Guesstimate : a greater than 1% chance of 90% die-off of all life by 2035


There is a greater than >1% chance that 90% or more of all multi-cellular life on our biosphere could die-off by 2035 - if we do not slow down climate change. That's my guesstimate today.

However, I am jazzed that every time I choose to use less fossil fuels, live more eco logically, or make my work or the world more sustainable, this biosphere gets to live a little longer, and we get to have more fun. I am going to work hard to lower that percentage.

For all the life, Stele Ely 2/1/2019
[Green Minute Rule]

Basis for >1% chance of 90% multi-cellular die-off by 2035 Guesstimate

My rough guesstimate is based on the assessments, articles and resources from climate scientists and non-scientists listed below, other assessments, and my own anecdotal experiences.

Here are a few of my comments on those resources.

Climate Shock authors Gernot Wagner and Martin L. Weitzman state in table 3.1 that there is a 1.2% chance of a >6 C warming potential at 500ppm CO2e.

In January 2019 we were at about 410ppm CO2 and about 495ppm CO2e. A 1.2% chance of >6 C is too high for me to feel all cushy. Most assessments say that at >6 C our planet would be largely uninhabitable.

In February 2018 we were at about 408ppm CO2 and 492ppm CO2e.

The same Climate Shock table also says there is a 3% chance of a >6 C warming potential at 550ppm CO2e. We could be at 550ppm CO2e in less than 15 years. That Climate Shock table also says there is a 5% chance of a >6 C warming potential at 600ppm CO2e. That Climate Shock table says there is a 10% chance of a >6 C warming potential at 700ppm CO2e. Wow!

Assessments / Resources / [~S = Stele comments]

+'s timelines for possible human extinction articles. These articles are written by Sam Carana, other scientists and non-scientists. has over 24 scientists and other non-scientists who are listed there as contributors. These non-dissenting contributors are not substantially disputing the possible human extinction assessments in those articles. There is a Debate and Controversy page for that purpose. Sam Carana is an anonymous writer or writers for This writer(s) may be anonymous to protect their professional or personal life(s).
[The percentage of multi-cellular biosphere die-off that would result in human extinction was not precisely stated in this source, as far as I have seen. ~S]
[It seems very probable to me, Stele, that it would take a very large die-off of multi-cellular life on our biosphere to result in human extinction. ~S]

+ Carbon Dioxide Is Rising at Record Rates / Brian Kahn / The annual growth of 3 parts per million in 2016 is the slightest shade below the jump in 2015 of 3.03 ppm. Both years mark the first time carbon dioxide has risen more than 3 ppm in a single year in ESRL’s 59 years of monitoring.

+ A rise of 18°C or 32.4°F by 2026? / Sam Carana / A catastrophe of unimaginable proportions is unfolding. Life is disappearing from Earth and all life could be gone within one decade. Study after study is showing the size of the threat, yet many people seem out to hide what we're facing. In the Arctic alone, four tipping points look set to be crossed within a few years: 1] Loss of the Arctic sea ice's ability to act as a buffer to absorb incoming ocean heat. 2] Loss of Arctic sea ice's ability to reflect sunlight back into space (albedo). 3] Destabilization of sediments at the seafloor of the Arctic Ocean. 4] Permafrost melt.

+ Maximum warming occurs about one decade after a carbon dioxide emission / Katharine L Ricke and Ken Caldeira / via Using conjoined results of carbon-cycle and physical-climate model intercomparison projects (Taylor et al 2012, Joos et al 2013), we find the median time between an emission and maximum warming is 10.1 years, with a 90% probability range of 6.6–30.7 years.

+ The time lag between a carbon dioxide emission and maximum warming increases with the size of the emission / Kirsten Zickfeld1 and Tyler Herrington Our results indicate that as CO2 continues to accumulate in the atmosphere, the full warming effect of an emission may take several decades, if not centuries to emerge. A large fraction of the warming, however, will be realized relatively quickly (93% of the peak warming is realized 10 years after the emissions for the 1000 PgC pulse). This implies that the warming commitment from past CO2 emissions is small, and that future warming will largely be determined by current and future CO2 emissions. Each additional CO2 emission will contribute to warming that will persist almost indefinitely. Thus, emission reductions implemented today will equally benefit current and future generations.

