A paper co-authored by some eminent climate scientists and just published in the prestigious scientific journal  Nature, analyses critical tipping points impacted by man-made climate change, and  concludes: “Act now… the evidence from tipping points alone suggests that we are in a state of planetary emergency: both the risk and urgency of the situation are acute…  The stability and resilience of our planet is in peril. International action — not just words — must reflect this”.

A climate change-related “tipping point” for a particular phenomenon (e.g. loss of Arctic summer sea ice)  is the point  at which the change is irreversible. Successive IPCC reports   over past decades warned of the likelihood of tipping points being reached  at various degrees of global warming. However the authors provide a Figure showing that IPCC-estimated “High” to “Very High” risk of rapid and irreversible changes in the climate system has progressively occurred at lower average warming over the last 20 years.   Thus an approximate simplification of this Figure is that IPCC-perceived “High” to “Very High” risk occurred at +5.5C (2001), +5C (2007), +4C (2013) and +2C (2018) [1].

The authors conclude that “If current national pledges to reduce greenhouse-gas emissions are implemented — and that’s a big ‘if’ — they are likely to result in at least 3 °C of global warming. This is despite the goal of the 2015 Paris agreement to limit warming to well below 2 °C… if tipping points are looking more likely, then the ‘optimal policy’ recommendation of simple cost–benefit climate-economy models aligns with those of the recent IPCC report [2]. In other words, warming must be limited to 1.5 °C. This requires an emergency response” [1].

Noting a “Moderate” risk of tipping points exceedances in the range of + 1-2C and that the global warming is now about +1C above the pre-industrial,  one can well ask whether  a sane individual would board a plane that had a “Moderate” risk of crashing.

The authors then considered some key tipping points and their assessments are summarized below (with global  consequences and amplifications in brackets).

(1). West Antarctica (Amundsen Sea embayment): the tipping point may have been exceeded  (this  could destabilize the rest of the West Antarctic ice sheet leading to circa 3 metres of sea-level rise on a timescale of 100s to 1000s of years, noting that this has happened in the past).

(2). East Antarctic ice sheet (Wilkes Basin):  approaching a tipping point ( 3-4 metres in sea level rise on a timescale of 100s of years).

(3). Greenland ice sheet:  melting at an increasing  rate and the tipping point may be the circa +1.5C expected in about 2030 ( 7 metres sea level rise over 1000s of years).

(4). Arctic sea ice:  massive sea ice loss already ( at +2C there is a  10–35% probability of near-total summer sea ice loss).

(5). Coral reefs: mass coral bleaching worldwide and loss of 50% of the coral of  Australia’s iconic Great Barrier Reef due to warming, ocean acidification, pollution and Crown of Thorn predator  population explosion (99% of tropical corals are predicted to be  lost at +2C with massive loss of  marine biodiversity and fisheries).

(6). Amazon rain  rainforest:  estimated tipping point at 20% – 40% deforestation with about 17% lost since 1970 ( the world’s largest rainforest, contains 1 in 10 known species, has a continent-scale  climate impact, and is presently burning on a huge scale).

(7). North American boreal forest: warming in the sub-Arctic has led to insect pest population explosion, boreal (high latitude) tree die-off and fires ( some boreal forest regions are converting from being carbon sinks to a carbon sources).

(8). Arctic permafrost:  irreversible thawing and release of carbon dioxide (CO2) and methane (CH4) with Arctic warming about  2 times bigger than  the global average (CH4 has an estimated Global Warming Potential (GWP) as low as 21 relative to the same mass of CO2 on a 100 year time-scale, but on a 20 year time scale and with aerosol impacts included it is 105).

(9). Atlantic Meridional Overturning Circulation (AMOC): a key salt- and heat-conveying Atlantic Ocean circulation system subject to a 15% slow-down since the mid-20th century  (Arctic sea-ice loss is increasing  regional warming;  Arctic warming and Greenland melting are putting  fresh water into the North Atlantic; slowdown in the AMOC is destabilizing the West African monsoon, impacting drought in the Sahel region,  drying the Amazon, disrupting the East Asian monsoon and warming the  Southern Ocean with increased  Antarctic ice loss).

The authors  provide a further Figure that dramatically summarizes how the key changes summarized above can variously impact on each other,  with AMOC having a key centrality. The authors comment: “We argue that cascading effects might be common. Research last year analysed 30 types of regime shift spanning physical climate and ecological systems, from collapse of the West Antarctic ice sheet to a switch from rainforest to savanna. This indicated that exceeding tipping points in one system can increase the risk of crossing them in others. Such links were found for 45% of possible interactions” [1].

