Climate Change · Dams · Hydropower

Dams are not Climate Friendly: Readings from IPCC WG II Report

Inter-governmental Panel on Climate Change’s (IPCC) Fifth Assessment is falling into place. On the 31st March 2014, the report titled ‘Climate Change 2014: Impacts, Adaptation, and Vulnerability’, from Working Group II[1] was issued in Yokohoma, Japan. Working Group II assesses “the vulnerability of socio-economic and natural systems to climate change, negative and positive consequences of climate change, and options for adapting to it. It also takes into consideration the inter-relationship between vulnerability, adaptation and sustainable development.”[2]

This can be called as one of the more incisive Working Group Reports from IPCC. It states unequivocally that the effects of climate change are already occurring on all continents and across the oceans and world is ill-prepared for risks from a changing climate. According to Co-Chair of Working Group II, Chris Field, “The report concludes that people, societies, and ecosystems are vulnerable around the world, but with different vulnerability in different places. Climate change often interacts with other stresses to increase risk”.[3]

The report consists of two volumes. First volume contains a Summary for Policymakers, Technical Summary, and 20 chapters assessing risks by sector and opportunities for response. The sectors include freshwater resources, terrestrial and ocean ecosystems, coasts, food, urban and rural areas, energy and industry, human health and security, and livelihoods and poverty. A second volume of 10 chapters assesses risks and opportunities for response by region. These regions include Africa, Europe, Asia, Australasia, North America, Central and South America, Polar Regions, Small Islands, and the Ocean.

The summary for policymakers paints a sombre picture: “Climate change over the 21st century is projected to reduce renewable surface water and groundwater resources significantly in most dry subtropical regions, intensifying competition for water among sectors. In presently dry regions, drought frequency will likely increase by the end of the 21st century under RCP8.5. In contrast, water resources are projected to increase at high latitudes. Climate change is projected to reduce raw water quality and pose risks to drinking water quality even with conventional treatment, due to interacting factors: increased temperature; increased sediment, nutrient, and pollutant loadings from heavy rainfall; increased concentration of pollutants during droughts; and disruption of treatment facilities during floods. Adaptive water management techniques, including scenario planning, learning-based approaches, and flexible and low-regret solutions, can help create resilience to uncertain hydrological changes and impacts due to climate change.”

“Risks are unevenly distributed and are generally greater for disadvantaged people and communities in countries at all levels of development.”

Links with water

Being an integral and cross cutting issue, water features prominently in all of Chapters of the Working Group Report. Sections on Freshwater Resources, Costal systems and low lying areas, Food Security, Inland systems, etc. include important findings. It is significant to note that dams, hydropower projects, infrastructure measures like channelization, embankments, etc., are also mentioned in nearly all the chapters of the report. Couple of references indicate dams as a possible adaptation measure, but overwhelming references point to the contrary.

The collective picture that is arising through these reference is very important. A collation and analysis of all specific references to water infrastructure projects, read in tandem with the report indicates that: 

1. Dams and infrastructure projects contribute significantly to “non-climate impacts” which, after interacting with changing climate, exacerbate the overall impact on human societies and ecosystems

o   Sediment Trapping by reservoirs, exacerbates impact of  sea level rise

o   Hydropower affects local options

o   Climate  change and dams together affect a greater eco-region

o   Increased flow fluctuations by dams exacerbate through climate change

2. In case of Flood Protection, dams and embankments may do more harm than good. Ecological measures would fare better.

3. Dams and Hydropower projects affect biodiversity, which is critical in facing climate change challenges.

4. In the tropics, global warming potential of hydropower may exceed that of Thermal Power

5. Dams increase vulnerability of weaker sections to climate change

6. Existing Dams have to be managed sustainably, with ecological considerations

7. Hydropower itself is vulnerable to Climate Change


The references used in WG II report are peer reviewed research from several authors.The specific references given below will play an important role in debunking the simplistic myth that dams and hydropower projects are climate friendly and can be considered as de facto adaptation measures to cope with Climate Change.

