Carbon Order

climate context

Figure 1 Total anthropogenic GhG emissions by gases 1970-2010


Figure 1: Total anthropogenic GHG emissions by gases 1970-2010

SOURCE: Wg3 AR5 Summary for Policy Makers, IPCC March 2014


Figure 2: Annual athropogenic CO2 emissions. Emissions of CO2 alone in the Representative Concentration Pathways (RCPs) (lines) and the associated scenario categories used in the WGIII (coloured areas show 5 to 95% range.  The WGIII scenario categories summarise the wide range of emission scenarios published in the scientific  literature and are defined on the basis of CO2 eq concentration lvels (in pm) in 2100.

SOURCE: Wg3 AR5 Summary for Policy Makers, IPCC March 2014

Figure 3: Projected world population, in millions


Figure 3: Projected world population, in millions

SOURCE: The Guardian 29.07.15 (quoting from UN Department of Economic and Social Affairs)

Figure 4: Fastest-growing populations


Figure 4: Fastest-growing populations

SOURCE: The Guardian 29.07.15 (quoting from UN Department of Economic and Social Affairs)

Figure 5: World GDP Volumes


Figure 5:  World GDP Volumes

SOURCE: Baseline 2013 edition. Based on OECD Economic Outlook, Conference Board and IMF World Economic Outlook; 2015 edition OECD Envionment Directorate GDP projections

Figure 6 GDP volumes in OECD, the emerging economies and the rest of the world (2010 =100)


Figure 6: GDP volumes in OECD, the emerging economies and the rest of the world (2010 =100)

SOURCE: Baseline 2013 edition. Based on OECD Economic Outlook, Conference Board and IMF World Economic Outlook; 2015 edition OECD Envionment Directorate GDP projections

Figure 7:  World economic output over 50 years, 1984-2034 (2005 PPP dollars)


Figure 7:  World economic output over 50 years, 1984-2034 (2005 PPP dollars)

SOURCE: The emerging middle class in developing countries, Homi Kharas, OECD Development Centre, January 2010

Figure 8: Warming versus cumulative CO2 emissons.  Global mean surface temperature increase at the time global CO2 emissions reach a given net cumulative total, plotted as a function of that total from various lines of evidence.  Coloured plume shows the spread of past and future projections from a hierarchy of climate-carbon cycle models driven by historical emissions and the four RCPs over all times out to 2100, and fades with the decreasing number of available models.  Ellipses show total anthropogenic warming in 2100 versus cumulative CO2 emissions from 1870 to 2100 from a simple climate model (median climate response) under the scenario categories used in WGIII.  The width of the ellipses in terms of temperature is caused by the impact of different scenarios for non-CO2 climate drivers.  The filled black ellipse shows observed emissions to 2005 and observed temperatures in the decade 2000-2009 with associated uncertainties.

Figure 8: Warming versus cumulative CO2 emissions

SOURCE: Wg3 AR5 Summary for Policy Makers, IPCC March 2014

Figure 9:  Global average surface temperature change (relative to 1986-2005).

Figure 9:  Global average surface temperature change (relative to 1986-2005).

SOURCE: Wg3 AR5 Summary for Policy Makers, IPCC March 2014

Figure 10:  GHG emission pathways 2000-2100:  All AR5 scenarios

Figure 10:  GHG emission pathways 2000-2100:  All AR5 scenarios

SOURCE: Wg3 AR5 Summary for Policy Makers, IPCC March 2014

Figure 11: On the road to 2 degrees centigrade:  Policy pillars of the Bridge Scenario

Figure 11: On the road to 2 degrees centigrade:  Policy pillars of the Bridge Scenario

SOURCE: IEA World Energy Outlook Special Report on Climate and Energy June 2015

Figure 12: Global energy related GHG emissions reduction by policy measure in the Bridge Scenario relative to the INDC scenario

Figure 12: Global energy related GHG emissions reduction by policy measure in the Bridge Scenario relative to the INDC scenario

SOURCE: IEA World Energy Outlook Special Report on Climate and Energy June 2015

Figure 13:  Energy-related CO2 emission levels and GDP by selected region in the Bridge Scenario

Figure 13: Energy-related CO2 emissions levels and GDP by selected region in the Bridge Scenario

SOURCE: IEA World Energy Outlook Special Report on Climate and Energy June 2015

Figure 14:  Energy-related GHG emissions reduction in CO2 eq terms by policy measure and region in the Bridge Scenario relative to the INDC Scenario, 2030

Figure 14:  Energy-related GHG emissions reduction in CO2 eq terms by policy measure and region in the Bridge Scenario relative to the INDC Scenario, 2030

SOURCE: IEA World Energy Outlook Special Report on Climate and Energy June 2015

Figure 15:  Average annual GDP growth by scenario by selected region, 2013-2030

Figure 15:  Average annual GDP growth by scenario by selected region, 2013-2030

SOURCE: IEA World Energy Outlook Special Report on Climate and Energy June 2015

Figure 16: Global cumulative CO2 emissions reductions in the 450 scenario relative to the Bridge Scenario by measure, 2015-2040

Figure 16: Global cumulative CO2 emissions reductions in the 450 scenario relative to the Bridge Scenario by measure, 2015-2040

SOURCE: IEA World Energy Outlook Special Report on Climate and Energy June 2015

Figure 17:  CO2 captured in the 450 scenario by sector and region


Figure 17:  COcaptured in the 450 scenario by sector and region

SOURCE: IEA World Energy Outlook Special Report on Climate and Energy June 2015

Figure 18: Global energy-related CO2 emissions by scenario


Figure 18: Global energy-related COemissions by scenario

SOURCE: IEA World Energy Outlook Special Report on Climate and Energy June 2015

Figure 19: Global committed CO2 emissions through 2040 from new power plants


Figure 19: Global committed CO2 emissions through 2040 from new power plants

SOURCE: IEA World Energy Outlook Special Report on Climate and Energy June 2015

Figure 20:  Global emissions from power plants, existing and under construction


Figure 20:  Global emissions from power plants, existing and under construction

SOURCE: IEA World Energy Outlook Special Report on Climate and Energy June 2015

Figure 21: Global energy subsidies 2011-2015

Figure 21: Global energy subsidies 2011-2015

Figure 22: Environment gain from removing energy subsidies 2013


Figure 22: Environment gain from removing energy subsidies 2013

Figure 23:  Welfare gain from removing energy subsidies 2013

Figure 23:  Welfare gain from removing energy subsidies 2013

Figure 24:  Economic value of global fossil fuel consumption subsidies by region


Figure 24:  Economic value of global fossil fuel consumption subsidies by region

 Figure 25: Global GHG emissions savings from fossil-fuel subsidy reform in the Bridge Scenario relative to the INDC Scenario


Figure 25: Global GHG emissions savings from fossil-fuel subsidy reform in the Bridge Scenario relative to the INDC Scenario

Figure 26: source 'Get used to low economic growth - it's here to stay' Jorgen Randers, The Guardian 5th February 2014


Figure 26: 'Get used to low economic growth - it's here to stay' Jorgen Randers, The Guardian 5th February 2014

Figure 27:  'Get used to low economic growth - it's here to stay' Jorgen Randers, The Guardian 5th February 2014


Figure 27: 'Get used to low economic growth - it's here to stay' Jorgen Randers, The Guardian 5th February 2014

Figure 28:  World model from Limits to Growth:  A Thirty Year Update, 2005


Figure 28:  World model from Limits to Growth:  A Thirty Year Update, 2005

Figure 29: 2C Carbon budget and probability of success


Figure 29: 2oC Carbon budget and probability of success

Figure 30: IPCC and carbon tracker Co2 budgets from 2012-2100 against fossil fuel reserves


Figure 30: IPCC and carbon tracker CO2 budgets from 2012-2100 against fossil fuel reserves

Figure 31:

Figure 31

Figure 32: Carbon Countdown - How many years of current emissions would use up the IPCC's carbon budgets for different levels of warming?

