Is it really getting warmer?
"It depends upon your point of view. In relation to the broad sweep of geological time, the Earth is definitely going through a chilly period. We are currently in an Ice Age, a rare occurrence in the history of the Earth. Of course the term Ice Age is very broad, masking the fact that within an Ice Age there are periods of relative warmth and periods of harsh, arid cold. We are currently living through one of those periods of warmth, which are relatively short-lived and uncommon within the context of an Ice Age.
The short lived periods of warmth (called interglacial periods) are themselves not uniform and stable, but constantly changing from relative warmth to relative cold. The Little Ice Age (as it is misleadingly known) was a period of general global cooling that saw glaciers advance worldwide from the mediæval period up until the beginning of the last century. Since then global climates have fluctuated, but there has been a general global trend of warming, back to pre-Little Ice Age levels.
This is, of course, where the trouble starts. Coincident with the natural swing of temperature, humankind has been releasing vast quantities of CO2 into the atmosphere. This gas is known to have a ‘greenhouse effect’ and is likely to lead to global warming of itself. Certainly, we know that the Earth is becoming warmer as compared to the extremes of the Little Ice Age (at least 5% of Iceland’s glaciers have melted away since 1960, for example). But can we demonstrate that this recent global warming is simply the Earth warming naturally, or is it warming in an accentuated manner, due to human activity? From the perspective of a scientist interested in Ice Ages, it may not be important, as the next Ice Age is slowly heading toward us, but from the perspective of the human life-span, the question of the causes of global warming is, quite literally, the burning question of our time."
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