What is the definition of Climate Change?

Definition of climate change

It may depend who you ask. We have chosen a definition of climate change, as follows, based upon the an examination of the definitions of the prominent agencies and organizations below:

Climate change is a change in the statistical distribution of weather patterns, when that change lasts for an extended and relevant period of time (i.e., decades to millions of years). Climate change may refer to a change in average weather conditions, or in the time variation of weather around longer-term average conditions (i.e., more or fewer extreme weather events)

Here are the definitions and sources we examined:

  • USA EPA : Climate change refers to any significant change in the measures of climate lasting for an extended period of time. In other words, climate change includes major changes in temperature, precipitation, or wind patterns, among others, that occur over several decades or longer.."
  • Wikipedia (February 9, 2015) "Climate change is a change in the statistical distribution of weather patterns when that change lasts for an extended period of time (i.e., decades to millions of years). Climate change may refer to a change in average weather conditions, or in the time variation of weather around longer-term average conditions (i.e., more or fewer extreme weather events).
  • IEA (International Energy Agency) - "Climate change is the change in climate (i.e. regional temperature, precipitation, extreme weather, etc.) caused by increase in the greenhouse effect. "
  • IPCC (Intergovernmental Panel on Climate Change) - "Climate change in IPCC usage refers to a change in the state of the climate that can be identified (e.g. using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer. It refers to any change in climate over time, whether due to natural variability or as a result of human activity. This usage differs from that in the United Nations Framework Convention on Climate Change (UNFCCC), where climate change refers to 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 observed over comparable time periods."
  • Ecolife.com - "Climate change is the long-term shift in weather patterns in a specific region or globally. Unlike global warming, which refers to just one aspect of climate change - a rise in the surface temperature of the earth's surface - climate change refers to changes in a regions overall weather patterns, including precipitation, temperatures, cloud cover, and so on."
  • Oxford Dictionary - "NOUN - A change in global or regional climate patterns, in particular a change apparent from the mid to late 20th century onwards and attributed largely to the increased levels of atmospheric carbon dioxide produced by the use of fossil fuels."
  • Dictionary.com: "noun. a long-term change in the earth's climate, especially a change due to an increase in the average atmospheric temperature:
    'Melting glaciers imply that life in the Arctic is affected by climate change.' "

OK, we have a working definition. The Earth's climate has changed throughout history. Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago marking the beginning of the modern climate era - and of human civilization. Most of these climate changes are attributed to very small variations in Earth's orbit that change the amount of solar energy our planet receives. Other likely causes are solar flares, asteroid/meterorite strikes, volcanic eruptions and changes in sea currents due to movement of the earth's crust's tectonic plates.

And what about "global warming"? Basically, that is simply climate change, when the change is in the direction of a warming planet, rather than a cooling planet. The term has fallen into disfavor and largely replacedby "climate change"

So how to we observe and objectively measure to see if it is occurring?