Socioeconomic and Hydrological Impacts of Climate Change By Shishir Reza

Climate change is becoming an ever more crucial issue in our lives. We have come to realise that the modern ways of man place a enormous amount of stress on the Earth that nature simply cannot handle. Some of the climatic problems that are developing today, such as global warming, ozone depletion and El Nino, will have severe effects on reef ecosystems all around the world. Reefs might give us an early indication of the effects of global climate changes, as slight variations in sea temperature caused by climatic variations have already been shown to produce extreme responses from reef ecosystems.
The world is warming up. As we burn up the planet’s coal, oil and gas reserves, and cut down its remaining forests, greenhouse gases are pouring into the atmosphere. The delicate balance of atmospheric gases that sustains life is thickening, trapping more and more heat and irreversibly changing our world.
The United Nations Framework Convention on Climate Change defines climate change as, “a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods”.
Climate change is caused by the emission of heat-trapping gases –mostly carbon dioxide (CO2) from vehicles, industry, power plants and deforestation. As these gases build up, they act like a thick blanket, overheating the planet, changing our health economy and natural environment.
The terms global warming and climate change are often used interchangeably, but the two phenomena are different. Global warming is the rise in global temperatures due to an increase of heat-trapping carbon emission in the atmosphere.
Climate change, on the other hand, is a more general term that refers to changes in many climatic factors around the world .These changes are happening at different rates and different ways.

Factors of Climate Change
Scientists around the world now agree that the climatic changes occurring internationally are the result of human activity. Although responsibility for the causes of climate change rests primarily with the developed and industrialized nations, the costs of climate change will be borne most directly by the poor. Many factor are responsible for Climate change but mainly it can be divided in to two factor man made factor & natural factor
The main man made factor of Climate change is greenhouse gasses (GHGs), which enhance the “greenhouse” properties of the earth’s atmosphere. These gasses allow solar radiation from the sun to travel through the atmosphere but prevent the reflected heat from escaping back into space. This causes the earth’s temperature to rise.GHG emissions have been raising since industrialization in the 1900s, due to increased burning of fossil fuels. Further significant increases in GHG levels are expected, particularly as developing countries become more industrialized. Deforestation is also the reason of climate change .Every country must have 25% but many have not sufficient forest.
Natural factor are also responsible for Climate change such as earthquake, bushfire, etc natural factor can not control but it can be protect, but man made factor are mainly responsible for climate change. It is due time to take stapes to protect climate change otherwise it may be too late .