Some Relevant Extracts from Working Group II Report:

  1. Dams and infrastructure projects contribute significantly to “non-climate impacts” which, after interacting with climate impacts, exacerbate the overall impact of climate change on human societies and ecosystems 
  • Sediment Trapping by reservoirs, exacerbates impact of  sea level rise

“Most large deltas in Asia are sinking (as a result of groundwater withdrawal, floodplain engineering, and trapping of sediments by dams) much faster than global sea-level is rising.” (Chapter 24: Asia)

“Human activities in drainage basins and coastal plains have impacted the coastal zone by changing the delivery of sediment to the coast. Sediment trapping behind dams, water diversion for irrigation, and sand and gravel mining in river channels all contribute to decrease sediment delivery, whereas soil erosion due to land-use changes help increase it. It is estimated that the global discharge of riverine sediment was 16-–19 Gt/ yr in the 1950s before widespread dam construction and it has decreased to 12–13 Gt/ yr. Out of 145 major rivers with mostly more than 25-year record, only 7 showed evidence of an increase in sediment flux while 68 showed significant downward trends. The number of dams has increased continuously and their distribution has expanded globally. As of early 2011, the world has an estimated 16.7 million reservoirs larger than 0.01 ha. Globally, 34 rivers with drainage basins of 19 million km2 in total show a 75% reduction in sediment discharge over the past 50 years. Reservoir trapping of sediments is estimated globally as 3.6 Gt/ yr to more than 5 Gt/ yr (Syvitski et al., 2005; Walling, 2012; Milliman and Farnsworth, 2011). Human pressure is the main driver of the observed declining trend in sediment delivery to the coastline.(Chapter 5 Coastal systems and Low Lying areas)

“Attributing shoreline changes to climate change is still difficult due to the multiple natural and anthropogenic drivers contributing to coastal erosion.” (Chapter 5 Coastal systems and low lying areas)

“The combined impact of sediment reduction, relative sea level rise, land-use changes in delta and river management on channels and banks has led to the widespread degradation of deltas. The changes of sediment delivery from rivers due to dams, irrigation and embankments/dykes creates an imbalance in sediment budget in the coastal zones. Degradation of beaches, mangroves, tidal flats, and subaqueous delta fronts along deltaic coasts has been reported in many deltas (e.g. Nile and Ebro, Sanchez-Arcilla et al., 1998; Po, Simeoni and Corbau, 2009; Krishna-Godavari, Nageswara Rao et al., 2010; Changjiang, Yang et al., 2011; Huanghe, Chu et al., 1996; very high confidence). Deltaic coasts naturally evolve by seaward migration of the shoreline, forming a delta plain. However, decreasing sediment discharge during the last 50 years has decreased the growth of deltaic land, even reversing it in some locations (e.g. Nile, Godavari, Huanghe). Artificial reinforcement of natural levees also has reduced the inter-distributory basin sedimentation in most deltas, resulting in wetland loss.” (Emphasis added.)

“The major impacts of sea level rise are changes in coastal wetlands, increased coastal flooding, increased coastal erosion, and saltwater intrusion into estuaries and deltas, which are exacerbated by increased human-induced drivers. Ground subsidence amplifies these hazards in farms and cities on deltaic plains through relative sea level rise. Relative sea level rise due to subsidence has induced wetland loss and shoreline retreat (e.g. the Mississippi delta, Morton et al., 2005; Chao Phraya delta, Saito et al., 2007; high confidence).” (Chapter 5 Coastal systems and low lying areas)

“There have been local variations in precipitation and runoff since 1950, but changes in sediment load are primarily attributed to over 50,000 dams and vegetation changes.”  (Chapter 18: Detection and attribution of observed impacts)

  • Hydropower affects local options

“Hydropower dams along the Mekong River and its tributaries will also have severe impacts on fish productivity and biodiversity, by blocking critical fish migration routes, altering the habitat of non-migratory fish species, and reducing nutrient flows downstream. Climate impacts, though less severe than the impact of dams, will exacerbate these changes.”(Chapter 24: Asia)

