New Evidence That Climate Change Poses a Much Greater Threat to Humanity Than Recently Understood Because the IPCC has been Systematically Underestimating Climate Change Risks: An Ethical Analysis


Three papers have been recently published that lead to the conclusion that human-induced climate change poses a much more urgent and serious threat to life on Earth than many have thought who have been relying primarily on the conclusions of the Intergovernmental Panel on Climate Change (IPCC). This paper first reviews these papers and then examines the ethical questions by the issues discussed in these papers.

I. The Three Papers

On July 31, 2018, a paper was published in the Proceedings of the National Academy of Sciences which should create a shiver of fear in all humans everywhere. The paper, Trajectories of  the Earth System in the Anthropocene by Steffen, explains how human-induced warming is rapidly approaching levels that may trigger positi climate feedbacks which could greatly accelerate the warming already plaguing the world by causing record floods, deadly heat waves and droughts, increasing tropical diseases, forest fires, more intense and damaging storms, sea level rise, coral bleaching, and acidification of oceans, all of which are contributing to increasing the number of refugees which are destabilizing governments around the world. This paper explains that, contrary to common assumptions made by many in the international community that positive feedbacks in the climate system that could cause abrupt temperature increases would not likely be triggered if warming could be limited to 20 C above pre-industrial levels, positive feedbacks could be initiated between current temperatures and 20 C. Moreover, once triggered the additional warming caused by these feedbacks could initiate other feedbacks creating a cascade of positive feedbacks, each of which could speed up the warming which is already causing great harm and suffering around the world. The paper claims this mechanism could make life on much of the Earth uninhabitable which could lead to social collapse on the global scale and ultimately to warming increases that human reductions of greenhouse gases (ghg) emissions alone would not prevent until the global system reached a new temperature equilibrium at much higher temperatures than the human race has ever experienced. In other words, cascading positive feedbacks in the climate system could result in humans losing control over preventing disastrous warming.

Another recent paper published in mid-August in Nature Communications by Anthony et. al., 21st-Century Modeled Permafrost Carbon Emissions Accelerated by Abrupt Thaw Beneath Lakes, concludes that models used to predict climate impacts have failed to incorporate abrupt carbon feedback from permafrost decay that recent evidence has revealed is now possible. In fact, the paper claims that early stages of processes that lead to permafrost degradation are already underway, a phenomenon which leads to release of dangerous amounts of methane and CO2. This paper further concludes that carbon emissions from melting permafrost could increase soil carbon emissions by 125–190% compared to gradual thaw alone.

This paper summarizes major conclusions from a third recent paper which analyzes IPCC’s consistent underestimation of climate change impacts. This paper, What Lies Beneath: On the Understatement of Existential Climate Risk, (hereinafter “WLB”), recently published by the Breakthrough Institute, claims both that the risks posed by climate change are far greater than is evident from the conclusions of IPCC and examines why IPCC has frequently underestimated threats from climate change.

The WLB report also further concludes that climate change is now an existential risk to humanity, that is an adverse outcome that could either annihilate intelligent life or permanently and dramatically curtail its potential. (WLB, p.13)

Although the WLB report acknowledges IPCC has done “critical, indispensable work of the highest standard in pulling together a periodic consensus of what must be the most exhaustive scientific investigation in world history” however, the IPCC process suffers from all of the dangers of consensus-building in such a wide-ranging and complex arena. (WLB, p. 5) The report also attributes the overly conservative conclusions of the IPCC to the consensus building nature that IPCC must follow to get governments to approve IPCC final reports and to IPCC’s following scientific norms that condemn speculation. (WLB. p. 5) As a result, the report concludes that much of the climate research on which IPCC has relied has tended to underplay climate risks and as a result, IPCC has exhibited preferences for conservative estimates of climate change impacts. (WLB, p. 5)  This practice the WLB reports labels as “scholarly reticence.” (WLB, p. 5)

This WLB report further claims that climate science has succumbed to the norm followed by most physical sciences to refrain from any speculation that cannot be grounded in empirically determined probability calculations. This epistemic norm, the report claims, is not well-suited to guide predictions about very scientifically complex matters such as earth system dynamics. The report calls this approach the Probability Obsession of science which is not well suited to predict future states of complex systems about matters for which there are no historical antecedents. (WLB, p. 2)

The WLB report also notes that a conservative approach to climate science began to dominate and as a result, the planetary future has become a hostage to national economic self-interest. Thus, the paper claims it became “alarmist” to claim the climate change is an existential threat to life on earth. (WLB, p.4)

The report further notes that although “a fast emergency-scale transition to a post-fossil fuel world is absolutely necessary to address climate change…. yet this is excluded from consideration by policymakers because it is considered to be too disruptive.” And so the paper claims “we have a policy failure of epic proportions.”  (WLB, p. 4)