Impact’s of Climate Change on Bangladesh Economy:
In recent times, the global climate change is one of the most discussed issues among the environmentalists, scientists and concerned people. The scientific community around the globe is fully convinced that climate change is a reality and the adverse impacts of climate change will be both irreversible and disproportionate on the poor. There are scientific evidences to suggest that concentrations of certain ‘heat trapping’ gasses in the atmosphere, popularly known as the greenhouse gasses, are on the rise. GHGs are emitted primarily when fossil fuels are burnt for industrial activities, electricity generation and transportation. Scientists fear that gradual accumulation of such gases would eventually cause a rise in atmospheric temperature and thereby, the global surface temperature. Based on atmosphere-ocean-terrestrial heat exchange mechanism, it is postulated that a general rise in surface temperature would also cause swelling of ocean water, an increase in melting of snow-caps at the peaks and ice-sheets and overall rise in mean sea level. A combination of such events will have discernable impacts primarily on natural system and also on ecosystems. Such an adverse effect is generally known as the ‘greenhouse effect’.
The global scientific community has already forecast that the impacts of greenhouse effect will be devastating in many parts of the world, especially in the low-lying coastal areas .In Bangladesh climate change effected in everywhere especially in the economy . Coastal agriculture will be devastated due to tidal inundation and salinity in Bangladesh for this reason many crops cannot cultivated and many species are destroyed .Infect it create a big economic loss.
For climate change many people loss their home and they become poor and poor and people face many health problem for this purposes they also face economic travel Low-lying lands and wetlands will be submerged with saline waters for saline water many water-bodies loss their life and which people are depends on this water-bodies they are affected .
Human settlements and physical infrastructure will be destroyed due to prolonged inundation and tidal surges; economic activities will be adversely affected; and recreational and tourism facilities will have to be abandoned permanently – all such effects will be not only in observed in the coastal areas but also observed all area in Bangladesh .It is right time to protect our environment otherwise it will be too late.
Climate affects agriculture , a fact well known to every farmer. Year to year variations in harvest are largely due to variations in temperature and precipitation that can make the difference between bountiful bumper crops and economic ruin. Agriculture is extremely vulnerable to climate change. Higher temperatures eventually reduce yields of desirable crops while encouraging weed and pest proliferation. Changes in precipitation patterns increase the likelihood of short-run crop failures and long-run production declines. Although there will be gains in some crops in some regions of the world, the overall impacts of climate change on agriculture are expected to be negative, threatening global food security. Agriculture – on which we all depend for our food – is under threat from climate change.
There is no doubt that systems worldwide will have to adapt, but while consumers may barely notice in developed countries, millions of people in developing countries face a very real and direct threat to their food security and livelihoods.
Climate change will have serious impacts on world food supplies , especially in the less developed countries. Global warming will probably shift growing areas by several hundred kilometers per degree increase in temperature , increasing agricultural productivity in some areas of the world, while drastically decreasing it in others. In the developed countries of the temperature zone , climate change will probably have little negative impact on agricultural production.
Changes in atmospheric carbon di oxide , temperature, precipitation , and soil moisture , individually or together, could alter crop production. Computer models can estimate the effects of climate change on agricultural production and crop prices. Dynamic crop growth models use physiological, morphological, and physical process to predict crop or yield under different environmental conditions. A variety of economic models can then estimate the effects of climate change on the agricultural sector of the economy.
Climate change presents many complex risks to different groups and sectors over different timeframes and localities. Adaptation is likely to be successful if people are informed about climate change, how it affects them, and options for doing something about it. Successful climate change interventions are dependent on high-quality accessible information to allow effective decision making. As the impacts of climate change are difficult to predict accurately, adaptation activities need to be flexible and responsive to new information, and robust to withstand a wide range of plausible futures. The use of risk management and coping thresholds is an area of applied adaptation research of growing importance (Jones and Boer 2003).A
Agricultural climate information is now used to advise farmers about their choice of crops and methods of cultivation, which in turn has provided major benefits in terms of increased yields and preventing food shortages. Similarly, better information and early warning systems for farmers can reduce vulnerability to inter-annual climate variations and enable responses to be proactive rather than reactive.

