Even though there has been a substantial increase in carbon dioxide concentration in the atmosphere

during the recent decades (see figure 1), global temperatures (both air and water temperatures), have not

increased to the extent as predicted by various models. The reason lies in the fact that not only the greenhouse

gases, but there are other parameters, such as clouds, aerosols, and the ocean that influence the temperature.

Since 1960s, scientists have developed models to understand the ocean’s role in moderating the climate

Ramesh Kumar, M R

Climate change is a complex, long-term crisis about two centuries in the making. It has come to be

recognised as one of the most critical challenges ever to the humankind. The world has now recognized that

climate change is no longer solely an environmental problem. Rather, it has become an economic, trade and

security issue that will increasingly dominate global and national policies as its impacts become more

apparent. There are few human activities that do not contribute to it and as such, the scale of response

needed is so large and widespread

Dinesh Kumar, P K

CMFRI Digital Repository

CMFRIWinter School onImpact of Climate Changeon Indian Marine FisheriesLecture NotesPart 2Compiled and Edited byE. Vivekanandan and J. JayasankarCentral Marine Fisheries Research Institute (CMFRI),(Indian Council of Agricultural Research)P.B. No. 1603, Cochin - 682 018, Kerala(18.01.2008 - 07.02.2008)CMFRI - Winter School on Impact on Climate Change of Indian Marine Fisheries 189Climate change: global issuesCLIMATE CHANGE: GLOBAL ISSUESP.K. Dinesh KumarNational Institute of Oceanography, Regional Centre, Kochi  682 018dineshku@nio.orgIntroductionClimate change is a complex, long-term crisis about two centuries in the making. It has come to berecognised as one of the most critical challenges ever to the humankind. The world has now recognized thatclimate change is no longer solely an environmental problem. Rather, it has become an economic, trade andsecurity issue that will increasingly dominate global and national policies as its impacts become moreapparent. There are few human activities that do not contribute to it and as such, the scale of responseneeded is so large and widespread.Scientists believe that a temperature rise of above 2 - 2.5ºC risks serious and intolerable impacts.Along with impacts such as sea level rise, melting of ice caps/glaciers with rising temperatures, it is predictedthat frequency of heat waves, droughts, heavy rainfall events etc. will very likely increase, thus affectingagriculture, forests, water resources, industry, human health and settlements. Developing countries, wheregreater poverty and vulnerability limit the capacity to act, will be the most seriously harmed, particularlythe poorer segments. The situation is known to be one of the worst human-made environmental crises of thecentury.Several key features distinguish climate change from other environmental issues and thus it isprofoundly different from most other environmental problems that humanity faces. It is one of the first trulyglobal environmental challenges. In the last few decades, the earth has been warming at a rate that is fasterthan at any point in human history and studies invariably established that human activities resulting into theemission of greenhouse gases is responsible to this alarming situation.The Greenhouse effectThe greenhouse effect is very simple. We are increasing emissions of greenhouse gases and thustheir concentrations in the atmosphere are going up. As these concentrations increase, the temperature ofthe earth rises. This, in turn, leads to changes in the patterns of precipitation and to sea level rise. And astemperatures, precipitation and sea level change, there is reason to worry about adverse effects on ecological,socio-economic systems and human health.The world’s climate has always varied naturally but compelling evidence from around the globeindicates that there is now a discernible human influence on the earth’s climate system, foreshadowingdrastic impacts on people, economies and ecosystems. If there is no global agreement to try and limitgreenhouse gas emissions, the temperature of the earth is expected to increase between 1.0 and 3.5ºC overthe next century. Such a rate of change has not been experienced at any time during the past 10,000 years.Greenhouse gases last for a long time in the atmosphere. Their long life means that, if effectivemeasures are not taken, the world’s climate will inevitably change. It will take not years, not even decades,but centuries to reverse the damage. The full ramifications of those changes will primarily be felt by futuregenerations.The IPCC ReportThe Intergovernmental Panel on Climate Change (IPCC) has been in existence since 1988 havingestablished by the World Meteorological Organisation and the United Nations Environment Programme.CMFRI - Winter School on Impact on Climate Change of Indian Marine Fisheries 190Climate change: global issuesDuring this period, the panel has not only brought out four assessment reports, which present a comprehensiveassessment of knowledge on all aspects climate change, but has also produced several special reports dealingwith specific issues related to climate change. As part of the Fourth Assessment Report (AR4), three volumesrepresenting the contributions of Working Group I, II, and III have been completed and released. TheSynthesis Report bringing together the major findings of the three working groups too is published. TheAR4 has incorporated several advances in scientific knowledge related to climate change. This has had amajor impact on public opinion and awareness among world leaders on knowledge related to observedclimate change in recent dates as well as projections fro the future. Overall, the IPCC’s AR4 has had a majorimpact on awareness and knowledge on various aspects of climate change across the globe.Observed ImpactsOne major finding of the AR4 has been the fact that climate change is now unequivocal and thehuman influence on the earth’s climate is now very well established. The average temperature increaseacross the globe during the 20th century was around 0.74ºC and sea level rise around 17 cm. These changeshave been accompanied by changes in precipitation as well, including an increase in precipitation in thehigher latitudes and a decline in the lower latitudes. However, these changes have also been accompaniedby an increase in the frequency and intensity of extreme precipitation events. While any single event thatoccurs cannot be linked to human induced climate change, the pattern observed across the globe providesabundant evidence of this trend. It is also observed that floods and droughts are increasing in frequency andintensity and this trend is likely to increase.Future TrendsProjections of temperature rise in the 21st century have been made on the basis of established andplausible scenarios of the future. At the lower end of these scenarios, the best estimate of temperatureincrease by the end of the 21st century is placed at 1.8ºC and at the upper end of the scenarios, the bestestimate is approximately 4 ºC. These projections are of course based on the assumption of no specificaction towards mitigation of emissions of greenhouse gases.Unequal ImpactsThe impacts of climate change vary across regions and communities. In general, these are mostsevere in those regions, which display high vulnerability on account of a number of factors including poverty.For instance, during the 20th century, glaciers and ice caps have experienced widespread mass losses, whichare likely to have major consequences for water supply in several areas of the world. Data confirm thatlosses from the ice sheets have contributed to sea level rise over the period 1993-2003.Ecosystem DisruptionOther observed impacts of climate change include more intense and longer droughts, wide spreadchange in extreme temperatures as well as changes in biodiversity. In general, it was assessed that climatechange will reduce biodiversity and perturb the functioning of most ecosystems and