The authors adduce paleo-climatological  evidence that: “Atmospheric CO2 is already at levels last seen around four million years ago, in the Pliocene epoch. It is rapidly heading towards levels last seen some 50 million years ago — in the Eocene — when temperatures were up to 14 °C higher than they were in pre-industrial times. It is challenging for climate models to simulate such past ‘hothouse’ Earth states. One possible explanation is that the models have been missing a key tipping point: a cloud-resolving model published this year suggests that the abrupt break-up of stratocumulus cloud above about 1,200 parts per million of CO2 could have resulted in roughly 8 °C of global warming” [1].

Finally, the paper provides a compelling mathematical analysis: “We define emergency (E) as the product of risk and urgency. Risk (R) is defined by insurers as probability (p) multiplied by damage (D). Urgency (U) is defined in emergency situations as reaction time to an alert (τ) divided by the intervention time left to avoid a bad outcome (T). Thus: E = R × U = p × D × τ / T . The situation is an emergency if both risk and urgency are high. If reaction time is longer than the intervention time left (τ / T > 1), we have lost control” [1].

The authors conclude: “Act now. In our view, the evidence from tipping points alone suggests that we are in a state of planetary emergency: both the risk and urgency of the situation are acute… We argue that the intervention time left to prevent tipping [T] could already have shrunk towards zero, whereas the reaction time to achieve net zero emissions [τ] is 30 years at best. Hence we might already have lost control of whether tipping happens. A saving grace is that the rate at which damage accumulates from tipping — and hence the risk posed — could still be under our control to some extent. The stability and resilience of our planet is in peril. International action — not just words — must reflect this”.

Final comments.

The authors considered the Terminal Carbon Pollution Budget for a 50% chance of not exceeding  +1.5C: “ The world’s remaining emissions budget for a 50:50 chance of staying within 1.5 °C of warming is only about 500 gigatonnes (Gt) of CO2. Permafrost emissions could take an estimated 20% (100 Gt CO2) off this budget, and that’s without including methane from deep permafrost or undersea [CH4-H2O] hydrates. If forests are close to tipping points, Amazon dieback could release another 90 Gt CO2 and boreal forests a further 110 Gt CO2. With global total CO2 emissions still at more than 40 Gt per year, the remaining budget could be all but erased already” [1].

In 2018 the  IPCC issued a Report that detailed the numerous bad outcomes of a global +1.5 degree Centigrade (+1.5C) of warming versus the catastrophic outcomes from a +2C e.g. a further 70-90% decline of coral reefs at +1.5C versus more than 99% loss at +2C. Crucially, the IPCC Report says that for less than +1.5C  coal burning must cease by 2050 but also declares that the Terminal Carbon Pollution Budget for a 66% chance of avoiding +1.5C (420 Gt CO2) will be used up in 10 years at a rate of 42 Gt Co2 per year [2-4].

Indeed the IPCC in its  Fifth Assessment Report (AR5)  stated (2014): “Emissions ranges for baseline scenarios and mitigation scenarios that limit greenhouse gas concentrations to low levels (about 450 ppm CO2-eq, likely to limit warming to 2°C above pre-industrial levels) are shown for different sectors and gases in Figure SPM.14” [5]. However  according to Professor Ron Prinn (from100-Nobel-Laureate MIT) we may have already reached 478 ppm CO2-equivalent in 2013  [6-10] ( it is presently at nearly 500 ppm CO2-equivalent).

The German WBGU (2009) and the Australian Climate Commission (2013) have estimated that no more than 600 billion tonnes of CO2 can be emitted between 2010 and zero emissions in 2050 if the world is to have a 75% chance of avoiding a catastrophic +2C temperature  rise [11, 12]. However a revised global annual GHG pollution of 64 Gt CO2-equivalent (properly taking  land use and CH4 in to account) [13] means that this Terminal Carbon Pollution  Budget was exceeded in 2019.

Australia (0.3% of world population, but with Domestic GHG pollution 2.1% of global GHG pollution and 4.5% with its huge Exported GHG pollution included) has a climate criminal policy (supported by both the ruling Coalition and the Labor Opposition)  of unlimited coal, gas and iron ore  exports,  and it can be estimated that complete exploitation  of Australia’s huge resources in these areas would mean exceeding the  whole world’s  2009 Terminal  Carbon Pollution Budget by a factor of 3 [14]. Similarly, the Global Warming Potential (GWP) of CH4 on a 20 year time frame and with aerosol impacts considered is 105 times that of CO2 [15] and the 50 Gt (billion tonnes) CH4 in the East Siberian Arctic Shelf that is predicted to be released in coming decades [16] is thus equivalent to 50 billion tonnes CH4 x 105 tonnes  CO2-equivalent/tonne CH4 = 5,250 tonnes CO2-equivalent or about nine (9) times more than the world’s Terminal  Carbon Pollution Budget. We are doomed unless we can stop this massive Arctic CH4 release [4, 8-10].

