What actions are the most efficient to slow global warming?

Comparative efficiencies of different measures to combat climate change are unclear. The Economist has presented an assessment for effectiveness of various efforts to prevent emissions of greenhouse gases. The Russian Social Ecological Union believes that the key way to solve the problem of climate change is combining development of a variety of renewable energy sources and reduction of energy consumption due to energy conservation and efficiency.

After the failure of the global climate summit in Copenhagen in 2009, the world leaders have gathered again in New York at the most representative forum of the UN Climate Change only on September 23, 2014. Development of a new climate agreement meets considerable difficulties. Comparative effectiveness of various measures to combat climate change remains quite unclear. Governments are persistently averse to providing estimates of how much carbon a policy saves. The Economist has made an attempt to assess effectiveness of various efforts aimed at the prevention of GHG emissions (http://www.economist.com/news/briefing/21618680-our-guide-actions-have-d...). The analysis results are approximate and largely moot, as the authors admit themselves.

Many readers were surprised that the authors put implementation of the Montreal Protocol on Substances that Deplete the Ozone Layer (effective from 1 January 1987) in the first place in the rating of policies against climate change. The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. The molecules of these compounds are relatively persistent in the atmosphere until a rise in the middle layers of the stratosphere, where they dissociate being exposed to ultraviolet radiation, and their decomposition products cause the destruction of large quantities of ozone in the stratosphere. The Montreal Protocol has been successfully executed. Chlorofluorocarbons (CFCs), widely used in refrigerators, air conditioners and aerosols, have been replaced by less hazardous substances. At the same time, CFCs are greenhouse gases. And they are extremely potent ones, causing thousands of times more warming per molecule than carbon dioxide does. That means stopping CFC production, which was in the range of millions of tonnes a year, delivered a climate benefit equivalent to cutting carbon-dioxide emissions by 5.6 billion tons of CO2 annually.

Hydropower gives the second highest volume of prevented CO2 emissions. If the energy produced by hydropower were obtained by burning fossil fuels, the annual CO2 emissions would be greater by 2.8 billion tons. It could seem that this renewable source of energy is the right way to solve the problem of climate change. However, most of the hydro energy is produced by large hydroelectric stations, whose construction and operation causes significant environmental and social problems. Reservoirs of large-scale hydropower stations inundate highly populous and the most fertile lands. Creation of the reservoirs requires relocation of a large number of people. For example, 1.3 million people were relocated when filling the reservoir of the Three Gorges Dam in China. Natural ecosystems, migration routes of animals and fish, and spawning grounds are destroyed. For instance, construction of the Volkhov hydropower station destroyed spawning grounds and led to extinction of the Baltic sturgeon and blocked spawning path for Volkhov whitefish. Negative environmental and social impacts of large hydropower are so disastrous that most public organizations in the world, including the Russian Social Ecological Union (RSEU), oppose construction of new large hydroelectric dams.

Nuclear power takes the third place in the volumes of cutting CO2 emissions; it is responsible for reduction of 2.2 billion tons of CO2 annually. However, nuclear energy is economically unprofitable and is associated with significant environmental problems and risks. After Chernobyl and Fukushima catastrophes, more and more countries abandon plans to build new nuclear power plants and decide to decommission existing ones. The RSEU and other environmental organizations are strongly opposed to consider nuclear energy as one of the possible solutions to the problem of climate change.

Renewables (without hydropower) take the fourth place. They contribute to 0.6 billion tons per year of CO2 emissions cut. And finally, the fifth place among the measures to combat climate change belongs to efforts on prevention of deforestation in Brazil (0.4 billion tonnes of CO2 per year). Other measures lead to results less than 0.2 billion tons of CO2 annually. It is worth noting that the authors traditionally do not consider boreal forests, which make a significant contribution to the carbon balance of the planet. The RSEU believes that absorption of CO2 by forests is a crucial aspect for climate activities in Russia, which should be considered separately from other country's commitments to reduce greenhouse gas emissions. Forestry projects shall have the possibility to be financed from domestic and international sources (http://www.rusecounion.ru/kankun_101210).

It is interesting to note that sometimes quite unexpected events and actions are attributed to factors that may lead to reduction of GHG emissions. For example, in 2007, the representative of the Chinese Foreign Ministry said that, in the absence of policies to reduce fertility in China, greater consumption would lead to GHG emissions by 1.3 billion tons greater. In fact, the likely consumption in China would remain the same and the per capita one correspondingly smaller.

Collapse of the Soviet Union and the subsequent economic collapse in post-soviet countries caused actual reduction of greenhouse gas emissions by 118 million tonnes of CO2 annually. Despite the fact that Russia has not imposed stringent climate and general environmental constraints on the recovering economy, GHG emissions in Russia have not exceeded 70 % of the 1990 level yet.

What will happen next? The Montreal Protocol has been implemented, further reducing the emissions of GHGs listed in it is impossible. Despite all the efforts and some progress in the fight against deforestation, our planet loses over 440 sq. km of forests every day. Large dams are harmful, and there are not so many rivers left without dams. Nuclear energy is unprofitable and dangerous. And the concentration of greenhouse gases in the atmosphere continues to grow, as does the average global temperature.

According to The Economist, measures to prevent deforestation in Brazil can prevent emissions of about 1 billion tons of CO2 in 2020. The same effect is expected from increasing energy efficiency of enterprises in China. Development of renewable energy sources (without hydropower) in the European Union will result in prevention of 0.8 billion tons of CO2 emissions, and in China - 0.5 billion tons. Energy efficiency in transport sector will play an important role. Only in the United States due to the stricter standards for GHG emissions by vehicles (e.g., for passenger cars, 140 g CO2/km in 2016, 113 g CO2/km in 2020, and 89 g CO2/km in 2025) the expected result is 0.3 billion tons of CO2 in 2020. Energy efficiency measures in buildings in the EU will contribute 0.2 billion tonnes of CO2, etc.

Olga Senova, the Head of the Climate Secretariat of the Russian Social Ecological Union, believes that urgent actions to slow down climate change are necessary and possible. These actions shall combine development of various renewable energy sources and reduction of energy consumption due to energy saving and energy efficiency measures. All countries without exception shall take actions against climate change, concerted by a comprehensive and legally binding global climate agreement.