therefore compromiseon the services that they currently provide. On the species that were assessed it was found that 20 to 30percent of plant and animal species would be at risk of extinction if increases in global annual temperaturesexceed 1.5 to 2.5ºC. Some ecosystems such as coral reefs and marine shell organisms are particularlyvulnerable. As genetic and species diversity is lost, and the types of ecosystems are changed, the goods andecological services, which are so important to sustainable development, would be threatened. For example,the bio-geochemical cycling of the earth will alter. This in turn will change inputs of CO2, methane andnitrous oxide and hence have a feedback effect on the earth’s climate systemFood InsecurityAnother major area of serious impacts is in the field of agricultural production. Malnutrition, forinstance would be further exacerbated by the reduced length of the growth seasons. In some countries,CMFRI - Winter School on Impact on Climate Change of Indian Marine Fisheries 191Climate change: global issuesyields from agriculture could be reduced by up to 50 percent by 2020. With the growing scarcity of water indifferent regions of the world, it was also assessed that 75 to 250 million people would be exposed toincreased water stress in 2020 in Africa alone. In the case of sub-tropical and tropical regions, a temperatureincrease above 1.5 to 2.5ºC is expected to lead to a decline in agricultural productivity of crops such asmaize and wheat. In fact, there is growing evidence in South Asia, for instance, that the wheat crop isalready being affected adversely by climate change.Coastal FloodingAnother serious impact of climate change is seen most prominently in the Asian region where themega deltas such as Kolkatta, Dhaka and Shanghai are at risk of coastal flooding and negative impacts.There are other cities in the world, also located in coastal seas, with high density populations at the risk ofcoastal flooding and other impacts with the prospect of high sea levels. Once the sea level rise process is setinto motion, it cannot be slowed down in anything less than a few millennia. A sea level rise of up to 1 meterwill displace tens of millions of people in the low-lying deltaic areas of Bangladesh, Egypt and China.Bangladesh could lose as much as 18 per cent of its land surface and suffer a significant decrease in agriculturalproductivity. Small-island states would be wiped out. India too has good reason to be concerned about.Who is responsible? Who is affected?Major components of our biosphere have been altered by the intensity of human exploitation of theearth’s resources in the twentieth century.  Responsibility is with the developed as well as developingcountries and must be understood in terms of two major global trends that lead to increased greenhouse gasemissions and reduced ‘sinks’ for carbon dioxide: population growth and increasing consumption (especiallyof fossil fuels).World population has doubled over the past fifty years, where as, total energy consumption hasincreased fivefold during the same period of time. We depend mainly on fossil fuels for the energy generationand the growth in consumption has brought on parallel increases in greenhouse gas emissions. Carbondioxide concentrations increased several times since the industrial revolution. The United States aloneaccounts for as much as twenty-one percent of the total world emissions while being home to only fivepercent of the world’s population. In contrast, 136 developing countries are collectively responsible fortwenty-four percent of global emissions.Studies conclusively established that those countries have ‘common but differentiated responsibilities’with regard to environmental degradation. The comparative susceptibility to adverse climate impacts liesalso along a developing country-developed country axis, but in an inverse relation to historical responsibility.Though most of the emissions of greenhouse gases have been put into the atmosphere by the developedworld, it is the developing countries that are particularly vulnerable to climate change. The costs would beextremely significant for some parts of the world.Development challengesThe economy of the future will be low carbon. The sustainable solution to several of the problems isto replace fossil fuels with renewable energy sources (RES). It will need new technologies and new solutions.Leading edge developments are important for driving the development of low-carbon technology andproviding confidence that new products will deliver the benefits. But technology alone cannot solve theglobal climate challenge and we cannot afford to do nothing as we wait for the next generation of climatefriendly technology advances.Sharing the Responsibility- Kyoto to Bali and BeyondThe divergence between the countries most responsible for, and the countries most affected by climatechange creates a profound ethical dilemma. Developed countries have the capacity to act. Yet some of themare unwilling to do so without the assurance of substantial emission reductions on the part of developingCMFRI - Winter School on Impact on Climate Change of Indian Marine Fisheries 192Climate change: global issuesnations. However, countries in the South resent the imposition of high economic costs for the ameliorationof what they perceive that the developed nations have caused environmental problem.In the last 10 years since the parties to the United Nations Framework Convention on Climate Changereached their last major agreement to reduce greenhouse emissions, the Kyoto Protocol, progress toward atruly global accord to combat the mounting threat has been held hostage by a stand off between some of theworld’s largest greenhouse gas emitters. Mounting scientific evidence demands that we pursue all of theemissions reductions opportunities we can find, and without delay. All these demands for a truly globalagreement in time to avoid a temperature rise of 2ºC. Further, these existing emissions commitments expireafter 2012. The ‘Bali Summit’ was the largest such meeting ever held to form a binding post-2012 climateframework. The critical issue is whether the new road map sets governments on a course towards establishingbinding multilateral commitments.Global climate change requires a response encompassing the North and the South, local communitiesand the local community of nations. Ranging from global negotiations to individual choices, a diverse set ofactors with different resource endowments and diverging values and aspirations would need to be involved.Concerns for equity and justice, however, are central to effective response to global climate change.Differences in the perceptions of developed and developing countries as to what is fair and equitable havepresented enormous difficulties in constructing governance mechanisms for addressing climate change.The challenge of climate change demands unprecedented national and international coordination andcooperation.Despite all the debate, the confrontations and the frustration, we have begun to move in the rightdirection. The issue now is the pace at which we are moving. The longer we wait before taking seriousaction, the more difficult and costly will it be to mitigate climate change. Although it is too early to predictthe future nature and scope of the climate regime, adaptation and technology transfer are certain to be thecentral themes. In addition, emerging technologies will expand the options for reducing greenhouse gasemissions and thus for international cooperation.Further ReadingAgrawala, S., 1998.  Context and early origins of the Intergovernmental Panel on Climate Change, ClimateChange, 39, 605-620.Agrawala, S., 1998. Structural and   process history of the Inter-governmental Panel on Climate  Change,Climate Change, 39,   621-642.Gommes, R, Duerny , Nachtergaele, F, Brinkman, R,1997. Potential    impacts of sea level rise on populationsand agriculture, FAO, Rome, 175 p.Ramanathan, V., 1988.  The greenhouse theory of climate change: A test by an inadvertent  global experiment.Science, 240, pp. 293-309.http://www.ipcc.chhttp://unfccc.int

