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Global Warming Natural Cycle
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The idea that Global Warming is a natural cycle is well understood from paleo data covering the past 1 million years. Is there a difference between current climate, and the natural cycle? For the past million years the natural climate has oscillated between warm periods and ice ages. This shifting in and out of warm periods and ice ages is correlated strongly with Milankovitch cycles. In order to understand the difference between natural cycle and human-caused/influenced global warming, one needs to consider changes in radiative forcing and how this affects systems on Earth such as the atmosphere, vegetation, ice and snow, ocean chemistry and ocean heat content overturn cycles and related effects. The current radiative forcing levels are clearly outside of the natural cycle range.
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Natural Variation
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Natural variation includes internal and external variability influences such as the solar Schwabe cycle, oceanic cycles, seasonal influences based on changes caused by the interaction of the various natural oscillations in the climate system. These variations combined influence regional climate and weather on periodic basis as well as influence weather event patterns.
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North Atlantic Oscillation (NAO)
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The North Atlantic Oscillation (NAO) is a measure of the strength of the westerlies across the North Atlantic. Originally defined by Sir Gilbert Walker in 1932 as the difference in pressure between Ponta Delgada on the Azores and Stykkisholmur in Iceland.
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El Nino Southern Oscillation (ENSO)
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ENSO stands for El Niño/ Southern Oscillation. The ENSO cycle refers to the coherent and sometimes very strong year-to-year variations in sea- surface temperatures, convective rainfall, surface air pressure, and atmospheric circulation that occur across the equatorial Pacific Ocean. El Niño and La Niña represent opposite extremes in the ENSO cycle.
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Southern Oscillation Index (SOI)
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The Southern Oscillation Index (SOI) is one measure of the large-scale fluctuations in air pressure occurring between the western and eastern tropical Pacific (i.e., the state of the Southern Oscillation) during El Niño and La Niña episodes. Traditionally, this index has been calculated based on the differences in air pressure anomaly between Tahiti and Darwin, Australia.
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Pacific Decadal Oscillation (PDO)
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The Pacific Decadal Oscillation is a long-term fluctuation of the Pacific Ocean that waxes and wanes between cool and warm phases approximately every 5 to 20 years. In the cool phase, higher than normal sea-surface heights caused by warm water from a horseshoe pattern that connects the north, west and southern Pacific, with cool water in the middle. During most of the 1980s and 1990s, the Pacific was locked in the oscillation's warm phase, during which these warm and cool regions are reversed. http://www.jpl.nasa.gov/news/news.cfm?release=2008-066
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Solar Influence
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Observations of sunspots began in the time of Galileo, about 400 years ago. Heinrich Schwabe recognized the 11.1 year solar cycle average in 1843. Science is working to improve our understanding of solar activity but beyond 400 years it becomes increasingly speculative.
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Weather v. Climate
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What is the difference between weather and climate? Weather is considered short-term variability, while climate is long-term trend based on multiple factors. These factors depend on context. In other words, one persons weather is another persons climate. Generally speaking, in the context of human caused global warming, climate is considered 30+ years of trend with attribution.
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