S.R. Gupta and Arun Lekha
Mangroves are taxonomically diverse group of salt tolerant, broad-leaved evergreen trees and shrubs that grow primarily in tropical and subtropical coastal regions of Asia, Australia and America. Mangroves are made up of salt tolerant evergreen trees and act as natural buffers against tropical cyclones. Mangroves have special aerial roots, prop roots and buttresses to live in muddy, shifting and saline conditions. Theses mangrove systems are the nurseries of many invertebrate species and fish. The Sundarban Mangrove forest, covering an area of 16,000 km2 of land and water, is the longest mangrove forests in the world. Sundarban mangrove lies within the delta of the Ganges, Brahamputra and Meghna rivers in the Bay of Bengal; 60% of the area lies in Bangladesh and 40% area in India. It is a biosphere reserve and the core area (Sundarban National Reserve) is world Heritage site. Under the project Tiger, the Government of India has established a Tiger Reserve in Sundarban.
The Sunderbans Mangrove harbours a rich biodiversity of plants and animals, and is the only habitat for the endangered Royal Bengal Tiger. There is great abundance of invertebrates, birds, insects, monkeys and reptiles. The mangrove ecosystem provides income to the local people from the collection of mollusks, crustaceans, fish and honey. A large number of species of prawns and shrimps are exploited commercially. According to IPCC report 2007, sea level rise is the greatest threat to the Sundarban mangrove system because of flooding of low-lying delta, retreat of shoreline, saliniztion and acidification of soil, changes in water table and adverse effect on livelihood of local people. Mangrove will be affected greatest by sea-level rise. In the case of a 45cm rise in global sea level will cause a destruction of the 75% of the Sundarbans mangrove. Some climate change models also predict increased frequency of tropical cyclones in coastal regions that will impact the biodiversity and resilience of the mangroves.
POSSIBLE CLIMATE CHANGE IMPACT ON MANGROVES
Possible Impact
Temperature Increase
Change in seasonal patterns of reproduction of plants and animals
Elevated CO2
May cause species specific variations
Sea- level changes
Decrease in geographic distribution
Change in species composition
Change in species diversity of mangroves on small islands
Tropical storms
Increased frequency and intensity of storms will affect salinity levels, flooding of low lying areas and wetland sediment budget
Precipitation Change
Effect on plant growth and aerial extent
Sources:
IPCC (2007), and Brij Gopal and Malavika Chauhan(Aquatic sciences, 2007)
Monday, May 26, 2008
Global Climate Change: Science and Policy
Dr Sharda R. Gupta
At the start of the 21st Century, we are confronted with a crisis of climate change. The Fourth Assessment Report of the Intergovernmental panel on Climate Change has established an overwhelming scientific consensus that climate change is real and happening due to human activities.
WHAT MAKES THE CLIMATE CHANGE?
Climate change refers to any change in climate over time, whether due to natural variability or as a result of human activity. The Earth’s climate is influenced by many factors, mainly by the amount of solar radiation coming from the sun, the amount of greenhouse gases, water vapour, aerosols in the atmosphere and the properties of the Earth’s surface which determine how much of this solar energy is retained or reflected back to space. The phenomenon of trapping and reradiating heat by the greenhouse gases in atmosphere is referred as greenhouse effect.
The atmospheric concentrations of greenhouse gases (GHG) such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) have significantly increased since the beginning of the industrial revolution. This is mainly due to human activities, such as the burning of fossil fuels ( coal, oil, and natural gas), deforestation and change in land use, and agriculture.
The current atmospheric concentrations of 380 ppm (CO2 molecules per million molecules of air) of carbon dioxide far exceed levels of last 420,000years ( 180 to 280 ppm) as determined by the scientists from Vostok ice core (Figure 1) and that of 650, 000years record of the European Project for Ice Coring in Antarctica ( EPICA). In recent times, the direct measurements of CO2 have been carried out in Antarctica , Mauna Loa Observatory, Hawaii, USA ( Figure2); Point Barrow Alaska; American Samoa and Trinidad. Climatologists reporting for the United Nations Intergovernmental Panel on Climate Change (IPCC) have clearly shown that global warming has been caused by human activities
CLIMATE CHANGE INDICATORS
1. Global temperature increase over the last 100years (1906-2005) by 0.740C.
2. Reduction of Arctic Sea Ice summer extent; being lowest in September, 2007 according to the latest report published in New Scientist on 28 April, 2008 ( Figure3).
