Climate variability refers to shorter term deviations of climatic variations (seasonal, annual, inter-annual, several years). This includes the fluctuations caused by El Niño and La Niña.

Climate change refers to changes in the long-term trends of climate averages and variability (i.e. global warming, changes in frequency, severity and duration of extreme events etc).

more info - http://www.wmo.int/pages/prog/wcp/ccl/faqs.html

Adaptation to one or the other would generally relate to these time-scales. Measures taken to deal with or adapt to short term variability such as a drought / dry year may be (but not necessarily always) different from those needed to adapt to the changes expected over a longer time frame such as 30-50 years.

Climate variability refers to shorter term deviations of climatic variations (seasonal, annual, inter-annual, several years). This includes the fluctuations caused by El Niño and La Niña.

Climate change refers to changes in the long-term trends of climate averages and variability (i.e. global warming, changes in frequency, severity and duration of extreme events etc).

more info - http://www.wmo.int/pages/prog/wcp/ccl/faqs.html

Adaptation to one or the other would generally relate to these time-scales. Measures taken to deal with or adapt to short term variability such as a drought / dry year may be (but not necessarily always) different from those needed to adapt to the changes expected over a longer time frame such as 30-50 years.

Dear Phil Morley

Thank you very much.

Mohammad Kazemi

adjusting to short term changes is acclimatization and for long term changes is adaptation. acclimatization is a process through which adpatation starts. While acclimatization is a reversible process in an organisms life time, adaptation normally should not be a reversible process in the life time of an organism.

Agree with Rao

@Kottapalli Rao. Though your definition is the ideal one and the one I use, take note that many physiologists define "adaptation" as a feature of individuals. That is, "adaptation" means an adjustment by the organism at the cellular or physiological (or whole-organism scale) to stimuli. It's critical to understand the dual definition of this term so we can take advantage of the historical literature and apply it to current questions about climate shifts.

@PhilMorley. Thanks for the interesting link. I am struck, though, by the similarity of definition between climate variability and change. Both definitions use the mean and a measure of variance to describe these two phenomena. If this is the way these definitions are used in the literature, this is problematic and could be simplified greatly. To me, climate change encompasses both changes in mean tendency (i.e. median precipitation, median temperature) as well as changes in variance. Thus, it's not a question of "climate change" versus "climate variability." Rather, we should think of these as hierarchical and create another sub-category of climate change to indicate shifts in the central/modal value of climate. Perhaps, something like "Climate median change" or some other equally poor term! I don't think that either metric can or should be defined by the time scale on which they act. We need a simple and strait-forward distribution-based definition. Changes in the median values of climates can occur on any temporal scale (within a day, across weeks, from year-to-year, etc.) and they can occur independently of changes in variability.

Kelley thanks for a nice explanation.

Thank You all , Interesting opinions.

Mohammad Kazemi

Thanks for Morley. A very hot topic.

Dear Zhi-jun Dai

Thank you very much for your attention also thanks for Morley.

Thanks for the support you gave me on this question.

Mohammad kazemi

It just dawned on me that several posters have mentioned 30-50 years as an important time scale for measuring adaptability. I can't believe I didn't catch this before. Absolute time scales such as this shouldn't be used to distinguish climate change from "weather." And it should not be used to estimate the potential that an organism will be able to adjust (via a plastic or evolved response) to changing climate means or its variation. It is good to remember that we must gauge organisms' responses to changing climate as a function of [1] climatic variation, [2] ability to plastically adjust behaviors, and [3] evolvability (generation time). We cannot ignore fundamental life-history traits when considering the feedback between the environment and the organism and the way in which organisms modify their own environments (e.g. choice of microclimates, etc.). Climate change to one organism is not climate change to another.

Yes you are right that climate induced genetic changes will take 100s of year probably to be prominent.

Dear Kenneth

It is interesting that "people's memory" about the effects of weather variables on plants or animals is the basis of distinction between "climate" and "weather" and this fact is used vastly in scientific papers. If possible please let me know your opinion about it.

Thank you

Mohammad Kazemi

Dear Kennet

I Completely agree with you. But also a few scientist believed that the climate change in historical view is natural and do not need any mitigation such as reducing green house gases. Is this true?

Thanks again.

In my opinion climate variability, or call it weather variability, may be cyclic and hence organisms can adapt to it. Climate change, i.e. the long-term change, in contrast leads to climatic conditions direct ancestors have not been faced with and in this may be more difficult for adaptation.

Endemic species often can be found in climatically stable conditions which are by the same time often montaneous habitats with weather conditions not so nice (at least for us). This may be due to the steep relief of mountains in which species do not need to move a long way to get suitable climatic, or weather, conditions.

Climate Variability and Climate Change are two different things. Details have been discussed further up. I feel that the ways to adapt to both are partly similar, but depending on how severe climate change enhances the exposure to people to particular risks and stresses adaptation measures need to be stronger at times. E.g. in case flooding is an issue that has always been in a particular location, it might no more be sufficient to build houses on stilts that are 30 cm high but it now needs to be 100 cm. Or people better would leave flood prone areas (which earlier was not needed). A lot depends on circumstances and predictions. Climate variability as as little to excatly predict than climate change and both happen at the same time, meaning that in times of climate change there is still climate variability. This is what people often do not realize and argue that climate variability has been replaced by climate change.

I would make a few (I believe) critically important distinctions between climate variability and climate change. While it is true that climate change generally happens on geological time frames, climate variability IS happening on human time frames and is far more immediate and impactful particularly as it relates to forest fires. C.M. Countryman did some excellent research in the 1950's (giving a paper at the Society of American Foresters meeting in Portland, Oregon which they conveniently couldn't find) where he measured the temperatures in the canopy, on the forest floor and 200 feet into a clear cut. He found at 8am the canopy was 68 degrees and the forest floor was 50 degrees. At 10 am the canopy was 84 degrees and the floor was 77 degrees. At 2 pm the canopy and forest floor were both 87 degrees while on the ground in the clear cut it was 153 degrees. With additional fuel loads after harvests and little shade our management choices are effectively 'baking' the fuel loads in an oven every day of sun. So with the extensive clear cutting of the last 70 years we have created the context for cataclysmic fire everywhere we have 'practiced' this management. To not see the absurdities of incomplete or false analysis ( ie climate change and suppression as 'at cause') and not our management choices is criminal at this stage, in my humble opinion.