  • Climate  change and dams together affect a greater eco-region

“For one climate scenario, 15% of the global land area may be negatively affected, by the 2050s, by a decrease of fish species in the upstream basin of more than 10%, as compared to only 10% of the land area that has already suffered from such decreases due to water withdrawals and dams (Döll and Zhang, 2010). Climate change may exacerbate the negative impacts of dams for freshwater ecosystems.” (Chapter 3: Freshwater resources)

  1. Flood Protection: Dams and embankments may do more harm than good. Ecological measures fare better.
  • “On rivers and coasts, the use of hard defences (e.g. sea-walls, channelization, bunds, dams) to protect agriculture and human settlements from flooding may have negative consequences for both natural ecosystems and carbon sequestration by preventing natural adjustments to changing conditions. Conversely, setting aside landward buffer zones along coasts and rivers would be positive for both. The very high carbon sequestration potential of the organic-rich soils in mangroves and peat swamp forests provides opportunities for combining adaptation with mitigation through restoration of degraded areas.” (Chapter 3 Freshwater Resources)
  • “Ecosystem based adaptation (EBA) can be combined with, or even a substitute for, the use of engineered infrastructure or other technological approaches. Engineered defenses such as dams, sea walls and levees adversely affect biodiversity, potentially resulting in maladaptation due to damage to ecosystem regulating services. There is some evidence that the restoration and use of ecosystem services may reduce or delay the need for these engineering solutions. EBA offers lower risk of maladaptation than engineering solutions in that their application is more flexible and responsive to unanticipated environmental changes. Well-integrated EBA can be more cost effective and sustainable than non-integrated physical engineering approaches (Jones et al., 2012), and may contribute to achieving sustainable development goals (e.g., poverty reduction, sustainable environmental management, and even mitigation objectives), especially when they are integrated with sound ecosystem management approaches.” (Chapter 3 and Also Chapter 15 Adaptation Planning and Implementation)
  1. Dams and Hydropower projects affect biodiversity, which is critical in facing climate change challenges
  • “Freshwater ecosystems are considered to be among the most threatened on the planet. Fragmentation of rivers by dams and the alteration of natural flow regimes have led to major impacts on freshwater biota.” (Chapter 4: Terrestrial and Inland Water Systems)
  • “Damming of river systems for hydropower can cause fragmentation of the inland water habitat with implications for fish species.” (Chapter 4 Terrestrial and Inland Water Systems)
  •  “Freshwater ecosystems are also affected by water quality changes induced by climate change, and by human adaptations to climate-change induced increases of streamflow variability and flood risk, such as the construction of dykes and dams”. (Chapter 3: Freshwater resources)
  • “Hydropower generation leads to alteration of river flow regimes that negatively affect freshwater ecosystems, in particular biodiversity and abundance of riverine organisms, and to fragmentation of river channels by dams, with negative impacts on migratory species. (Chapter 3: Freshwater Resources)
  • “Hydropower operations often lead to discharge changes on hourly timescales that are detrimental to the downstream river ecosystem.”
  • “Climate change and habitat modification (e.g., dams and obstructions) impact fish species such as salmon and eels that pass through estuaries.” (Chapter 5 Coastal Systems and low lying areas)
  1. In Tropics, global warming potential of hydropower may exceed Thermal Power
  • “In tropical regions, the global warming potential of hydropower, due to methane emissions from man-made reservoirs, may exceed that of thermal power; based on observed emissions of a tropical reservoir, this might be the case where the ratio of hydropower generated to the surface area of the reservoir is less than 1 MW/km2”.
  • “Reservoirs can be a sink of CO2 but also a source of biogenic CO2 and CH4” (Chapter 4 Terrestrial and Inland Systems)
  1. Dams increase vulnerability of weaker sections to climate change
  • “A number of studies recognize that not every possible response to climate change is consistent with sustainable development, since some strategies and actions may have negative impacts on the well-being of others and of future generations .For example, in central Vietnam some responses to climate change impact, such as building dams to prevent flooding and saltwater intrusion and to generate power, threaten the livelihood of poor communities. First, the relocation of communities and the inundation of forestland to build dams limit households’ access to land and forest products. Second, a government focus on irrigated rice agriculture can reduce poor households’ ability to diversify their income portfolio, decreasing their long-term adaptive capacity. Indeed, the consequences of responses to climate change, whether related to mitigation or adaptation, can negatively influence future vulnerability, unless there is awareness of and response to these interactions. Here, the role of values in responding to climate change becomes important from a variety of perspectives, including intergenerational, particularly when those currently in positions of power and authority assume that their prioritized values will be shared by future generations. (Chapter 20: Climate-resilient pathways: adaptation, mitigation, and sustainable development)