Climate change: Global issues. In: Winter School on

Impact of Climate Change on Indian Marine Fisheries held at CMFRI, Cochin 18.1.2008 to 7.2.2008

Cities are causes and victims of climate change. Many cities have developed along the coasts and

they multiply out of control with resources used with thoughtless abandon. Cochin, the biggest city along

the west coast of India after Bombay functions as the nerve centre of distribution of goods due to its

proximity to the port. As elsewhere, Cochin too has expanded rapidly and heavily stressed from environmental

perspectives. Cochin has good reason to be concerned as global climate change issues pose severe problems

to its coast and coastal structures. This paper presents some results of the combined analysis of impact

assessment studies of the coast and coastal structures around Cochin to address the anticipatory issues of

the selected sea level rise scenarios

CMFRIWinter School onImpact of Climate Changeon Indian Marine FisheriesLecture NotesPart 2Compiled and Edited byE. Vivekanandan and J. JayasankarCentral Marine Fisheries Research Institute (CMFRI),(Indian Council of Agricultural Research)P.B. No. 1603, Cochin - 682 018, Kerala(18.01.2008 - 07.02.2008)CMFRI - Winter School on Impact on Climate Change of Indian Marine Fisheries 193Climate change vulnerability: Local perspectivesCLIMATE CHANGE VULNERABILITY: LOCAL PERSPECTIVESP.K. Dinesh KumarNational Institute of Oceanography, Regional Centre, Cochin 682 018(dineshku@nio.org)IntroductionCities are causes and victims of climate change. Many cities have developed along the coasts andthey multiply out of control with resources used with thoughtless abandon. Cochin, the biggest city alongthe west coast of India after Bombay functions as the nerve centre of distribution of goods due to itsproximity to the port. As elsewhere, Cochin too has expanded rapidly and heavily stressed from environmentalperspectives.  Cochin has good reason to be concerned as global climate change issues pose severe problemsto its coast and coastal structures.  This paper presents some results of the combined analysis of impactassessment studies of the coast and coastal structures around Cochin to address the anticipatory issues ofthe selected sea level rise scenarios.Study Area, MethodsThe area under study is about a 60 km coastal strip, where the shoreline is oriented in a NNW-SSEdirection, which varies in its width from north to south. The bordering beaches are composed of fine sandsand, in general, have low profile. Shore protection structures in the form of seawalls exist along the southernstretch. They are in a dilapidated condition at several reaches.Beach transect data generated in the region has been analysed to determine the effects of projectedsea level rise scenarios on the anticipatory sedimentary responses such as erosion. Besides the destructionthrough inundation and increased rates of erosion, sea level rise situations also increase the risk of flooding.In order to elucidate the responsible factors, analysis has been carried out to determine the effects of tropicalcyclones in the study area.  The present era of intense utilization of the coast and the corresponding demandfor construction of coastal protection structures to stabilize the shore necessitates long-term developmentplanning for sustainability. Moreover, knowledge of this dimension will be of considerable use in planningthe development programmes including the designing of coastal protection structures. Considering alsothat the region is densely populated and supports a broad range of economic activities, the potential impactof sea level rise forms an important focus for such assessments.Sea level rise scenariosThe future sea level changes to be expected are the function of our understanding of the past andpresent trends. Periodic assessments of the IPCC were designed to provide a comprehensive survey of thestate of knowledge about climate change for use by national and international decision makers as the generalprojections on average global sea level rise, which is readily used in the present investigation as the projectedsea level rise scenarios.The historic sea level rise for Cochin is estimated to have been 2 cm in the last one century (Emeryand Aubrey, 1989; Das and Radhakrishna, 1993).  Assuming that the local effects remain essentially thesame, global trends can be added to the local estimates to develop the total sea level rise projections for agiven location. The scenarios of future sea level were obtained by adding the projected values for a givenyear to the local trend of 0.02 cm per year times the number of years from present.Data obtained from Cochin Port trust (CPT), Cochin and the global data bank of Permanent Servicefor Mean Sea Level (PSMSL) based at Bidson Observatory, UK for the tidal station at Cochin have beenused to compute the monthly mean and long term seasonal trends of sea level. All data are referred to localdatum.CMFRI - Winter School on Impact on Climate Change of Indian Marine Fisheries 194Climate change vulnerability: Local perspectivesResultsInterannual changes and the long-term seasonal cycle of tidesDaily mean sea level is computed from the average of hourly data extracted from the tidal recordsspanning up to year 2003 beginning with the year 1939. This averaging will significantly eliminate theinfluences of diurnal, semidiurnal and shorter tidal components in the data (Pugh, 1987).  The monthlyaverage, in turn, is effective in reducing all effects with period less than a month. The monthly means arecomputed from the daily means. Regression technique was used for the determination of trend equation(Spiegel, 1981) (Fig. 1).Fig. 1. Long term trend based on monthly mean sea level anomaliesMonthly mean sea level variationsThe climatological seasonal cycle derived from the data has shown a range of about 17 cm, theincrease from the lowest to highest occurring from August to December (Fig. 2). The sea level is found to bethe lowest during the southwest monsoon, even though the rainfall and river discharges are maximumduring this period. This can be explained in relation to the prevailing monsoonal forcings and associatedupwelling in the region.  During this period, the coastal region off Cochin experiences upwelling by whichdenser seawater is brought to the surface, which overrides the effects of river discharges.Fig. 2. Mean monthly values and seasonal cycle of sea level at Cochin for 1939-2003CMFRI - Winter School on Impact on Climate Change of Indian Marine Fisheries 195Climate change vulnerability: Local perspectivesAn increase in mean sea level will affect waves, currents and bottom pressure in the near shoreregion. In general, an increase in mean water depth will be accompanied by an increase in mean waveheight, resulting in a more severe wave attack on the coast and a greater wave induced littoral drift. Thoughit is established that both the morphological and ecological systems of the coastal zones will be affected bya rise in mean sea level, relatively little is understood about wave-induced onshore transport processes.The effects of future sea level rise on coastal processes and anticipatory sedimentary responses inthe study region under various scenarios were examined. For this, the relationship between rising sea leveland the rate of shoreline recession (Bruun, 1962), which was widely accepted for derivation of sandycoastlines, was applied (Dinesh Kumar, 2000). Two conditions of erosion were investigated for the studyarea, which are shoreline recession and associated erosion assuming the existence of a beach seaward of theseawall and erosion/scour at the seawall where there is no beach above mean low water. The erosion due tosea level rise for the region is estimated to be 7125 m3 per year, implying an erosion rate of -- 0.3 x 106 m3--per year, which could be attributed to the effects of wave attack. Using the extreme conditions of waveheight and sea level rise, future erosion potential is expected to increase by 15.3% by the year 2100. Thusthe erosion due to wave attack for the low scenario of sea level would be expected to increase considerably.An estimate of the future erosion and shoreline recession rates and scenarios of future erosion at the existingcoastal structures was also made. From the results obtained, it has been found that the effects of climatechange and associated sea level rise scenarios will bring profound effect on the coast as well as coastalsedimentary environments, and the land loss along the coastline will be significant.InundationBesides destruction through increased rates of erosion, sea level rise situations also increase the riskof flooding (Nicholls et al., 1999).  