A story of targets
This is taken from Shaw, C., (2010)The Dangerous Limits of Dangerous Limits: Climate Change and the Precautionary Principle in Nature, Society and Environmental Crisis. Carter, B., and Charles, N (Eds). Oxford: Wiley Blackwell.
The first appearance in print of the two degree limit seems to be in a 1967 paper wherein the authors write of ‘a convincing calculation that a doubling of CO2 would raise temperatures by roughly 2 degrees centigrade’ (Manabe and Weatherald, cited Weart, 2003 p203). Oppenheimer & Petsonk identify a 1979 paper by the economist W.D Nordhaus as the first attempt to describe two degrees of warming as a dangerous limit (Oppenheimer and Petsonk, 2005)1. Oppenheimer and Petsonk’s citation of the Nordhaus paper focuses on his argument that two degrees centigrade of warming is the limit of warming which has occurred naturally over the last 10,000 years. Humanity has survived these previous levels of warming and so two degrees can reasonably be claimed as a desirable limit to human forcing of the climate (Nordhaus, cited in Oppenheimer and Petsonk, 2005 p197). This idea of two degrees as a natural limit in climate variation is central to the construction of the two degree limit and is reiterated in a highly influential set of reports from the German Advisory Council on Global Change (WBGU 1995, 1997, 2003) which I return to below.
The 1967 and 1979 papers reach their conclusions about a two degree limit on the basis of climate sensitivity calculations. Whilst the topic of climate sensitivity is important to climate science and much of the climate change commentary in the social sciences, I can only briefly outline the main features of the concept here.
A question of central concern to a technical construction of climate change is ‘How much warming will arise from x increases in atmospheric concentrations of carbon dioxide?’ This relationship is known as climate sensitivity. Attempts to calculate climate sensitivity have focussed on modelling what happens when atmospheric concentrations of carbon dioxide are doubled. In fact, so ubiquitous has the assumptions of a doubling of carbon dioxide been in these calculations that the term ‘climate sensitivity’ does not refer to calculations of warming from a range of different increases in carbon dioxide, but refers only to the consequences of a doubling of carbon dioxide. A climate scientist who has written extensively on the climate sensitivity story explained to me the standardisation of the climate sensitivity calculations as a structurally imposed constraint. Climate sensitivity was being calculated by a large body of scientists over a large span of space and time, requiring standardisation between the models so that comparisons could be made between the results being generated. This process was beyond the computational power of any one computer, hence the need for this co-ordination. And why a doubling of carbon dioxide? Firstly because one needs the parameters used for the modelling to be sufficiently different from current conditions for the results to have any statistical significance. And secondly
doubling looked like it was a plausible likelihood. It was going to happen anyway given the trend of increasing that was going on. It wasn’t going to be that long, that unimaginably far in to the future. It counts as an interesting extension of existing modelling so ….in that sense it was plausible. Its going to happen sometime whether its 50 years or 100 years doesn’t really matter.
(Climate scientist and academic researcher [3], June 2008).
Looking at the early work on climate sensitivity and warming, it would appear a certain inevitability about a doubling of carbon dioxide and two degrees of warming has been entrenched into the research from the very beginning. Van der Sluijs, in a history of the climate sensitivity concept, concluded the ‘sensitivity to doubling’ concept was a hypothetical research entity which has become reified in scientific assessment. In addition they claimed that their research revealed that the concept of climate sensitivity is much more complex and indeterminate than acknowledged by the climate science community and that climate scientists are adverse to re-examination of assumptions which might reflect badly on their community (Van der Sluijs et al, 1998 pp312-313). The aversion to any reappraisal of the assumptions of the climate sensitivity model has been matched by the absence, until very recently, of any re-examination of the assumptions about the safety of two degrees of warming.
Weart (2003); Oppenheimer & Petsonk (2005); Boehmer-Christiansen (1994); Newell (2000); Pearce (2007); and Walker and King (2008) have all provided an extensive history of the development of the climate change debate since the middle of the twentieth century. For reasons of space I content myself here with an overview of some key papers that appeared after the UNFCCC came into force in 1992. The two degree target developed out of the United Nations Framework Convention on Climate Change (UNFCCC) which requires signatories to take steps to avoid dangerous climate change (UNFCCC, 1992 Article 2). The UNFCCC did not quantify what amount of climate change should be considered dangerous, leaving it to the signatories to reach agreement on such a definition. Explaining the role of the precautionary principle in reaching that agreement is the concern of this chapter .
The period from 1992 to the present day saw the idea of a two degrees dangerous limit become increasingly central to discourses about the climate change risk (Details available in Shaw, 2010).
