What is climate change?
To be clear
Definitions of climate change are as numerous as its effects.
Let's attempt to provide a clear and simple definition. The Canadian government defines climate change as "designating a long-term modification to the climate measured by changes in temperature, precipitation, wind and other indicators." So far, there's nothing complicated; climate change is therefore a simple modification of the climatic system from the way we are used to it.
To this definition we add an important specification: "Climate change can be caused both by natural processes (ex: variations in the sun's speed or quantity of volcanic dust in the atmosphere), and also human activities. Therefore, humans can modify the composition of the atmosphere through certain activities like the combustion of fossil fuels. (ex: use of fuel, coal or natural gas) ."
This climate modification lead to an increase of extreme climate events (such as drought, flood and fire) that have consequences on our Mother-Earth but also on our economy, health, infrastructures and landscapes.
Who?
In 1988, the World Meteorological Organization (WMO) and the United Nations Program for the Environment (UNPE) created the Intergovernmental Panel on Climate Change (IPCC) in order to assess scientific information on climate change, measure the environmental and socio-economic consequences and finally, formulate realistic strategies. In 2007, the group published an assessment report that provided an overview on climate change and emphasized their risks and repercussions, and proposed options on how to adapt to or mitigate them.
What should be gathered from the GIEC report
(Excerpt from the Synthesis Report intended for the decision-makers of the 4th IPCC assessment report.)
Finding
The warming of the climate system is unequivocal. We already noted that, globally speaking, an increase in the average temperatures of the atmosphere and ocean, a massive melting of snow and ice and an increase in the average sea level. Observations made on all the continents and in most of the oceans shows that a multitude of natural systems are affected by regional climate change, particularly the increase in temperatures.
Causes
Global GG emissions caused by human activity have increased since the pre-industrial era; they increased by 70% between 1970 and 2004. The main cause of the increase in the concentration of CO² is the use of fossil fuels. It is very probable that the observed increase in the concentration of methan (CH4) stems mostly from agriculture and of the use of fossil fuels. We can confidently assert that human activities since then have had the net effect of warming the climate.
Effects
Considering the mitigation measures and sustainable development practices already in place, global GG emissions will continue to increase during the next decades. It is very probable that these changes will be greater than those observed during the 20th century. Man-made global warning can have sudden or irreversible consequences according to the scope and rhythm of the climate's evolution.
It is probable that climate change will have a certain number of irreversible impacts. If the average warming rate of the planet exceeds the period of 1980-1999 by 1.5 to 2.5 °C, 20 à 30% of all species surveyed so far risk extinction (confidence degree medium). If the temperature increases by more than about 3.5 °C, the models predict that 40 to 70% of the species surveyed could disappear from the surface of the earth.
Adaptation
The capacity to adapt is a dynamic process that forms the production basis of any society: natural resources and economic means, networks and social programs, human capital and institutions, mode of government, national income, health and technology. Even societies equipped with a great capacity for adaptation remain vulnerable to the evolution and variability of the climate along with climatic extremes. Several factors are likely to amplify vulnerability to climate change, namely poverty, unequal access to resources, food insecurity, the economic globalization trend, current conflicts and the incidence of diseases such as HIV/AIDS, without forgetting existing climatic threats. But adaptation can mitigate vulnerability, especially if it enters into broader sectoral initiatives. Governments can implement a broad range of policies and instruments intended to stimulate mitigation […]
The modification of lifestyles, behaviours and management practices can also contribute to mitigate the effects of climate change in all sectors.