Climate is Always Changing

This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.


Objection:

Climate has always changed, why are we worried now and why does it have to be humans fault?

Answer:

Yes, climate has varied in the past and it has varied for many different reasons, some better understood than others. The present day climate change is very well understood and is different. Simply noting that something happened before without humans does not in any logical way show that humans are not causing it today.

For example, we see in ice core records from Antarctica and Greenland that the world cycled in and out of glacial periods over 120Kyr cycles. The cause for that climate cycle’s timing is fairly well understood to be the results of changes in the orbit of the Earth, though the mechanism behind the resulting response has not been conclusively established. These orbital cycles are regular and predictable and they are definitely not the cause of today’s warming. The other important difference between the glacial-interglacial cycles and today is the rapidity of the current change. The rate of warming is on the order of 10 times faster today than seen in the ice cores.

Such rapid warming on a global scale is very rare in the geological record, and while it may not be unprecedented, there is very strong evidence that whenever such a change has happened, whatever the cause, it was a catastrophic event for the biosphere.


This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.


“Climate is Always Changing” was first published here, where you can still find the original comment thread. This updated version is also posted on the Grist website, where additional comments can be found, though the author, Coby Beck, does not monitor or respond there.

51 thoughts on “Climate is Always Changing

  1. “For a start, the absorption spectrum of CO2 and water vapour overlap”

    Except they don’t overlap. They interleave over many frequencies. But interleave is not overlap.

    That they overlap is a holdover from the 19th Century measurements where the instruments were not accurate enough to discern the gaps.

    You will get miniscule amounts of vapour from water at above -30C, depending on dust content, so even at -18C there’d be *some* H2O greenhouse effect. Just an extremely small one.

    Like

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