Climate change is a change in the "average weather" that a given region experiences. Average weather includes all the features we associate with the weather such as temperature, wind patterns and precipitation.

When we speak of climate change on a global scale, we are referring to changes in the climate of the Earth as a whole. The rate and magnitude of global climate changes over the long term have many implications for natural ecosystems.

As human societies adopt increasingly sophisticated and mechanized lifestyles, the amounts of heat-trapping gases in the atmosphere have been increased. By increasing the amount of these gases, humankind has enhanced the warming capability of the natural greenhouse effect. It is the human-induced enhanced greenhouse effect that causes environmental concern. It has the potential to warm the planet at a rate that has never been experienced in human history.

The Political Declaration of the Bonn International Conference for Renewable Energies 2004, that was discussed and adopted by ministers and government representatives from 154 countries, acknowledged that "in the context of Renewable 2004, renewable energy sources and technologies include: solar energy, wind energy, hydropower, biomass energy including biofuels and geothermal energy," with no distinction with respect to scale. This is consistent with the discussions that took place at the World Summit on Sustainable Development held in 2002.

A shortage of access to energy is recognized as one of the great obstacles to development, impeding business activity and disproportionately affecting the poor who have traditionally the least access. Many OECD countries have developed more than 80% of the potential of their economically-viable hydropower, and hydropower development has been a vital platform for economic growth. This is in contrast to 20% in developing countries as a whole, and under 5% in African countries. Developing countries themselves have repeatedly stressed the importance they attach to utilizing this large domestic source of energy, particularly when oil prices are increasing by the day.
 

Industrialized countries have to implement domestic policies and measures to reduce green house gas emissions. These domestic measures have to generate the most significant part of the emission reductions used by an industrialized country to achieve its compliance targets according to the Kyoto Protocol, and emissions reductions earned through CDM and other market mechanisms can only be supplementary to these domestic actions.

It is estimated that the cost to meet emission reduction commitments made under the Kyoto Protocol is in the order of billions of dollars. Given that they reduce cost of compliance, flexible mechanisms such as the Clean Development Mechanism are relevant to the long-term engagement of the global community to combat global climate change.

For developing countries, the Clean Development Mechanism represents an opportunity to attract investments from the public and private sectors in climate-friendly technologies, and to contribute to the global combat on climate change. In order to be eligible, CDM projects have to be above and beyond business-as-usual, and must contribute to sustainable development as defined by the host country (developing country). Participation in the Clean Development Mechanism is entirely voluntary.
  

With the entry into force of the Kyoto Protocol on February 16, 2005, more than one hundred and forty countries agree to work together to fight global climate change. The thirty six industrialized countries that ratified the Protocol - namely Canada, Japan, members of the European Union, as well economies in transition from Central and Eastern Europe - agree to put in place policies and measures to collectively reduce 5 percent of their emissions between2008 to 2012 as measured against 1990 levels. To meet this binding commitment, industrialized countries have the option to reduce part of their emissions domestically, and they can also emission reductions from developing countries (through the Clean Development Mechanism), or from countries with economies in transition (through Joint Implementation or International Emissions Trading).