+ Climate Shock book and/or presentations / Gernot Wagner and Martin L. Weitzman / "[There is] about a 10 percent chance of eventual temperatures exceeding 6°C (11°F) [at greater than 700ppm CO2e] unless the world acts much more decisively than it has." "...500 ppm [CO2e] [has] a chance of [>6 C] catastrophe [at] 1.2 percent." Fat Tails chapter.

+ Global Extinction Within 18 - 34 Months / Malcolm Light / Humanity is facing the final, western corporate capitalist, fossil fuel initiated, catastrophic Arctic methane hydrate destabilization and Permian style methane blowout - firestorm that will culminate in 1 to 4 years (2020 to 2023).

+ Abrupt Climate Change from Arctic to Antarctic: Facts, Opinions, and Analysis / Paul Beckwith /

+ Will humans be extinct by 2026? / Sam Carana, et al /

+ Rapid climate change has happened before / . [5 C rise in global-average temperature 55 million years ago during a span of 13 years. ~S]

+ New Climate-Economic Thinking / The Institute for New Economic Thinking / Gernot Wagner and Martin L. Weitzman Instead of focusing on averages then, climate ought to be seen as a risk management problem. Some greenhouse gas concentration thresholds should simply not be crossed. The risks are too high.

+ : The Science of Abrupt Climate Change: Should we be worried? / Jeffrey Masters, Ph.D."...As seen in Figure 1, the ice core record showed frequent sudden warmings and coolings of 15°F (8°C) or more. Many of these changes happened in less than 10 years. In one case 11,600 years ago, when Earth emerged from the final phase of the most recent ice age (an event called the Younger Dryas), the Greenland ice core data showed that a 15°F (8°C) warming occurred in less than a decade, accompanied by a doubling of snow accumulation in 3 years. Most of this doubling occurred in a single year."

+ Global-warming Armageddon? It may be more likely than you thought / Colin Goldblatt Author of a paper published online in the 28 July 2013 issue of Nature Geoscience, "The runaway greenhouse may be much easier to initiate than previously thought."

+ CNN : On 6 degrees of climate change / John Sutter, CNN senior writer

+ Arctic Methane Monster I and II videos and articles / Jennifer Hynes .

+ Guy McPherson's timeline for possible human extinction stated in his Climate Change Summary and Update, articles and presentations.
Guy McPherson's near term human extinction assessment may be wrong - and we will be slap happy if and when he is proven wrong.
[Note: The percentage of multi-cellular biosphere die-off that would result in human extinction was not precisely stated in this source, as far as I have seen.]

+ Half-way to Catastrophe -- Global Hothouse Extinction to be Triggered by or Before 2100 Without Rapid Emissions Cuts / Robert Scribbler

More Assessments / Resources

+ "Let us consider, in that context, the prospects for warming well in excess of what we might term “dangerous” (typically considered to be at least 2C or 3.6F warming of the planet)." / Michael E Mann / "How likely, for example, are we to experience a catastrophic 6C = 11F warming of the globe, if we allow greenhouse gas concentrations to reach double their pre-industrial levels (something we’re on course to do by the middle of this century given business-as-usual burning of fossil fuels)?
Well, the mean or average warming that is predicted by models in that scenario is about 3C, and the standard deviation about 1.5C. So the positive tail, defined as the +2 sigma limit, is about 6C of warming. As shown by Wagner and Weitzman (see figure below), the likelihood of exceeding that amount of warming isn’t 2% as we would expect for a bell-curve distribution. It’s closer to 10%!"

+ National Academy of Sciences [NAS] : Abrupt Climate Change Inevitable Surprises (2002) by 29 scientists and writers.

+ United Nations Environment Programme (mid 2017): 3.2 C by 2100. / The 3.2 C May be based on assumption of countries meeting the Paris Agreement. The report states, "Implementation of the unconditional NDCs and comparable action afterwards is consistent with a temperature increase of about 3.2°C by 2100 relative to pre-industrial levels. Full implementation of the conditional NDCs would lower the projection by about 0.2°C." [Nationally Determined Contributions (NDCs) form
the foundation of the Paris Agreement.]

+ Year 2100 Projections: Based on climate action pledges of UN member countries. / +"...Confirmed Proposals As of March 1, 2011, Temperature Rise (2100)4.0°C, 800 ppm CO2, 1060 ppm CO2e, 103.40 Gt..."

