Thursday, December 10, 2015

Tragedy of Chennai and Climate Change

 Abhay Kumar



Chennai has been receiving a high rainfall this year, which is unprecedented in the recent memory of the city. A more or less similar situation exists in other parts of Tamil Nadu and Peninsular India. In general, Peninsular India receives major rainfall during this time of the year caused by the Northeast monsoon also known as retreating southwest monsoon. Cool wind from Himalayas picks up moisture from the Bay of Bengal and causes rain in the peninsular India during these four months from December to March. What is unprecedented is the amount of rain that this region has already received in a month when this amount of rainfall generally occurred over a period of 3-4 months in this region. The grim situation can further be gauged from the data given below (table 1 & 2).

Incidences of extreme weather events have been increasing world over in the recent times mainly due to climate change. A large number of human causalities in Tamil Nadu due to the rainfall and floods is a grim reminder to the fact that we as a country and society cannot afford to take issues of environment and climate change flippantly any longer. A few years ago sudden flood caused by heavy rainfall in a very short span of time and an overflowing moraine killed thousands in Uttarakhand.  Kashmir witnessed a similar devastation last year. Rampant destruction of wetlands, annihilation of rivers, over-burdened storm drains in the cities have made it even more difficult to face such disasters whenever they strike. Development without social equity and environmental concerns will invariably end in such calamities for the people. Such a paradigm for development is not sustainable at all. Urban planning must factor in these issues to face such eventualities. A similar effort is required in case of disaster response systems.

The world is debating the climate change in Paris presently. Decades have gone into addressing the issue without a solution in sight. It’s a do or die situation now. The issue is not of reversing the global warming. Enough fossil fuels have been burned. The average temperature of the earth will rise and is rising. The issue is to prevent the average temperature of the earth from increasing beyond 20 C. Which would mean that the temperature of some parts of the world will rise by more than 20 C. By all indications India falls in such region. Whether or not Paris will give world a legally binding treaty for reducing the emissions of green house gases by the countries, the developing, economically less developed countries and poor people will continue to face the brunt of the climate change in years to come.

Table 1. Observations recorded at 0830 hrs IST of 01.12.2015 / 10th  Agrahayana, 1937 (SAKA) 

TEMPERATURE
Deg.  Cel.
CHN
AP
CHN
RELATIVE
HUMIDITY
CHN
AP
CHN
RAINFALL
(mm)
CHN
AP
CHN
Max. past 24 hrs.
28.2
28.4
At 0830 hrs IST
96
95
Past 24 hours
64.1
39.6
Dep. from normal
-1.1
-0.8
Dep. from normal
15
14
Since 01.10.15
1401.3
1248.8
Min. past 24 hrs.
21.9
24.0
at 1730 hrs IST on 30.11.15
93
92
Dep. from normal
765.1
547.7
Dep. from normal
-0.2
1.7
Dep. from normal
23
19
At 0830 hrs. IST
25.0
26.0
Source: http://www.imdchennai.gov.in/rdwr.htm

Table 2. Observations recorded at 0830 hrs IST of 01.12.2015 / 10th  Agrahayana, 1937 (SAKA)

STATIONS
(TAMIL NADU
AND PUDUCHERRY)
TEMPERATURE
Degree celsius
HUMIDITY
Percentage
RAINFALL
Weather remarks
Maximum
Minimum
Millimeters
Centimetres
Past
24 hrs.
Dep.
from normal
Past
24 hrs.
Dep.
from normal