Figure 32: Carbon Countdown - How many years of current emissions would use up the IPCC's carbon budgets for different levels of warming?

Figures 35 & 36

Figures 33 & 34:

Figure 37:


Figure 35



Figure 38

Figure 36




Figure 37

Figure 37: Modelled temperature change in 2055-2060 with 10-year doubling time for freshwater



Figure 38a



Figure 38 b


Figures 38 a and b: Greenland and Antarctic ice mass change based on Velicongna et al (2014) gravity data green (dashed) curve for Greenland is freshwater discharge used in our climate model. Blue curves are gravity data for Greenland (and Antarctica) only; small Arctic ice caps and ice shelf melt are additional.  Monthly data points are the difference between the ice sheet mass at the point plotted and the mass in the same month one year earlier.  The 12-month running mean is plotted at mid-point of the year.

SOURCE: Predictions Implicit in 'Ice Melt' Paper and Global Implications, James Hansen and Makiko Sato, Climate Science, Awareness and Solutions, Earth Institute 21.09.15

Figure 43: Example cascade of tipping points (with/without interactions between them)


Figure 39: Example cascade of tipping points (with/without interactions between them)

Figure 44: Early warning of climate tipping points

Figure 40: Early warning of climate tipping points

Figure 41

Figure 41:  Preventing climate change requires reducing CO2 emissions today

Figure 45: Decay of instantaneous (pulse) injection and extraction of atmospheric CO2 (b) atmospheric CO2 if fossil fuel emissions terminated at end of 2011, 2030, 2050


Figure 42: Decay of instantaneous (pulse) injection and extraction of atmospheric CO2 (b) atmospheric CO2 if fossil fuel emissions terminated at end of 2011, 2030, 2050



Figure 43


Figure 43: A reconstruction of Earth's global mean temperature over the last 784,000 years, on the left of the graph, followed by a projection to 2100 based on new calculations of the climate's sensitivity to greenhouse gases (Friedrich, et al (2016))

INTRODUCTION

The ultimate potential for DAC depends on evolving climate policy in defining need, opportunity and timing. That substantial DAC investment will be necessary is beyond question – the issue is how much, for which applications, and at what point will these become not simply desirable but inevitable? The answer will, to a large extent depend on the degree to which climate policy falls short of what is necessary to achieve its objective: strong policies, including a price on carbon, will accelerate  DAC deployment for ongoing emissions reduction and reduce the required scale for atmospheric reduction. Conversely, weak policies will impede mitigation, resulting in higher cumulative emissions, and increasing need and urgency for greater atmospheric reduction – but at a later stage.

For this reason, it is worth considering the efficacy of climate policies to date and the extent to which existing deficiencies will necessitate stronger remedial action.

 

POLICY BACKGROUND

Despite 25 years of climate negotiations, underpinned by an extraordinarily impressive body of scientific evidence, there is a growing recognition that the world is losing the climate race: so tortuous and protracted is the process of translating the science into policy that the lagtimes involved are longer even than those of climate change itself. In consequence, its manifestations and impacts have been accelerating considerably faster than the world’s apparent willingness to mitigate them.

 

EMISSIONS GROWTH

Annual GHG emissions grew on average 2.2% a year from 2000 to 2010 compared to 0.4% a year from 1970 to 2000. Total anthropogenic emissions were the highest in recorded history from 2000 to 2010, with the global economic crisis only temporarily reducing emissions (figures 1 & 2).  Over the same period, the twin drivers of rising emissions – economic and population growth – outpaced emissions-reduction from improvements in energy intensity, reversing the long-standing trend of gradual decarbonisation of the world’s energy supply (1) (figures 3-7).  This changed in 2014. Energy-related CO2 emissions, representing 2/3 of the world’s greenhouse gases, plateaued despite 3% growth in the global economy – an outcome unprecedented in the last 40 years outside economic crisis, and potentially indicating a long presaged decoupling of economic output and energy use. The energy intensity of the global economy dropped 2.3%, more than double the average rate of decrease over the last decade (2).  Energy-related emissions continued to plateau in 2015, with a 0.6% increase, and again in 2016 (with an estimated rise of 0.2%) (2a).


COP 21

Negotiations on global climate policy are conducted through the 195-nation members of the UNFCCC. In what has been hailed as a landmark development, agreement was reached at the annual COP (Conference of the Parties) meeting in Paris in December 2015. In the broadest terms, this was intended to build on understandings reached in particular over the last five years, most importantly in the 2009 Copenhagen Accord which commits ‘to hold the increase in global temperature to 2 oC and to take action to meet this objective consistent with the science and on the basis of equity’, and at Durban in 2011 where it was agreed ‘to launch a new platform of negotiations under the Convention to deliver a new and universal greenhouse gas reduction protocol, legal instrument or other outcome with legal force by 2015 for the period beyond 2020’. The conference further agreed ‘to scope out and then conduct a fresh global review of the emerging climate challenge, based on the best available science and data, first to ensure whether a maximum 2oC rise is enough or whether an even lower 1.5 oC degree limit is required, and then to ensure that collective action is adequate to prevent the average global temperature rising beyond the agreed limit’ (3).


However, whilst it was agreed ‘to pursue efforts to limit the temperature increase to 1.5oC, the NDCs (Nationally Determined Contributions) at the heart of the agreement will, even if fully delivered on, result in a 670 ppm CO2 and a rise of 3.5oC (3a) — over double the desired limit now recognised as the danger zone for ‘serious tipping points in the world’s climate’ (3b). This reduces to 3.2oC (630 ppm) if pledged reductions continue after 2030; to 3.0oC (600 ppm) if China includes other GHGs and reduces emissions by 2%/year after peaking in 2030; to 2.6oC (555 ppm) if other developing countries peak by 2035; and to 1.8oC (450 ppm) if all countries peak by 2030. Only if developed countries make deeper cuts, and all countries peak by 2025 and reduce steadily will the temperature increase be limited to 1.5oC (425 ppm) (3c).


Paris 21 is now seen as a milestone in a continuing process from which regular five-yearly reviews and progressive tightening of emissions targets will bridge the inevitable emissions gap.

