Climate variability and changes

                     Climate change and variability

             

                              Climate variability includes all the variations in the climate that last longer than individual weather events, whereas the term climate change only refers to those variations that persist for a longer period of time, typically decades or more. 

                            In the time since the industrial revolution the climate has increasingly been affected by human activities that are causing global warming and climate change.

Ex.. of climate change and variability ::-

                - include changes in solar output and volcanism.

        

                   

 - Climate change and variability..

Terminology ::-

                           

                             Climate variability is the term to describe variations in the mean state and other characteristics of climate (such as chances or possibility of extreme weather, etc.)

          "on all spatial and temporal scales beyond that of individual weather events."

                                                 

                                       ^Some of the variability does not appear to be caused systematically and occurs at random times. Such variability is called random variability or noise. On the other hand, periodic variability occurs relatively regularly and in distinct modes of variability or climate patterns.

Causes ::-

            

                  Factors that can shape climate are called climate forcings or "forcing mechanisms".

                     These include processes such as variations in solar radiation, variations in the Earth's orbit, variations in the albedo or reflectivity of the continents, atmosphere, and oceans, mountain-building and continental drift and changes in greenhouse gas concentrations. External forcing can be either anthropogenic (e.g. increased emissions of greenhouse gases and dust) or natural (e.g., changes in solar output, the earth's orbit, volcano eruptions).

                     There are a variety of climate change feedbacks that can either amplify or diminish the initial forcing. There are also key thresholdswhich when exceeded can produce rapid or irreversible change.

Internal variability ::-

                                      Climatic changes due to internal variability sometimes occur in cycles or oscillations. For other types of natural climatic change, we cannot predict when it happens; the change is called random or stochastic.

                                                   ^From a climate perspective, the weather can be considered as being random.^If there are little clouds in a particular year, there is an energy imbalance and extra heat can be absorbed by the oceans. Due to climate inertia, this signal can be 'stored' in the ocean and be expressed as variability on longer time scales than the original weather disturbances.

                        Scientists generally define the five components of earth's climate system to ::-

                  include atmosphere, hydrosphere, cryosphere, lithosphere (restricted to the surface soils, rocks, and sediments), and biosphere.

Ocean-atmosphere variability

 

Oscillations and cycles ::-

         A climate oscillation or climate cycle is any recurring cyclical oscillation within global or regional climate.

• the El Niño Southern Oscillation (ENSO) – A large scale pattern of warmer (El Niño) and colder (La Niña) tropical sea surface temperatures in the Pacific Ocean with worldwide effects.
• the Madden–Julian oscillation (MJO) - An eastward moving pattern of increased rainfall over the tropics with a period of 30 to 60 days, observed mainly over the Indian and Pacific Oceans.
• the North Atlantic Oscillation (NAO) – Indices of the NAO are based on the difference of normalized sea level pressure(SLP) between Ponta Delgada, Azores and Stykkisholmur/Reykjavik, Iceland. 

Ocean current changes

See also: Thermohaline circulation

A schematic of modern thermohaline circulation. Tens of millions of years ago, continental-plate movement formed a land-free gap around Antarctica, allowing the formation of the ACC, which keeps warm waters away from Antarctica.
The oceanic aspects of climate variability can generate variability on centennial timescales due to the ocean having hundreds of times more mass than in the atmosphere, and thus very high thermal inertia
Example ::-

                     alterations to ocean processes such as thermohaline circulation play a key role in redistributing heat in the world's oceans.