A detailed study on the various sea level rise and tropical storm surgescenarios in the study area helped in determining the effects, which quantified the inland extent of permanentand episodic inundation that may be expected, if the retreat option to sea level rise is taken into consideration.A quantitative estimate of permanent and episodic land loss resulting from sea level rise and from tropicalcyclone induced storm surges was made. Considering an average beach slope of 1 percent for the studyregion, together with a value of +2.0 mm/year (Das and Radhakrishna, 1993), and also assuming that effectsof eustatic sea level changes are negligible in the vicinity, the amount of land that is vulnerable to bothpermanent and episodic flooding from storm surges was determined. For the purpose of comparison, theeffects of the minimal tropical storm, minimal hurricane and maximum storm surge-producing hurricane inthe current climate state have also been calculated.Flooding would increase along the coast. A higher sea level would provide a base for storm surgebuild-up enabling a storm that occurs once in a few years to flood many areas that are flooded today only bystorms with recurrence intervals of hundred years or more. The destruction or over wash of barrier lands byincreases in sea level would destroy ocean front properties and leave inland properties vulnerable to stormwaves. Higher water levels would reduce coastal drainage gradients. Reductions in these gradients wouldincrease flooding attributable to rainstorms, promote saltwater intrusion into coastal aquifers and forcewater tables to rise and in some areas to emerge at the surface. Thus, the effects of sea level rise scenariosof land loss on the coastline in the study area are significant. The low dunes that overlook the beaches alongthe coast will provide no hindrance to inland flooding and the relatively shallow slope of the coast willresult in significant loss of land as sea level rises and beaches erode and retreat inland. The unconsolidatedsediments that make up the coastline will present no obstacle to erosion caused by the rising waters of theArabian Sea. The higher wave energies (i.e., deeper water will allow larger waves to break onshore) willincrease erosion. The monetary losses involved will be significant, as the amount of property inundated bythe sea and the number of zones subject to temporary flooding will increase.Modifications to existing structuresStorm events, raised water levels and associated impacts necessitate the designing of safe, stable andfunctional coastal structures. However, until recently most planning had taken place against a conceptualframework of relative environmental constancy. However, the adequacy of short term economic planningCMFRI - Winter School on Impact on Climate Change of Indian Marine Fisheries 196Climate change vulnerability: Local perspectivesfor achieving sustainable development has already been severely criticised (Weaver and Green, 1998). Thechange in perspective outlined above is now nowhere more important than in human use in the coastal zone.Designing a safe, stable and functional coastal structure requires water levels that may occur throughout thelife of the structure. An assessment of the impact of low and high sea level rise scenarios on the coastalprotection structures in the region was made. Depth limited breaking wave criteria (Anonymous, 1984)were used to estimate the design wave heights over the next century for the chosen sea level scenarios. The50-year return interval water levels were used in conjunction with the scour depth estimates seaward of theseawall to establish the design conditions for any given year. The increases in beach erosion, assuming theexistence of a beach as the source for eroded material were considered. Sea floor profile changes that wouldoccur as a result of the sea level rise scenarios were described and it was found that erosion/scour at the toewill be accelerated when there is no beach seaward of the seawall (Dinesh Kumar, 2000). These changeswere estimated for two conditions for each sea level rise scenarios by assuming no shore protection worksbeyond those currently existing and after the berm will have eroded back to the sea wall. As sea level rises,land and structure elevations that are currently not affected by water levels will begin to be inundated orovertopped, and the increased flooding will result directly from the increase in high tide levels as the sealevel rises and from the increased frequency of which a certain elevation will be inundated by storm events.The crest of the seawall is at an elevation such that during a 50-year return interval event with present sealevels, approximately 60 percent of the waves will overtop the structure. The change in yearly probabilityof some damage, intermediate damage and serious damage to the existing sea wall was found to be afunction of the projected sea level rise scenarios. In general, it was revealed that, if the study region is toremain in its present form, extensive coastal engineering projects, including the upgrading of the existingstructures  will have to be implemented for the accelerated sea level rise scenarios investigated. However,the costs of these measures would be significant.Discussion     As explained, anticipated sea level rise, stemming from global climate warming will affect thecoastal zones of Cochin through permanent inundation of low-lying areas with  accelerated  beach erosionand greater frequency of flooding events. Sea level rise would inevitably bring substantial losses fromshoreline retreat and associated processes, and the indirect consequences may bring greater damages thanthe direct ones. The vegetation and life in the coastal environments are expected to be affected with harmfuleffects for the population in the region. Other conditions being equal, the more sensitive landscapes willsuffer greater catastrophe. Damages to this coastal city cannot be observed in isolation because it is linkedwith other regions through economic and cultural ties. Changes will affect the hinterlands also and chainreactions may follow. Urban planning will be confronted with a number of anticipatory issues includingadaptation strategies.Further ReadingBruun, P., 1962.  Sea level rise as a cause of shore erosion. J. Waterways Harbours Div., Am. Soc. Civ.Engg., pp. 117-130.Emery, K.O and Aubrey D.G. 1989. Tide gauges of India. J Coast. Res., 5, pp.489-500.Das, P.K. and Radhakrishna, M. 1993.  Trends and the pole tide in Indian tide gauge records.  Proc. Ind.Acad. Sci., (Earth Planet. Sci.), 102(1), pp. 175-183.Dean,R.G.and Maurmeyer, E.M.1983. Models for beach profile responses.  In : Handbook of CoastalProcesses and Erosion,  Komar, P.D., (ed.), CRC Press Inc., Boca Raton, Florida, pp. 151-165.Dinesh Kumar, P.K. 2000. Studies on the impact of selected sea level rise scenarios on the coast and coastalstructures around Cochin, Ph.D. Thesis, Mangalore University, India, 125 p.Nicholls, R.J., Hoozemans, F.M.J., and Marchand, M. 1999. Increasing flood risk and wetland losses due toglobal sea level rise: Regional and global analyses. Global Environmental Change, 9,  pp. S69-S87.Pugh, D.T., 1987.  Tides, Surges and Mean Sea Level: A Handbook for Engineers and Scientists, JohnWiley and Sons, N.Y., 472 p