For reasons of space I will limit my analysis to the WBGU. I focus in particular on the 1995 paper as the papers from 1997 and 2003 reproduce the claims made in the 1995 publication. I claim these papers as central to the shaping of the two degree limit following similar claims for their importance made by Tol (2007) and the scientists interviewed for this study. In addition, these reports have been key in shaping EU climate change policy The WBGU reports of 1995, 1997 and 2003 were commissioned by the German government at the behest of the EU and feed directly into the creation of the Kyoto Protocol (WBGU 1995, WBGU, 1997) and current EU policy (WBGU, 2003).
The 1995 WBGU report was produced for the First Conference of the Parties to the Framework Convention on Climate Change in Berlin of 1995. This conference is an important one because it brought together the signatories to the UNFCCC for the first time, the purpose being to clarify the definitions of dangerous climate change which featured in the UNFCCC. The WBGU report was intended to propose some definitions of dangerous which could be used to develop policy.
The primary purpose of the report was to answer the question ‘How quickly, and by how much, do we need to reduce emissions of carbon dioxide in order to avoid dangerous climate change’ At a purely scientific level, answering that question required the definition of two points
i) How much warming is dangerous?
ii) How much carbon dioxide will cause this dangerous warming? (Climate sensitivity).
Our interest here is in the former question. To avoid dangerous climate change the report argued that warming should be limited such that we can be assured of the ‘preservation of Creation in its current form’ (WBGU, 1995 p13). This has been described as a ‘peculiar’ goal for a secular government to support (Tol, 2007 p246). The sort of temperature range that might allow for the preservation of Creation was derived from the same premise as that which informed Nordhaus’ analysis from 1979. The WBGU report identifies the highest global average temperatures during the previous 10,000 years (the period in which human civilization developed) as being around 16.1 degrees centigrade. The report suggests that if this temperature is exceeded then ‘dramatic changes in the function and composition of today’s ecosystems can be expected’ (WBGU 1995, p13). Today’s global average temperature is calculated by the WBGU to be around 15.3 degrees centigrade, leaving only 0.8 degrees of warming before the climate warms dangerously. However, the WBGU report adds 0.5 degrees of warming to the assumed tolerance range on the basis of humanity’s ‘improved adaptive capacity’ (WBGU 1995, p13). That allows for 1.3 degrees of warming before change becomes dangerous. The earth has warmed by 0.7 degrees since the pre-industrial average. The 1.3 and the 0.7 give us the two degree limit.
The report does not provide any rationale for assuming that industrial humanity is more adaptable to climate change than our hunter-gatherer forebears nor why, if such adaptability did exist, it would equate to 0.5 degrees of warming. In addition, the desire to preserve creation mentioned above was one of two principles used to calculate the emissions cuts required, the other being ‘the prevention of excessive costs’. Thus, rather than being an expression of the precautionary principle, which one might expect given it was commissioned at the behest of the EU, this report is a simple cost-benefit analysis.
The 1997 WBGU report to the Kyoto Conference reconfirms the basic premise which informed its 1995 report, a premise which underpins the adoption of a two degree limit in the EUs current Climate and Energy Strategy. The EU released its Energy and Climate Strategy in 2007. As we have seen there was an extensive discussion of the precautionary principle between the time of the WBGU reports and 2007. The spirit of precaution seems absent from the rather cavalier attitude adopted in the calculating of a two degree limit in the WBGU reports, a process described by one academic as based on a ‘sloppy’ methodology and ‘inadequate’ reasoning (Tol, 2007 p424). The EU has not seen fit to re-examine the two degree limit despite the supposed incorporation of the precautionary principle into its environmental policy. This despite the fact that even before the EU released its Energy and Climate Strategy, the two degree consensus was beginning to break.
Doubts about the dangerous limit
Agreement on the idea of a two degree limit has, until recently, been widespread, but not universal. The most significant challenge to the consensus came from the US president George W. Bush who said "…no one can say with any certainty what constitutes a dangerous level of warming, and therefore what level must be avoided."
(U.S. President George W. Bush, 11 June 2001, cited in Singer and Avery, 2007 p223).
But for all those actors articulating a discourse on the need for action, whether political, corporate or environmental, the response has almost always been framed within the rubric of a two degree limit.
Since around 2005 however, faith in the idea that the dangerous limit lies at two degrees of warming has become shaken (see Shaw, 2010 for further details).
I'll give the final word to the horse's mouth as it were.
