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  Global Warming:

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What should be done against Climate Change?

Although there are still some uncertainties, it is widely recognized that global climate change is one of the most serious threats to the environment. If no action is taken to significantly reduce greenhouse gas emissions, global warming is likely to have serious - even possibly catastrophic - consequences.

Unfortunately, there is no single action that will solve the problem. The first step would be to reduce the energy consumption in industrialized countries - by shifting the tax burden to CO2 emitting activities and products, by rethinking the planning of cities, and by improving public transportation. But also, CO2-friendly energy sources must increasingly be developed: renewable energies, CO2 underground storage, and nuclear power plants.

Actions could and should include all of the following:

  • Reducing our energy consumption: a large reduction would probably be achieved in the industrialized countries just by raising taxes on fossil fuel consumption - progressively but fast, in a planed fashion - and reducing other taxes, notably on employment, in exchange. The market mechanisms would play spontaneously, bringing two benefits: decreased emissions of greenhouse gases and increased employment.
    Notably, plane travel has the highest production of CO2 per mile (about as much CO2 per passenger as an average car occupied by one person). It is competitive only because kerosene fuel is not taxed: tax it, air tickets will become less cheap and customers will choose more CO2-friendly transportation...

    Unfortunately such actions alone would not be sufficient to reduce greenhouse gas emissions: the energy consumption in developing countries is expected to rise significantly faster than industrialized countries could reduce theirs...
  • Better thinking of the layout of the cities would help reducing the greenhouse gases emitted by transportation. Too often, office buildings are located in the center and residential areas in the outskirts, which create dense peak hour traffic, long commuting distances and unnecessary CO2 emissions. Instead, office districts should be distributed in several locations, closer to resident neighborhoods and well connected by public transport. Unfortunately, this requires political common sense in urban planning, and decisions can only have an impact on CO2 emissions long after they have been taken...
  • Improving public transport and rail freight: they are generally poorly run by ineffective state-owned monopolies. Open them wisely to competition and they will become better run, more attractive and play a greater role in CO2 reduction. Also, measures promoting carpooling are effective, such as "slugging" and lanes reserved for "HOVs" (High Occupancy Vehicles) available in many cities in the USA.
  • Developing electric vehicles: they are clearly the most sustainable personal transportation, as they use significantly less primary energy and emit nearly a quarter of the CO2 emitted by equivalent fuel vehicles (see the report published at
  • Developing renewable energies, including biomass fuels, wind turbines, solar panels and geothermal energy. Although renewable sources could and should be more utilized, there are limits to their generalization at the present state of technology:
    • Biofuels can be used right now in existing cars and trucks, mixed with gasoline or diesel - and they make the combustion cleaner and reduce urban pollution. But they consume a lot of energy in their production (25 to 75% of the energy recovered). They also require converting agricultural or natural landscapes for their production, impacting food availability and ecosystems. And they could only cover a fraction of our energy needs in the long term.
    • Wind turbines are also an excellent solution in several instances. Unfortunately, if it had to become the only energy source, a significant part of the land would be covered with wind turbines. Also, wind turbines only work when the wind blows and therefore should require expensive energy storage plants if generalized.
    • Solar heating panels are already very effective for producing hot water or heating swimming pools. However, they are far less effective in cloudy weathers and during winters, when they often need to be complemented with conventional heaters.
    • Solar photovoltaic panels are already useful in remote locations where mainstream electricity is not available. With current technologies, their can only convert a very small fraction of the solar energy available and remain very expensive. However, there is a huge potential: more research will likely increase significantly theirs yield and reduce their cost to the point where they could in a few decades become a very competitive source of energy: for instance, they could be used widely in sunny regions to produce hydrogen (see below).
      We recommend that more money should be spent in developing photovoltaic solar panel technologies.
    • Geothermal energy is widely used in some volcanic countries like Iceland where it is easily available. There are probably many other volcanic regions where it could be developed, possibly for producing hydrogen (see below), but with current technologies the potential is limited.
  • Storing CO2 underground: CO2 emitted by large sources, such as power plants, hydrogen production plants and some industrial facilities, could be purified then safely stored in underground formations. However, Carbon Capture and Storage is energy consuming and would therefore accelerate the depletion of our fossil fuel reserves.
    Read the summary of the IPCC special report on Carbon Capture and Storage...

  • Developing nuclear energy is, by many aspects, the safest, cleanest and most sustainable energy source currently available, with still a lot of potential for development. But with current technologies, nuclear plants increase the risk of nuclear weapons' proliferation, so they should be commercialized with the greatest caution (until fourth generation reactors are available). Also, the problem of nuclear waste need to find a solution: technically, it could be stored deep underground where it would remain safely for millions of years, but a a political agrement still needs to be found.

Hydrogen could be used as a fuel for transportation. Its combustion is clean (it produces essentially water) and therefore would reduce urban pollution.
However, hydrogen is NOT an "energy source": it needs to be produced by other energy sources. Because there are inevitably energy losses in its production, transport and use, hydrogen requires much more energy to produce that it can deliver in engines or in fuel cells.
But hydrogen could become a great "energy vector": for instance, it could be produced in remote locations where an energy source is abundant (for instance by solar energy in deserts, geothermal energy, or with dedicated nuclear plants). Then it would be transported to filling stations for distribution to cars and trucks - thus contributing to CO2 reduction. Some technologies for producing, transporting and using hydrogen have been developed, but unfortunately, more research and many more years will still be needed before hydrogen can effectively become a widely used fuel.

Revised April 23, 2015