‘It was warmer during the Holocene Climatic Optimum’–This period was not global and not like today
(Part of the How to Talk to a Global Warming Skeptic guide)
Objection: It was warmer during the Holocene Climatic Optimum than it is today — without any human influence.
Answer: Though some temperatures during that period were in the same range as today, they were confined to the northern hemisphere and the summer months.
What’s more, the cause is understood (orbital forcing similar to what controlled the Ice Ages), just as today’s cause is understood (CO2 emissions), and these causes are very different. NOAA has a page on this that contains the following quote:
In summary, the mid-Holocene, roughly 6,000 years ago, was generally warmer than today, but only in summer and only in the northern hemisphere. More over, we clearly know the cause of this natural warming, and know without doubt that this proven “astronomical” climate forcing mechanism cannot be responsible for the warming over the last 100 years.
As an aside, it’s worth noting that even if the Holocene had been as warm as or warmer than today, it would do nothing to undermine the theories and data that indicate today’s warming is rapid and anthropogenic.
More stories in this series:
(Part of the How to Talk to a Climate Skeptic guide) Objection: Despite what the computer models tell us, there is actually no evidence of significant global warming. Answer: Global warming is not an output of computer models; it is …
(Part of the How to Talk to a Global Warming Skeptic guide) Objection: CO2 levels are recorded on top of Mauna Loa … a volcano! No wonder the levels are so high. (image courtesty of Global Warming Art)
(Part of the How to Talk to a Global Warming Skeptic guide) Objection: The apparent rise of global average temperatures is actually an illusion due to the urbanization of land around weather stations, the Urban Heat Island effect.
(Part of the How to Talk to a Global Warming Skeptic guide) Objection: One hundred and some years of global surface temperatures is not long enough to draw any conclusions from or worry about anyway. Answer: The reliable instrumental record …
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