Humanity and the Biosphere are existentially threatened by nuclear weapons and climate change [17]. Eminent physicist Professor  Stephen Hawking has stated the problem and solution very succinctly : “We see great peril if governments and societies do not take action now to render nuclear weapons obsolete and to prevent further climate change” [18, 19]. A paper co-signed by over 11,000 scientists  has detailed trends in 24 climate-related  areas over the last 40 years.  Scientists became aware of the climate change threat from greenhouse gas (GHG) pollution in the 1980s,  but in 21 of these 24 areas the trends are (a) huge, (b) in the wrong direction, and (c) linear or quasi-linear functions of time , with this allowing extrapolation from the present climate emergency to a climate catastrophe in 2030 [20-23] .

What can decent people do? It is effectively too late to avoid a catastrophic +2C temperature rise but decent people are obliged to do everything they can to make the future “less bad” for future generations. Decent people must  act individually or better still act collectively (e.g. I am the secretary of the climate action group  Banyule Climate Action Now (BCAN) that is based in Melbourne in the City of Banyule that has recently declared a Climate Emergency) [24].

Decent folk must   (a) inform everyone they can  about the worsening Climate Emergency, Climate Genocide and Intergenerational Inequity, (b) urge a climate revolution (peaceful and non-violent  of course) with hundreds of millions out in the streets inspired by the likes of teenage activist Greta Thunberg, and (c) urge and apply Boycotts, Divestment and Sanctions (BDS) against all  people, politicians, parties, collectives, corporations and countries disproportionately  involved in the worsening Climate Genocide that is presently set to kill 10 billion people this century en route to a sustainable human population of merely 0.5-1.0 billion in 2100 [25].  There is no Planet B.


[1]. Timothy Lenton, Johan Rockstrom, Owen Gaffney, Stefan Rahmsdorf, Katherine Richardson, Will Steffen and Hans Joachim Schellnhuber,  “Climate tipping points – too risky to bet against” , Nature 575, 592-595, 27 November 2019: https://www.nature.com/articles/d41586-019-03595-0 .

[2]. IPCC, “Global warming of 1.5 °C”, 8 October 2018: http://www.ipcc.ch/report/sr15/ .

[3]. IPCC, “Global warming of 1.5 °C. Summary for Policymakers”, 8 October 2018: http://report.ipcc.ch/sr15/pdf/sr15_spm_final.pdf .

[4]. Gideon Polya, “IPCC +1.5C avoidance report – effectively too late but stop coal burning for “less bad” catastrophes”, Countercurrents, 12 October 2018: https://countercurrents.org/2018/10/12/ipcc-1-5c-avoidance-report-effectively-too-late-but-stop-coal-burning-for-less-bad-catastrophes/ .

[5].  IPCC, “Climate Change 2014 Synthesis Report, Approved Summary for Policy Makers”, 1 November 2014: http://www.ipcc.ch/pdf/assessment-report/ar5/syr/SYR_AR5_SPM.pdf ).

[6]. Ron Prinn, “400 ppm CO2? Add other GHGs and its equivalent to 478 ppm”, Oceans at MIT, 6 June 2013: http://oceans.mit.edu/featured-stories/5-questions-mits-ron-prinn-400-ppm-threshold .

[7].  Gideon Polya, “International consensus-based IPCC Summary For Policymakers (2014) downplays acute seriousness of Climate Crisis”, Countercurrents,  12 November, 2014: http://www.countercurrents.org/polya121114.htm .

[8]. “Are we doomed?”: https://sites.google.com/site/300orgsite/are-we-doomed .

[9]. “Methane Bomb Threat”: https://sites.google.com/site/methanebombthreat/ .

[10]. “Too late to avoid global warming catastrophe”: https://sites.google.com/site/300orgsite/too-late-to-avoid-global-warming .

[11]. WBGU, “Solving the climate dilemma: the budget approach”: http://www.ecoequity.org/2009/10/solving-the-climate-dilemma-the-budget-approach/ .

[12 ]. Australian Climate Commission, “The critical decade 2013: a summary of climate change science, risks and responses”, 2013, p7: http://climatecommission.gov.au/wp-content/uploads/The-Critical-Decade-2013-Summary_lowres.pdf  .

[13]. [49]. Robert Goodland and Jeff Anfang, “Livestock and climate change. What if the key actors in climate change are … cows, pigs and chickens?”, World Watch, November/December 2009: http://www.worldwatch.org/files/pdf/Livestock%20and%20Climate%20Change.pdf .

[14]. Gideon Polya, “Australia ‘s Huge Coal, Gas & Iron Ore Exports Threaten Planet”, Countercurrents, 15 May 2012: http://www.countercurrents.org/polya150512.htm .

