Climate change: anthropogenic climate change is not 100% certain, just highly likely. How likely is our is our ability to stop it?

It can seem like the word is divided between those who will who will not accept any evidence of anthropogenic climate change, and those who will not will not listen any questioning of the need for action to prevent climate change.

Reality is neither group is correct because no case is 100% certain.  Even the official statements from the IPCC do not declare 100% certainty on C02 output driving climate change. The world is actually grey – not black or white.  The real key is dealing with probability rather than certainty.

Most of us will insure our home without needing 100% certainty that our home will burn down. We do not use lack of 100% as a valid argument for inaction with our home, so why advocate lack of 100% certainty as an argument for inaction on the entire planet?  The risk certainly justifies taking out insurance!  The real uncertainty worthy of  attention is “what if actions to prevent climate change will be ineffective or are insufficient?”  Typical of insurance, what if the ‘policy’ will not payout to cover the risk?

I heard a statement from a prominent “anti climate change” advocate: “Climate change is natural, it is happening all the time”.

The person making the argument was not known for great logic, but just consider for a moment, what if there is valid point?  Climate change can occur even without the meddling of humans. What if the current changes would continue even without further human This raises the possibility that, even if accepting that humans are a source of climate change, there may also be natural underlying change in combination. Or perhaps, human induced climate change has or will trigger additional natural climate change that may continue even if human behaviour changes.

How certain to you need to be that your house will burn down to take out insurance?  When the risk is high take out the insurance.  Anthropogenic induced climate change may not be certain, but it is clearly at a risk level where we need to take out our insurance.  Now consider, do we also need insurance that current steps will not prevent climate change as well?

Consider some background: Ice Ages.

Technically we are currently an interglacial period within Ice Age.  Ice ages have interglacial periods (like now) and glacial periods like in the move ‘Ice Age’.  You could call a glacial period a ‘very ice age’ and what is thought of in the popular vernacular as an ice age, but in fact the presence of even polar ice caps like we currently have qualifies as an ice age.  Over the past 100 million years the earth has spent more time outside ice ages (no polar caps at all) , than within ice ages (either polar caps like the present or glacial periods).  No ice age at all means way higher sea levels (as much 200 meters higher), and a glacial period results in lower sea levels (as much as 130 meters lower).

Over the past 3 million years (the entire time humans have existed) the Earth has alternated between the glacial and non glacial periods of an Ice Age.  The last time the Earth was truly outside an Ice Age was before humans existed, which may be why glacial periods also get called ‘Ice Ages’. Humans have not existed in a time ‘less Ice Age’ than things are at present.  However, the normal state of the Earth of the past 100 million years is to be outside an Ice Age… something humans have never experienced.  Within an Ice Age (as we technically are) the most common state is a glacial period, but we have had around 11,000 years in the current interglacial period.   Human civilization has really only existed in a inter-glacial period.  The least common state, of the least common state of the climate of the Earth.

Humans have live through the change from glacial to interglacial, but not civilization, and very specifically not a global civilization supporting over 7 billion people.  We have a very fragile system that is unlikely to support anywhere near our current population in a change to either a glacial period (never experienced by civilization) or the most common state of the Earth, completely devoid of polar ice caps, which has never been experienced by humans at all.

Now consider, are we really confident we can stop climate change?  Yes it is urgent that we do what ever we can to minimise, or even eliminate our own contribution to climate change, but we should not be over confident that anything we do will actually stop climate change, rather than just reduce the impact.

 

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