This article throws light upon the seven major consequences of global warming. The consequences are: 1. Sea Level Change 2. Global Warming and the Potential Water Crisis 3. Global Warming and Tropical Monsoon Change 4. Global Warming Crop Production 5. Climate Change and Food Security 6. Decline of Biodiversity 7. Global Warming and Vector Borne Disease.
Consequence # 1. Sea Level Change:
Global mean sea level rose 10 to 20 cm in the 20th century and in the 21st century, human induced climate change will contribute to a global rise of 20 to.100 cm. Additionally it is assumed that 20% and 40% people who are living within 30 km and 100 km from the coast will be affected by coastal flooding.
Global mean sea level rise will be induced by:
1. Thermal expansion of sea water,
2. Melting of land based ice viz:
3. Human modification to the Hydrological cycle.
Subsequently local sea level change will be induced by:
1. Land uplift/subsidence and
2. Ocean changes viz:
(ii) Wind pressure, and
(iii) Ocean currents
A recent sea level rise trend is shown in Fig. 14.6.
Consequence # 2. Global Warming and the Potential Water Crisis:
World faces water crisis as global warming upsets balance. The ice sheets of Antarctica—the world’s largest reservoir of fresh water—are shrinking faster than new snow can fall, scientists have reported in their comprehensive survey of the continent.
Thus, global warming will make water crisis into non-replenisable state in the near future. The water cycle will intensify, causing extreme weather events such as hurricanes and increasing the frequency and severity- of droughts and floods.
Intensifying rains and droughts are related to climate change and to the melting of glaciers. Climate change has exacerbated flooding and water scarcity. The water crisis threatens the security, stability and susceptibility of the planet and consequently, humanity itself.
Consequence # 3. Global Warming and Tropical Monsoon Change:
Some circumstantial evidence points to the possibility that global warming will yield stronger monsoons. Increases in sea surface temperatures, land heating, and air temperatures suggest the potential for an increase in summer rainfall.
1. It is observed that monsoon precipitation variability in the central Himalayas over the past three centuries is due to the increase of temperature in Northern Hemisphere and melting of ice core.
2. This indicate that increase of summer monsoon precipitation in High Asia is a consequence of global warming.
3. For the period 1900-1995 Indian monsoon precipitation in the Himalayas, Nepal, Bangladesh and Northern India and transportation of water vapour from tropical Indian ocean is highly correlated with the thermal contrast between the Tibetan Plateau and the tropic Indian Ocean.
4. An assessment of climate change on Africa’s waterways revealed that they are highly sensitive to shifts in rainfall patterns.
Consequence # 4. Global Warming Crop Production:
Agricultural activities serve as both sources and sinks for greenhouse gases, so specific agricultural practices could slow the pace of global warming. Methane dynamics are linked closely to livestock production practices and wetland agriculture, such as rice production.
Global assessment suggests that a doubling of the atmospheric carbon dioxide concentration will lead to only a small decrease in the global crop production. Altered weather patterns can increase crop vulnerabilities to infection, pest infestations, and choking weeds.
Some overall effects of global warming on agriculture is shown in Fig. 14.7.
Consequence # 5. Climate Change and Food Security:
Overall, climate change, including global warming and increased climate variability, could result in a variety of impacts on agriculture.
Some of these effects are biophysical, some are ecological, and some are economic:
1. A shift in climate and agricultural zones towards the poles
2. Changes in production patterns due to higher temperatures
3. A boost in agricultural productivity due to increased carbon dioxide in the atmosphere
4. Changing precipitation patterns
5. Increased vulnerability of the landless and the poor.
6. It seems obvious that any significant change in climate on a global scale should impact local agriculture and thereby affect the world’s food supply.
7. Climate change-over the next century may have significant effects on food supply, i.e., how much food is produced, as well as food security.
Consequence # 6. Decline of Biodiversity:
In contrast with the environmental constraints, biodiversity decline exerts a mostly indirect and long-term impact. We shall need all the genetic variability we can find to cope with both present pests and diseases and future problems such as the vagaries of climatic change.
There is an unprecedented premium on crop types with resistance to too little or too much rainfall, increased UV-B radiation, and new pathogens. Yet we are losing in the region of 50,000 species a year from a planetary complement of 10 million species (minimum reckoning), and probably a much higher proportion of species’ populations.
This extinction rate is accelerating rapidly: we may well witness the demise of half of all species and most populations of surviving species by the middle of the next century.
Consequence # 7. Global Warming and Vector Borne Disease:
In the past five years, there has been increasing discussion about global warming and its potential impact on diseases like malaria and dengue fever in the tropics and even in temperate zones. Indeed, many scientists point to global warming as a factor in the spread of malaria and other vector borne infectious diseases and new epidemics of malaria, yellow and dengue fever and encephalitis.
Rising temperatures could also extend the transmission season for the dengue.
Major global climate change, demographic and societal changes of the past 50 years have directly affected the emergence/resurgence of vector-borne and other infectious diseases. Other societal changes, such as agricultural practices and deforestation increase the risk for vector-borne disease transmission.
Although many consider the introduction or re-establishment of vector-borne diseases in temperate zones to be of primary concern, the authors emphasise that tropical ecosystems that have experienced repeated stress may be less resilient and more vulnerable to the effects of climate change.