 

INDC EMISSIONS IMPACT

Addressing this emerging reality, the IEA World Energy Outlook Special Report ‘Energy and Climate Change’ released in June 2015 (5), notes that as at May 14th, ‘with INDCs submitted so far [representing 34% of energy-related global CO2 emissions], and  the planned energy policies in countries which have yet to submit, the world’s estimated remaining carbon budget consistent with a 50% chance of keeping the rise in temperature below 2oC is consumed by around 2040 — eight months later than is projected in the absence of INDCs'.  Whilst IEA projections show a weakening link between economic output and energy-related GHG emissions, economic growth of 88% by 2030 ensures that emissions still increase 8% over the same period. There is no emissions peak by 2030.

Absent stronger commitments, the current NDC path would be consistent with an average temperature increase of 3.5oC by 2100. This equates to an atmospheric CO2e level in excess of 650ppm, and a trajectory in line with RCP 6.0 on the IPCC pathways (6) (see figures 8-10).  

 

IEA PROPOSALS

The IEA sees the need for 'national pledges submitted for COP 21 to form the basis of a virtuous circle of rising ambition’, and identifies ‘four pillars’ that could support this (1) Peak in emissions (2) Five-year revision (3) Lock in the vision (4) Track the transition) (see side panel and figures 11-15 for further detail).

 

450 SCENARIO

In addition to the Bridging Strategy, the IEA also suggests a more ambitious '450 Scenario'. This adopts a specified outcome — achievement of the necessary action in the energy sector to ensure a 50% chance of limiting warming to 2oC — and illustrates the steps by which this may be ensured. These include (i) remedy of what it describes as ‘one of the main deficiencies of current climate policy’ namely introduction of a price on CO2 in the power generation and industry sectors in OECD countries and other major economies (ii) fossil fuel subsidies are removed by 2040 in all regions except the Middle East (iii) CO2 pricing is extended to the transportation sector everywhere,  and (iv) further tightening of energy performance standards in the transport and buildings sectors. In this scenario the concentration of greenhouse gases peaks above 450ppm by the middle of the century and stabilises after 2100 at around 450ppm (see figures 16-20 for scenario comparisons)

The key findings of the IEA Special Report were endorsed by Ministers at its biennial meeting on 17-18th November 2015.

 

CARBON PRICING: THE MISSING INGREDIENT

Ends without the means remain merely aspirations. For decades, the potential for decarbonisation has been constrained by a fiscal environment diametrically at odds with this objective. The IMF has calculated that the cost of global subsidies and externalities for fossil fuels in 2015 at $5.3 trillion — equivalent to $165 per tonne of CO2 (7) (figures 21-25).  The IEA has recognised that without addressing this glaring disconnect, NDC commitments, let alone more ambitious targets necessary to avoid breaching the 2oC ceiling, will remain critically disadvantaged.


Encouragingly, there is progress on this issue.  Momentum for global carbon pricing is building. In 2014, the World Bank stated that ‘pricing carbon is inevitable if we are to produce a package of effective and cost-efficient policies to support scaled up mitigation (8). The World Bank’s 2015 publication, State and Trends of Carbon Pricing, reports that currently about 40 national jurisdictions and over 20 cities, states and regions, representing almost a quarter of global greenhouse gas (GHG) emissions are putting a price on carbon, and that the number of carbon pricing instruments has almost doubled since 2012 (8a). Globally, at least 150 companies use an internal carbon price. Nearly 350 global institutional investors, managing $24 trillion in assets, have called on government leaders to establish a meaningful price on carbon and phase out subsidies for fossil fuels (8a).  It concluded that ‘pricing carbon is inevitable if we are to produce a package of effective and cost-efficient policies to support scaled up mitigation’.(8)

 

IEA SCENARIO

Projections in all of the IEA scenarios are sensitive to underlying assumptions concerning key economic and demographic factors. World GDP is assumed to grow at an average annual rate of 3.5% from 2013 to 2040, increasing the global economy two and a half times over this period. World population – another important driver in the demand for energy services in all scenarios – is expected to grow by 0.9% a year on average to 9.0 billion in 2040. Both of these parameters are subject to a wide range of interpretations.  Other estimates for economic growth range from a bullish 4.7% per annum (9) to ‘permanent recession’ for OECD countries (10) and even depression (11) (figures 26-28). Population growth estimates are similarly diverse, spanning 8.1bn (12)  to 10.9bn (13) by 2050, with the latest UN projections recently increased to 9.7bn (14). This revision alone represents a 37% upward adjustment of population growth of the 1.9m over this period assumed in the IEA scenarios.


While assumptions on economic and population growth are the same, carbon prices vary across the three scenarios, reflecting different levels of policy intervention. In the 450 scenario, it is assumed that carbon pricing is adopted in all OECD and some major non-OECD markets, reaching $140/tonne CO2 by 2040.

 

GLOBAL CLIMATE POLICY: HOW ROBUST ARE THE ASSUMPTIONS?

Beyond the extent to which national and global policy commitments, or indeed the more ambitious IEA Bridging and 450 Scenarios, are implemented and realised lie more fundamental questions as to whether or not these policy objectives will realistically succeed in averting dangerous climate change. These are examined in the sections following.

 

CARBON BUDGETS AND RISK PROBABILITIES: IS 50:50 AN ACCEPTABLE RISK LEVEL FOR DANGEROUS CLIMATE CHANGE?

The latest IPCC AR5 report defines the global carbon budget as the amount of carbon which humanity can emit and still have a reasonable prospect of staying below the 2oC threshold (15). For a 66% probability, this is 1000 bn tonnes (GtC). Including allowance for other greenhouse gases reduces this to about 800 GtC (16 ibid). By 2011, human activity had already added about 531 GtC, leaving 269 GtC ‘headroom’ (NOTE: this is equivalent to 986 GtCO2). Increasing the budget reduces the odds of limiting the rise to 2oC: at 840 GtC, these fall to 50%; at 880 bn tonnes, they halve to 33%. Conversely, the adoption of more prudent probability levels reduces the budget available – for a risk-averse strategy (<10%), the budget is zero. A 93% probability implies stabilization of CO2 eq concentrations at, or below 350ppm (17) (see figures 29-32).


Risk-definition is critical to climate policy realism. The Copenhagen Accord, Cancun Agreements and EU climate policy adopt resolutions in language that could reasonably be interpreted as commitment to a low, or very low probability of exceeding the 2oC limit (say 1-10%), consistent with the approach taken in catastrophic risk management. Climate change contains many possibilities for catastrophic failure. Yet the IPCC only includes carbon budgets for 33%, 50% and 66% probabilities of keeping to 2oC; higher probabilities are not considered. The most stringent – at 66% –  has a one in three chance of failure, and a range of outcomes of 1.3oC to 3.1oC (within 95% confidence limits) (18, ibid).


