The Sun and the Earth are connected!

Solar winds constantly bombard the earth. The earth (in center) is protected by its magnetic field. The more active the sun, the greater the solar winds and the more cosmic radiation from deep space is pushed back, which seems to have a dramatic effect on the earth's climate by warming the earth.  From NASA http://science.nasa.gov/ssl/pad/sppb/edu/magnetosphere/mag3.html

 

During periods of gusty solar wind when the sun is very active with solar flares and coronal mass ejections, powerful magnetic storms in space near the Earth cause vivid auroras, radio and television static, power blackouts, navigation problems for ships and airplanes with magnetic compasses, and damage to satellites and spacecraft. Although the total solar irradiance is increased only slightly, the solar winds caused by the active sun interact with the earth's magnetosphere which also triggers changes in the electrical and chemical properties of the atmosphere, the ozone layer, and high-altitude temperatures and wind patterns.

Simulated coronal mass ejection. Coronal mass ejections (or CMEs) are huge bubbles of gas threaded with magnetic field lines that are ejected from the Sun over the course of several hours. Click photo to watch video segment on solar/cosmic radiation/earth temperature theory

As more research is done, scientists are realizing the sun plays a critical role in controlling earth's climate. Solar winds are also known to push back or dampen cosmic radiation originating from super novas in deep space. There is a significant correlation between the amount of cosmic radiation entering the earth’s surface and the amount of low elevation cloud formation. The more cosmic radiation the more low elevation clouds that are formed. The more clouds, the greater the amount of solar energy that is reflected back into space, and the earth cools. When the sun is very active and there is a lot of solar wind, there is less cosmic radiation reaching earth, fewer low elevation clouds are formed, and the earth warms. This relationship itself can account for most of the warming in the twentieth century. As we start the 21st century, the reverse is happening. The sun has been extraordinarily quiet and scientists have found the solar winds have declined to the lowest levels ever measured. This should cause the earth to start cooling, which it did starting in 2007.

But that's not all the sun does. It also affects planetary wind patterns. What perhaps is the clearest evidence that nature, not man, caused the twentieth century warming was the discovery in the past few years that the oceans are playing a far greater role than previously recognized. Although poorly understood, either the sun directly, or through the winds it helps create, phenomena like El Niños and La Niñas are formed in the tropical ocean. (See NASA animation) These equatorial El Niño and La Niña phenomenon have been well known since the early 1900s, but their significance was not realized until the late 1900s.

As scientists began to realize the impact of El Niños and La Niñas  on climate across the world, they also began to notice there was a larger oscillation within which they occurred, extending well beyond the tropics.  By 1997 they had named them the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO). Like El Niño and La Niña, the PDO and AMO have warm and cold cycles. While El Niños and La Niñas only last 1-3 years, the PDO usually lasts from 15 to 30 years and the AMO, 20 to 40 years. In the case of the PDO, the warm phase has more El Niños while the cold phase has more La Niñas. Together they have a profound affect on earth’s climate, and when compared to earth’s temperature, the correlation is considered good, but not great.  Nonetheless, it is far better than CO₂, which only has a poor correlation with temperature. (Watch an Accuweather 5 min. clip on the PDO)

The Pacific Decadal Oscillation (PDO) is a long-term ocean fluctuation of the Pacific Ocean. The PDO waxes and wanes approximately every 20 to 30 years. Scientists now think we have just entered the 'cool' phase. The 'cool' phase is characterized by a cool wedge of lower than normal sea-surface heights/ ocean temperatures in the eastern equatorial Pacific and a warm horseshoe pattern of higher than normal sea-surface heights connecting the north, west and southern Pacific. In the 'warm' or 'negative' phase, which appears to have lasted from 1977- 1999, the west Pacific Ocean becomes cool and the wedge in the east warms. Notice that the surface wind directions (arrows) tend to reverse themselves in the two phases. NASA

Figure: Pacific Decadal Oscillation. (top) Typical wintertime sea surface temperature (colors), sea level pressure (contours), and surface wind stress (arrows) anomaly patterns during positive and negative phases of the Pacific Decadal Oscillation (PDO), as derived from the TOPEX/Poseidon satellite plus other ocean/atmosphere data. Temperature anomalies (colors) are in degrees Celsius. (bottom) Monthly values for the PDO index, 1900-2004. Credit: S. Hare and N. Mantua, University of Washington.

Although scientists believe the sun plays a role in creating the PDO & AMO, they do not understand how it works. Nor do they know if the relatively high correlation between the two and earth’s temperature is a direct cause and effect relationship, or whether the sun or something else directly affects both the PDO/AMO and temperature. It may be both.