Even as Al Gore took his apocalyptic dog and pony show to Capitol Hill, we learned from NASA that long-term climate changes are correlated with solar output.
Long-term climate records are a key to understanding how Earth's climate changed in the past and how it may change in the future. Direct measurements of light energy emitted by the sun, taken by satellites and other modern scientific techniques, suggest variations in the sun's activity influence Earth's long-term climate. However, there were no measured climate records of this type until the relatively recent scientific past.
Scientists have traditionally relied upon indirect data gathering methods to study climate in the Earth's past, such as drilling ice cores in Greenland and Antarctica. Such samples of accumulated snow and ice drilled from deep within ice sheets or glaciers contain trapped air bubbles whose composition can provide a picture of past climate conditions. Now, however, a group of NASA and university scientists has found a convincing link between long-term solar and climate variability in a unique and unexpected source: directly measured ancient water level records of the Nile, Earth's longest river.
Alexander Ruzmaikin and Joan Feynman of NASA's Jet Propulsion Laboratory, Pasadena, Calif., together with Dr. Yuk Yung of the California Institute of Technology, Pasadena, Calif., have analyzed Egyptian records of annual Nile water levels collected between 622 and 1470 A.D. at Rawdah Island in Cairo. These records were then compared to another well-documented human record from the same time period: observations of the number of auroras reported per decade in the Northern Hemisphere....
Well, whaddaya know? They found correlations!
They even propose a mechanism.
The researchers found some clear links between the sun's activity and climate variations. The Nile water levels and aurora records had two somewhat regularly occurring variations in common - one with a period of about 88 years and the second with a period of about 200 years.
So what causes these cyclical links between solar variability and the Nile? The authors suggest that variations in the sun's ultraviolet energy cause adjustments in a climate pattern called the Northern Annular Mode, which affects climate in the atmosphere of the Northern Hemisphere during the winter. At sea level, this mode becomes the North Atlantic Oscillation, a large-scale seesaw in atmospheric mass that affects how air circulates over the Atlantic Ocean. During periods of high solar activity, the North Atlantic Oscillation's influence extends to the Indian Ocean. These adjustments may affect the distribution of air temperatures, which subsequently influence air circulation and rainfall at the Nile River's sources in eastern equatorial Africa. When solar activity is high, conditions are drier, and when it is low, conditions are wetter.
This last is important, because a great deal of the anthropogenic scare scenario depends not just on predictive models but on a plausible mechanism for explaining how climate changes. Now you have not only contrary evidence indicating a solar rather than human agency, you also have a plausible mechanism for the alternative scenario being proposed.
The case for the anthropogenic apocalypse just keeps getting weaker and weaker.
Read the whole thing here.