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human activity and the destruction of the planet


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An alarmists guide to climate change

This is an article written by Prof Bill McGuire of University College, London and published by Scientists for Global Responsibility, as well as in: Responsible Science journal, no.1; Advance online publication: 14 February 2019.

Below is copied in its entirety from SGR magazine: http://www.sgr.org.uk/resources/alarmist-s-guide-climate-change

ProfBillMcGuire

Prof. Bill McGuire, University College London

“Have you noticed how the term ‘alarmist’ has been hijacked? In the context of climate breakdown, habitat and wildlife loss and other environmental issues, it has become synonymous with scaremongering; with the voice of doom. In certain circles it is frowned upon and judged to be a hindrance to getting the global warming message across. Iconic broadcaster David Attenborough is the latest to express the view that ‘alarmism’ in the context of the environment can be a ‘turn-off’ rather than a call to action. But are such viewpoints justified, especially when our world and our society teeter on the edge of catastrophe? After all, the simplest, most straightforward, meaning of an ‘alarmist’ is someone who raises the alarm. Is this not what we need now more than ever; to be told the whole story – warts and all? The alternative, it seems to me, is to play down the seriousness of our predicament; to send a message that is incomplete, and to conveniently avoid or marginalise predictions and forecasts that paint a picture regarded as too bleak for general consumption. Surely, this is the last thing we need at this critical time?

No-one could ever accuse the Intergovernmental Panel on Climate Change (IPCC) of being alarmist. Because every sentence of IPCC report drafts is pored over by representatives of national governments – some of whom are lukewarm or even antagonistic to the whole idea of climate change – the final versions are inevitably conservative. The closest the IPCC has come to sounding an alarm bell can be found in its latest report Global Warming of 1.5ºC, published in October. Here it warns that emissions must be slashed within 12 years (by 2030) if there is to be any chance whatsoever of keeping the global average temperature rise (since pre-industrial times) below 1.5ºC, and fall to zero by 2050.

Notwithstanding the unlikelihood of achieving net zero global emissions in a little more than three decades, the pace and degree of climate change are about more than just anthropogenic emissions. They are also influenced by tipping points and positive feedback loops; sudden changes in the behaviour of ice sheets, carbon sources and sinks, and ocean currents, which can accelerate warming and its consequences way beyond the expected. Depressingly, but perhaps not surprisingly, the latest IPCC report’s Summary for Policymakers [1] – let’s face it, the only bit likely to be read by the movers and shakers – includes just one brief mention of feedbacks and has nothing at all to say about tipping points. The justification for this appears to be that because it is not possible to assign levels of confidence to such known unknowns, they cannot be included. But it is difficult not to conclude that the real reason is to tone down the threat in order to appease those governments that view climate change as a nuisance that they would like to go away.

The decision to bury concerns over tipping points and feedbacks in the depths of the full report rather than flagging them in the Summary is nonsensical. Touting the critical importance of drastic action while at the same time soft peddling the threat has the potential to backfire, providing the obvious get out: well, if the situation is not so bad, maybe the response doesn’t need to be that urgent. If drastic, life-changing, action is being mooted, people need to know – have a right to know – why. They need to be presented with a complete picture showing how bad things might get – however scary or poorly constrained.

Bringing the potential consequences of tipping points and feedbacks into the equation inevitably transforms perceptions of the dangers we face. Suddenly, climate change ceases to be something vaguely inconvenient that we can leave future generations to deal with. Instead, it becomes far more of an immediate threat capable of tearing our world apart. Take sea level, for example. The IPCC’s 5th Assessment Report, [2] published in 2013 and 2014, predicts – for a worst-case scenario – that global mean sea level could be about a metre higher by the end of the century. Bad enough for millions of coastal dwellers, but nothing compared to what our descendants might experience if a tipping point is crossed that sees the Greenland and/or West Antarctic ice sheets start to disintegrate in earnest. Models that do incorporate this, point to sea level rising far more rapidly. One suggests that the ice loss in Antarctica could occur at a much faster rate than expected, leading to global average sea level being more than 3m higher at the end of the century. [3] Another, based upon correlations between temperature and sea levels during the last interglacial, which ended around 115,000 years ago, proposes that sea level – in theory at least – could climb by as much as 5m by 2100. [4]