EQUITABILITY: EMISSIONS BUDGETS ANNEX 1 VS NON-ANNEX 1

Setting aside for the time being the questionable appropriateness of risk exposure at odds no better than evens, the world will exceed its carbon budget in less than 20 years. For Annex 1 (OECD) countries, the situation is far worse. The Copenhagen Accord makes explicit reference to the need to develop climate policy between Annex and non-Annex 1 countries ‘on the basis of equity’.  Studies published in Philosophical Transactions of the Royal Society (Anderson and Bows 2008, and 2011) (19, 20) show that, even adopting extremely challenging assumptions for non-Annex 1 emissions growth – peak emissions in year 2025 and 7% per annum reductions thereafter – the available budget for Annex 1 nations, calculated by deducting the non-Annex 1 from the global budget, necessitates emissions-reduction of 8-10% per annum for Annex 1 countries and, even then, only with a 50% probability of remaining within the 2oC limit (21) see note in side panel for update.  


The prospects for developing countries achieving peak year emissions by 2025 are, to say the least, unlikely. China, with a population of 1.4bn and the world’s largest carbon emitter, is approaching EU levels in emissions per capita despite income per capita still being around 5% of OECD levels (22). India, with a population of 1.6bn in 2028 (23) currently ranks 4th in the world, but is due to overtake the EU in total emissions by 2019. Its per capita level of 1.9 tonnes/year (24, op. cit.) is low by international standards, but with per capita income at 2% of OECD levels (25, op. cit.), this merely indicates the enormous potential for growth. It is inconceivable that peak emissions will occur before 2030 in what will by then be the world’s most populous country.

Virtually every 2oC emission scenario developed by integrated assessment modellers assumes that reductions in absolute emissions greater than 3-4% a year are incompatible with economic growth. For an economy growing at 2% a year, a 4% per annum reduction in emissions requires a 6% per annum reduction in carbon intensity. In fact, annual reductions greater than 1% have ‘been associated only with economic recession or upheaval’ (26, op.cit.).

 

IS 2oC A SAFE LIMIT?

The foregoing would be less disconcerting if the 2oC limit itself were scientifically unchallengeable as the adopted boundary for safety. Unfortunately, for multiple reasons, this is not the case. Earth’s climate is a dissipative, highly non-linear system with many instabilities driven by dynamic positive and negative feedback processes governing transitions between multiple stable states. Such transitions have sensitive thresholds which can be triggered by climate forcing, notably anthropogenic GHGs. Scientific evidence, particularly from paleoclimate data, indicates that the current level of climate forcing is such that Earth is ‘poised to experience strong amplifying polar feedbacks in response to moderate global warming’ (27). Indeed, a raft of peer-reviewed scientific evidence indicates that this has already begun.


The 2oC target maximum has come under increasing fire from climate scientists concerned that it is not supported by the science.  It rests on our understanding over a decade ago when the impacts of a 2oC rise were considered to represent the boundary between acceptable and dangerous climate change.  Since then, these impacts have been revised in scale and intensity such that 2oC now more accurately represents the boundary between dangerous and extremely dangerous climate change.


The ‘burning embers’ diagram of the third IPCC report in 2001 was revised and updated in 2009 (28) (figures 33 & 34), and has been updated again in the 2014 IPCC AR5 (29) (figure 35) report to include the colour purple to indicate worsening climate risks.  It provides five ‘reasons for concern’.

  1. Risk to unique and threatened systems
  2. Risk of extreme weather events
  3. Distribution of impacts
  4. Aggregate (total economic and ecological) impacts; and
  5. Risk of large-scale discontinuities (abrupt transitions, ‘tipping points’).


A growing body of evidence now suggests that the threshold of safety has been crossed in all five critical measures, substantiating the case for lowering of the benchmark to around a 1.0oC increase in global average temperatures.  As we are now at the threshold of the 1oC benchmark, it is too late, politically and practically, for this to be adopted as a guardrail; however, acceptance of 1.5oC as the new 2oC confirms a much lower boundary for the danger zone.


CLIMATE SENSITIVITY:

Arguably, the key parameter in climate modelling is climate sensitivity, defined as the change in global mean surface temperature at equilibrium that is caused by a doubling in atmospheric CO2 concentration.

Definitions of climate sensitivity take several forms differing in the types of climate feedback they include and, therefore, in the projected climate response.

  • Fast feedback sensitivity specifically includes changes in atmospheric lapse rate, water vapour, clouds, sea ice, snow cover and natural aerosols, with feedbacks occurring on timescales of decades or less.
  • Earth system sensitivity (ESS) also includes ice sheet and vegetation albedo feedbacks, and
  • Earth system sensitivity plus climate-greenhouse gas feedbacks include all of the system responses

The long accepted paradigm, including in IPCC assessment reports, defines climate sensitivity only in terms of fast feedback climate response. Earth system feedbacks are either not considered or are part of the forcing. Further, no attempt is made to discriminate between changes in atmospheric GHG concentrations due to anthropogenic emissions and those resulting from changes in natural carbon sinks, since the forcing is regarded as the total atmospheric GHG change. Thus – reflecting uncertainties in climate system behaviour giving rise to a range of possible temperature responses – the IPCC AR5 determined climate sensitivity to be between 1.5oC and 4.5oC, and very unlikely greater than 6oC (30).


There is, however, a mounting body of argument that the definition of climate sensitivity should also include slower feedbacks: not only do these occur over a timeframe prior to equilibrium and, therefore should be included as part of the ‘at equilibrium climate response’, but there is now considerable evidence that such feedbacks are already occurring or may do so much faster than hitherto anticipated.


Calls for redefinition of climate sensitivity are growing. A July 2013 peer-reviewed paper (31) co-authored by twelve leading climate scientists argues that climate sensitivity should include all three feedbacks, noting that this would increase the temperature impact of doubled CO2 from 3oC (representing the average of 1.5-4.5oC) to 4-6oC if ice sheet/vegetation albedo is included and higher still with climate-GHG feedbacks. Their reasoning relies on evidence in the paleoclimate record of sea-level changes of several metres per century (32)), as well as observation and modeling studies showing that vegetation response can occur on decadal-to-centuries timescales. This is consistent with numerous earlier studies. Hansen et al (2008) (33-36) estimated Earth system sensitivity, including ice sheet and vegetative feedbacks, of about 6oC for doubled CO2. Lunt et al. (2010) estimated ESS at 4-4.5oC.


About 57% of anthropogenic CO2 is taken up by the ocean and terrestrial biosphere, with 43% remaining as the ‘airborne fraction’ (37). Because this takes place within about a year, it is considered as part of the forcing, not as feedback. However, changes in the magnitude of these sinks due to climate change are a feedback. Both climate-carbon-cycle models (38) and ice core records (39) indicate that the ability of these sinks to sequester CO2 decreases with climate warming, signifying a positive CO2 climate feedback. The strength of this feedback varies between models, with projections for 2100 of 20-200ppm (40),  leading to additional warming of 0.1-1.5oC (on this note, it is disconcerting that from 2013-2016, atmospheric concentrations rose by a yearly average of nearly 3ppm, possibly indicating sink capacity limits) (41& 41a)).


Other factors cited by the authors include the impact of higher temperatures on net primary production, drought incidence, wildfires, climate-related pest incidence, and land-use changes from larger human populations. Oceanic impacts include reduced ‘buffering’ capacity through conversion of carbonate to bicarbonate, weakened thermohaline circulation, vertical mixing and effective atmospheric interface, and impaired biological carbon cycles.