[15 ]. Drew T. Shindell , Greg Faluvegi, Dorothy M. Koch ,   Gavin A. Schmidt ,   Nadine Unger and Susanne E. Bauer , “Improved Attribution of Climate Forcing to Emissions”, Science, 30 October 2009: Vol. 326 no. 5953 pp. 716-718: http://www.sciencemag.org/content/326/5953/716  .

[16]. Gail Whiteman, Chris Hope and Peter Wadhams, “Vast costs of Arctic change”, Nature, 499, 25 July 2013: http://www.nature.com/nature/journal/v499/n7459/pdf/499401a.pdf .

[17]. “Nuclear weapons  ban, end poverty & reverse climate change”: https://sites.google.com/site/300orgsite/nuclear-weapons-ban .

[18]. Professor Stephen Hawking quoted in  Will Dunham, “Nuclear, climate perils push Doomsday Clock ahead”, Reuters, 22 January 2007: https://www.reuters.com/article/idUSN17314370 .

[19].  Stephen Hawking, “Brief Answers to the Big Questions”, John Murray, 2018, Chapter 7.

[20 ]. William Ripple et al.., “World scientists’ warning of a climate emergency”, BioScience,  5 November 2019: https://academic.oup.com/bioscience/advance-article/doi/10.1093/biosci/biz088/5610806 .


[21]. Gideon Polya, “Extrapolating 11,000 scientists’ climate emergency warning to 2030 climate catastrophe”, Countercurrents, 14 November 2019:  https://countercurrents.org/2019/11/extrapolating-11000-scientists-climate-emergency-warning-to-2030-catastrophe .)

[22]. William J. Ripple et al., 15,364 signatories from 184 countries, “World scientists’ warning to Humanity: a second notice”, Bioscience, 13 November 2017: https://academic.oup.com/bioscience/advance-article/doi/10.1093/biosci/bix125/4605229 .

[23]. Gideon Polya, “Over 15,000 scientists issue dire warning to humanity on catastrophic climate change and biodiversity loss”, Countercurrents, 20 November 2017: https://countercurrents.org/2017/11/20/over-15000-scientists-issue-dire-warning-to-humanity-on-catastrophic-climate-change-and-biodiversity-loss/ .

[24]. “Banyule Climate Action Now”: https://sites.google.com/site/banyuleclimateactionnow/ .

[25]. “Climate Genocide”: https://sites.google.com/site/climategenocide/ .

Dr Gideon Polya taught science students at a major Australian university for 4 decades. He published some 130 works in a 5 decade scientific career, most recently a huge pharmacological reference text “Biochemical Targets of Plant Bioactive Compounds” (CRC Press/Taylor & Francis, New York & London , 2003). He has published “Body Count. Global avoidable mortality since 1950” (G.M. Polya, Melbourne, 2007: http://globalbodycount.blogspot.com/ ); see also his contributions “Australian complicity in Iraq mass mortality” in “Lies, Deep Fries & Statistics” (edited by Robyn Williams, ABC Books, Sydney, 2007: http://www.abc.net.au/radionational/programs/ockhamsrazor/australian-complicity-in-iraq-mass-mortality/3369002#transcript   ) and “Ongoing Palestinian Genocide” in “The Plight of the Palestinians (edited by William Cook, Palgrave Macmillan, London, 2010: http://mwcnews.net/focus/analysis/4047-the-plight-of-the-palestinians.html ). He has published a revised and updated 2008 version of his 1998 book “Jane Austen and the Black Hole of British History” (see: http://janeaustenand.blogspot.com/  ) as biofuel-, globalization- and climate-driven global food price increases threaten a greater famine catastrophe than the man-made famine in British-ruled India that killed 6-7 million Indians in the “forgotten” World War 2 Bengal Famine (see recent BBC broadcast involving Dr Polya, Economics Nobel Laureate Professor Amartya Sen and others: http://www.open.edu/openlearn/history-the-arts/history/social-economic-history/listen-the-bengal-famine  ;  Gideon Polya: https://sites.google.com/site/drgideonpolya/home  ; Gideon Polya Writing: https://sites.google.com/site/gideonpolyawriting/ ; Gideon Polya, Wikipedia: https://en.wikipedia.org/wiki/Gideon_Polya ) . When words fail one can say it in pictures – for images of Gideon Polya’s huge paintings for the Planet, Peace, Mother and Child see: http://sites.google.com/site/artforpeaceplanetmotherchild/ and http://www.flickr.com/photos/gideonpolya/  .



One Comment

  1. Eliminate fossil fuels, uranium use and exposure of living beings to uranium, eliminate dams. NOW according to a survival plan. Preserve forests, ecologically regenerate forests, even if they are a new set of forests. Involve the people. Truly democratically.