When will Temperatures start to fall? Part1

Guest post by Tony Brown

“If Europeans truly mobilize around the delivery of the 2050 goal, every business decision, lifestyle choice, political swing, every hallmark of European culture — from annual ski trips, to Champions League Football matches, to French cheese — will need to be tested against its contribution to climate change.” European Commission ‘Green Deal’ March 2020

This is an article with a simple proposition.  Science tells us that rapidly rising Co2 in turn causes rising temperatures, which has become a very serious problem for humanity.

The three questions I ask, in the expectation that the answer can be provided from main stream published science is;

“Assuming we reach zero carbon emissions by 2030-Extinction Rebellion (XR) requirement,  or 2050 -the aim of most governments under the Paris Accord- 1) how long would it take for Co2 levels to naturally fall below the’ safe upper limits’ of 350ppm espoused by such as James Hansen; 2) for it to fall further to 280ppm -the previous pre industrial level -AND 3) when will temperatures start to fall in turn, to achieve pre industrial levels, said to be 1 to 2 degrees Centigrade below present, according to the IPCC.”

There are all sorts of caveats of course, with methane, water vapour, clouds, feedbacks, ocean response, natural variations etc but having scoured various ‘official’ web sites I can find no definitive estimate. An examination of the Extinction Rebellion web site demonstrates they are anarchists, rather than a serious green organisation. A couple of more reasoned attempts to track the consequences of zero carbon emissions are given in Note 3 below the graphic-Figure 1 together with a variety of other useful background information.

Whether the reader personally believes excess Co2 to be a problem is not a matter this article is concerned with.  Let’s take science at face value –our respective Governments  have overwhelmingly agreed that humanity has added some 140ppm of Co2 to the pre industrial 280ppm and that, as a result, temperatures have risen substantially and are at a dangerous level and causing extremes of weather.

As a result of this scientific advice, Governments around the world intend to take dramatic measures to curb both Co2 levels and thereby limit temperature increases. The answer to my question must be in the public domain in a readily understandable form, in order for politicians-rarely versed in science- to feel it necessary to make the far reaching changes proposed. In this connection the EU’s position in Note 2 under the graphic will reward a read, as it will likely reflect the position of your own Government, or in the case of the USA-the opposition parties. 

General comments on the subject are of course welcome, but If you wish to make a specific prediction of the Co2 reduction time and/or temperature reduction  please quote evidence  in the form of an equation, or a reference, or link to a science paper.

So here are the simple questions again. Assuming we reach zero carbon emissions by 2030-Extinction Rebellion (XR) requirement,  or 2050 -the aim of most governments under the Paris Accord- 1) how long would it take for Co2 levels to naturally fall below the’ safe upper limits’ of 350ppm espoused by such as James Hansen; 2) for it to fall further to 280ppm -the previous pre industrial level -AND 3) when will temperatures start to fall in turn, to achieve pre industrial levels said to be 1 to 2 degrees Centigrade below present, according to the IPCC.

Note 1; Figure 1 below assumes a 430ppm concentration by 2030 or 450 ppm by 2050 based on Co2 levels  continuing to rise from 2020 until towards the chosen date, when they would taper off, before becoming net zero. Consequently any estimated reductions need to start from that point. Figure 1 is left blank waiting for data from replies to be inserted;

Figure 1; Co2 and temperature-timescales and trajectory

Background information

Some 10 or 12 years ago, when I first started writing climate related articles, I emailed around a dozen leading climate scientists to ask that if  emissions stopped dead, how long would it take temperatures to drop back towards the desired pre industrial levels?. That is to say around a couple of degrees centigrade. (This doesn’t take into account that the temperature by 2030 or 2050 should be higher than now as Co2 continues to increase, plus there is the ‘heat in the pipeline’)

Most responded. Some had never done the calculations, others didn’t feel there was sufficient data for accurate projections. One said we should start to see a slight reduction in temperatures in around 400 years, but the full effect would not come about for possibly thousands.

Until Covid 19 took over public debate, climate was a very hot topic and will do so again as the immediate effects of the pandemic recede into the rear view mirror.

Consequently it is relevant to ask the question again in the light of much more research and knowledge accumulated over the last decade or so. This has provided data that has persuaded governments to adopt stiff targets in such International agreements as the Paris Accord and encouraged the rise of activists like Greta Thunberg and Extinction Rebellion, whereby the ‘climate crisis’ is being forcibly placed into the centre of the public domain.

In a future article, once the data is in, I hope to explore the measures needed to achieve the stated objectives and surmise whether the public would be more or less willing to accept the sacrifices and lifestyle changes needed, bearing in mind the drastic changes in everyone’s lives over the past few months.

 In respect of climate mitigation ambitions, readers will find it worth spending a few minutes exploring the EU position under Note 2)   

Note 2 ; This is a small segment from the Politico web site about EU plans, .which will mirror the views of many other signatories to Paris. The title is self-explanatory

https://www.politico.eu/article/europe-climate-goal-revolution-net-zero-emissions/

“Cutting the Continent’s emissions to “net zero” — meaning Europe would sequester at least as much greenhouse gases as it produces — by 2050 will require a radical overhaul of nearly every aspect of the modern economy. Dramatic cuts in carbon will wipe out entire industries, transform others and force people to change the way they eat, work, live and travel”

“If Europeans truly mobilize around the delivery of the 2050 goal, every business decision, lifestyle choice, political swing, every hallmark of European culture — from annual ski trips, to Champions League Football matches, to French cheese — will need to be tested against its contribution to climate change.

The European Climate Law, proposed by the Commission in March, would submit every EU law, past and future, to a test of its compatibility with climate neutrality — a “tectonic shift,” according to E3G, a think tank that advocates for emission cuts.”

Note 3 A variety of papers, sensationalist and more rational, sketch out a wide variety of scenarios making it difficult to separate reality from fantasy. A couple of more reasoned attempts to track the consequences of zero carbon emissions are given below. ‘The Conversation’ has a recent editorial policy of not publishing ‘denialist’ climate comments or articles.

Summary from ‘The Conversation.’

Temperatures will stabilise at a higher temperature with some 0.6C of heat in the pipeline with, for the foreseeable future an irrevocable rise of temperature of up to 4C.

There is no real road map of temperatures coming down, and elevated levels of Co2 will remain for many hundreds of years. The article is from 2017.

https://theconversation.com/if-we-stopped-emitting-greenhouse-gases-right-now-would-we-stop-climate-change-78882

From Nature, who reckon on a temperature rise for hundreds of years whilst Co2 will stay at an elevated level for thousands.

https://www.nature.com/scitable/knowledge/library/what-happens-after-global-warming-25887608/

The Future?

The 2020 Covid economy, whereby Co2 emissions have continued to rise but more slowly than recently, provides some clarity as to the fundamental changes needed from industry and the public to actually achieve net zero. This effectively means ‘more of the same’ restrictions as during the pandemic. Much less air travel, fewer personal means of transport and more reliance on public transport, much less consumption, fundamental changes to industry, supplemented by measures on addressing additional sectors of the economy year on year, to permanently ratchet up the effect.

This will likely include less meat eating, less imported foods and drink, fewer electrical items including mobile phones and servers, the phasing out of gas central heating, a substantial reduction in home temperatures with thermostats set to 19degrees C ((66 degrees F) no wood or coal burning devices, phasing out of most conventional power sources, a much greater reliance on renewable energy and likely a carbon allowance and alterations to  tax structures to encourage a change in behaviour. This is expected by governments to result in a gentler, slower, less polluted and more sustainable way of life, centred more round the local community.

Tony Brown August 2020

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August 28, 2020 at 04:22PM

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