Given that these slow amplifying feedbacks – including in particular ice-melt – are happening very much faster and earlier than previously anticipated, this redefinition of climate sensitivity is critical to (i) the framing of climate policy, and therefore to (ii) the prospects for avoiding accelerating climate change.


New research (41a) by an international team of climate scientists examining Earth's climate over nearly 800,000 years suggests that climate sensitivity may be substantially underestimated, because it is more sensitive to greenhouse gases when it is warmer.  The authors argue that, because we are currently in a warm, interglacial phase, future projections of warming should take account of this increased sensitivity to higher carbon dioxide levels which, under one scenario, could be in the range 4.78oC to 7.36oC by 2100 (see figure 43).


Another recent study (42b) reporting on a global survey of soil data over the last 20 years, provides further evidence of such amplifying feedback.  Unlike other surveys, this considered carbon losses from polar regions, where rising temperatures are stimulating the release of carbon through decomposition by microbes, which are normally less active in colder conditions.  The study estimates that an additional 55GtC (200 Gt CO2e) of emissions in the form of CO2 and methane would be released under a business-as-usual scenario.  This alone reduces by roughly half the 2oC carbon budget remaining for energy-related emissions to 2100, as calculated in the analysis by Professor Kevin Anderson, referred to in the right hand side column.

 

GLOBAL DIMMING:

The current CO2 level of 400 ppm is sufficient to cause global warming of 1.5oC.  Including all GHGs (equivalent today to 430ppm; uncertainty range 340-520ppm) increases this to 2.4°C (based on current fast-feedback conventions), but this is largely countered by short-lived aerosols in a phenomenon called global dimming, which could suppress temperatures by up to 1°C (43) (figure 36). Removal of these aerosols, now a priority for China and other heavily polluted countries (44), would raise temperatures by an estimated 0.25-0.5°C within a decade (45).  IPCC RCPs (Representative Concentration Pathways) allow for aerosol reduction through strengthened regulation associated with rising incomes, but do not provide for potentially very rapid pollution reduction in Asia in response to serious and  growing health and other consequences.

 

SLOW AMPLIFYING FEEDBACKS:

The exclusion of slow amplifying feedbacks is not limited to the definition of climate sensitivity, but extends also to most climate models.  The original rationale for this – that their impacts occur over centennial or millennial timescales and are not therefore relevant – is evidentially misplaced, as these are already manifest and accelerating, most particularly in polar regions where temperature change is amplified three or four times the global average.  This predictive failure remains, with models based on linear rather than non-linear dynamics, resulting in potentially catastrophic under-estimation of ice melt and sea level rise trajectories:

 

(I)    ARCTIC ICE MELT:

This is occurring at a far faster rate than projected by IPCC models which, although updated from 2007 predictions of ice-free summers by the end of the century (46), still envisage nearly ice-free summers (ie in September, when the sea ice is at its lowest point) as late as 2050 (under RCP 8.5; for RCP 4.5, this is delayed to 2080), (47) when more realistic model projections indicate an ice-free state potentially as early as 2020. (48) Such are the implications for amplifying feedback impacts – including, inter alia, albedo effects equivalent to 20 years of anthropogenic GHG emissions, or +0.5°C of warming (49) – that Arctic ice retreat is now regarded as a tipping point, potentially triggering irreversible melt in the Greenland Ice Sheet, as well as other regional and even planetary change, including possibly large-scale methane release (see below) (50)

(II)    GREENLAND ICE SHEET (GIS):

Whereas earlier studies estimated centuries to millennia for new climates to produce temperature increases deep in the GIS, recent research suggests that meltwater can accelerate this to decades. Satellite mapping of ice mass confirms exponentially accelerating loss rates with a short-run doubling time of as little as five years (51). A ten-year doubling time implies a contribution to sea level rise of five metres by 2090 (52).  And this is only for Greenland.

(iii)    ANTARCTIC ICE SHEET:

These are, if anything, less stable than the GIS with recent studies overturning earlier assumptions that they would remain so over centuries or millennia. Both the West Antarctic Ice Sheet (WAIS) and the East Antarctic Ice Sheet (EAIS) are melting far faster than model projections. Large parts of the WAIS rest on bedrock up to two kilometres below sea level and are susceptible to warm water ingress and, therefore, disintegration. Recent studies have described ice retreat in the Amundsen Sea area as ‘unstoppable’,  capable alone of adding a metre to sea levels, but also of potentially triggering the collapse of the entire WAIS, and a three to four metre rise. (53,54) Like the WAIS, the EAIS is also now considered more vulnerable to change than previously assumed, with recent studies confirming acute sensitivity to regional temperature variation (55). The latest ESA CryoSat satellite survey, in May 2014, confirms that all three areas, the Antarctic Peninsula, the WAIS and EIS are losing ice at twice the rate of the last survey in 2005-10, consistent with a five-year doubling time. (56,57)


A groundbreaking paper (58) released in July 2015, authored by Hansen and 16 other climate scientists, deepens our understanding of these non-linear processes by comparing (i) IPCC climate simulations, but with growing freshwater sources in the North Atlantic and Southern Oceans (ii) exhaustive multi-source late-Eemian paleoclimate evidence to elucidate key processes in the climate model (iii) modern data to show that these processes are already happening (figures 37 & 38).


The paper finds that rapid large sea level rise may occur sooner than generally assumed. Amplifying feedbacks, including slowdown of the Southern Meridional Ocean Circulation (SMOC) and cooling of the near-Antarctic ocean surface with increasing sea ice, may spur non-linear growth of Antarctic ice sheet mass loss, leading to sea level rise of several meters with the only uncertainty being how rapidly it will occur. Greenland ice sheet loss, while less subject to such non-linear disintegration, is still faster than carbon cycle or ocean thermal recovery times, so if climate forcing continues, amplifying feedbacks will result in large eventual mass loss. With the present growth of freshwater injection from Greenland, we may already be on the verge of substantial North Atlantic climate disruption. Increased storm strength, caused by a stronger temperate gradients between the tropics and latitudes affected by ice melt, conjoin with sea level rise to cause devastating coastal damage.


The paper concludes that, of all the impacts of climate change, 'sea level rise sets the lowest limit on allowable human-made climate forcing and CO2 because of the extreme sensitivity of sea level to ocean warming and the devastating economic and humanitarian impacts of  multi-metre sea level rise…  Ice sheet response time is shorter than the time for natural geologic processes to remove CO2 from the climate system, so there is no morally defensible excuse to delay phase-out of fossil fuel emissions as soon as possible’.


The latest projections for sea level rise support these findings with an estimated increase of 3 metres by 2100 (41b).


It further warns that the 2°C ‘guardrail' is not safe as 'such warming would likely yield sea level rise of several meters along with numerous other severely disruptive consquences for human society and ecosystems ... ongoing changes in the southern ocean, while global warming is less than 1oC, provide a strong warning, as observed changes tend to confirm the mechanisms amplifying change'.


Finally, the paper questions whether global temperature change should be the fundamental metric for global climate, suggesting that the first-order requirement is to correct Earth’s energy imbalance through reduction of atmospheric CO2 levels to 350ppm.

