Ice at poles on Mars shows climate history

Dramatic climate variations on Mars, recorded in layers of ice and dust at the planet's poles, are driven by energy from the sun, Danish scientists say. Researchers from the Niels Bohr Institute at the University of Copenhagen report layers in the ice cap on the planet's' north pole reveal variations in solar insolation, a measure of solar radiation energy received, providing a dated climate history for Mars. The layers, first spotted in satellite images, are believed to reflect past climate on Mars in the same way that Earth's climate history can be determined by analyzing ice cores from the ice caps on Greenland and Antarctica, researchers said. Solar insolation on Mars has varied dramatically over time, mainly due to large variations in the tilt of its rotational axis, they said, leading to dramatic climate variations on the Red Planet. "We have developed a model for how the layers are built up based on fundamental physical processes and it demonstrates a correlation between ice and dust accumulation and solar insolation," Christine Hvidberg at the Center for Ice and Climate at the Niels Bohr Institute said. "The model dates the upper 500 meters (1,600 feet) of the northern ice cap on Mars, equivalent to approximately 1 million years and an average accumulation rate of ice and dust of 0.55 millimeters (0.0216 inches) per year. "It links the individual layers to the maxima in solar insolation and thereby establishes a dated climate history of the north pole of Mars over 1 million years," Hvidberg said.