The WLB report further notes that although it has widely been reported that if the ghg emissions reductions commitments or Nationally Determined Commitments (NDCs)  made by governments so far under the Paris Agreement are complied with, the Earth’s temperature is expected to rise to  3.40 C by 2100 without taking into account “long-term” carbon cycle feedbacks. (WLB, p.15) Yet if the positive feedbacks are fully considered, the temperature path defined by the NDCs could result in around 5° C of warming by 2100 according to a MIT study. (WLB, p.13) Yet, the report claims that even if warming reaches 3° C, most of Bangladesh and Florida would drown, while major coastal cities – Shanghai, Legos, Mumbai – would be swamped likely creating larger flows of climate refugees. Most regions of the world would see a significant drop in food production and an increasing number of extreme weather events, whether heat waves, floods or storms. (WLB, p.13)

The WLB report concludes warming of 4°C or more could reduce the global human population by 80% or 90%, and the World Bank reports “there is no certainty that adaptation to a 4°C temperature rise would be possible.” Quoting Professor Kevin Anderson, the report claims a 4°C future “is incompatible with an organized global community and is likely to be beyond adaptation by the majority of people.” (WLB, p. 14)

The WLB report also claims that the often-quoted prediction of likely temperature increases if current NDCs are complied with of approximately 3° C rise does not take into account the considerable risk that self-reinforcing feedback loops could be triggered when certain thresholds are reached leading to an ever-increasing rise in temperature. These potential thresholds include the melting of the Arctic permafrost releasing methane into the atmosphere, forest dieback releasing carbon currently stored in the Amazon and boreal forests, with the melting of polar ice caps that would no longer reflect the light and heat from the sun. (WLB, p. 14)

The report cites a recent study by the European Commission’s Joint Research Center found that if global temperature rose to 4° C that extreme heat waves with “apparent temperatures” peeking over 550 C (1310 F) will begin to regularly affect many densely populated parts of the world, forcing much activity in the modern industrial world to stop. (WLB, p.14)

The paper claims that one study found that even a 2° C warming “would double the land area subject to deadly heat and expose 48% of the population to deadly heat.” (WLB, p.14)

According to the WLB report, a 4° C warming by 2100 would subject 47% of the land area and almost 74% of the world population to deadly heat which could pose existential risks to humans and mammals alike unless massive adaptation measures are implemented. (WLB, p.14)

The WLB paper also explains how IPCC’s understatements of likely climate change impacts affect what is generally claimed among climate policy-makers about elements of climate science including climate models, climate tipping points, climate sensitivity, carbon budgets, permafrost and carbon cycles, arctic sea ice, polar ice-mass loss, and sea-level rise. The following summarizes some of the main paper’s conclusions on these matters, although we recommend that interested parties read the WLB’s full description of these issues. The full paper also should be consulted for footnote sources of the following conclusions.

Climate Models

Climate modeling is at the core of the work by IPCC, and in developing future emission and warming scenarios a 2007 report by the US Center for Strategic and International Studies Center for New American Security recognized the that: “Recent observations indicate the projections from climate models have been too conservative,” and  “the effects of climate change are unfolding faster and more dramatically than expected,” and, “multiple lines of evidence support the position that the 2007 IPCC reports’ projections of impacts are systematically biased low.” (WLB, p.18) For instance, the paper concludes:

The models used to project future warming either omit or do not account for uncertainty in potentially important positive feedbacks that could amplify warming (e.g., release of greenhouse gases from thawing permafrost, reduced ocean and terrestrial CO2 removal from the atmosphere, and there is some evidence that such feedbacks may already be occurring in response to the present warming trend. Hence, climate models may underestimate the degree of warming from a given amount of greenhouse gas emitted into the atmosphere by human activities alone. Additionally, recent observations of climate system responses to warming (e.g. changes in global ice cover, sea level rise, tropical storm activity) suggest that IPCC models underestimate the responsiveness of some aspects of the climate system to a given amount of warming. (WLB, p.18)

Climate models simply omit emissions from warming permafrost, but we know that is the wrong answer because this tacitly assumes that these emissions are zero and we know that’s not right. (WLB, p.18)

The WLB report characterizes IPCC reports as presenting “detailed, quantified (numerical) modeling results-such as feedbacks that the models account for in a descriptive non-quantified form. Sea-levels, polar ice sheets, and some carbon-cycle are three examples. Because policymakers and the media are often drawn to the headline numbers, this approach results in less attention being given to the most devastating, high-end, non-linear and difficult to quantify outcomes.” (WLB, p. 19).

The WLB report concludes about this tendency: “The emphasis on consensus in IPCC reports has put the spotlight on expected outcomes which then become anchored via numerical estimates in the minds of policymakers.” (WLB, p. 19)

The WLB report also notes that one of the problems with IPCC is the strong desire to rely on physical models. (WLB, p. 20)

Tipping Points

A tipping point may be understood as the passing of a critical threshold in the earth climate systems component – such as major ocean and atmospheric circulation patterns, the polar ice sheet, and the terrestrial and ocean carbon stores – which produces a steep change in the system. (WLB, p. 21) Progress toward a tipping point is often driven by positive feedbacks, in which a change in the component leads to further changes that eventually “feedback” onto the original component to amplify the effect. A classic case is global warming is the ice-albedo feedback, or decreases in the area of polar ice change surface reflexivity, trapping more heat, producing further sea ice loss. (WLB, p. 21)