 

OTHER TIPPING POINTS AND TIPPING POINT MODELLING:

The second category of slow amplifying feedbacks is climate-induced GHG release of which methane, with a warming impact 23 times that of CO2 (and 83 fold over twenty years), is potentially the most serious. Large-scale thawing of permafrost has already started, reinforcing expectations that the Arctic will turn from a carbon sink to a net source by the 2020s. (59) Recently published paleoclimate studies confirm that a global average temperature increase of 1.5°C is sufficient to start a generalised permafrost melt (60), consistent with another study in North East Russia, which found that temperatures locally were ~8°C warmer than today in the mid-Pliocene when CO2 was at 400ppm (61). Significantly, this is supported by other research also indicating that the tipping point for large scale loss of permafrost carbon is a regional temperature increase of 8-18°C  – within expected cyclic variation around the 2°C target ceiling in global climate policy. (62) Further research confirms that much of this regional warming is a consequence of an ice-free Arctic. (63) In addition to land-based methane release, methane plumes of up to a kilometre wide have been recorded in the East Siberian Sea, and subsequently more generally in the Arctic region, suggesting that rising ocean temperatures are now melting undersea permafrost and potentially frozen clathrates. (64)


Complexity has inhibited the development of tipping point models, but recent advances have enabled the construction of a ‘tipping point cascade’, identifying a series of thresholds around 1.5°C which could result in multiple trigger points toward accelerated change (65) (figures 39 & 40). It was, apparently, the concern about such tipping points around 1.5oC threshold which was, in large part, responsible for its adoption as the preferred limit on warming.  Given the recently updated increase of the global average temperature rise to 1°C (66), the further increase of at least 0.3-0.6 ‘in the system’, and the 0.5°C warming impact of ice-free Arctic summers, the planet is already on course for warming of a minimum of 2°C, excluding allowance for continuing anthropogenic GHG emissions and their attendant feedbacks (67).


CONCLUSIONS

In summary, existing climate policy does not reflect the extremely serious implications of current science, and will lead to substantial overshoot of GHG emissions, risking a global temperature increase significantly higher even than the 2°C target maximum, itself at least double the level now considered acceptable by many climate scientists in terms of climate impacts.  Worse, insufficient allowance has been made in much of the mainstream modelling for amplifying feedback effects and tipping points which are not only strongly associated in the paleoclimate record with existing GHG levels and the temperature range we are entering, but are already evident in numerous well-documented phenomena, such as rapidly accelerating polar ice-melt, the release of undersea methane, and carbon release from permafrost taiga peatlands.


These ‘supply chain’ deficiencies in mainstream climate science and policy framing effectively guarantee that the global policy response emerging from Paris and beyond  will fail to address the problem at the scale, intensity and urgency required, with the result that climate change will continue to accelerate, presenting ever more challenging barriers to effective intervention the later such action is deferred.  These downstream consequences of an inadequate policy response will, however, ultimately need to be addressed, inevitably leading to the imposition of more radical policy options the longer serious intervention is delayed.


The implications for DAC are significant in terms mainly of its relative application to specific markets, not ultimate potential. There are now no realistic emissions trajectories which limit warming to 2oC without recourse to negative emissions strategies (figure 41).  As already noted in the opening paragraph of this section, the opportunity and demand for DAC is substantial under scenarios of either ambitious or weak climate policy, but the balance of applications varies according to each. In the former, DAC deployment to reduce ongoing emissions is accelerated as a result of favourable policy, but conversely, the requirement for atmospheric reduction is smaller. In the latter, peak atmospheric CO2 levels are higher, necessitating larger scale – and ultimately more urgent DAC deployment – for atmospheric reduction.


Broadly, for climate policy to achieve a 450 Scenario will involve a global carbon price of at least equivalent to the cost of air capture (say $125/tonne). Irrespective of this, anticipated solar electrolysis cost reductions by 2020 will reduce the price of synthetic fuels to a level which will be completely transformational for the global transportation and other hydrocarbon fuel markets, worth over $3 trillion a year. A peak atmospheric CO2 level of 450ppm will need to be reduced by at least 100ppm which, allowing for re-emission from natural carbon sinks, translates to a 167ppm reduction requirement (see explanation opposite (figure 42) (63)). Assuming, for the purposes of this exercise, that half is sequestered via DAC over the course of 65 years, this equates to approximately 10 GtCO2/year. Even at $100/tonne CO2, this represents a market of over $1 trillion/year. Other sectors, such as renewable energy storage, may increase this by a further $1 trillion/year. The total potential market under this scenario is therefore circa $5 trillion/year.


In a scenario of ineffectual climate policy, atmospheric CO2 levels could exceed 650ppm, necessitating a 300ppm reduction, or 510ppm including allowance for re-emission from sinks. Under such circumstances, other sequestration options may be more constrained (68); assuming therefore that 60% of this requirement is undertaken via DAC, this translates to a 2.4 trillion tonne CO2 reduction, or 40 Gt CO2/year over 60 years — a $4 trillion a year market.  However, even with a climate policy response no better than that currently prevailing, the market opportunity for DAC to address ongoing emissions is still likely to be at least (say) 20% of that generated under an ambitious climate policy scenario, equating to an additional $1 trillion and, therefore, a potential market of again $5 trillion/year.






‘Today, in 2013 we face an unavoidably radical future. we either continue with rising emissions and reap the radical repercussions of severe climate change, or we acknowledge that we have a choice and pursue radical emission reductions: no longer is there a non-radical option’.

Professor Kevin Anderson, Deputy Director, Tyndall Centre for Climate Change Research, speaking at the Radical Emissions Reduction Conference, The Royal Society 10th - 11th December 2013


'the carbon budgets needed for a reasonable probability of avoiding the 2°C characterisation of dangerous climate change demand profound and immediate changes to the consumption and production of energy. The IPCC’s own 1,000 GtCO2 carbon budget for a “likely” chance of 2°C, requires global reductions in emissions from energy of at least 10% p.a. by 2025, with complete cessation of all carbon dioxide emissions from the energy system by 2050.

whilst speculative negative emissions are de rigueur, similarly imprecise Earth system processes (but with the potential to reduce the available budgets) are seldom included in quantitative scenarios.

Of the 113 scenarios with a 'likely' chance (66% or better) of 2°C (with 3 removed due to incomplete data), 107 (95%) assume the successful and large-scale uptake of negative emission technologies. The remaining 6 scenarios all adopt a global emissions peak of around 2010. Extending the probability to a 50% chance of 2°C paints a similar picture. Of the additional 287 scenarios, 237 (83%) include negative emissions, with all the remaining scenarios assuming the successful implementation of a stringent and global mitigation regime in 2010.

In plain language, the complete set of 400 IPCC scenarios for a 50% or better chance of 2°C assume either an ability to travel back in time or the successful and large-scale uptake of speculative negative emission technologies. A significant proportion of the scenarios are dependent on both ‘time travel and geo-engineering’.

