Global warming is not a new phenomena. Around 1000 C.E., there was a "Medieval Warm Period" and few centuries later the "Little Ice Age." Skeptics of the global warming theory point to these historical fluctuations when arguing that current trends are natural.
Since scientists have only begun precisely measuring changes in temperature since the 1850s, some people debate the past atmosphere's exact temperature. However, it is widely accepted that these past several decades have been the warmest ever.
Historical changes in temperature, though similar in size to today's change, occurred at much slower rates. Unless there is a big reduction in greenhouse gas emissions, experts predict that the global warming situation will only get worse at a much faster rate (meaning, the future could be A LOT hotter...).
