**2. Causal factors of climate change and forecast**

The various physical processes in our environment at a local scale combined with responses to global climatic phenomena at a large scale form the basis of 'regional climates'. Notable examples of global-scale climatic phenomena and their respective variability in present times include Monsoon Systems, Tropical Phenomena (including the popular El Nino Southern Oscillation), Cyclones, Blocking, Atlantic Multidecadal Oscillation, Pacific South American Pattern, etc [1]. These phenomena are largely considered relevant to climate dynamics because of perceived or proven confidence that they can influence regional climate and are likely to change over time. Various physical parameters are taken into account while understanding the dynamics of regional climate, such as overall transfer of heat and moisture, and their

#### *Understanding the Impact of Global Climate Change on Abiotic Stress in Plants… DOI: http://dx.doi.org/10.5772/intechopen.109618*

momentum into a region [1]. According to recent updates, there continues to be a debate around the causality of natural and anthropogenic factors towards influencing climate change and also the impact of each of the causal factors. One of the latest findings has suggested that both natural and anthropogenic factors are responsible for temperature changes, contrary to what one might think, that the anthropogenic factors majorly contribute to the global rise in temperature. In addition to this, the study also indicates that there is a connection between the rise in temperature and concentration of greenhouse gases [2]. The current trend of temperature variability is arguably accredited to both natural and anthropogenic factors. For instance, sharp deviation from the present greenhouse warming trend has been noted in regions with variable volcanic activities—a period of unusually heavy activity is followed by strong cooling, while a period of low activity is accompanied with greater warming [3]. However, it is still supported by several studies that by limiting the timescale of climate analyses to more recent times, we can see that anthropogenic factors have been the major contributors to the greenhouse global warming trend. Additionally, the anthropogenic aerosols as well as greenhouse gases have influenced climate change through influencing regional temperatures and long-term changes in monsoons [3].

Despite the need to understand and precisely delineate the underlying causes of the changes in climatic conditions (such as temperature change and precipitation variability), we also need to keep an eye on the current trend of climate variability. Keeping in mind the Indian subcontinent, we have presented here the status of and predictions for climate change in South East Asia. It has been reported that S.E. Asia has observed a rise in temperature at the rate of 0.14–0.20°C per decade since the 1960s [4]. This is also accompanied by an increase in number of hotter days and warmer nights, with a simultaneous decrease in cooler weather [5, 6]. The trend for incidence of heavy and light rain episodes is positive, while that of moderate rain episodes is negative [7]. The annual rainfall on total wet day has increased at an average of 22 mm per decade, while that on extreme rain days has increased at an average of 10 mm per decade [6, 8]. It is indicated that warming is expected to persist, with extensive variation on regional basis [1]. Also, there is likely to be moderate increase in precipitation, with the exception of the part of Indonesia near to the southeast Indian Ocean. In parts of terrain, variation in precipitation is most likely to be strong [1].