There are some causes for concern about agriculture in Bangladesh. Over the course of the 21st century and beyond, sea level rise will threaten hundreds of thousands if not more than a million hectares of agricultural land. For example, Islam et al. (undated) estimated that in eastern Bangladesh alone 14,000 tons of grain production would be lost to sea level rise in 2030 and 252,000 tons would be lost by 2075 (current agricultural production for the country is 30 million tons; WRI, 2001). Threatening the richest and most productive region of the country, sea level rise could have dramatic consequences for the Bangladeshi economy. A recent study estimates that a GDP decrease in the range of28% to 57% could result from a 1m sea level rise.
Drought a prolonged, continuous period of dry weather along with abnormal insufficient rainfall. It occurs when evaporation and transpiration exceed the amount of precipitation for a reasonable period. Drought causes the earth to parch and a considerable hydrologic (water) imbalance resulting water shortages, wells to dry, depletion of groundwater and soil moisture, stream flow reduction, crops to wither leading to crop failure and scarcity in fodder for livestock. Drought is a major hazards faced by communities directly dependent on rainfall for drinking water, crop production, and rearing of animals. Since ancient times droughts have far-reaching effects on mankind. Large land areas often suffer damages from dust storms and fire. Drought could be the reason for migration of early human communities.
In Bangladesh drought is defined as the period when moisture content of soil is less than the required amount for satisfactory crop-growth during the normal crop-growing season. Droughts are common in the northwestern districts of Bangladesh. Some of these droughts usher in famine. One definite manifestation of the onset of the drought is the ‘top burning’ of the bamboo and betel nut trees, that is, they loose green foliage and the fresh leaves turn brown because of lack of moisture in soil and air. The condition often culminates to their death, if there is no rain or irrigated water for a substantially long time. However, drought can also occur in areas that usually enjoy adequate rainfall and moisture levels. Due to drought severity, crop loss ranges between 20 and 60 percent or even may be more for transplanted aman and other rice varieties. Depending on the intensity of drought, the estimated yield reduction of different crops varies from 10% to 70%. The yield loss may considerably be reduced through judicious and limited irrigation at the critical stages of crop growth (Banglapedia,2008).
The average highest temperature of the Barind region ranges from 35°C to 25°C for the hottest season and 12°C to 15°C for the coolest season. Generally this particular region of the country is rather hot and considered as a semi-arid region. In summer, some hottest days experience the temperature of about 45°C or even more in the Rajshahi area, particularly at Lalpur. Again in the winter the temperature even falls at 5°C in some places of Dinajpur and Rangpur districts. So this older alluvium region experiences the two extremities that clearly contrast with the climatic condition of the rest of the country.
Drought mostly affects Bangladesh in pre-monsoon and post-monsoon periods. From 1949 to 1979 drought conditions had never affected the entire country. The percentage of drought affected areas were 31.63% in 1951, 46.54% in 1957, 37.47% in 1958, 22.39% in 1961, 18.42% in 1966, 42.48% in 1972 and 42.04% in 1979. During 1981 and 1982 droughts affected the production of the monsoon crops only. During the last 50 years, Bangladesh suffered about 20 drought conditions. The drought condition in northwestern Bangladesh in recent decades had led to a shortfall of rice production of 3.5 million tons in the 1990s. If other losses, such as, to other crops (all rabi crops, sugarcane, tobacco, wheat etc) as well as to perennial agricultural resources, such as, bamboo, betel nut, fruits like litchi, mango, jackfruit, banana etc are considered, the loss will be substantially much higher.
Large increases in the volumes of greenhouse gases in the atmosphere are already apparent. At current rates of change, carbon dioxide concentration in the atmosphere will double by the end of the next century (2100 AD). Calculations indicate that this rate of change in carbon dioxide alone will may result in a warming of between 1.5 and 4.5°C. Some researchers have calculated that we have already experienced a rise of about 0.7°C since the start of the century. The most likely effect of sustained global warming will be a melting of the polar ice caps, and a rise in sea level, while on land the deserts will expand. It is feared that sea level could rise by as much as 80cm by the end of the year 2100. Coral reefs could possibly keep up with the rise in sea level, but a global rise in sea temperature could be devastating (see bleaching below). The deep ocean may eventually absorb most of the temperature rise, but this may take hundreds or thousands of years. Another threat to marine ecosystems is the increase in ultraviolet radiation (UV) penetrating the atmosphere. This is a separate issue to the Enhanced Greenhouse Effect, but comes about due to the destruction of the ozone layer by greenhouse gases. Ozone is important in the high atmosphere to absorb UV radiation, and gases such as CFC’s (which are entirely man-made) destroy it. UV radiation is harmful to many animals and plants, and one of the most important effects of increased UV is the inhibition of photosynthesis in plants and algae. Phytoplankton in the ocean may decrease in productivity, and this means that less energy is entering the food chain at the primary level, affecting the entire oceanic ecosystem. Another effect of increased UV is a possible change in the community structure of marine communities as they react to decreased production from plants, and animals resistant to UV replace more sensitive animals and plants. 

The Writer is an Environmental Analyst & Associate Member,  Bangladesh Economic Association.