Definition 1
Climate Change means a change in the state of the climate that can be identified and that persists for an extended period of time and where the change is caused directly or indirectly by:
[[(a)] human activity [(including but not limited to the burning of fossil fuels)] that alters the composition of the global atmosphere and which is in addition to natural climate variability[; or
(b) natural processes, including from volcanic eruptions and changes of solar cycles]
[including feedback loops between human activities and natural processes.]
Definition 2
Climate Change means a change in the state of the climate that can be identified and that persists for [an extended period of time] and where changes in the composition of the global atmosphere are caused directly or indirectly by an accumulated increase in Scope 1, 2 and 3 anthropogenic Greenhouse Gas Emissions, which is in addition to natural climate variability.
Drafting notes and guidance
Changes to the climate system can occur in the atmosphere, ocean, cryosphere and biosphere. Examples of climate change include major changes in temperature, precipitation or wind patterns, as well as changes in the risk of severe weather events occurring with higher frequency and intensity.
Option 1
This definition differs from that of the United Nations Framework Convention on Climate Change (UNFCCC), as limb (b) includes changes that result from natural processes or climate variability. Legal agreements may consider the cause of climate change immaterial since the important point is that steps are taken to mitigate it and also reduce its impact (adaptation), including its impact and adaptation measures in regards to human infrastructure and social equity.
Those using this definition to draft national climate laws (where the causes of climate change may be more relevant) may want to adapt the definition to only focus on human-induced climate change, in other words, limb (a) of the definition.
Feedback loops, such as deforestation reducing carbon sinks and accelerating warming, in turn drive further ecological loss and amplify climate change over time. These mutual reinforcements shape the long-term dynamics of climate change.
Option 2
This definition is more akin to that of the UNFCCC, as it focuses solely on human-induced climate change and makes use of the categories of anthropogenic Greenhouse Gas Emissions – Scope 1, 2 and 3.