Tony Bradshaw, Buckinghamshire
Recently, debate about global warming on Earth has been intensified by the observation that Mars appears to be undergoing a period of climate change. It has been suggested that warming is therefore a result of natural processes rather than human activity.
However, climate change on Mars is mostly determined by changes in the tilt and shape of its orbit and the only reliable evidence merely indicates that Mars ended its most recent ice age about 400,000 years ago. Although some studies in the 2000s purportedly showed evidence of climate change on Mars, these were shown to be either localised effects due to Martian ‘weather’ and dust storms rather than ‘climate’.
The most recent studies show that there have been no significant changes in the average Martian temperature since at least the time of the Viking landers in the 1970s. So there is no evidence that Mars is actually heating up at all.
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