Global climate models project a best estimate of a further two to four degree (Celsius) increase in the mean temperature of the Earth by the end of this century. Although this may seem insignificant on an intuitive level, the resulting impacts are of significant concern. Sea-level rise is the most significant threat for coastal areas as a result of melting glaciers. Apart from this threat, changing weather patterns will result in drought and inland flood threats for some areas. As a general principle of climate change, changes to the mean of meteorological extreme value distributions can be expected but an increase in tail thickness (or variability) is of greater concern. The day-to-day variability that we see today will likely expand.
The most pervasive hazard of global warming is coastal flooding. A sea-level rise of at least 25 to 50 centimeters can be expected by the end of the century (with the understanding that a wide range of sea-level rise scenarios exist). This is obviously of great significance for coastal cities and communities. It is of particular concern to fishing and agricultural communities located on the Asian coasts, many of which are located on low-lying and flat geographical areas.
The recent consequences of Cyclone Nilam in Eastern India and Superstorm Sandy in the U.S. Northeast are examples of the flooding threat, and such impacts will likely become more severe as sea levels rise. The impacts of tropical cyclones, extratropical cyclones and tsunamis will all be amplified for vulnerable areas if sea levels rise in line with expectations, posing significant socieoconomic threats.
Changing Precipitation Patterns - Flood
According to the IPCC, evidence to assess climate-driven changes in the magnitude and frequency of flooding events is hampered by limited flood gauge data and the unknown influence of changes in land use and engineering. However, it also adds that some regions have seen significant trends in the number of heavy precipitation events (most seeing increases rather than decreases) while acknowledging that there have been strong regional variations. (1)
Many inland areas of the world prone to flood face an increasing threat under global warming. In fact, some regions, even with a reduced annual total of rainfall, face the prospect of increasing rainfall rates as a consequence of global warming. Storm water management systems, particularly those of older design, are generally not equipped to handle the events of today’s climate and urban flood is certainly an issue as a result. The Thailand floods of 2011 demonstrate the impacts of this threat. This hazard will increase in severity under global warming.
1. IPCC SREX, 2012.