In some cases, passing one threshold will trigger further threshold events, for example, where substantial greenhouse gas releases from polar permafrost carbon stores increase warming, releasing even more permafrost carbon in a positive feedback, but also pushing other systems, such as polar ice sheets past their threshold point. (WLB, p. 21)

In a period of rapid warming, most major tipping points, once crossed are irreversible in human time frames, principally due to the longevity of atmospheric CO2 (a thousand years). (WLB, p. 21)

Climate models are not yet good at dealing with tipping points. (WLB, p.21) This is partly due to the nature of tipping points, where particularly complex confluence of factors abruptly change the climate system characteristics and drive it into a different state. (WLB, p.21) To model this, all the contributing factors and their forces have to be well identified, as well as their particular interactions, plus the interactions between tipping points. (WLB,  p.21)  Some researchers say that “complex, nonlinear systems typically shift between alternative states in an abrupt, rather than the smooth, changes, a challenge that the climate models have not yet been able to adequately meet. (WLB, p. 21)

Risks associated with tipping points increase disproportionately as temperature increases from 1° C to 2° C and become high above 3° C. Yet political negotiations have consistently disregarded the high-end scenarios that could lead to abrupt or irreversible climate change. (WLB, p. 21)

IPCC has published few projections regarding tipping-point thresholds, nor emphasized the importance of building robust risk-management assessments of them in absence of adequate quantitative data. (WLB, p. 210)

The world is currently completely unprepared to envision and even less deal with the consequences of catastrophic climate change. (WLB, p. 21)

Climate Sensitivity

Climate sensitivity is the amount by which the global average temperature will rise due to a doubling of atmospheric greenhouse gas levels, at equilibrium. IPCC reports a focus on what is generally called equilibrium climate sensitivity (ECS). The 2007 IPCC report gave a best estimate of climate sensitivity of 3° C and said it is likely to be in the range 2° C to 4.5° C. (WLB, p. 22)

The 2014 IPCC report says that “no best estimate for equilibrium climate sensitivity can now be given, because of lack of agreement on values across lines of evidence and studies” and only gives a range of 1.5° C to 4.5° C. (WLB, p. 22)

The IPCC reports fail to mention that the ECS measure omits key “long-term” feedbacks that a rise in the planet’s temperature can trigger. (WLB, p. 22) These include the permafrost feedback, other changes in the terrestrial carbon cycle, a decrease in the ocean’s carbon-sink efficiency, and the melting of polar ice sheets creating a cold ocean-surface layer underneath that accelerates the melting of ice shelves and hastens the rate of ice-mass loss. (WLB, p. 22)

There is a wide range of literature that suggests that climate sensitivity which includes these feeedbacks-known as Earth System Sensitivity (ESS), is 4-6 0 C. (WLB, p. 22).

Long-term feedbacks have already begun to appear on short time frames, climate-carbon cycle coupling is expected to add carbon to the atmosphere as the climate warms, although the magnitude of feedback is uncertain. (WLB, p. 22)

Conclusions about climate sensitivity should take into account that:

  1. Biogeochemical feedbacks (such as less efficient land-ocean sinks, including permafrost loss) effectively increases carbon emissions to 2100 by about 20% and can enhance warming by up to 0.5°C, compared to the baseline scenario. (WLB, p. 23)
  2. Warming has been projected to increase methane emissions from wetlands by 0 – 100% compared with present-day wetland methane emissions. A 50% increase in wetland methane emissions by 2100 is expected in response to high-end warming of 4.1 – 5°C which could add at least another 0.5°C warming. (WLB, p. 23)
  3. It is important to use high-end climate sensitivity because some studies have suggested the climate models have underestimated three major positive climate feedbacks: positive ice albedo feedback from the retreat of Arctic sea ice; positive cloud albedo feedbacks from retreating storm track clouds in mid-latitudes, and positive albedo feedback by the next phase (water and ice) clouds. When these are taken into account the ECS is more than 40% higher than the IPCC mid-figure, at 4.5 to 4.7° C. (WLB, p. 23)

Some recent research concludes that climate sensitivity is higher in warmer, interglacial periods (such as present) and lower in colder glacial periods. Based on a study of glacial cycles and temperatures over the last 100, 000 years one study concludes that in warmer periods climate sensitivity is 4.88 0 C. (WLB, p. 23) The higher figure would mean that an atmospheric concentration 450 ppm CO2, a figure that current trends will reach in 5 years, would be around 30 C in rather than the 20 C number bandied about in policy making circles. (WLB, p. 23)

Carbon Budgets

A carbon budget is the estimate of the total future human-caused ghg emissions in tons of CO2 or CO2 equivalent, that would be consistent with limiting warming to a specific figure, such as

1.5 0 C or 20 C with a given risk of exceeding the target such as 50%, 33%, or a 10% chance. (WLB, p. 24)

Carbon budgets are usually based on mid-term climate sensitivity numbers of around 30 C. (WLB, p. 22)

Yet there are reasons to believe climate sensitivity is closer to 4C. In fact, as we have seen, climate sensitivity may be between 4-60 C. (WLB, p. 22)

Carbon budgets are routinely proposed that have a substantial and unacceptable risk of exceeding specified targets and hence entail large and unmanageable risks of failure., (WLB, p. 24)

Research in 2017 the compared role climate models used by IPCC with models that are “observationally informed” produce 15% more warming by 2100 than IPCC claims and therefore supports the conclusion that carbon budgets should be reduced by 15% for the 20C target. (WLB, p. 24)

The IPCC reports fail to say that once projected emissions from future food production and deforestation are taken into account there is no carbon budget for fossil-fuel emissions for a 20C target. (WLB, p. 24).