'I think that 2 degrees is rather arbitrary. It’s not clear to me that the answer shouldn't be three degrees, or more, or less. We don't have a scientific basis for selecting the two degree number - it's a hunch, a guess'
Marburger, J. the president of the American Association for the Advancement of Science
The first appearance in print of the two degree limit seems to be in a 1967 paper wherein the authors write of ‘a convincing calculation that a doubling of CO2 would raise temperatures by roughly 2 degrees centigrade’ (Manabe and Weatherald, cited Weart, 2003 p203). Oppenheimer & Petsonk identify a 1979 paper by the economist W.D Nordhaus as the first attempt to describe two degrees of warming as a dangerous limit (Oppenheimer and Petsonk, 2005)1. Oppenheimer and Petsonk’s citation of the Nordhaus paper focuses on his argument that two degrees centigrade of warming is the limit of warming which has occurred naturally over the last 10,000 years. Humanity has survived these previous levels of warming and so two degrees can reasonably be claimed as a desirable limit to human forcing of the climate (Nordhaus, cited in Oppenheimer and Petsonk, 2005 p197). This idea of two degrees as a natural limit in climate variation is central to the construction of the two degree limit and is reiterated in a highly influential set of reports from the German Advisory Council on Global Change (WBGU 1995, 1997, 2003) which I return to below.
The 1967 and 1979 papers reach their conclusions about a two degree limit on the basis of climate sensitivity calculations. Whilst the topic of climate sensitivity is important to climate science and much of the climate change commentary in the social sciences, I can only briefly outline the main features of the concept here.
A question of central concern to a technical construction of climate change is ‘How much warming will arise from x increases in atmospheric concentrations of carbon dioxide?’ This relationship is known as climate sensitivity. Attempts to calculate climate sensitivity have focussed on modelling what happens when atmospheric concentrations of carbon dioxide are doubled. In fact, so ubiquitous has the assumptions of a doubling of carbon dioxide been in these calculations that the term ‘climate sensitivity’ does not refer to calculations of warming from a range of different increases in carbon dioxide, but refers only to the consequences of a doubling of carbon dioxide. A climate scientist who has written extensively on the climate sensitivity story explained to me the standardisation of the climate sensitivity calculations as a structurally imposed constraint. Climate sensitivity was being calculated by a large body of scientists over a large span of space and time, requiring standardisation between the models so that comparisons could be made between the results being generated. This process was beyond the computational power of any one computer, hence the need for this co-ordination. And why a doubling of carbon dioxide? Firstly because one needs the parameters used for the modelling to be sufficiently different from current conditions for the results to have any statistical significance. And secondly
doubling looked like it was a plausible likelihood. It was going to happen anyway given the trend of increasing that was going on. It wasn’t going to be that long, that unimaginably far in to the future. It counts as an interesting extension of existing modelling so ….in that sense it was plausible. Its going to happen sometime whether its 50 years or 100 years doesn’t really matter.
(Climate scientist and academic researcher [3], June 2008).
Looking at the early work on climate sensitivity and warming, it would appear a certain inevitability about a doubling of carbon dioxide and two degrees of warming has been entrenched into the research from the very beginning. Van der Sluijs, in a history of the climate sensitivity concept, concluded the ‘sensitivity to doubling’ concept was a hypothetical research entity which has become reified in scientific assessment. In addition they claimed that their research revealed that the concept of climate sensitivity is much more complex and indeterminate than acknowledged by the climate science community and that climate scientists are adverse to re-examination of assumptions which might reflect badly on their community (Van der Sluijs et al, 1998 pp312-313). The aversion to any reappraisal of the assumptions of the climate sensitivity model has been matched by the absence, until very recently, of any re-examination of the assumptions about the safety of two degrees of warming.
Weart (2003); Oppenheimer & Petsonk (2005); Boehmer-Christiansen (1994); Newell (2000); Pearce (2007); and Walker and King (2008) have all provided an extensive history of the development of the climate change debate since the middle of the twentieth century. For reasons of space I content myself here with an overview of some key papers that appeared after the UNFCCC came into force in 1992. The two degree target developed out of the United Nations Framework Convention on Climate Change (UNFCCC) which requires signatories to take steps to avoid dangerous climate change (UNFCCC, 1992 Article 2). The UNFCCC did not quantify what amount of climate change should be considered dangerous, leaving it to the signatories to reach agreement on such a definition. Explaining the role of the precautionary principle in reaching that agreement is the concern of this chapter .
The period from 1992 to the present day saw the idea of a two degrees dangerous limit become increasingly central to discourses about the climate change risk (Details available in Shaw, 2010).
