Common misconceptions: 1. Climate change

[John Nissen]

Hi everyone,

I am frequently reading articles in which the author has misunderstandings of one kind or another.  The following is an attempt to dispel a few misconceptions about climate change.

It is often said that climate change causes weather extremes, wildfires, biodiversity loss, and other adverse effects.  But rising temperatures cause climate change, not the other way round.  And the growth in weather extremes is how most of us experience climate change.  The full story is quite complex.

The causal chain starts with the emission of greenhouse gases, in particular CO2 and methane.  Such gases have a blanket effect: their presence in the atmosphere reduces the amount of heat escaping from the planet, so the planet's temperature rises.  

CO2 lasts a long time in the atmosphere.  The accumulation of CO2 in the atmosphere is the main cause (or "driver") of global warming.  As the accumulation grows, global warming accelerates.  Since 1900, the level of CO2 in the atmosphere has grown from 280 ppm to around 420 ppm today.  Until we achieve net zero emissions, the accumulation will grow and we can expect temperatures to rise faster and faster.  When net zero is achieved, the acceleration will end, so there will just be a steady rise in temperature.  There is no natural plateau or peak of temperature in sight: at least not this century.

The rate of global mean temperature rise has approximately doubled over the past forty or fifty years, from 0.18C per decade to 0.36C per decade according to James Hansen.  At a steady 0.36C per decade, without further acceleration, global warming would reach over 3.5C in the next 60 years.  Catastrophic climate change and sea level rise become inevitable, even with net zero achieved tomorrow.

However the danger is much more immediate.  During this first quarter of a century, temperature extremes have been rising even faster than global temperatures.  This cannot be explained without some kind of temperature amplification.  Such amplification is observed in the Arctic, whose mean temperature has been rising approximately four times as fast as the global mean temperature.  As snow and sea ice retreat due to global warming, open ground and open water are exposed to sunshine.  This extra heating adds to the heat from global warming: we have mutually reinforced feedback, also known as "albedo positive feedback".  This is the main temperature amplification mechanism for the Arctic.  It has an effect far beyond the Arctic, as follows.

Rapid Arctic warming, through this amplification, reduces the temperature gradient between the Arctic and the tropics.  This causes the polar jet stream both  (i) to meander further to north and south, and (ii) to get stuck in blocking patterns more often and for longer periods.  This in turn leads to the increase in weather extremes that we can observe at medium to high latitudes in the Northern Hemisphere.  Other mechanisms can account for the disruption of monsoons in the tropics and subtropics with a growth in extremes of flooding.  

Thus the causal chain starts with emissions, then global warming, then Arctic Amplification with a disruption of jet stream behaviour causing an accelerated trend in weather extremes which is how most of us experience climate change.  The weather extremes are accompanied by wildfires, loss of biodiversity, etc.

Emissions reduction cannot stop climate change, let alone reverse it.  If we want a reversal of climate change, then the Arctic temperature needs to be reduced quickly.  Besides reversing the trend towards ever worse weather extremes, this would save the Greenland Ice Sheet from disintegration and it would save the permafrost from complete thaw with the release of megatons of methane.  It could also strengthen the AMOC, whose decline threatens global ocean circulation with disastrous consequences for many countries.

Cheers, John

[Tom Goreau]

https://truthout.org/articles/arctic-ecosystems-are-falling-apart-under-strain-of-warming-climate/?utm_source=Truthout&utm_campaign=8334f7952d-EMAIL_CAMPAIGN_2025_08_02_06_33&utm_medium=email&utm_term=0_bbb541a1db-8334f7952d-650156989

 

 

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[Peter Wadhams]

[John Nissen]

Hi Tom,

Thanks for the article.

Re Arctic Amplification: 

To add to the albedo feedback I mentioned, we have atlanticisation (the incursion of Atlantic water) as exemplified by Svalbard heating particularly rapidly described in the Truth Out article you referred to [1],  On top of this there is permafrost methane feedback to Arctic warming, also mentioned in the article.  

These three feedbacks combined are mutually supportive and cause rapid surface water melting in summer.  But then the water freezes solid when the temperature falls again.  This is devastating for the reindeers which the locals herd, as explained in the article.

Permafrost methane is a tipping element: the feedback could become self-sustaining, even without any increase in global mean temperature.  The level of methane in the atmosphere has more than doubled since pre-industrial times (actually it's risen by about 250%).  However the point of no return comes when there is an outburst of methane at the megatons per annum level.  Shakhova is concerned that there is enough methane in or under permafrost that only a small percentage in a burst, of say 50 megatons over 20 years, would more than double the current rate of global warming (i.e. double the rate of temperature increase, currently approaching 0.36C per decade).  There is a Truth Out article worth reading about the potential apocalypse [2].

The methane feedback was why I formed the Arctic Methane Emergency Group (AMEG) in 2011.  Peter Wadhams was a founder member.  I am copying these two important articles to them.

There is absolutely no doubt that the world community, as well as the Arctic community, should rally behind a programme of refreezing the Arctic before it is too late (i) to restore Arctic ecosystems, (ii) to prevent a climate apocalypse, and (iii) to prevent the collapse of the Greenland Ice Sheet with metres of sea level rise.

Cheers, John

[1] Matt Simon (GRIST, August 2025)

Arctic Ecosystems Are Falling Apart Under Strain of Warming Climate

https://truthout.org/articles/arctic-ecosystems-are-falling-apart-under-strain-of-warming-climate/

[2] Dahr Jamail (2017)

Release of Arctic Methane "May Be Apocalyptic," Study Warns

https://truthout.org/articles/release-of-arctic-methane-may-be-apocalyptic-study-warns/