A word on nomenclature. Runaway greenhouse could not occur for Earth as it has on Venus. Earth is not close enough to Sun, nor is it likely to be during the time humans inhabit this planet. No climatologist worth his salt has ever predicted runaway greenhouse for Earth. Also, concerning insolation (INcoming SOLar radiaTION) on Mars. First, data citing only regional observations of Martian polar ice phenomena can not be extrapolated to a "global" temperature scenario for Mars. Second, global mean temperature on Mars is very sensitive to the strength and duration of hemispheric dust storms. Mean temperatures between Martian years (687 days) can vary by many degrees. For example, Viking measurements in the 1970's show significant planet- wide cooling relative to current temperatures recorded by Mars Global Surveyor. This is due, primarily, to increased large-scale dust storms on Mars in the 1970's compared to global atmospheric dynamics at present. Insolation forcing during this period was not a significant factor for global climate temperature differences observed by Viking, nor is it significant now. Recently, changes in south polar ice cover are, most likely, a consequence of topographic forcing of regional atmospheric dynamics. The changes are not due to a "global warming" trend on Mars. Take the time to read Nature, vol. 435, 12 May 2005, pg. 184-188. Isn't it ironic that regional polar changes on Mars, instantly, signals "global warming" to some people while, at the same time, much more persuasive evidence in favor of man's contribution to Earth's global warming is, repeatedly, denied? Dave Gary