There are also problems with carbon budgets which incorporate “overshoot” scenarios, in which warming exceeds the target before being cooled by carbon drawdown. (WLB, p.24)  Pam Pearson, Dir. of International Cryo-sphere Climate Initiative, said that most cryo-sphere thresholds are determined by peak temperatures, and the length of time spent at the peak warning rather than “later decreasing temperatures after the peak are largely irrelevant, especially with higher temperatures and longer duration peaks.” Thus “overshoot scenarios” which are now becoming the norm in policymaking hold much greater risks. (WLB, p. 24)

Permafrost and the Carbon Cycle

The failure to adequately consider long-term feedbacks in IPCC models, and hence in projections of future warming, lies at the heart of the problem with the IPCC reporting process. (IPCC, p.25) Over century time-scales, amplifying feedbacks may ultimately contribute 28-68% of total warming, yet they comprise only 1-7% of current warming. (WLB, p. 25)

The land sink (storage capacity) for CO2 appears much smaller than is currently factored into some climate models. Thus future patterns of warming may be distinctly different from past patterns making it difficult to predict future warming by relying on past observations. (WLB, p. 25)

Soil Carbon. A 2016 study concluded that a soil carbon cycle feedback “has not been incorporated into computer models used to project future climate change, raising the possibility that such models are underestimating the amount of warming that is likely to occur. (WLB, p. 24) The projected loss of soil carbon from climate change is a potentially large but highly uncertain feedback to warming, however, there is likely to be strong carbon-climate feedbacks from colder northern soils. (WLB, p.24)

Forests. At the at the moment about one-third of human-caused CO2 emissions are absorbed by trees and other plants. But rapid climate warming and unusual rainfall patterns are jeopardizing many of the world’s trees, due to more frequent droughts, pest outbreaks, and fires. (WLB, p. 25) This is starting to have profound effects on the Earth’s carbon cycle. (WLB, p. 25)  In 2009 researchers found that 2° C of warming could cut in half the carbon sink of tropical rainforests. Some tropical forests – in the Congo and Southeast Asia – have already shifted to a net carbon source. The tropics are now a net carbon source with losses owing to deforestation and reductions in carbon density within standing forests being double that of gains resulting from forest growth. Other work has projected a long-term, self-reinforcing carbon feedback from mid-latitude forests to the climate system as the world warms. (WLB, p. 25)

There has been an observed decline in the Amazon carbon sink.  Negative synergies between deforestation, climate change, and widespread use of fire indicate a tipping point for the Amazon system to flip to non-forest ecosystems in eastern, southern, and central Amazonia at 20 – 25% deforestation. Researchers say that severe droughts of 2005, 2010 and 2015-16 could well represent the first flickers of this ecological tipping point and say the whole system is oscillating. (WLB, p.25)

Permafrost. The world’s permafrost holds 1.5 trillion tons of frozen carbon, more than twice the amount of carbon in the atmosphere. On land it covers an area of 15,000,000 km². The Arctic is warming faster than anywhere on earth, and some permafrost degradation is already occurring. Large-scale tundra wildfires in 2012 added to the concern, as have localized methane outbursts. (WLB, p. 25)

The 2007 IPCC assessment on permafrost did not venture beyond saying “changes in snow ice and frozen ground have with high confidence increase the number and size of glacial lakes, increased ground instability in mountain and other permafrost regions and led to changes in some Arctic and in Antarctic ecosystems. It reported with high confidence that methane emissions from tundra and permafrost have accelerated in the past two decades and are likely to accelerate further. It offered no projections regarding permafrost melts. (WLB, p.25).

The effect of the permafrost’s carbon feedback has not been included in the IPCC scenarios including the 2014 report. (WLB, p. 26). This is despite clear evidence that “the permafrost carbon feedback would change the Arctic from a carbon sink to a source after the mid-2020s and is strong enough to cancel 42 – 88% of the total global land sink. (WLB, p. 26)

In 2012, researchers found that, for the 2100 median forecasts, there would be a 0.23 – 0.27°C of extra warming due to permafrost feedbacks. Some researchers consider that 1.5°C appears to be something of a “tipping point” for extensive permafrost thaw. (WLB, p.26)

A 2014 study estimated that up to 205 billion tonnes equivalent of CO2 could be released due to melting permafrost, This would cause up to 0.5° C extra warming for the high mission scenario and up to 0.15° C of extra warming for the 2° C scenario. The authors say that; “climate projections in the IPCC Fifth Assessment report, and any emissions targets based on these projections, do not adequately account for emissions from thawing permafrost and the effect of the permafrost carbon feedback on global climate. (WLB, p.26)