At 0830 hrs.
Dep. from normal
Past
24 hrs.
Season's total from 01.10.15
Dep. from normal
Year's total from 01.01.15
Annual normal
ºC
ºC
ºC
ºC
%
%
mm
mm
mm
cm
cm
Chennai
28
-1
24
2
95
14
40
1249
548
168
140
r
Chennai AP
28
-1
22
0
96
15
64
1401
765
198
138
r
Coimbatore AP
29
-1
23
3
81
0
1
215
-51
66
59
m*d
Cuddalore
29
0
23
2
98
13
97
1071
441
148
134
r
Dharmapuri
27
-2
19
1
95
18
6
423
142
101
91
r
Kanyakumari
30
0
23
-1
92
19
3
503
204
97
75
r
Madurai AP
30
0
24
2
75
-4
tr
230
-122
101
85
d
Palayamkottai
31
-1
24
0
83
2
17
689
343
97
73
r
Pamban
29
0
25
0
87
6
tr
466
-5
94
91
d
Parangipettai
30
-
24
-
100
-
159
1476
793
193
139
r
Puducherry
29
-1
23
0
100
19
153
1032
385
161
134
r
Salem
30
-1
23
3
88
14
5
367
72
110
102
z*r
Thanjavur
29
-1
24
2
98
11
20
535
163
100
95
r
Tiruchirapalli AP
30
0
23
1
88
9
3
505
200
102
87
m*r
Tondi
31
1
25
2
84
1
2
492
115
108
88
d
Toothukudi
28
-2
25
2
94
13
1
631
279
89
63
d
Uthagamandalam
20
0
12
4
81
7
1
493
184
130
116
d
Vellore
28
-2
22
3
96
10
26
821
496
154
103
r
*  Weather at 0830 hrs. IST. Other remarks refer to preceding 24 hrs.  D- Dust-storm   d-Drizzle   f-Fog   h-Hail   l-Lightning   m-Mist  p-Shower   r-rain   s-Snow   z-Haze  t-Thunderstorm AP-Airport  tr-Rainfall 0.1 to 0.4 mm  Tr-Rainfall 0.01 to 0.49 cm     SFD-Safdarjung.  The plus sign is omitted when the departure are above normal.

Source: http://www.imdchennai.gov.in/rdwr.htm

What is Climate

Climate change has emerged as one of the important concerns of the human society in 21st century. Scepticism around the science of climate change has weakened in face of mounting evidences in favour of climate change and its impacts such as global warming and increased incidences of extreme weather events. As the science of climate change and predictions based on it are becoming more and more certain, it is imperative for the people in general to have a better understanding of the issue so that the society is prepared to face its consequences and an informed debate can at least be carried out.

So, before we discuss the ‘change’, let us first look into the question, viz., what is climate? Climate refers to the average weather pattern of a place over a long period of time, usually 30 or more years. There is a difference between weather and climate. Weather refers to conditions of atmosphere (temperature, humidity, pressure, rain, etc.) of a place at a particular time. Climate, therefore, is considered as the sum total of weather patterns of a place over a long period of time (~30 years).

Now, what drives climate? Considering climate as a system; climate has various components such as atmosphere, hydrosphere (oceans, rivers, lakes, ponds, etc.), lithosphere (land surface), cryosphere (ice-covered region) and biosphere (vegetation and other living beings). These components interact with each other non-linearly. Each of these interactions along with the external forcings on these components such as Sun’s intensity, Earth’s rotation around the Sun and plate tectonics drive climate, also causing climatic variations. Sun’s intensity, Earth’s orbit and plate tectonics are some of the examples of natural forcings. There could be human induced forcings too such as enhanced concentrations of greenhouse gases (GHGs) in atmosphere. So, climate can also be considered as a function of complex interactions between various components and various factors described above. A schematic representation of these components and their interactions are illustrated in the figure 1.

What is Climate Change

So, what is climate change and why are we concerned about it? Climate change has been typically defined as a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. Whatever may be the reasons for climate change; natural or anthropogenic, it is a change in average weather conditions, or in the distribution of weather around the average conditions (i.e., more or fewer extreme weather events). In the Earth’s history, climate has changed several times. In the geological time scale of Earth’s past, one finds that the Earth has either cooled off or heated up repeatedly.

All these changes have had profound impacts on Earth’s biosphere. A similar warming is happening now, which is a cause for concern since it has been happening at a faster rate and caused by human activities. It has far reaching consequences on energy scenario of the world and on our ways of life.