  •  “Some documented impacts on dams, reservoirs and irrigation infrastructure are: reduction of sediment load due to reductions in flows (associated with lower precipitation), positively affecting infrastructure operation (Wang et al., 2007); impacts of climate variability and change on storage capacity that creates further vulnerability; and failures in the reliability of water allocation systems (based on water use rights) due to reductions of streamflows under future climate scenarios” (Chapter 9: Rural Areas)
  • “Infrastructure (e.g. roads, buildings, dams and irrigation systems) will be affected by extreme events associated with climate change. These climate impacts may contribute to migration away from rural areas, though rural migration already exists in many different forms for many non-climate-related reasons.” (Chapter 9 Rural Areas)
  • “Changes in water use, including increased water diversion and development to meet increasing water demand, and increased dam building will also have implications for inland fisheries and aquaculture, and therefore for the people dependent on them” .
  • “In the case of the Mekong River basin, a large proportion of the 60 million inhabitants are dependent in some way on fisheries and aquaculture which will be seriously impacted by human population growth, flood mitigation, increased offtake of water, changes in land use and overfishing, as well as by climate change. Ficke et al. (2007) reported that at that time there were 46 large dams planned or already under construction in the Yangtze River basin, the completion of which would have detrimental effects on those dependent on fish for subsistence and recreation.” (Chapter 7 Food security and food production systems)
  1. Existing Dams have to be managed sustainably, with ecological considerations:
  • “Suggested strategies for maximizing the adaptive capacity of ecosystems include reducing non-climate impacts, maximizing landscape connectivity, and protecting ‘refugia’ where climate change is expected to be less than the regional mean. Additional options for inland waters include operating dams to maintain environmental flows for biodiversity, protecting catchments, and preserving river floodplains.” (Chapter 24:Asia )
  1. Hydropower itself is vulnerable to Climate Change
  • “Climate change affects hydropower generation through changes in the mean annual stream-flow, shifts of seasonal flows and increases of stream-flow variability (including floods and droughts) as well as by increased evaporation from reservoirs and changes in sediment fluxes. Therefore, the impact of climate change on a specific hydropower plant will depend on the local change of these hydro-logical characteristics, as well as on the type of hydropower plant and on the (seasonal) energy demand, which will itself be affected by climate change”
  • “Projections of future hydropower generation are subject to the uncertainty of projected precipitation and stream-flow. In regions with high electricity demand for summertime cooling, this seasonal stream-flow shift is detrimental. In general, climate change requires adaptation of operating rules which may, however, be constrained by reservoir capacity. Storage capacity expansion would help increase hydropower generation but might not be cost-effective.”
  • “Observations and models suggest that global warming impacts on glacier and snow-fed streams and rivers will pass through two contrasting phases. In the first phase, when river discharge is increased due to intensified melting, the overall diversity and abundance of species may increase. However, changes in water temperature and stream-flow may have negative impacts on narrow range endemics. In the second phase, when snowfields melt early and glaciers have shrunken to the point that late-summer stream flow is reduced, broad negative impacts are foreseen, with species diversity rapidly declining once a critical threshold of roughly 50% glacial cover is crossed.” (Chapter 3 Freshwater Resources)

Let us hope that these collated finding will be helpful in addressing the myth that dams and hydropower projects are climate friendly and can even be looked at as adaptation measures. Let us also hope that the Working Group III Report, which will come out in less than a week’s time from now, will have lessons for hydropower development in line with the above statements in the WG II report.