Recently attention has turned to the question of the stability of large methane hydrate stores below the ocean floor on the shallow East Siberian Arctic shelf. (Methane hydrates are cage-like lattices of ice within which methane molecules are trapped). (WLB, p. 26)

These stores are protected from the warmer ocean temperatures above by a layer of frozen sub-sea permafrost. The concern is that warmer water could create taliks (areas of unfrozen permafrost) through which large-scale methane emissions from the hydrates could escape into the water column above and into the atmosphere. (WLB, p. 26)

A deceptively optimistic picture is painted when the potential impacts from the degradation of permafrost and methane hydrates are underplayed. (WLB, p. 26)

Arctic Sea-Ice

IPCC has consistently underestimated the rate of Arctic sea ice melt. (WLB, p.27)

Arctic sea ice is thinning faster than every IPCC climate projection, tipping points have been crossed for sea ice free summer conditions, and today scientists say an ice-free Arctic summer could be just years away, not many decades. (WLB, p. 27)

The loss of sea ice reduces the reflectivity of the planet and adds to warming but this feedback is not fully incorporated into models in circumstances where the rate of sea-ice loss is more rapid than expected in the models, as is occurring now. (WLB, p.27) To keep global temperature increase below 20 C, global CO2 emissions would need to reach zero 5-15 years earlier and the carbon budget would need to be reduced by 20-51% to offset this additional source of warming. (WLB, p. 27)

Because climate models are missing key real-world interactions and generally have been poor at dealing with the rate of Arctic sea ice retreat, expert elicitation’s play a role in considering whether the Arctic has passed a very significant and dangerous tipping point. But the IPCC has done none of this. (WLB, p.27)

Polar Ice-Mass Loss

2001 IPCC report said little change in Greenland and Antarctic ice sheet is expected over the next 50-100 years.  (WLB, p. 28)

Greenland Ice Sheet

The 2007 IPCC report said there were “uncertainties in the full effects of ice sheet flow” and a suggestion that “partial loss of ice sheet on polar land could imply meters of sea-level rise….Such changes are projected to occur over millennial time scales.” The reality is very different.” (WLB, p. 28)

IPCC said in 2007 that current models suggest virtually complete elimination of the Greenland ice sheet and a resulting contribution to sea-level rise of about 7 meters if global warming were sustained for millennia in excess of 1.9 to 4.60 C relative to pre-industrial values. (WLB, p. 28) This was despite that two 2006 studies found that the Greenland ice cap “may be melting three times faster than indicated by previous measurements, warning that we are close to being close to being committed to a collapse of the Greenland ice cap and reports that rising Arctic regional temperatures are already at “ the threshold beyond which glaciologists think the [Greenland] ice sheet may be doomed.” (WLB, p. 28)

In 2012 then NASA climate science chief James Hansen told Bloomberg that: “our greatest concern is that the loss of Arctic sea ice creates a great threat of passing over passing two other tipping points – the potential instability of the Greenland Ice Sheet and methane hydrates…These latter two tipping points would have consequences that are practically irreversible on time scales of relevance to humanity.’ On this very grave threat, IPCC is mute. (WLB, p. 29)

Antarctic Ice Sheet

The 2007 IPCC assessment proffered: “Current global model studies project that the Antarctic ice sheet will remain too cold for widespread surface melting and gain mass due to increased snowfall.” (WLB, p. 29) However, the net loss of ice mass could occur if dynamical ice discharge dominates the ice sheet mass balance. Reality and new research would soon undermine this one-sided reliance by IPCC on models with poor cryosphere performance. (WLB, p. 29)

By the 2014 IPCC assessment, the story was: “Based on current understanding from observations, physical understanding, and modeling, only the collapse of the marine-based sectors of the Antarctic ice sheet, if initiated could cause global mean sea level to be substantially above the likely range during the 21rst Century.” (WLB, p. 29) There is medium confidence that the additional contribution would not exceed several tenths of a meter of sea-level rise during the 21rst Century. And “abrupt and irreversible ice loss from the Antarctic is sheet is possible, but current evidence and understanding is insufficient to make a quantitative assessment.” This was another blunder. Observations of accelerating ice mass in West Antarctic were well established by this time. (WLB, p. 29) It is likely that the Amundsen Sea sector of the West Antarctic ice sheet has already been destabilized. (WLB, p. 29) Ice retreat is unstoppable for current conditions, and no acceleration in climate change is necessary to trigger the collapse of the rest of the Antarctic Ice Sheet, which comes with a 3-5 meter sea level rise. (WLB, p. 29), Such an event would displace millions of people worldwide. (WLB, p. 29)

In 2016, another significant study concluded that: “Antarctica has the potential to contribute more than a meter of sea-level rise by 2100 and more than 15 meters by 2500.” Compare this to the IPCC report, just a year earlier, that Antarctica’s contribution to sea levels “ would not exceed several tenths of a meter…during this century. ” (WLB, p. 29) As well, partial deglaciation of the East Antarctic ice sheet is likely for the current level of atmospheric CO2 contributing ten meters or more of sea-level rise in the longer run, and five meters in the first 200 years. (WLB, p. 29)