Fig. 1. Schematic view of the components of the global climate system (bold), their processes and interactions (thin arrows) and some aspects that may change (bold arrows). (Source: http://www.grida.no/climate/ipcc_tar/wg1/pdf/tar-01.pdf {accessed in December, 2012})


What are the evidences of climate change being witnessed by us? There has been a constant rise in the sea level. Sea level rises because of thermal expansion of sea-water due to climatic warming and melting of ice. The global average surface temperature of the Earth has almost steadily increased since 1970. The top 700 metres of ocean have shown a marginal increase (0.30F) in its temperature. The Greenland and Antarctic ice sheets have decreased in mass and the Arctic sea ice has also declined in volume. Glaciers world over have retreated. Figure 2 shows the data or satellite images of these evidences (source: climate.nasa.gov).

How are we so sure that these large-scale climatic changes are human induced and not due to natural external forcings. The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), a body of scientists and experts formed by the United Nations, concluded that there was a more than 90 percent probability that human activities over the past 250 years have warmed our planet. Solar irradiance is primarily responsible for Earth’s climate. Any change in Sun’s irradiance accordingly influences Earth’s climate. It is believed that the last change in Earth’s climate called Little Ice Age between 1650 to 1850 was triggered by the decreased solar activity. However, the present climate change is not related to solar activity as there has been no flare up in Sun’s activity since 1750 and if it was indeed caused due to increase in solar irradiance then a uniform increase in temperature in all layers of atmosphere would have been observed. However, top layers of atmosphere show cooling while warming is observed only in the lower layers of the atmosphere, caused by the greenhouse gases. Finally, no climate model fits well unless greenhouse gases are taken into account.

What is Greenhouse Effect

So. What is greenhouse effect?  The Earth’s average surface temperature is about 150C. Greenhouse gases, viz., CO2, Water vapour, CH4, N2O, CFCs, Ozone, etc, present in the atmosphere act as blanket around the earth by trapping and radiating back the escaping radiation, which is mostly in infrared region (IR, having heating effects), from the earth’s surface. Had there been no GHGs in atmosphere, the Earth’s surface would be frozen and the average surface temperature would have been close to -140C. It is this warming of the earth by the GHGs is termed as greenhouse effect. Figure 2 depicts the greenhouse effect.


Fig 2. Greenhouse effect

Therefore, greenhouse effect in itself is not worrying. It is the enhanced concentration of greenhouse gases in atmosphere that is causing global warming and thus leading to climate change. Fig. 3 shows the graph pointing an increase of CO2 in atmosphere since Industrial revolution.  The graph is based on data collected after analysing atmospheric core samples and recent direct measurement of atmosphere (climate.nasa.gov/evidence). Analysing ice core samples (of both ice layers and trapped gases) provide a good peek into the past climate.




Fig 3. Graph showing CO2 concentration in atmosphere (ice core samples and direct measurement). [climate.nasa.gov/evidence; accessed in December, 2013]

However, it should be remembered that there are other factors too (natural or human induced), as discussed earlier, which may have positive or negative forcing on climate. Each of these factors either may cause warming or cooling effect. Scientists have used the term, radiative forcing to describe the process of these interactions. A positive radiative forcing is when it leads to warming while negative radiative forcing implies cooling. So, what would happen to climate change would largely depend upon the final balancing between positive and negative radiative forcings. There are still some uncertainties involved especially in regard to the roles of aerosols (suspended particulate matter in atmosphere). Aerosols absorb energy, aerosols reflect energy, aerosols as nucleating agents help in the formation of precipitation. So, how and in what ways it finally affects climate is still being debated.

What are the greenhouse gases? As mentioned above, gases that contribute to the greenhouse effect include:

§    Water vapour: Water vapour is the most abundant greenhouse gas, which on the one hand contributes in warming the earth and on the other hand warming will also mean more water vapour in atmosphere thus leading to both increased precipitation and more warming.
§    Carbon dioxide (CO2): CO2is released through natural processes such as respiration and volcano eruptions and through human activities such as deforestation (chlorophyll in green plants in presence of sun light fixes CO2; so cutting trees in a way help in building up of CO2in atmosphere), land use changes, and burning fossil fuels.
§    Methane (CH4): CH4 is less abundant than CO2and having more potential than CO2 in causing climate change, is produced from anoxic decomposition of wastes in landfills and guts of domestic livestock.
§    Nitrous oxide (N2O): N2O is produced in biomass burning, fossil fuel combustion and due to use of fertilisers.
§    Chlorofluorocarbons (CFCs). CFCs are no longer in use after International Treaty (Montreal Protocol) phased out its production due to its ability in destroying the ozone layer. However, they are strong greenhouse gas.