3. In the Antarctica in southern hemisphere, 87% of glaciers have retreated over the last 50 years.
4. The volume of summit glacier on Kilimanjaro Mountain in Africa has decreased by 81% from the year 1912-2000..
5. Gangotri Glacier, one of the largest glaciers in Himalaya, has retreated by as much as 30m per year in the past decade ( Figure 4).
6. Global sea level has risen by 17cm during the 20th century.
7. In the Arctic Circle, the Inuit are loosing their hunting cultures due to retreating Arctic Ice and permafrost.
8. Mumbai in its suburb Santa Cruz received a very high rainfall of 94.4 cm with in a span of less than 24 hours on July 25, 2005..
PROJECTED IMPACTS OF GLOBAL WARMING
Based on Fourth Assessment Report of the Intergovernmental Panel on Climate Change ( IPCC), 2007.
Elevated temperatures of the biosphere
The best estimates for global temperature increase from the 1980s to the end of the 21st century range from 1.8°C to 4.0°C
Melting of Glaciers
- melting of polar ice in both the Arctic and Antarctic
- Melting of glaciers, glacier lake outburst, increase in flooding
- increase in sea level (flooding of major cities)
- increase in thaw depth of permafrost in the arctic region
Water and Coasts
- More rainfall during shorter periods in continental areas
- more floods and storms in coastal regions
- More evaporation and soil moisture deficiencies
- Rock avalanches from destabilized slopes
- High exposure of population and infrastructure on small islands states ( e.g. Mauritius).
Ecosystems
- Terrestrial biosphere tends towards a net carbon source
- species migration and increasing risk of extinction
- In tropical oceans, increased coral bleaching and widespread coral mortality
- Significant extinction of species around the globe
Food
Cereal productivity to decrease in some regions
Adverse impacts on subsistence farmers and fishers
Decline in yields of corn, wheat, rice and other major crops
Human Health
- heat stress, floods and drought
- Malnutrition and increased disease burden
- migration of disease vectors
INTERNATIONAL ACTION
The Kyoto Protocol ratified on 16 February, 2005 requires countries to take appropriate measures to reduce their overall greenhouse gas emissions to a level at least 5.2% below the 1990 level during the initial commitment period 2008-2012. As of April 2008, 178 member Parties have ratified the Kyoto Protocol of the United Nations Framework Convention on Climate Change (UNFCCC 2008). Under the Clean Development Mechanisms (CDM) of Kyoto Protocol, greenhouse gas reduction projects in developing countries like India, China, Brazil, Indonesia, etc., can earn certified emission reductions.
The Nobel Peace Prize for the year 2007 has been awarded to the Intergovernmental Panel on Climate Change (IPCC) jointly with Mr Al Gore. Dr R.K. Pachauri ( Director General, Tata Energy and Resources Institute, TERI, New Delhi), and presently Chairman of the IPCC.
STABILIZING OUR CLIMATE: THE NEED FOR ACTION
15% of world population in developed countries account for almost half of emission of CO2. A recent report has shown that high income nations produce 5.7 times more greenhouse gases emission than low income nations, but low income nations bear greater burden of climate changes (PNAS, February 2008).
There is need to reduce annual carbon emission by about 7 billion tons by 2050. Professor Robert Socolow, Princeton University, USA argues that we already have the science and technology to do so and has given the seven wedges stabilization triangle comprised the various technological solutions. A “wedge” is a strategy to reduce carbon in confronting the problem of greenhouse warming; we must strive to speed up every one of these options over 50 years to provide at least one wedge (Figure 5).
The World Environment Day slogan for 2008 is Kick the Habit! Towards a Low Carbon Economy. Thus, it is important to take initiatives that promote low carbon economies and life-styles, such as :
1. To improve efficiency of buildings, ground transport, industrial processing, and lighting, thermal power plants.
2. Renewable Energy from wind, photovoltaic , hydropower, and organic wastes.
3. Reduced deforestation, afforestation and new tree plantations.
4. Improving biological productivity of Agricultural lands.
5. By changing life styles, managing the wastes and conserving our biodiversity.
Promoting eco-friendly consumption.
CONLUSION
The climate change process is not only biophysical, but also has social profile. Most of the work on climate change has to date focused on mitigation and adaptation strategies to address its causes and consequences to the environment. More recently, the promotion of sustainable development and poverty reduction have brought into focus the human dimension. Today, a much needed step forward in the direction would be to fully integrate human rights when meeting the climate change challenges. Now, it is time to look at some of the deeper implications of climate change, in particular its implications for global fairness and equity.
