Climate change and global warming is apparent from the increase in global average temperatures both in the air and in the sea, melting of the ice, rising mean sea-levels and a number of extreme phenomena such as droughts and hurricanes. It has evolved into one of the greatest environmental, social and economic threats on the planet and the scientific community warns for immediate action, by urgently increasing deployment of renewable energy technologies.
The Earth’s average temperature has been increased by 0.75°C (33.35°F) since 1850 with most of the increase occurring the last 50 years. In its Fourth Assessment Report published in 2007, the Intergovernmental Panel on Climate Change (IPCC) estimates that without any action to reduce GHG emissions, the global average temperature for the end of the 21st century (2090-2099) is estimated to increase by 1.8 – 4.0°C (35,24 – 39.2°F) and in the worst case by up to 6.4°C (43.52°F).
CO2 emissions from fossil fuel-use and from the effects of changes in the use of land are the primary sources of increased atmospheric CO2. Since 1750, it is estimated that about 2/3 of anthropogenic CO2 emissions are due to the use of fossil fuel and about 1/3 from changes in the use of land. Figure 1 depicts the energy-related CO2 emissions in the US (currently the largest energy consumer worldwide) which account for some 82% of all anthropogenic GHG emissions and result from the combustion of fossil fuels. The rising CO2 emissions during the last 150 years when large-scale industrialization began are evident in Figure 2.
As a result, carbon reduction has become a major driving force that leads scientists, governments, and the public opinion to an urgent call for creating a low-carbon economy built upon a combination of measures: renewable energy, clean coal technologies, energy efficiency and conservation of energy, carbon capture and storage (CCS) and new technologies, all falling under the umbrella of sustainable development.
In its World Energy Outlook of 2008, the International Energy Agency (IEA) has estimated that under a CO2 450ppm (parts-per-million atmospheric CO2 concentration) policy scenario (corresponding to approximately 2°C global temperature rise), the reductions in energy-related CO2 emissions can come from 54% energy efficiency, 23% renewables and biofuels, 14% CCS and 9% nuclear. Under this scenario, CO2 price in 2030 reaches $180/tCO2 whereas additional investment needed to achieve the CO2 reductions is estimated to 0.6% of GDP. Moreover, even if OECD countries alone reduce their emissions to zero, the world cannot be put onto a 450ppm trajectory because of the emissions of non-OECD countries. In its 2006 World Energy Outlook, the IEA has estimated that delaying emission-reduction actions by ten years would reduce the impact on emissions in 2030 by 75%.
According to IEA, time is short as there has never been such a large need for investments in energy infrastructure as will occur over the next decade. Both China and India will build the new infrastructure necessary to support their economic boom whereas in Europeand North-America a large part of the infrastructure is near the end of its useful life and will need to be replaced. This has two primary consequences for policy making: a) The right policies need be created now. If we wait to introduce the required new policies only over the next ten years, a large part of the investments will have been completed and locked-in. b) Chinaand Indiahave to get on board. The IEA truthfully concludes that W.I.N = Worldwide Implementation Now. So if we want to save the environment we need to invest in renewable energy sources now.