Climate change vulnerability: local perspectives. In: Winter School on

Impact of Climate Change on Indian Marine Fisheries held at CMFRI, Cochin 18.1.2008 to 7.2.2008

To maintain the global water balance, the evaporation from oceans worldwide should be balanced

by precipitation into the oceans plus runoff from the continents. The earth’s atmosphere contains only

0.001% of the earth’s water, yet it is an important part of the global hydrological cycle. Atmospheric currents

carry water vapor to land which gives precipitation and which in turn sustains life on land

CMFRIWinter School onImpact of Climate Changeon Indian Marine FisheriesLecture NotesPart 1Compiled and Edited byE. Vivekanandan and J. JayasankarCentral Marine Fisheries Research Institute (CMFRI),(Indian Council of Agricultural Research)P.B. No. 1603, Cochin - 682 018, Kerala(18.01.2008 - 07.02.2008)CMFRI - Winter School on Impact of Climate Change on Indian Marine Fisheries 71Role of the oceans in climate changeROLE OF THE OCEANS IN CLIMATE CHANGEM. R. Ramesh KumarPhysical Oceanography Division,National Institute of OceanographyDona Paula, Goa  403004IntroductionTo maintain the global water balance, the evaporation from oceans worldwide should be balancedby precipitation into the oceans plus runoff from the continents. The earth’s atmosphere contains only0.001% of the earth’s water, yet it is an important part of the global hydrological cycle. Atmospheric currentscarry water vapor to land which gives precipitation and which in turn sustains life on land.Increasing atmospheric concentrations of greenhouse gases (GHGs), mainly carbon dioxide, haveled to a warming at the surface, by nearly 0.6oC during the twentieth century, and it is widely believed thatthis trend will continue in the twenty-first century, leading to a higher sea surface temperature, among otherfactors.One important consequence of a warmer ocean surface is a larger vapor pressure difference betweenthe sea surface and adjacent atmosphere, which in turn will enhance the evaporation rate and hence increasethe other components of the hydrologic cycle.Evidence of Hydrologic ChangesThe following evidences suggest that the hydrological cycle has measurably intensified:a) Daily minimum temperatures have increased at twice the rate of the day time temperatures since1950. This in turn will increase cloudiness and humidity at night and increased evaporative coolingduring daytime.b) Radio-sonde and satellite data suggest that the mean (average) atmospheric water vapor hasincreased. This will help the cyclones to generate more precipitation and also we will have moreintense rainfall events.c) Precipitation amounts have changed in different ways in various regions during the last severaldecades. They have increased significantly in the middle and high latitudes, often in excess of10%. The largest increase in precipitation is expected in the polar regions.d) Decrease in precipitation is also noted in several regions. In the northern hemisphere tropics,especially in Africa, a significant decrease in rainfall has occurred since 1950.e) Changes in rainfall events such as monsoon rains can have either beneficial or detrimental effects,namely, decreased rainfall can cause water shortage, and increased rainfall can aggravate flooding.Consequences of Global WarmingAn enhanced hydrological cycle, in turn, may enhance global warming through several mechanisms.One such mechanism is the water vapor feedback, because water vapor is a key GHG. Also, increasedcloudiness heats the planet, at least if the clouds are high or deep, as in the case for most of the storms orcyclones. This is because high or deep clouds reduce the outgoing longwave radiation (OLR, Gruber andKrueger, 1984) more than the net incoming solar radiation. We should look at the role of global warming onthe various air-sea interaction parameters such as sea surface temperature, surface wind speed and otherrelated air sea fluxes over the tropical Indian Ocean in the context of marine activities, such as coral bleachingand migration of fisheries which takes over the Indian Ocean.CMFRI - Winter School on Impact of Climate Change on Indian Marine Fisheries 72Role of the oceans in climate changeSatellite OceanographyReliable sea surface temperature (SST) and wind measurements from the space based sensors havebeen a major goal of the oceanographers. This was achieved way back in 1978 when SEASAT was launched.In the current satellite scenario, the Tropical Rainfall Monitoring Mission provides the SST, with the helpof the microwave sensor TMI which can penetrate the clouds. Further, the QuikSCAT can provide windvelocity (both speed and direction) over the ocean. QuikSCAT can provide high resolution wind mapswhich can be used to study specific process such as coastal upwelling, and synoptic scale process such as ElNino.The Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data (HOAPS) set is acompletely satellite-based climatology of precipitation, turbulent heat fluxes and freshwater budget(evaporation minus precipitation) as well as related atmospheric state variables over the global oceans. Themain advantage of this dataset is that both daily, pentad and monthly datasets of various air-sea interactionparameters such as sea surface temperature, specific humidity, wind speed, evaporation, rainfall, freshwater flux, integrated columnar water vapour and cloud liquid water are available for ice free regions overthe global oceans from 80o S to 80o N for more than 18 years (i.e., from 7th July 1987 to 31st December,2005). All variables are derived from SSM/I passive microwave radiometers, except for the SST, which istaken from AVHRR measurements. The dataset includes multi-satellite averages, inter-sensor calibration,and an efficient sea ice detection procedure. Changes in this version are a longer time series, now containingdata from 1987 to 2005, a new neural network based precipitation algorithm, and inclusion of the RSMAS/NODC Pathfinder Version 5 SST fields. Additionally a new 85 GHz synthesis procedure has beenimplemented, making a continuous time series for all parameters.All pentad (5-day) mean products are distributed in separate monthly files. The first day of a 5-dayaverage period determines the monthly file wherein it is saved. Each year is subdivided in 73 pentadsstarting at the same day of the year. During leap years, the twelfth pentad (starting at February 25) is theaverage of six days. Apart from pentad (5-day) and monthly means on a global 0.5o x 0.5o grid, twice-dailymulti-satellite composite data on a global 1o x 1o grid are available. More information of the dataset isavailable at http://www.hoaps.org/.SummaryThe satellite data has given a totally new dimension to oceanographic studies which in conjunctionwith the complementary ship, buoy and other oceanographic data can give valuable information about thevarious marine features and processes taking place over the ocean such as coastal upwelling, oceanic frontsand phytoplankton blooms, which was not possible earlier.