A 2018 study showed that ocean-driven melting has caused rates of ice-loss from West Antarctica to triple from 53 + or – 29 billion to 159 + or – 26 billion tons per year from 1992 to 2017. (WLB, p. 29) Forty percent of the total mass loss over that period has occurred in the last and five years, suggesting a recent and significant acceleration in the loss rate. (WLB, p. 29)

Over the same period, ice-shelf collapse had increased the rate of ice loss from the Antarctic Peninsula almost five-fold from 7 + or – 13 billion to 33 + or- 16 billion tonnes per year. (WLB, p. 29)

Sea Level Rise

In the 2001 assessment report, the IPCC projected a sea-level rise of 2 millimeters per year. By 2007, the researchers found that the range of the 2001 predictions were lower than the actual rise. Satellite data had shown that sea levels had risen by an average of 3.3 millimeters per year between 1993 and 2006. (WLB, p. 30) IPCC did not use this data to revise its projections. (WLB, p. 30) James Hansen warned of “scientific reticence” in regard to ice sheet stability and sea-level rise. (WLB, p. 30) In 2008, the US Geological Survey warned that sea-level rise could top 1.5 meters by the end of the century. And by the end of 2009, various studies offered drastically higher projections than IPCC. (WLB, p. 30) The Australian government identified research that estimated sea level rise range from 0.5 to 2.0 meters by 2100. (WLB, p. 30) Yet in 2014, IPCC reported a smaller figure (0.55 meters compared to 0.59 meters in 2007) despite mounting evidence of polar ice-mass loss. (WLB, p. 30) Noting inconsistent evidence, IPCC said that the probability of specific levels above the likely range cannot be evaluated. (WLB, p. 30)

An NOAA sea level report in August of 2017 recommends a revised worst-case sea level scenario of 2.5 meters by 2100, 5.5 meters by 2150 2150, and 9.7 meters by 2200. (WLB, p. 31)

Today the discussion among experts is for sea-level rise in this century of at least one meter, and perhaps in excess of two meters. (WLB, p. 31)

Goals Abandoned

The WLB report claims that the warming levels already reached at approximately 1.10 C are already “dangerous” and that future warming would need to be limited to 1.20 C to save the Great Barrier Reef. (WLB. p. 37) Therefore, the WLB report concludes that the UNFCCC process has already abandoned the goals of the UNFCCC of “preventing dangerous interference with the climate system.” The report also argues that other key goals of the UNFCCC including that “food production is not threatened’’ and “achieving reductions in a time frame sufficient to allow ecosystems to adapt naturally to climate change” have been abandoned for all practical purposes.”

Conclusion-Ethical Issues Raised by IPCC’s Consistent Underestimation of Climate Change Impacts.

A. Failure to Apply a Precautionary Science

As we have seen, the “What Lies Beneath” Report attributes IPCC’s consistent underestimation of climate change impacts to both the consensus process that IPCC follows in which governments must approve aspects of final IPCC reports and to IPCC’s following norms often followed by scientists which eschew making any claims that cannot be supported by empirically tested observations.

As we have claimed before in, there is a potential conflict between IPCC’s mission to synthesize the peer-reviewed climate change scientific literature, which normally requires adequate levels of scientific proof before drawing conclusions, and the precautionary principle stated in article 3 of the United Nations Framework Convention on Climate Change (UNFCCC), which requires governments to act despite scientific uncertainties. A precautionary science would identify all scientifically plausible impacts, not only those impacts that can be identified with high levels of scientific certainty or impacts about which quantitative probability statements derived from empirical observations can be stated.  If the precautionary principle is to be taken seriously then decision-makers should be informed about all potentially dangerous impacts even if quantitative probability statements about these impacts can’t be derived from observations of how a physical system works.  Since the UNFCCC expressly adopted the precautionary principle, a strong case can be made that IPCC should identify all scientifically plausible impacts. If it were to do this, IPCC should, of course, be clear that some impacts are less certain than others.

Identifying all scientifically plausible climate impacts is also required as a matter of ethics once there is a reasonable basis for concluding that certain human behavior is dangerous to others.

Who should have the burden of proof and how much proof should be required to satisfy the burden of proof in the face of scientific uncertainty about dangerous behavior are fundamentally ethical questions, not ‘value-neutral’ scientific matters, yet scientists are rarely trained in ethical reasoning and very rarely spot the ethical issues raised by decisions about dangerous human behavior that must be made in the face of scientific uncertainty.  Given that the potential harms from climate change include an existential threat to life on Earth, as a matter of ethics, those who claim that scientific uncertainty is justification for not taking strong action to reduce the threat of climate change should have the burden of proof of demonstrating with very high levels of proof that ghg emissions levels are safe.