Worrying evidence that we might be at a tipping point in Antarctica comes from a very recent study on the rate of ice loss from 2012 to 2017. During this five-year period, Antarctic ice loss shot up threefold, from 76 billion tonnes annually, to a colossal 219 billion tonnes. [5] In total, more than 2.7 trillion tonnes of Antarctic ice has melted in the last quarter century, adding three quarters of a centimetre to global sea level. At the new rate, the contribution over the next 25 years would be 1.5cm. Not enough to worry about in its own right. If, however, the rate of increase is maintained over this period, then the annual rise by 2043 would be close to a catastrophic five centimetres a year. And this is without the growing contribution from Greenland and from the increasing expansion of sea water as the oceans warm.

And there are other causes for serious concern too. None more so than the behaviour of the Gulf Stream and associated currents (together making up the AMOC – Atlantic Meridional Overturning Circulation) that warm north-west Europe and also have a big influence on global weather patterns. In the distant past, surges of meltwater from shrinking ice sheets have caused the Gulf Stream to shut down. Now, it looks as if it might be in danger of doing so again as huge volumes of freshwater from the crumbling Greenland Ice Sheet pour into the North Atlantic, forming a so-called ‘cold blob’.

The IPCC’s official line is that another complete shutdown is ‘very unlikely’, but this is not the same as ruling it out. And there are certainly some worrying signs. The Gulf Stream has slowed by 15 – 20 percent since the middle of the 20th century and is now at its weakest for at least 1600 years. [6] The Gulf Stream has a tipping point, and – evidence from the past shows – can shut down in just a few years when this is crossed. The problem is that no-one knows when – or even if – this will happen. If it does, the ramifications will be sudden and widespread. The North Atlantic region will cool dramatically, particularly across the UK, Iceland and North West Europe, while sea ice will expand southwards (without, it should be emphasised, counteracting the trajectory of climate change). Sea-levels along the eastern seaboard of North America could rise at three to four times the global average rate. Further afield, changes to weather patterns are forecast to include a weakening of Indian and East Asian monsoons, which could have devastating consequences for crop yields. No-one is saying that the Gulf Stream is in imminent danger of collapse. Nonetheless, the threat is not insignificant, and as such should be soberly touted, not wilfully ignored.

Of the many and varied feedback loops and tipping points linked with rapid anthropogenic warming, perhaps the most disquieting involves the vast tracts of permafrost at high latitudes – both on land and beneath the sea. Trapped beneath this frozen crust are colossal quantities of methane, a greenhouse gas that has a warming effect 86 times greater than carbon dioxide. Fortunately, methane has a relatively short residence time in the atmosphere and breaks down to carbon dioxide within a few decades. Nonetheless, major outbursts of methane from the rapidly thawing permafrost are capable of causing climate mayhem with little or no warning. The geographic region of most concern is probably the submarine permafrost that floors the East Siberian Continental Shelf, where an estimated 1400 billion tonnes of carbon, in the form of methane, is lurking beneath a frozen carapace that is thawing rapidly.

According to Natalia Shakhova and colleagues, [7] as much as 50 billion tonnes of this is available for sudden release at any time, which would – at a stroke – hike the methane content of the atmosphere 12 times. According to a study published in 2013, [8] a discrete methane ‘burp’ on this scale, could advance global warming by 30 years and cost the global economy US$60 trillion – a figure close to four times the US national debt. Once again, the occurrence of such an outburst is far from a certainty and there are other issues to consider, including how much methane is absorbed by the ocean as it bubbles upwards. Notwithstanding this, there is a potential danger here that needs to be promulgated rather than hidden away, so that the scale of the climate change threat is clear to everyone.

