Himalaya, and recent studies have brought out that shrinking of glaciers is taking place at alarming rate. Observations over Central Himalayan region have revealed an average retreat of glaciers about 17 m in last six decades, and Gangotri, Chaurabari, Pindari, and Dokriani are some of the major glaciers of Uttarakhand Himalaya that have experienced the impact of climate change. The Central Himalayan region is endowed with efficient hydrological cycle fed by prevailing favorable weather patterns such as western disturbances in winter and monsoons in summer, but there has been a general trend of depleting water availability at source region due to climate change in past century. Climate change has adversely affected the water resources, forest and biodiversity, agriculture and human health; all these aspects are summarized in the context of Uttarakhand state. As per IPCC 2013 report and the analysis of long period available data on rainfall suggests that extreme weather events and natural disasters are likely to increase. An example of natural disaster took place at Deoli village in Almora district is also presented.

The pronounced consequences and future threats of climate change mainly affecting the fragile mountain system of Himalayan Uttarakhand need to be addressed through suitable policies and mitigation strategies. This chapter describes briefly the policies to be adopted in various sectors which are relevant to the climate change issues and specific to the state of Uttarakhand. The major contribution to improve the quality of life along with environmental management can come through modern ingredients in traditional agriculture practices and allied sectors such as watershed management, soil and water conservation, organic farming, agro-horticulture, herbal and aromatic plants. Based on the past observations and the projections of future climate change scenarios, it is expected that many species are likely to shift latitudinally northward in a relatively short span of time. Hence, state will have to be proactive in implementing the rules and regulations relating to forest, wild lives, and biodiversity reserves. The regulations and laws for the conservation, distribution, and use of water and allied sectors are almost non-existent and need to be framed by taking into account the community preparedness and partnership. Himalayan population of the Uttarakhand state is vulnerable to the natural disasters and needs to have a proper policy in place for reduction and relief, which may include the use of modern technology and involvement of the expertise from National institutes. This chapter also emphasizes on the impact of unorganized industries and transport sectors on the Uttarakhand mountain ecosystem as a whole, and the strategies to be adopted to avoid the potential threat of climate change.