Table 3 shows the comparative concentrations (preindustrial and current) of greenhouse gases (GHGs) and their respective residence time in atmosphere.

Table 3. Atmospheric concentrations of greenhouse gases (GHGs)

GHGs
Formula
Preindustrial concentration
Current Concentration
Atmospheric residence time (years)
Water vapour
H2O
1 to 4 %
1 to 4 %
1 Week
Carbon dioxide
CO2
280 ppm
379 ppm
50-200
Methane
CH4
715 ppb
1775 ppb
12
Nitrous oxide
N2O
270 ppb
319 ppb
114
Dichlorodifluoromethane (CFC-12)
CCl2F2
0
538 ppt
100
Chlorodifluoromethane(HCFC-22)
CHClF2
0
169 ppt
12
Carbon tetrafluoride
CF4
0
74 ppt
50000
Sulfur hexafluoride
SF6
0
5. 6 ppt
3200

                 
Figure 4 shows the annual greenhouse gas emissions by sectors. It is observed that if we take all greenhouse gases into account then power stations contribute maximally in GHGs emissions followed by industrial processes while waste disposal and treatment contributes least. In case of carbon dioxide, a similar trend is observed while agriculture sector contributes maximum in case of methane and nitrous oxide generation.
   

  
          


Fig 4. Pie charts of annual GHGs emissions by sector

Impacts of Climate Change

This brings us to the final issue of this article and that relates to the impacts of climate change. As the change in climate is real, the impacts of it are also going to be real. Climate change may result into a warmer and more humid climate. For a better understanding of it, the impacts may be described sector-wise and region-wise. Climate change has huge impacts on water, forest, agriculture, health, biodiversity, coastal areas, etc. Global warming will increase the glacial melting. Initially, more water will be available, which, however, will soon go deficient. Incidences of floods will also increase. Sea level will rise, which will not only endanger the low lying surrounding areas but will also affect the water quality as the saline water intrudes into the freshwater zones of the land. As CO2 concentration in atmosphere increases, more and more CO2 will be dissolved in oceans leading to its acidification (CO2 reacts with water to form carbonic acid). This will have impacts on marine biodiversity. It is believed that frequency of extreme weather events will also increase in future. There will be a general loss in biodiversity as some species become extinct unable to cope with the changing climate. A warm and humid climate will mean a rise in malaria and other related tropical diseases. Energy scenario especially in developing countries will remain bleak. Figure 6 depicts the likely changes of climate change in different regions (source IPCC, 2001). All these have bearing on socio-economic conditions of the countries. Developing countries will be more stressed than the developed countries.


Climate change concerns have led the countries of the world to debate and decide on concrete measures to mitigate the impacts of climate change. Unfortunately, the world has yet to see the concrete measures. CO2 emission remains to be the bone of contention as no country is willing to forego its rights to use fossil fuels given the importance of fossil fuels at current juncture. So far 20 Conference of Parties (CoP) have taken place. The 21st CoP is underway in Paris. Government of India (GOI) too has formulated a National Action Plan for Climate Change (NAPCC) with eight National Missions on “solar mission”, “enhanced energy efficiency”, “sustainable habitat”, “water”, “sustaining the Himalayan ecosystems”, “green India”, “sustainable agriculture“ and “strategic knowledge for climate change” forming the “core of the NAPCC representing multi-pronged, long term and integrated strategies for achieving key goals in the context of climate change”. (http://pmindia.gov.in/climate_change_english.pdf). Prime Minister of India chairs the advisory council providing guidelines to NAPCC in the matters related to climate change. However, situation remains grim and the peoples of the world have to rise as a collective to face this challenge effectively. 

Author is an Environmental Scientist.

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