Impacts of Climate Change

Impacts of Climate Change on Bio-geophysical Systems

The adverse effect of global warming i.e. climate change has become an unavoidable reality for the people of Bangladesh and are struggling to cope with the current climatic conditions and the impacts of extreme climatic events on livelihoods and food security. Bangladesh, due to its geographical location, high population density, low development and economic strength and lack of institutional capacity, makes it more vulnerable to climate change and its associated impacts, risks and vulnerability in present and future. The fearful fact is that the poorest of the vulnerable countries will be the worst hit and the adverse impacts of climate change will be disproportionately affected to the poor communities, intensify the vulnerability of the poor and disadvantage groups. In addition, climate change is likely to cause additional inequity and increase hunger all over the globe, especially in the vulnerable least developed countries of Africa and Asia.

Number of research initiatives indicates that the water resources of the country would most likely be affected extensively due to plausible changes (Ahmed et al., 1998; Ahmed, 2005). Most of the adverse effects of climate change will be in the form of extreme weather events, such as flood, drought, salinity ingress, river bank erosion, and tidal bore are likely to be increased, leading to large scale damages of crop production, natural resources, livelihoods and national economy (Huq et al., 1996; Asaduzzamanet al., 1997; Choudhuryet al., 2005). In 2009 the World Bank has made a list of the five main threats arising from climate change: droughts, floods, storms, rising sea levels, and greater uncertainty in agriculture.

Four of the world’s poorest nations top the list of the 12 countries at the highest risk (World Bank,2009) and Bangladesh heads the list of countries most at risk of flooding, second in storm and tenth in raising one meter of sea level.

Temperature and precipitation change
Projections for Bangladesh anticipated a warmer summer and wetter monsoon, with substantial special differences in rainfall. The surface average temperature will increase 1°C and 1.60C by the year 2030 and 2050 respectively. By 2100, temperature likely to increase up to 2.4°C. The rate of change in temperature is slightly higher in winter than that in monsoon. On an average, the annual mean rainfall will increase by about 4 and 10 percent by 2030 and 2100, respectively. The monsoon will be wetter by about 5 percent by the year 2030 and 12 percent by 2100, while winter rainfall is projected to decrease slightly.

Table- 1: GCM projections for changes in temperature and precipitation for Bangladesh.

 

Year

Temperature change (0C)

mean (Standard deviation)

Rainfall Change (%)

mean (Standard deviation)

Annual DJF JJA Annual DJF JJA
2030 1.0 (0.11) 1.1 (0.18) 0.8 (0.16) 3.8 (2.30) -1.2 (12.56) +4.7 (3.17)
2050 1.4 (0.16) 1.6 (0.26) 1.1 (0.23) +5.6 (3.33) -1.7 (18.15) +6.8 (4.58)
2100 2.4 (0.28) 2.7 (0.46) 1.9 (0.40) +9.7 (5.8) -3.0 (31.6) +11.8 (7.97)

 Note: Values for 2030 are considered as baseline average. DJF represents the months of December, January and February, usually the winter months. JJA represents the months of June, July and August, the monsoon months. Source: Agrawala et al., 2003.

 Observed Changes:

In Bangladesh, global warming induced changes in precipitation and temperature is already happening, influencing patterns and intensities of the natural hazards in different part of the country. Various model based projections also illustrate that changes in the climate are likely to take place more rapidly over the next few decades. Based on observed data, GoB (2005) reported that the temperature is generally increasing in the monsoon months, June, July and August. Maximum and minimum temperatures show an increasing trend annually at the rate of 0.05OC and 0.03OC, respectively in the average monsoon time. On the contrary average maximum and minimum temperatures in the winter season (December, January and February) show a decreasing and an increasing trend annually at the rate of 0.001OC and 0.016OC, respectively. Regional variations have been observed around the average trend.

SAARC Meteorological Research Centre (SMRC) also reported an overall increasing trend of the annual mean maximum temperature over the period of 1961-90. Based on surface climatological data on monthly and annual mean maximum and minimum temperature, and monthly and annual rainfall for the period of 1961-90, the SMRC study (2003) showed an increasing trend of mean maximum and minimum temperature in some seasons and decreasing trend in some others.

An increasing trend of about 1°C in May and 0.5°C in November during the period from 1985 to 1998 also observed (Mirza, 2002). NCC,B (2008) also reported a significant increasing trend in the monsoon rainfall, particularly in the month of September and October. Correspondingly Chowdhury (2007), observed the increase (10-15%) of September rainfall in the recent decade, compared to 1970-80 over the Ganges-Brahmaputra-Meghna (GBM) river system. From the decadal trends in the rainfall variability in Bangladesh, Chowdhury (2007) also observed significant changes in the length of the monsoon and increased precipitation, which generates additional volumes of runoff.

Extreme Climate Events: Natural Disaster in Bangladesh

Bangladesh has always been known as a country plagued by natural disasters, but in recent times, the frequency and intensity of these disasters have greatly increased. The number of natural disasters in the whole world has nearly doubled in 2000-2007 compared to the decade 1987-97, and most of these have been climate related. Compared to a mere one decade earlier, 30% more people are affected by natural disaster (IFRC,2007), and the liability for this world wide increase in natural disasters is laid on global warming, which causes climate change. Experts in climatology apprehend that the frequency and intensity of such natural disasters (flood, cyclones, droughts, heat waves etc.) will go on increasing. Specifically Bangladesh is expected to be the most frequent victim of such disasters (IPCC, 2007).

According to the Climate Risk Index prepared by Germanwatch, Bangladesh is the top sufferer of last two decade (1991-2010) in the world due to climate related disasters (Harmeling, 2011). By analyzing the impacts of extreme weather events during 1998 to 2007, Honduras, Bangladesh and Nicaragua ranks highest (Table:-2). In particular, the increase in stronger hurricanes in the Caribbean force on these statistics. But the author has given emphasis on the risks from more frequent events, such as in Bangladesh, India and Viet Nam.

Table 2: The Long-Term Climate Risk Index (CRI): Results (annual averages) in specific indicators in the 10 countries most affected in 1991 to 2010.

CRI 1991-2010

(1990-2009)

Country

CRI score

Death toll

Deaths per 100,000 inhabitants

Total losses in million US$ PPP

Losses per unit GDP in %

Number of Events (total 1991-2010)

1 (1)

Bangladesh

8.17

7,814

5.51

2,091

1.56

251

2 (2)

Myanmar

10.50

7,130

14.06

659

1.68

33

3 (3)

Honduras

11.67

327

5.05

662

2.93

56

4 (4)

Nicaragua

18.00

159

2.83

212

1.90

43

5 (6)

Haiti

21.17

340

3.95

155

1.12

51

6 (5)

Viet Nam

21.50

445

0.57

1,809

1.19

40

7 (8)

Dominican Republic

30.50

211

2.51

181

0.37

44

8 (37)

Pakistan

30.67

558

0.40

1,834

0.66

144

9 (-)

Korea, DPR

30.83

74

0.33

1,172

3.61

33

10 (7)

Philippines

31.83

801

1.03

660

0.30

270

(Source: Harmeling, 2011) 

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