Role of the oceans in climate change

 -Winter School on

Impact of Climate Change on Indian Marine Fisheries held at CMFRI, Cochin 18.1.2008 to 7.2.2008

CMFRIWinter School onImpact of Climate Changeon Indian Marine FisheriesLecture NotesPart 1Compiled and Edited byE. Vivekanandan and J. JayasankarCentral Marine Fisheries Research Institute (CMFRI),(Indian Council of Agricultural Research)P.B. No. 1603, Cochin - 682 018, Kerala(18.01.2008 - 07.02.2008)CMFRI - Winter School on Impact of Climate Change on Indian Marine Fisheries 65Climate change and monsoonCLIMATE CHANGE AND MONSOONM. R. Ramesh KumarPhysical Oceanography DivisionNational Institute of OceanographyDona Paula, Goa  403 004IntroductionEven though there has been a substantial increase in carbon dioxide concentration in the atmosphereduring the recent decades (see figure 1), global temperatures (both air and water temperatures), have notincreased to the extent as predicted by various models. The reason lies in the fact that not only the greenhousegases, but there are other parameters, such as clouds, aerosols, and the ocean that influence the temperature.Since 1960s, scientists have developed models to understand the ocean’s role in moderating the climate.Yet, several questions remain unanswered. In which way, does the ocean help to keep the globaltemperatures under control and partially offset global warming? Or in the long term, will the ocean amplifyand accelerate the warming trend? How will the changes in climate trend and climate variability affect lifein the ocean and on land? How will the changes in physics and biology of the oceans and their interactionchange the climate? How are the human activities contributing to the changes in the marine environment,and in turn, how will these changes affect the human beings?Ocean – Atmosphere InteractionThe Ocean interacts with the atmosphere in two different ways. The first way is through the exchangesof heat (latent and sensible) and momentum. Oceans cover about 70% of the earth’s surface and containabout 97% surface water. The oceans store enormous amounts of energy in the form of heat. Further, theocean has a relatively large temperature inertia, or resistance to change.Scientists were under the general impression that the oceans were sluggish in nature due slowcirculation (as compared to the more dynamic atmosphere) and its low biological productivity. But, now weAtmospheric Carbon DioxideMeasured at Mauna Loa, Hawaii390380370360350340330320310Carbon dioxide concentration (ppmv)1960 1970 1980 1990 2000Annual CycleJan Apr Jul Oct JanCMFRI - Winter School on Impact of Climate Change on Indian Marine Fisheries 66Climate change and monsoonknow that biological and physical functioning of the ocean system can change quickly over both small andlarge areas (i.e., during a cyclone or during an El Nino). Some scientists call the ocean as the “global heatengine”.Oceans play a very important role in the global climate system. They absorb most of the incomingshortwave solar radiation entering the earth atmosphere system and redistribute the heat and energy withoceanic environment by both horizontal and vertical oceanic movements. This energy is then furthertransported back into the atmosphere in the form of energy fluxes such as latent and sensible heat fluxes,and longwave radiation, which are the main sources of energy for atmospheric circulation. The tropicaloceans are the regions of net radiation gain. This excess energy is transported to the higher latitudes throughatmosphere and oceans to maintain the energy balance. Further, the tropical oceans are the regions whereactive air-sea interactions processes such as monsoons, El Nino and Southern Oscillations take place. Thusstudy of air-sea interaction parameters, fluxes and the hydrological cycle of the global oceans are quiteimportant for our understanding of climate variability. Of the three major oceans, the Pacific Ocean has thelargest longitudinal extension reaching over 140Ú. On the western part of the Pacific Ocean, there existsone of the warmest regions in the world, the so called “ warm pool”; and in the eastern equatorial Pacific, awell developed cold tongue exists towards the west. This large thermal gradient and the resulting surfacewinds in turn drive ocean currents. These winds and water vapor dramatically alter the meteorologicalconditions, resulting in the formation of clouds or even rain clouds that are vital for life on land.MonsoonThe southwest monsoon or the summer monsoon, which gives about 80% of the mean annual rainfallfor the subcontinent, is one of outstanding meteorological phenomena of the Indian Meteorology(Ananthakrishnan et al., 1983). A typical monsoon sets in over the Kerala coast by 1st June and covers theentire Indian subcontinent by 15th July. The quantum of monsoon rainfall also varies from year to year. Themonsoon rainfall is not continuous within the life cycle of monsoon; there are several spells of active, weakand break in monsoon conditions. The summer monsoon months of June to September contribute 21%,33%, 28% and 18% of the seasonal rainfall respectively. Thus it can be seen that the mid monsoon monthsJuly and August contribute about 61% of the mean seasonal rainfall. Hence, prolonged breaks in these midmonsoon months can create deficit monsoon or drought-like conditions as in the case of 2002, whichincidentally had the longest break spell of 34 days according to Ramesh Kumar and Uma (2004).Scientists have used the term “break” to refer the features such as convection and circulation overdifferent regions. Further they have used different durations and also looked them during different months.By analyzing 80 years (1888 – 1967) rainfall data, Ramamurthy (1969) suggested various synoptic situationsresponsible for the break in monsoon conditions. They include a) migration of monsoon trough to thefoothills of Himalayas, b) the absence of low level easterly winds over the northern India, and c) the increasedrainfall activity in the foothills of Himalayas and decreased rainfall over the rest of the country. The criteriaused by him were based on the surface pressure distribution and circulation.  