For reasons of space I will limit my analysis to the WBGU. I focus in particular on the 1995 paper as the papers from 1997 and 2003 reproduce the claims made in the 1995 publication. I claim these papers as central to the shaping of the two degree limit following similar claims for their importance made by Tol (2007) and the scientists interviewed for this study. In addition, these reports have been key in shaping EU climate change policy The WBGU reports of 1995, 1997 and 2003 were commissioned by the German government at the behest of the EU and feed directly into the creation of the Kyoto Protocol (WBGU 1995, WBGU, 1997) and current EU policy (WBGU, 2003).
The 1995 WBGU report was produced for the First Conference of the Parties to the Framework Convention on Climate Change in Berlin of 1995. This conference is an important one because it brought together the signatories to the UNFCCC for the first time, the purpose being to clarify the definitions of dangerous climate change which featured in the UNFCCC. The WBGU report was intended to propose some definitions of dangerous which could be used to develop policy.
The primary purpose of the report was to answer the question ‘How quickly, and by how much, do we need to reduce emissions of carbon dioxide in order to avoid dangerous climate change’ At a purely scientific level, answering that question required the definition of two points
i) How much warming is dangerous?
ii) How much carbon dioxide will cause this dangerous warming? (Climate sensitivity).
Our interest here is in the former question. To avoid dangerous climate change the report argued that warming should be limited such that we can be assured of the ‘preservation of Creation in its current form’ (WBGU, 1995 p13). This has been described as a ‘peculiar’ goal for a secular government to support (Tol, 2007 p246). The sort of temperature range that might allow for the preservation of Creation was derived from the same premise as that which informed Nordhaus’ analysis from 1979. The WBGU report identifies the highest global average temperatures during the previous 10,000 years (the period in which human civilization developed) as being around 16.1 degrees centigrade. The report suggests that if this temperature is exceeded then ‘dramatic changes in the function and composition of today’s ecosystems can be expected’ (WBGU 1995, p13). Today’s global average temperature is calculated by the WBGU to be around 15.3 degrees centigrade, leaving only 0.8 degrees of warming before the climate warms dangerously. However, the WBGU report adds 0.5 degrees of warming to the assumed tolerance range on the basis of humanity’s ‘improved adaptive capacity’ (WBGU 1995, p13). That allows for 1.3 degrees of warming before change becomes dangerous. The earth has warmed by 0.7 degrees since the pre-industrial average. The 1.3 and the 0.7 give us the two degree limit.
The report does not provide any rationale for assuming that industrial humanity is more adaptable to climate change than our hunter-gatherer forebears nor why, if such adaptability did exist, it would equate to 0.5 degrees of warming. In addition, the desire to preserve creation mentioned above was one of two principles used to calculate the emissions cuts required, the other being ‘the prevention of excessive costs’. Thus, rather than being an expression of the precautionary principle, which one might expect given it was commissioned at the behest of the EU, this report is a simple cost-benefit analysis.
The 1997 WBGU report to the Kyoto Conference reconfirms the basic premise which informed its 1995 report, a premise which underpins the adoption of a two degree limit in the EUs current Climate and Energy Strategy. The EU released its Energy and Climate Strategy in 2007. As we have seen there was an extensive discussion of the precautionary principle between the time of the WBGU reports and 2007. The spirit of precaution seems absent from the rather cavalier attitude adopted in the calculating of a two degree limit in the WBGU reports, a process described by one academic as based on a ‘sloppy’ methodology and ‘inadequate’ reasoning (Tol, 2007 p424). The EU has not seen fit to re-examine the two degree limit despite the supposed incorporation of the precautionary principle into its environmental policy. This despite the fact that even before the EU released its Energy and Climate Strategy, the two degree consensus was beginning to break.
Doubts about the dangerous limit
Agreement on the idea of a two degree limit has, until recently, been widespread, but not universal. The most significant challenge to the consensus came from the US president George W. Bush who said "…no one can say with any certainty what constitutes a dangerous level of warming, and therefore what level must be avoided."
(U.S. President George W. Bush, 11 June 2001, cited in Singer and Avery, 2007 p223).
But for all those actors articulating a discourse on the need for action, whether political, corporate or environmental, the response has almost always been framed within the rubric of a two degree limit.
Since around 2005 however, faith in the idea that the dangerous limit lies at two degrees of warming has become shaken (see Shaw, 2010 for further details).
I'll give the final word to the horse's mouth as it were.
'I think that 2 degrees is rather arbitrary. It’s not clear to me that the answer shouldn't be three degrees, or more, or less. We don't have a scientific basis for selecting the two degree number - it's a hunch, a guess'
Marburger, J. the president of the American Association for the Advancement of Science