Duality in Science, Prof. Kevin Anderson, Nature Geoscience (published online, October 2015)


The background calculations to the above statements can be summarised as follows:

  1. The IPCC 2014 Synthesis Report proposes a headline carbon budget of 1,000 billion tonnes of carbon dioxide (1,000 GtCO2)  for the period 2011 to 2100 for a 66% or better chance of remaining below 2oC

  2. Energy-only CO2 emissions totalled 140 Gt between 2011 and 2014 inclusive

  3. The IPCC’s most ambitious pathway for limiting deforestation and land-use change for the period 2011 to 2100  assumes emissions of 60 GtCO2

  4. Highly optimistic assumptions for cement emissions from 2011 to 2100 are 150 GtCO2

  5. The balance of around 650 GtCO2 for the period 2015 to 2100, less minimum emissions of 180 GtCO2 between 2015 and 2020 leaves a post-2020 budget of 470 GtCO2, requiring reductions rapidly ratcheting up to 10% per annum by 2025.

 

'Earth today is poised to experience strong aMplifying feedbacks in response to moderate additional warming.  Accelerating ice sheet mass loss supports our conclusion that earth has returned to at least the holocene maximum.  

A global mean temperature (increase) of 0.3oC above (current level) is close to, or into, the danger zone.  The suggestion that 2oC global warming may be a safe target is extremely unwise based on critical evidence accumulated over the past three decades.

Global mean temperatures 2oc higher than peak holocene have not existed since at least the pliocene, a few million years ago.  the sea level at that time was 15-25 metres higher than today'


The Case for Young People and Nature, a Path to a Healthy, Natural, Prosperous Future, James Hansen, Pushker Kharecha, Makiko Sato, Paul Epstein, Paul J Hearty, Ove Hoeghguldberg, Camille Paremsan, Stefan Rahmstorf, Johan Rockstrom, Eelco J Rohling, Jeffrey Sachs, Peter Smith, Konrad Steffan, Karina von Schuckmann, James C Zachos


'Even if rises are pegged at 2C, scientists say this will still destroy most coral reefs and glaciers and melt significant parts of the Greenland ice cap, bringing major rises in sea levels…..the world’s carbon emissions, currently around 50bn tonnes a year, will still rise over the next 15 years, even if all the national pledges made to the UN are implemented. The institute’s figures suggest they will reach 55bn to 60bn by 2030…..To put that figure in context, the world will have to cut emissions to 36bn billion tonnes of carbon to have a 50-50 chance of keeping temperatures below 2C’

The Guardian, quoting the Grantham Research Institute’s latest analysis of INDC pledges to the UN, 11.10.15



'With INDCs submitted so far, and the planned energy policies in countries which have yet to submit, the world’s estimated remaining carbon budget consistent with a 50% chance of keeping the rise in temperature below 2oC is consumed by around 2040 — eight months later than is projected in the absence of INDCs'

SOURCE: IEA Special Report on Energy and Climate Change, June 2015’



The IEA proposes a fourfold strategy to strengthen global climate policy post-Paris 2015 (source - as above):
 

PEAK IN EMISSIONS:

In order to retain the possibility of adhering to the 2°C target, the IEA proposes a Bridging Strategy to deliver a peak in global emissions by 2020. This depends on five measures: (i) increasing energy efficiency (ii) retirement of coal-fired plants (iii) raising renewable energy investment to $400bn/year by 2030 (iv) phasing out fossil fuel subsidies by 2030, and (v) reducing methane emissions from oil and gas production. The impact of such a programme would be considerable. Total energy-related GHG emissions  peak around 2020. Both the energy-intensity of the global economy and the carbon intensity of power generation improve 40% by 2030.  Coal use and oil consumption peak by 2020 with coal declining and oil plateauing thereafter.  China decouples economic expansion and emissions growth by 2020. The pace of this decoupling is 30% faster in the EU and the US. India also uses energy more efficiently, while reducing methane emissions and reforming fossil fuel subsidies are key targets for the Middle East and Africa.


FIVE-YEAR REVISION:

Whilst the Bridge Strategy can keep open the 2oC goal in the near term, ambition needs to be tightened beyond this, taking advantage of the improving cost and performance of low-carbon technologies. Five-yearly reviews are proposed to achieve this.


LOCK-IN THE VISION:

The 2oC goal needs to be translated into subordinate targets, in particular focusing on next-generation technologies such as energy storage for renewable power and the production of alternative fuels.


TRACK THE TRANSITION:

Progress toward INDC goals needs to be monitored closely. Post-2020 reporting and accounting frameworks may not be settled at COP 21, but the agreement should at least establish high-level principles.

 

'Fossil fuel companies are benefitting from global subsidies of $5.3tRn (£3.4tRn) a year, equivalent to $10m a minute every day, according to a startling new estimate by the international monetary fund. The imf calls the revelation 'shocking' and says the figure is an 'extremely robust' estimate of the true cost of fossil fuels. The $5.3tRn subsidy estimated for 2015 is greater than the total health spending of all the world's governments.

Fossil fuels subsidised by $10m a minute, says IMF, Damien Carrington, The Guardian 18th May 2015

 

'post tax energy subsidies are dramatically higher than previously estimated - $4.9tRn (6.5% of global gdp) in 2013, and projected to reach $5.3tRn (6.5% of global gdp) in 2015.  The fiscal, environmental and welfare impacts of energy subsidy reform are potentially enormous.  Eliminating post-tax subsidies in 2015 could raise government revenue by $2.9tRn (3.6% of global gdp), cut global co2 emissions by more than 20%, and cut premature air pollution deaths by more than half.  After allowing for the higher energy costs faced by consumers, this action woulD raise global economic welfare by $1.8tn (2.2% of global GDP)'

How Large are Global Energy Subsidies? David Coady, Ian Parry, Louis Spears, and Baoping Shang, IMF Working Paper May 2015
 


'73 countries and 11 states and provinces - together responsible for 54% of global greenhouse gas emissions and 52% of gdp - joined 11 cities and over 1,000 businesses and investors in signalling their support for carbon pricing through a series of initiatives being announced at the un secretary-general's climate leadership summit on tuesday.  The list includes countries like china anD south africa that are planning carbon pricing, as well as russia and countries at high risk from climate change, like the marshall islands.  it includes businesses ranging across industry, energy and transportation, and institutional investors with more than $24tn in assets'.

Rachel Kyte, World Bank Group Vice President and Special Envoy for Climate Change, 22nd September 2014



'Climate change is already contributing to the deaths of nearly 400,000 people a year and costing the world more than $1.2 trillion, wiping 1.6% annually from global GDP.'

Climate Vulnerability Monitor: A Guide to the Cold Calculus of a Hot Planet, DARA group report commissioned by 20 governments September 2012

'Developing nations could need as much as $500 billion a year by 2050 to adapt to the effects of a warming climate, the United Nations said, significantly revising its earlier figure of $100 billion a year estimated by the U.N.’s Intergovernmental Panel on Climate Change (IPCC).'

The Adaptation Gap Report 2014: A Preliminary Assessment Report, United Nations Environment Programme, December 2014



'Global warming of 2˚C would put over 50 per cent of the African continent's population at risk of undernourishment. Yet, the IPCC showed that without additional mitigation we are heading to 4˚C of warming.'