+ The Climate Scoreboard shows the progress that national plans submitted to the UN climate negotiations will make in mitigating climate change. / (2018) Our analysis shows that the national contributions to date, with no further progress post-pledge period, result in expected warming in 2100 of 3.3°C (with a range of uncertainty of 1.9 – 4.4°C)

+ Hadley Centre for Meteorological Research (October 2009): 4 C by 2060 /

+ Late in 2008, Hadley Center’s head of climate change predictions Dr. Vicky Pope calls for a worst-case outcome of more than 5 C by 2100. / Joe Romm /, "right now even Hadley [Centre] understands it [> 5 C] is better described as the 'business-as-usual' case."

+ Intergovernmental Panel on Climate Change (late 2007): >1.8 C by 2100 (up to 4.5 C, depending upon emissions scenarios) [NEEDS UPDATED]

+ (2017) + Based on climate action pledges of UN member countries Based on climate action pledges of UN member countries 4.0 C by 2100.

+ International Energy Agency (2017) / projection is up 4°C by the end of this century with business as usual.

+ Global Carbon Project, Copenhagen Diagnosis (November 2009) / Global mean air-temperature is projected to warm 2°C – 7°C above pre-industrial by 2100. The wide range is mainly due to uncertainty in future emissions.

+ Climate change occurring ten times faster than at any time in past 65 million years / Noah Diffenbaugh and Chris Field / Stanford Woods Institute for the Environment / ...the researchers note that, with continued emissions of greenhouse gases at the high end of the scenarios, annual temperatures over North America, Europe and East Asia will increase 2-4 degrees C by 2046-2065.

+ The Potential For Huge Abrupt Temperature Rise / Sam Carana, et al / The image below shows that temperatures typically moved up and down by roughly 10°C (ten degrees Celsius, or eighteen degrees Fahrenheit, i.e. 18°F) between a glacial and interglacial phase of the ice ages, suggesting that a 100 ppm rise of carbon dioxide and 300 ppb rise of methane go hand in hand with a 10°C temperature rise. In other words, it looks like high levels of greenhouse gases in the atmosphere have already locked us in for a future temperature rise of 10°C.

+ It’s Looking Like We’ll Never See Another Month Below 400 ppm CO2 Again / ...adding in all greenhouse gasses like Nitrogen compounds and Methane resulting from fossil fuel burning (and other human activities) and you end up with a CO2 equivalent in the atmosphere close to 490 parts per million. Such a level of forcing correlates more closely to an even more ancient climate period called the Middle Miocene of about 15 million years ago when global temperatures were between 3 and 4 C warmer than they are today.

+ World Scientists’ Warning to Humanity: A Second Notice : More than 15,000 signatories / stating, "To prevent widespread misery and catastrophic biodiversity loss, humanity must practice a more environmentally sustainable alternative to business as usual. This prescription was well articulated by the world's leading scientists 25 years ago, but in most respects, we have not heeded their warning. Soon it will be too late to shift course away from our failing trajectory, and time is running out. We must recognize, in our day-to-day lives and in our governing institutions, that Earth with all its life is our only home.

Yetmore Resources / Articles

+ National Snow and Ice Data Center: Advancing knowledge of Earth's frozen regions: Arctic Sea Ice /

+ NASA: Goddard Institute for Space Studies: Surface Temperature Analysis Graphs /

+ NASA: Climate change: How do we know? /

+ THE NOAA ANNUAL GREENHOUSE GAS INDEX (AGGI) See CO2-eq (ppm) chart / annual CO2 increase from 1 Jan 2016 to 1 Jan 2017 was 2.9 ± 0.1 ppm, and then, 1 Jan 2017 to 1 Jan 2018 was 2.1 ± 0.1 ppm

+ Runaway_climate_change / The scientific consensus in the IPCC Fourth Assessment Report is that "Anthropogenic warming could lead to some effects that are abrupt or irreversible, depending upon the rate and magnitude of the climate change."

+ National Academy of Sciences [NAS] : Abrupt Climate Change Inevitable Surprises / "...scientists have found that changes in climate have occurred quickly in the past—over the course of a decade. An example of an abrupt climate change event is the Younger Dryas (~12,000 years ago), a period of abrupt cooling that interrupted a general warming trend as Earth emerged from the last Ice Age. During the Younger Dryas period, average summertime temperatures in New England cooled by about 5-7°F (3-4°C).

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About Stele

Earth Lovers, Write enviro songs and make art with me to inspire peeps to join us in taking eco actions that help save our earth and slow down climate change. Peas, love and flaxseed butter, Stele

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