So – to conclude – be alarmed; be very alarmed. But don’t let alarm feed inertia. Use it instead to galvanise action. For your children’s and their children’s sake, stand up and do something about it. Drastically change your lifestyle; become an activist; vote into power a government that will walk the walk on climate change, not just talk the talk. Or – preferably – all three.”
Bill McGuire is Professor Emeritus of Geophysical and Climate Hazards at University College London and a co-director of the New Weather Institute. His current book is Waking the Giant: how a changing climate triggers earthquakes, tsunamis and volcanoes. He is a signatory of an academics’ letter in support of the School Climate Strike.
References

1. IPCC (2018). Global Warming of 1.5°C. Summary for Policymakers. http://report.ipcc.ch/sr15/pdf/sr15_spm_final.pdf

2. IPCC (2014). Fifth Assessment Report. http://ipcc.ch/report/ar5/

3. Le Bars D. et al (2017). A high-end sea-level rise probabilistic projection including rapid Antarctic Ice Sheet mass loss. Environmental Research Letters, vol.12.

4. Hansen J. et al (2016). Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous. Atmos. Chem. Phys., vol.16, pp.3761-3812.

5. The IMBIE Team (2018). Mass balance of the Antarctic Ice Sheet 1992 – 2017. Nature, vol.558, pp.219-222.

6. Caesar L. et al (2018). Observed fingerprint of a weakening Atlantic Ocean overturning circulation. Nature, vol.556, pp.191-196.

7. Shakhova N.E. (2008). Anomalies of methane in the atmosphere over the East Siberian shelf. Geophysical Research Abstracts, vol.10, EGU2008-A-01526. Abstract.

8. Whiteman G., Hope C., Wadhams P. (2013). Vast costs of Arctic change. Nature, vol.499, pp.401–403.


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Disappearing arctic polar ice cap – can this affect the Gulf Stream and the Jet Stream?

In Chapter 1 of my book, I provide evidence that the arctic ice is shrinking.  This is shown graphically in Figure 14 (page 34), which I reproduced, with acknowledgements to Andy Lee Haveland.  Because the size of the arctic ice varies throughout the year, and summer to winter, it is important to take measurements throughout the seasons of the year.

The figure below, published in my book with permission, gives an idea of what has been happening between 1979 and 2016.  arctic-death-spiral

Each colour represents a different month of the year and the difference in the size of the ice throughout the year shows how much it has shrunk during the period 1979-2016.  The stark difference between 1979 and 2016 can be seen best at the top of the graph.

Now, NASA has produced a time-lapse video showing the movement of the ice as it pulses through the seasons.  The video is posted on YouTube with this description, “Arctic sea ice has not only been shrinking in surface area in recent years, it’s becoming younger and thinner as well.”  The video can also be seen on the following website:

NASA releases time-lapse of the disappearing Arctic polar ice cap

This last winter (2017-18) has been very much colder in the UK and other parts of Europe and this has led to some people denying that global warming is happening.  The crazy thing is that, whilst Britain was in the grip of a lengthy period of freezing weather and large falls of snow, at the north pole it was warmer than usual, reaching melting point in some places, with temperatures up to 20 degrees higher than normal.  Similar temperature anomalies were also reported for some of the US and Canada.

The reality is that this phenomenon is all part of the unstable weather patterns that are being caused by climate change.

Now, in the latest issue of New Scientist (No. 3169, 17th March 2018), Colin Barras describes new research, which might suggest that changes in the North Atlantic current (the northern part of the Gulf Stream), could result in a shut-down, leading to even greater sea-level rise on Atlantic coasts and more intense droughts in Africa.

https://www.newscientist.com/article/mg23731693-200-polar-melt-may-shut-down-the-atlantic-current-that-warms-europe/

Marilena Oltmanns and her colleagues have studied the salinity of sea water and its temperature in the area just south of Greenland (Irminger Sea) between 2002 and 2014.  They found that, in summer, the sea had much warmer temperatures and lower salinity.  This would suggest that fresh water (melt from Greenland and the Arctic) is flooding into this area and affecting the currents and convection process.  This was more likely to happen after particularly mild winters.  In 2010-11, conditions were mild, resulting in an accumulation of fresh water in the sea, 40% of it still there even after the end of winter.  These findings are reported in Nature Climate Change, doi.org/cmbw.