He looked for the breaks onlyfor the period from 1st July to 31st August.De et al. (1998) have further classified the breaks for 30 years (1968 – 1997) and found some moreadditional features during the break in monsoon conditions, which include a) weak pressure gradient overthe west coast of India, b) presence of a trough in mid tropospheric westerlies over northern parts of thecountry, and c) strong westerlies in the northern part as compared to the westerlies over the peninsula. Theylooked for the breaks only for the period from 1st July to 30th September.Krishnan et al. (2000) defined the breaks as days with large positive outgoing longwave radiation(OLR) anomalies for at least four consecutive days or more over a wide region covering northwest andcentral India. They also kept a objective criterion that the OLR anomaly averaged over the region (18° - 28°N; 73° - 82° E) should exceed 10 watts per m2 during all the days of the break period. Further, they consideredbreaks only during the period from 15th June to 15th September.CMFRI - Winter School on Impact of Climate Change on Indian Marine Fisheries 67Climate change and monsoonGoswami and Ajaymohan (2001) define the breaks on the basis of the strength of the 850 hpa windat a reference point just south of the “monsoon trough” (15° N; 90° E). They also found that the frequencyof the occurrence of the “active” and “break” monsoon conditions were distinctly different during theexcess and deficit monsoon years. Further, they found that the most frequent pattern associated with anexcess (deficit) monsoon year is the ‘active’ (‘break’) condition with enhanced (decreased) cyclonic vorticityand convection over monsoon trough.Gadgil and Jospeh (2003) have looked into the breaks over the Indian subcontinent using rainfallover the monsoon zone, which they feel is representative of the all India summer monsoon rainfall. Theyobtained a negative and significant correlation between monsoon zone rainfall and number of rain breakdays (r = -0.56). They also obtained a positive and significant correlation between active and monsoon zonerainfall (r= 0.47).During the break in monsoon conditions, according to Joseph and Sijikumar (2004), the strong crossequatorial low level jet stream  (LLJ) with its core around 850 hPa is oriented southeastwards and it flowseast between Sri Lanka and equator. During active monsoon conditions, the LLJ axis passes from centralArabian Sea eastwards through peninsular India and it provides moisture for convection over the Bay ofBengal and for the formation of monsoon depressions over there.Ramesh Kumar and Uma (2004) have used a new parameter, namely, the all India daily rainfall,which they felt is truly representative of the rainfall conditions over the entire Indian subcontinent andhence will be better parameter suited to identify the breaks rather than the traditional parameters such asincrease in surface pressure or circulation features over the Indian subcontinent. They have also furthershowed that the breaks identified by this method are consistent with the breaks obtained by previous studiesand the duration of the breaks so identified matches very well with that reported by Ramamurty (1969) andGadgil and Joseph (2003).Ramesh Kumar and Uma (2004) classified a day as a break day if the all India monsoon rainfall wasless than 9 mm/day and it persisted for a minimum of three days and it occurred in the mid monsoon monthsof July and August. They confined their study only to mid monsoon months for the following three importantreasons:1. A delayed onset or an early withdrawal of the monsoon can create an artificial break if we considerthe months of June and September.2. The monsoon months of July and August together contribute 61% of the seasonal total, hence aprolonged break in these months can have effect on the seasonal rainfall total.3. There are large interannual variabilities with the monsoon covering the entire Indian subcontinentin 26 days in the year 26 days in 1980 and it took 76 days in the year 2002.The percentage of days during July and August for different rainfall regimes is given in Table 1. Inorder to obtain a further insight into monsoon activity during these months, these days have been furtherclassified as normal days (rainfall less than 9 mm/day),  normal days (rainfall between 9 mm/day and 15mm/day) and active days (rainfall greater than 15 mm/day). From the table it can be seen that about 34% ofthe days have rainfall less than 9 mm/day in July, while in the case of August, 53% of the days have rainfallless than 9 mm/day. Using this threshold, breaks were identified by Ramesh Kumar and Uma (2004) for thestudy period (1901-2002) and they were consistent with breaks identified by previous studies (Ramamurty,1969; De et al., 1998; Gadgil and Joseph, 2003). The frequency of breaks of different durations is given inTable 2. From the table it can be seen that 45% of the breaks are of 3-4 days duration. The percentage ofduration of breaks compared reasonably well with previous studies.A comparison of the monsoon activity for two contrasting years, 1908 (which incidentally had onlyfew break days) and 2002 (which incidentally had only few active days) is given in Figure 1a and 1b. Thecontrasts can be clearly seen in the daily rainfall activity for the months of July and August.CMFRI - Winter School on Impact of Climate Change on Indian Marine Fisheries 68Climate change and monsoonThe breaks for different ten-day periods of July and August have been catalogued in Table 