The FCCC defines climate change as "a change of climate that is attributed directly or indirectly to human activity, that alters the composition of the global atmosphere, and that is in addition to natural climate variability
over comparable time periods." By contrast, the IPCC defines climate change broadly as "any change in climate over time whether due to natural variability or as a result of human activity." These different definitions have practical implications for decisions about policy responses such as adaptation.
Is it natural climate variability
or something that we are doing to the planet?
These include land-cover changes resulting from human activities, natural climate variability
, the natural end of the previous "mini ice age," and the effect of sunspots or flares.
The authors offer a balanced interpretation on whether climate change has begun and conclude that the evidence regarding the link between observed temperature trends and the enhanced greenhouse effect is not absolutely proven because any trend is very difficult to discern from the background natural climate variability
. The authors' view is clear, however, in that continuing buildup of greenhouse gases will, sooner or later, warm the earth's surface.
Giving "natural climate variability
" or "other human factors" as the reasons for a lack of consistent positive response to the supposed driving force - increasing greenhouse gas emissions - is to defend one unproven hypothesis by invoking another.
A high-resolution (0.11[degrees]) RCM large ensemble--the Canadian Regional Climate Model (CRCM5) Large Ensemble (CRCM5-LE)--was produced to study the effects of natural climate variability
on hydrology and other local impacts.
"The oxygen in oceans has dynamic properties, and its concentration can change with natural climate variability
," Ito said.
A change of climate is directly or indirectly related to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability
over comparable time periods.
This warming is due to natural climate variability
and human induced climate change, and climate models project that it will keep getting warmer.
Today, the YWAS is perceived also as a "worst-case realisation" of natural climate variability
Similarly, the 2009-2010 winter cold spell was consistent with the natural climate variability
displayed in the climate records.