According to a new report which the Intergovernmental Panel on Climate Change (IPCC) published today, the sky is the limit for the expansion of renewable energy. With an investment of slightly less than 1% of global GDP, renewable energy could contribute up to 43% of the world's energy supply by 2030, and 77% by 2050. Such an increase could stabilize the CO2 concentration in the atmosphere at 450 ppm and may be just enough to avoid catastrophic climate change. It would also boost energy access for the 1.4 billion people who currently live without access to electricity.
The IPCC report presents a menu of actions such as feed-in tariffs for renewable energy that can be implemented immediately. It is cause for hope. From an environmental and human rights perspective, the new report has only one problem: against standard practice, it includes large hydropower projects among the technologies to be promoted. With this approach, the IPCC report ignores several key factors:
• Ecological impacts: While water is a renewable resource, the ecosystems that are destroyed by hydropower projects are not. Not least due to dam building, rivers, lakes and wetlands suffer from a higher rate of species extinction than any other major ecosystem. According to the Millennium Ecosystem Assessment, freshwater ecosystems lost 50% of their populations between 1970 and 2000. IUCN's Red List warns that 37% of all freshwater fish species are under threat of extinction. Large hydropower projects also have much more serious social impacts than the truly renewable sources of energy.
• Greenhouse gas emissions: Because of decomposing organic matter in reservoirs, dams emit greenhouse gases such as methane and CO2. In the case of shallow tropical reservoirs, the emissions from hydropower projects can be higher than those of thermal power projects with the same electricity output. Ivan Lima of Brazil's National Institute for Space Research estimated the total methane emissions from large dams at 104 million tons per year. Methane is a particularly potent greenhouse gas, and Lima's figure amounts to more than 4% of the total warming impact of human activities - roughly equal to the climate impact of the global aviation sector. (The figure includes reservoirs that were built for other purposes than hydropower, but not the emissions generated by the construction of dams.)
• Vulnerability to climate change: Countries need to diversify and decentralize their water and energy infrastructure in order to strengthen their resilience to the vagaries of climate change. In contrast, building big, clunky dams on the other hand will make water and energy sectors more vulnerable. As a World Bank report found earlier this year, "long-lifespan infrastructure, such as hydropower plants, is generally less adaptable to changes whereas short-lifespan infrastructure can be replaced in the long term as the climate changes." The report warns that "heavy reliance on hydropower creates significant vulnerability to climate change," and suggests that "an adaptation response may require a policy decision to diversify away from hydropower."
• Limited growth potential: Hydropower is a mature technology which has not seen major breakthroughs in past decades. The new IPCC report confirms that the technical potential of hydropower is vastly lower than the potential of wind, geothermal, solar and biomass energy. It also recognizes that "further cost reductions for hydropower are expected to be less significant than some of the other [renewable energy] technologies." Because of large hydropower's serious impacts and limited growth potential, limited financial resources should not be squandered on subsidies for further dam building.
By listing large hydropower among the technologies that deserve support, the IPCC contravenes international standard practice. Across the world, policy tools - for example portfolio standards, feed-in tariffs, and tax credits - only tend to consider small hydropower projects as a form of renewable energy. Small hydropower is generally defined as projects of less than 10 megawatts.
Why has the IPCC downplayed the ecological impacts of large dams, including their contribution to climate change, and included large hydropower among the technologies that deserve public support? The sad truth is that in addition to several independent scientists, the IPCC selected a number of authors who have a vested interest in the outcome of the hydropower chapter. The nine lead authors of this chapter include representatives of two of the world's largest hydropower developers, a hydropower consultancy, and three agencies promoting hydropower at the national level.
I highly value the IPCC's difficult work, and have no sympathy for the climate change deniers who will probably attack the new report for their own motives. I do not question the personal integrity of the report's authors, and personally respect the one industry representative among them whom I know. Yet it is not appropriate for IPCC to commission individuals with a business or institutional interest to prepare a report that is supposed to be unbiased and independent.
The authors' conflict of interest is reflected throughout the hydropower section of the report, which at times reads like a marketing brochure of the dam industry. The report ignores or downplays the evidence regarding the social and environmental impacts of dams that has been produced by the independent World Commission on Dams, and naively assumes that these impacts can essentially be mitigated. It further highlights the global changes of precipitation under climate change, but neglects the uncertainties regarding future rainfalls on the local level, which are much more relevant for hydropower projects. (A more detailed critique of the IPCC report's chapter on hydropower is available here.)
Combating climate change must be part of a holistic effort to save the world's ecosystems. We cannot afford to sacrifice the planet's arteries to save her lungs. The new IPCC report demonstrates that there is a vast potential for energy technologies that have much lower environmental and social impacts than large dams. These are the solutions that deserve our full support.