Ethics would require higher levels of proof of those who are engaged in dangerous behavior to prove their behavior is safe in proportion to how potentially dangerous the behavior is especially for harms to others who have not consented to be harmed and for behaviors that become more dangerous the longer one waits to reduce the uncertainty. Given that climate change actually threatens life on Earth including billions of people who have not consented to put at risk, and given that waiting to reduce ghg emissions makes the problem more threatening, ethics would shift the burden of proof to those who are most responsible for raising ghg emissions to prove with very high levels of proof that human emissions of ghg are safe even if there is some uncertainty about the amount of warming that different levels of ghg emissions will cause. For this reason, the problem created by IPCC’s underestimation of climate change impacts may not be exclusively the fault of IPCC.  The problem may also be the fault of policymakers who fail to respond to the enormous potential harms entailed by human-induced warming by demanding that opponents of climate change policies shoulder the burden of proof by demonstrating with high levels of proof that ghg emissions will not cause serious harms.

This website includes many articles which explain why policymakers and citizens have a strong duty to reduce ghg emissions in the face of some scientific uncertainty about climate change impacts. See, for example:

1. The Ethical Duty to Reduce Greenhouse Gas Emissions the face of Scientific Uncertainty;

2. On Confusing Two Roles of Science and Their Relation to Ethics.

Policymakers have a vital need for scientists to explain all scientifically plausible harms that may result from human activities even if the magnitude and creation of potential harms are uncertain. In fulfilling these responsibilities, scientists may not ignore potential harms because they are unable to determine probabilities about the likelihood of their occurrence based on empirical observations. Yet because scientists often follow the epistemic norms of their science when engaged in scientific research which usually require adequate levels of proof before making causal claims, policymakers need to be clear when interacting with scientists that their policymaking responsibilities require that they, the policymakers, protect citizens from all plausible harms.  Therefore policymakers need scientists to identify all scientifically plausible harms. Because IPCC’s mission is to synthesize the existing peer-reviewed climate science, which very likely does not include scientific conclusions about plausible harms partly based on speculation, IPCC cannot fulfill the role of science that policymakers need when policymakers are seeking to protect citizens from all plausible harms, namely to inform humanity about all plausible climate change impacts. Thus, there is a basic conflict between IPCC’s mission of synthesizing peer-reviewed climate change science and providing policy-makers with information about all scientifically plausible climate change impacts.

This need of policy-makers to understand all plausible harms creates an enormous challenge for mainstream scientific institutions which usually rely on peer-review in which scientists normally review scientific claims by comparing claims to empirically tested observations which are the ground of the scientific enterprise. Yet, as Hans Jonas explained in The Imperative of Responsibility, In Search of an Ethics in a Technological Age, the power of modern technology to create catastrophic harms such as those harms now foreseeable from human-induced climate change, ethics requires that policy-makers approach these matters with a “heuristics of fear,” replacing the former “projections of hope” that traditionally guided policy (Jonas, 1984, p.x), Yet, mainstream science is often uncomfortable with conclusions not grounded in scientific observations. If this is so, ethics requires that IPCC’s mandate be amended to synthesize scientifically plausible conclusions about climate change outcomes.

B. The Ethical Bankruptcy of Arguments Which Demand High Levels of Certainty Before Taking Action to Reduce the Threat of Climate Change

The WLB report also claims that quoting a 2014 article in the Guardian increasing evidence ‘that policy summaries on climate impacts and mitigation by the IPCC were significantly “diluted under political pressure from some of the world’s biggest greenhouse gas emitters, including Saudi Arabia, China, Brazil, and the United States.” (WLB. p. 34)

The WLB report consistently argues that the remedy to IPCC’s tendency to underestimate climate impacts is to allow or require more speculation about uncertain but plausible climate impacts. However, those governments that seek to restrict discussion of all impacts to those that have been proven with relatively high levels of proof would likely argue that speculation could lead to an overstatement of climate impacts. Yet following a precautionary science that identifies all plausible climate change impacts including those that have been based on speculation can guard against overstating the seriousness of climate impacts by allowing those who claim that the plausible impacts have been overstated to provide reasons for their claims so that policymakers can judge whether some of the plausible but not fully proven impacts are arbitrary or without any plausible scientific support. This would place the burden of proving harm appropriately, as a matter of ethics, on the parties that seek to justify continuing dangerous behavior.

Nations which have demanded high levels of proof before reducing their contributions to climate change have failed to abide by their ethical and legal duties to not harm others and not abide by the ” precautionary principle” which they agreed to UNFCCC and the Paris Agreement.

C. Ethical Problems with Economics Arguments Against Climate Change Policies

The WLB report also claims that some governments have advocated policies that would not be sufficient to achieve the goals of the UNFCCC to prevent dangerous climate change because they thought policies that achieve safer levels of warming ‘were too economically disruptive.” (WLB, p. 39). This report claims that in so doing,” policymakers are complicit today in destroying the very conditions which make life possible.” (WLB, p. 39) Further, the WLB report claims “There is no greater crime against humanity.” (WLB, p. 39)

An ethical analysis of those nations that refuse to adopt policies that may be necessary to prevent catastrophic harm on the basis of their economic interest would also strongly condemn these nations as deeply morally bankrupt.