Issues with WG III, Special Report on Renewable Energy

Findings of WG II contrast strikingly with Special Report on Renewable Energy Sources and Climate Change Mitigation (SRREN) [4]brought out by Working Group III in 2011.

SRREOne of the two lead coordinating authors of this report was Dr. Arun Kumar, from AHEC, IIT Roorkee. Notably, Dr. Kumar was also a part of the team which worked on Cumulative Impact Assessment of Hydropower projects in Upper Ganga basin of Uttarakhand[5]. The state suffered huge flood and precipitation damages in June 2013 (long after the report came out) and commissioned and under–construction hydropower projects had a large role to play in compounding the impacts of the disaster[6]. Ministry of Environment and Forests as well as the Supreme Court of India rejected this report. SANDRP had published a detailed critique of this CIA report at the outset.

Amazingly, the Hydropower Section of the above mentioned IPCC Special Report on Renewable Energy severely downplays and ignores the impacts of hydropower. For example, it does not allude to peoples protests to projects, impacts of projects by blasting and tunneling, downstream impacts, impacts of peaking, associated deforestation and related development, cumulative impacts of projects in a cascade, increasing climate vulnerability of the population, seismic impacts, increased disaster vulnerability of the region, etc.,. In fact, these impacts have been some of the most-discussed issues in hydropower discourse in many countries at the moment. The report makes strange statements like “trans-boundary hydropower establishes arena for international cooperation”, when we see across the world that hydropower projects on internationally shared rivers further conflicts and strife between nations. It also downplays methane emissions from hydropower.

In all, the section appears biased towards hydropower and does not do justice to IPCC’s rigorous and objective standards. The section should not have been accepted as it stands now.

Now, the Working Group III is yet to submit its Assessment Report to the IPCC. It will be discussed by the IPCC between 7-11 April 2014, in Berlin. We hope there is true depiction of hydropower in the Working Group III report, looking at the above mentioned impacts and also keeping in mind strong statements from Working Group II report made public on March 31, 2014.

Parineeta Dandekar,



[1] The IPCC Working Group I (WG I) assesses the physical scientific aspects of the climate system and climate change. Working Group II (WG II) assesses the vulnerability of socio-economic and natural systems to climate change, negative and positive consequences of climate change, and options for adapting to it. It also takes into consideration the inter-relationship between vulnerability, adaptation and sustainable development. The assessed information is considered by sectors (water resources; ecosystems; food & forests; coastal systems; industry; human health) and regions (Africa; Asia; Australia & New Zealand; Europe; Latin America; North America; Polar Regions; Small Islands). The IPCC Working Group III (WG III) assesses options for mitigating climate change through limiting or preventing greenhouse gas emissions and enhancing activities that remove them from the atmosphere. (







4 thoughts on “Dams are not Climate Friendly: Readings from IPCC WG II Report

  1. Dear Sri Thakkar,
    For a moment I agree with you that Dams are not climate friendly. Whether construction of roads and houses are climate friendly as they damage the environment through extraction of construction materials? Are thermal power stations environmental friendly? Are the white goods we use for our comfort environmental friendly? Is the increasing population environmental friendly?. I want your response to educate me. If they are not why are you not opposing them?
    Yours sincerely
    Devadutta Das


    1. Thanks for your response.

      The issue here is about the fact that dams are put forth as an adaptation measure against climate change, without studying their impacts. Thermal Power Plants are not. India’s proposed Tipaimukh Hydel project has the capacity to drown 25,000 hectares of forest, which will result in significant methane emissions in time. It was supposed to conduct Emissions Study as a clearance condition. It has not done so. This is but one such example.

      The issue here is not opposing dams, but not being ready to study the impacts and actually pushing them as climate friendly measures, ignoring their impacts.

      – Parineeta Dandekar


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