3. Further,three different types have been classified depending upon their duration a) Type I (short duration, breaks d”7 days), b) Type II (medium duration, breaks > 7 days and d” 15 days), and c) Type III (long duration,breaks >15 days). The decadal distribution these types are given in Table 4.In order to look at the role of the convective activity over the Indian Ocean on the break monsoonconditions of different durations, linear correlation was tried between the break day rainfall over the Indiansubcontinent and the OLR over the tropical Indian Ocean. Correlation was found between the convectiveactivity over the eastern equatorial Indian Ocean and type III breaks over the Indian subcontinent.The low pressure systems (LPS) and low pressure system days (Jadhav and Munot, 2004) play animportant role in the monsoon rainfall distribution. Majority of the low pressure systems, which form in theBay of Bengal travel in the northwesterly direction and give copious amounts of rainfall to large parts of theIndian subcontinent. The LPS days also showed an increasing trend during the first epoch of the studyperiod (Fig. 2). Interestingly, the LPS days also show a decreasing trend in the recent decades in tune withthe decreasing monsoon rainfall.Increasing convective activity (shown by negative trend) over the central and eastern equatorialIndian Ocean during 1979 – 2004 clearly indicates the recurrence of prolonged breaks over the Indiansubcontinent. Thus we clearly see that the equatorial Indian Ocean, especially the eastern equatorial IndianOcean has more influence on the monsoon activity over the Indian subcontinent during the recent decades.Thus the increase in the number of prolonged breaks and decrease in seasonal rainfall during the recentdecades, could be a part of the ‘climate change’ induced by the global warming.ConclusionsThere is a major shift in the monsoon rainfall pattern and there is a decrease in rainfall in the monthof July and increase in rainfall in the months of August and September.  The number of breaks and breakdays in July has increased by 30%, whilst the breaks in August have decreased in the second half of the lastcentury as compared to the first half. This major shift in the monsoon rainfall pattern could be attributed tothe climate change.ReferencesAnanthakrishnan, R and Pathan, J.M.. 1981. Pentad Rainfall charts and space time variations of rainfallover India and the adjoining areas, Contributions from the Indian Institute of Tropical Meteorology,Scientific Report.De, U.S., Lele, R.R., and Natu, J.C. 1998. Breaks in Southwest Monsoon Pre-Published Scientific ReportNo.1998/3, India Meteorological Department, Meteorological Office, Pune – 411 005, India.Gadgil, S., Joseph, S. 2003. On the Breaks of Indian Monsoon, Proceedings Indian Academy of Sciences(Earth and Planetary Sciences), 112, 529-558.Gruber, A.,  and Krueger, A.F. 1984: The status of NOAA outgoing longwave radiation data, Bull. Amer.Meteor. Soc.   65,  958-962. (1984).Jadhav, S.K., and Munot, A.A. 2004. Statistical Study of low pressure systems during summer monsoonseason over the Indian region, Mausam, 55, 15-30. (2004).Krishnan, R., Zheng, C and Sugi, M.. 2000. Dynamics of breaks in the Indian summer monsoon. J. Atmos.Sci., 57, 1354-1372.Krishnan, R., K.V. Ramesh, B.K.Samala, G.Meyers, J.M.Slingo and M.J.Fennessy. 2006. Indian OceanMonsoon Coupled interactions and impending monsoon droughts. Geophy.Res.Lett., 33, L08711,doi:10.1029/2006GL025811.CMFRI - Winter School on Impact of Climate Change on Indian Marine Fisheries 69Climate change and monsoonRamamurty, K. 1969. Monsoons of India: Some Aspects of the ‘Break in the Indian Southwest Monsoonduring July and August. Forecasting Manual No.IV-18.3. India Meteorological Department, Pune.India. 1-57.Ramesh Kumar, M.R. and Uma Prabhudessai. 2004. A new criterion for break in monsoon conditions overthe Indian subcontinent, Geophysical Research Letters, 31, L18201, doi:10.1029/2004GL020562.Ramesh Kumar, M.R., Shenoi, S.C, and Schulz, J. 2005. Impact of convection over equatorial trough andon the summer monsoon activity over India. Int. J. Rem. Sens. 26, 4747- 4762.Table 1. Percentage of days in July and August with rainfall (mm/day) in different rangeRange July August0-9 33.7 52.99-15 50.0 40.915-33 16.3 6.1Table 2. Comparison of the percentage of duration of the breaks with earlier studiesDuration Ramesh Kumar and Gadgil and Ramamurty(days) Uma (2004) Joseph (2003) (1969)3-4 45.4 44.8 49.55-6 23.2 22.8 19.87-8 11.7 14.3 16.29-10 6.1 6.7 6.3 11-12 3.6 4.8 4.513-14 3.4 3.8 1.0> 15 2.2 2.8 2.7Table 3.  Distribution of breaks (number of break days) for 10 day periods for July and August fordifferent decadesPeriod                                      July                                           August                                01-10        11-20        21-31        01-10         11-20       21-311951-1960 41              32             58             24             18              571961-1970 42              50             53             32              36             601971-1980 31              22             57             30              40             461981-1990 54              50             34             27              34             531991-2000 63              25             31             30              53            56CMFRI - Winter School on Impact of Climate Change on Indian Marine Fisheries 70Climate change and monsoonTable 4. Number of days of break (Short Duration Breaks (SDB), Long Duration Breaks (LDB) andVery Long Duration Breaks (VLDB) for two different epochs.Period SDB LDB VLDB1951-1976 77 26 021977-2002 69 27 04Fig. 1. Daily all India monsoon rainfall for two contrasting monsoon years 1908 and 2002for the months of July and AugustFig. 2. Number of low pressure system days during July and August from 1951 to 2003