Anthony et. al., 2018, 21st-Century Modeled Permafrost Carbon Emissions Accelerated by Abrupt Thaw Beneath Lakes, Nature Communications ,

Breakthrough Institute, 2018, What Lies Beneath, On the Understatement of Existential Climate Risk,

Jonas, H, 1984, The Imperative of Responsibility; In Search of an Ethics for a Technological Age, University of Chicago Press

Steffen, 2018, Trajectories in the Earth System in the Anthropocene, Proceedings of the National Academy of Sciences,



Donald A. Brown

Scholar in Residence and Professor

Widener University Commonwealth Law School

Harrisburg, Pa.



  1. It makes one sputter with frustration. Humanity has achieved so very much with our technology with a beginning understanding of the true deep roots of biology, our electronics, ability to talk with anyone anywhere in the world, our understanding of physics and on and on. And these venal, stupid, self serving politicians are going to wreck it all for a handful of silver and a feeling of power. Any reasonably bright year 12 student could tell them exactly what we have to be doing to avoid this catastrophe and they refuse to listen. The key to the whole sorry mess is the old adage WHO PAYS THE PIPER CALLS THE TUNE. As long as vested interests finance our politicians, the politicians will do their bidding and we will pay the price. We think we are getting some sort of a bargain by having someone else finance election campaigns instead of the money coming from our taxes but the cost to us is orders of magnitude larger than if we footed the bill. Only if we finance politicians will there be any chance of making headway on the many solutions we must put in place to survive as a society and perhaps as a species on into the future.


  2. Big topic, well presented, if a bit repetitive (I’m sure necessary) and a few typos.. but I agree with the need to consider all plausible scenarios. Broad dissemination of all knowledge gained in pursuit of greater understanding is crucial to good decision making and absolutely needs to be presented as many times as it takes to be included in our solutions!
    The Politicians we have are of course just a reflection of the level of responsibility of the society that is willing to vote them in, regardless of the role of media. Look deeper, most of us must at least have suspected there could be issues but voted them in anyway. So perhaps a more central focus of the ‘why’ about our general cultural intransigence could look to the time proven inertia encountered whenever we try to change behavioural wiring in the human brain with anything that threatens an established comfort i.e. we generally don’t want to do anything before we have to – just look at kids.
    Hence the very real problem of instigating a positive change as identified, is getting educated 1st world people to change before they are personally disturbed enough by the issue at hand, or be patient and wait until they are disturbed – easier said than done.
    You take those same political or public resource ‘leaders’ and place them into a situation which impacts/challenges the survival of their ‘world’ (family, status, wealth) and you may be surprised at how quickly they act to protect their interests in the name of humanity or whatever to correct the situation. It’s just not real to them, and given the same restricted ‘world’ any of us may act just the same, in fact most of us currently enjoying 1st world comforts are.. just with less resources to play with.
    Of course as with any catastrophe you see coming, the wealthier are in a much better position to adapt their living circumstances than the poor. So there is certainly an ethical and humanitarian question to be faced by those who chose to do nothing; but like it or not this question is already being answered through inaction.
    Whatever it takes, global cooperation is the only thing that could move humanity above the current fear based reaction toward insular politics and protectionism. Unfortunately it is likely too little too late for a large portion of our world’s population and perhaps those in big cities are more vulnerable than they think. Yep, this is already happening folks, shouldn’t be surprised after over fifty years of inaction.
    That’s not to say we can’t help our own future as a species … my sense is that if the experiment to shrink collective wit and knowledge doesn’t work then expanding perspective is the only way forward. Science is good but to assist it beyond any limitations of unwarranted conservatism, what about a bit of ying/yang in the mix, the pebble in the pond etc. If you understand that modern physics is now revealing that underlying what we’ve come to accept as reality is in fact a multidimensional universe. What does that mean? How could more than three dimensions relate to our experience in life? Answer: fundamental perceptions of time and space are not as we accept – fact. There may well be other dimensions that don’t have any space in them, where knowledge of other humans and their experience is available at all points in time, for anything willing to know to tap into? Is our experience of life not then just simply the sum of our physical form. This clearly raises a lot of questions about our nature and is really offensive to many, so not everyone is ready for this notion, real or not. whatever!, life goes on and let every person continue to steer their life’s experience as they choose!
    Perhaps the impending climate crisis will be coincident with a major change in human consciousness/culture as well? I vote for that, it is way past due!
    The question now is; if so many people currently get along in the belief that we are no more than a genetically evolved brain controlling a physical body, and yet one or more distributed (more real) dimensions exist and is accessible by anyone, then at what point during this rapid decline towards obliteration from the global stage will we as a conscious collective lifeform move to / accept such a higher level of functioning? One perhaps where we might realise we don’t really have to wipe each other or life out as we know it to get along? Hmmmm…just suggesting that there is always another way through here! Don’t forget if you love anyone you could love anyone.
    Back to the context of our current crisis, if we have the courage to experience enough of the cries of our fellow humans, THEN we will act? and without having to hold hands! Who are the visionaries out there? You’ve got to know what question to ask, before you have a hope of finding the answer.
    My sense is that the internet has already enabled and stimulated the distribution and pollination of unfettered knowledge and ideas across every world culture. If at any time in history we were capable of letting go racial and religious dogma and coming together somehow, it is with today’s technologies.
    Think big, we really all do need to network the experience based wisdom gained by every corner of humanity to have a chance of making it. I’m in!


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