Binilith Mahenge, President of AMCEN and Tanzania's Minister of State for Environment, reported in ‘Costs of Climate Change Adaptation Expected to Rise Far Beyond Africa’s Coping Capacity Even If Warming Kept Below 2C, UNEP News Centre 04.03.15

'Targetting CO2 emissions reductions at 450ppm is a receipe for disaster, not salvation'

James Hansen, NASA Goodard Institute for Space Studies Maksoko Sato, Columbia University Earth Institute,New York, January 2011



Losses in 2050 if an extreme weather weather event overwhelms sea-level-rise defenses of urban areas (Source: Nature Climate Change, September 2013, Stephanie Hallegatte et a;

Losses in 2050 if an extreme weather weather event overwhelms sea-level-rise defenses of urban areas
SOURCE: Nature Climate Change, September 2013, Stephanie Hallegatte et al



'Antarctic ice is melting so fast that the stability of the whole continent could be at risk by 2100…new research predicts a doubling of surface melting of the ice shelves by 2050. By the end of the century, the melting rate could surpass the point associated with ice shelf collapse. If that happened,  A natural BARRIER TO THE flow of ice from glaciers and land-covering ice sheets into the oceans would be removed.’

'Antarctic ice is melting so fast the whole continent may be at risk by 2100’  The Guardian, reporting on ‘Divergent trajectories of Antarctic surface melt under two twenty-first century climate scenarios’, Luke D. Trusel et al, Nature Geoscience Letters DOI: 10:1038/NGEO2563



'sea level rise sets the lowest limit on allowable human-made climate forcing and CO2 because of the extreme sensitivity of sea level to ocean warming and the devastating economic and humanitarian impacts of a multi-metre sea level rise…  Ice sheet response time is shorter than the time for natural geologic processes to remove CO2 from the climate system, so there is no morally defensible excuse to delay phase-out of fossil fuel emissions as soon as possible’.

'such warming [2oC] would likely yield sea level rise of several meters along with numerous other severely disruptive consquences for human society and ecosystems ... ongoing changes in the southern ocean, while global warming is less than 1oC, provide a strong warning, as observed changes tend to confirm the mechanisms amplifying change'

Ice melt, Sea Level Rise, and Super Storms; Evidence from paleocliamte date, climate modelling and modern observations that 2oC global warming is highly dangerous, J Hansen et al. at Moss. Chem. Phys discuss. 15, 20069-20179, 2015



while the adverse effects of climate change may not be as severe as many predictions, it is also quite possible that they may in fact be considerably worse. One very visible example is the reduction in Arctic perennial sea ice cover, which has diminished at a rate of 13 percent per decade (relative to the 1979-2012 mean….This reduction in ice cover far exceeded model predictions and serves as a stark indication that the challenges we may face with climate change may occur sooner rather than later. Such a circumstance underscores the potential mismatch between the timescales at which detrimental change may occur and the timescales at which meaningful mitigation strategies may be implemented.

Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration, National Research Council of the National Academies 2015

 

'It’s essential that policymakers begin to seriously consider the possibility of a substantial permafrost carbon feedback to global warming. If they don’t, I suspect that down the road we’ll all be looking at the 2°C threshold in our rear-view mirror’.

Methane release from melting permafrost could trigger dangerous global warming: A policy briefing from the Woods Hole Research Centre concludes that the IPCC doesn't adequately account for methane warming feedback’ The Guardian, 14.10.15, Robert Max Holmes, Woods Hole Research Centre

'Average global flood losses in 2005 are estimated to be approximately US$6 billion per year, increasing to US$52 billion by 2050 with projected socio-economic change alone. With climate change and subsidence, present protection will need to be upgraded to avoid unacceptable losses of US$1 trillion or more per year.'

Future flood losses in major coastal cities, Stephane Hallegatte et al, Letters, Nature Climate Change 18.08.13 DOI: 10.1038/NCLIMATE197

'business-as-usual trajectories of greenhouse gas emissions give rise to potentially large impacts on growth and prosperity in the future, especially after 2100. Indeed these impacts are large enough to feed back into future emissions via reduced activity, but the feedback is too small and too late for the system to self-regulate. Thus optimal emissions control is strong and strongly increasinG...the carbon price in a setting of globally coordinated policy, such as a cap-and-trade regime or a system of harmonised domestic carbon taxes, should be in the range $32-103/tCO2 (2012 prices) in 2015.'

Endogenous growth, convexity of damages and climate risk: how Nordhaus’ framework supports deep cuts in carbon emissions. Simon Dietz and Nicholas Sterrn, Centre for Climate Change Economics and Policy Working Paper No. 180/ Grantham Research Institute on Climate Change and the Environment, Working Paper No. 159. June 2014



Total economic cost of climate change under the BAU scenario in 2050 in South Asia

Total Economic Cost of Climate Change under the BAU Scenario in 2050 in South Asia

'The total cost of climate change in South Asia will increase over time and in the business-as-usual economic scenario, South Asia could lose an equivalent 1.8% of its annual gross domestic product (GDP) by 2050 due to climate change'

Assessing the Cost of Climate Change and Adaptation in South Asia, Asian Development Bank, June 2014

 

'There is a clear relationship between workplace heat conditions and economic performance and sustainable development. Beyond a certain heat exposure level (temperature beyond 30-40 °C, depending on humidity level) the hourly work capacity goes down:

 

♦ In Singapore the number of days per year when the heat index level (WBGT) in the shade goes above extreme heat (WBGT > 29 °C) has increased from 10 days in 1980 to 70 days in 2011 (Kjellstrom et al., 2013).

♦ The first quantitative estimates of the economic cost of excessive heat at work in various countries is the “Climate Vulnerability Monitor 2012” report, which concluded that the increased cost of heat induced labour productivity loss globally would be approximately US$2 trillion in 2030. Large individual countries could lose up to several percent of their annual GDP creating multi-billion dollar losses.

♦ the annual daylight work hours lost in India (the largest country in South Asia) may be 5% more in 2050 than in 1975 (see Figure below). If the percentage loss of annual “productive work hours” reduces the annual GDP for countries in a similar manner, the losses will be substantial. The GDP of India in 2050 has been estimated by PriceWaterhouseCoopers at US$21 trillion. Without climate change since 1975 it could be 5% — or US$1 trillion — larger. Similarly, for other large emerging economies the losses will be very high. If these economic outputs were not lost due to climate change, major community investments in health, education, energy supply, transport, etc, could be easier to provide. Labour productivity losses occur each year, so the accumulated economic losses after a few decades will have a significant effect on poverty reduction and economic development in many low and middle income countries.

♦ heat related losses of labour productivity in 2050 and 2090 in the United States would be the largest actual economic costs of climate change — amounting to approximately 0.2% of GDP in 2050. Heat related mortality costs would be even higher, but these estimates are based on “statistical value of life” for all age groups, and therefore are not so directly linked to the national economy.

 

% of productive workloss due to heat

SOURCE: Productivity losses ignored in Economic Analysis fo Climate Change.  Tord Kjellstrom, United Nations University 23.09.14