Oltmanns believes that, if several warm years occur in succession, there would be a build up of fresh water, impeding the process of convection.  This might result in a shut-down of the North Atlantic current.  This might bring about the end of the North Atlantic’s relatively mild climate and the ameliorating effects of the Gulf Stream.

Other writers and researchers are proposing other impacts too, as far reaching as Africa and South America, though at this time much of it is still speculation.

Further information about the North Atlantic current can be found in Wikipedia, from which the following diagram has been taken.

2000px-North_Atlantic_currents.svg

 

Could this mean that the prolonged freezing period experienced in the UK and Europe last winter could become the norm?

Since writing the above, I have come across a review of scientific articles about the state of the Arctic ice cap, written by Vanessa Spedding.  It can be found on the Scientists for Global Responsibility website, as follows:

http://www.sgr.org.uk/resources/state-arctic-heightens-focus-climate-policy

The main conclusion of this review is that the presence of a summer ice-free Arctic can be an indicator of how well the world is sticking to the 1.5 degree Paris Agreement target for global warming.  There is a very low chance of an ice-free Arctic at 1.5 degrees but at 2 degrees, the chance rises to 39%.  At 3 degrees, 73%.  Full details of this work can be seen in an article by Screen and Williamson at:

11. Screen JA, Williamson D (2017). Ice-free Arctic at 1.5 °C? Nature Climate Change, vol.7, pp.230–231. DOI: 10.1038/nclimate3248.  https://www.nature.com/nclimate/journal/v7/n4/full/nclimate3248.html

Another 15 articles are cited in Spedding’s review. One of them, from Prof. Jennifer Francis of the Institute of Marine and Coastal Sciences at Rutgers University in the USA, suggests that there is a link between a warming Arctic and a disrupted jet stream, with effects on Northern hemisphere weather patterns.

Now, in August 2018, a report in The Guardian suggests that the oldest and thickest sea ice in the Arctic has started to break up for the first time ever, opening waters north of Greenland that are normally frozen the year round – an area that is often called “the last ice area”.  It is believed that this has occurred because of the abnormal heatwave in northern Europe in the summer of 2018. In the past, the ice in this region has packed together and is over 4 metres thick, with ridges up to 20 metres.

Full details about this and other concerns of climate scientists can be seen at:

https://www.theguardian.com/world/2018/aug/21/arctics-strongest-sea-ice-breaks-up-for-first-time-on-record?CMP=twt_a-science_b-gdnscience

ANTARCTICA

As regards Antarctica, the situation is just as grim, though different from the Arctic. A British-led study, using satellite tracking, showed that a region of ice the size of Greater London vanished from the edge of Antarctica between 2010 and 2016.

The 1,463 square kilometres of underwater ice at the base of the Antarctic ice sheet melted under the influence of warm ocean water currents. Scientists demonstrated how the massive ice sheet is retreating as its edges, fed by a multitude of glaciers, are eroded.

See: https://www.aol.co.uk/news/2018/04/02/antarctic-ice-area-the-size-of-london-lost-in-six-years/?ncid=webmail

The lead researcher, Dr Hannes Konrad, from the University of Leeds, said: “Our study provides clear evidence that retreat is happening across the ice sheet due to ocean melting at its base, and not just at the few spots that have been mapped before now. This retreat has had a huge impact on inland glaciers, because releasing them from the sea bed removes friction, causing them to speed up and contribute to global sea level rise.”

The biggest changes were seen in West Antarctica, where more than a fifth of the ice sheet had retreated across the sea floor faster than the general pace of deglaciation.

The findings have been published on 2nd April 2018 in the journal Nature Geoscience. See: https://www.nature.com/articles/s41561-018-0082-z

Previous studies had indicated an expansion of sea ice in the antarctic region but this latest study used grounding lines as indicators of ice-sheet instability.

 

Further posts will be added here as they emerge.