Michael Grubb

Health and climate change: policy responses to protect public health

The 2015 Lancet Commission on Health and Climate Change has been formed to map out the impacts of climate change, and the necessary policy responses, in order to ensure the highest attainable stand ...

A review of Chinese CO2 emission projections to 2030: the role of economic structure and policy

The projections of 89 scenarios from 12 different models for the CO2 emissions of China to 2030 are reviewed, along with wider examinations of lessons from the history of energy forecasting in OECD countries, and of the Chinese macroeconomic situation. Even by 2030, emissions in the scenarios span a factor of almost 2.5, indicating significant range and uncertainty. Statistical analysis of Kaya components suggests the carbon intensity of energy supply to be the strongest determining factor. However, most scenarios assume that industry1 continues to account for more than 50% of total final energy demand. This is in contrast both to historical examples, which have consistently shown economies shifting from energy-intensive industrial bases to service-based structures as income per capita rises, and to recent Chinese policy statements, which reflect a similar ambition. It is also highly salient that major failures in energy and emissions projections can frequently be accounted for in retrospect by failures to anticipate such major economic structural shifts. In conclusion, while the future trajectory of Chinese emissions remains profoundly uncertain, the potential for a significant Chinese macroeconomic transition and its implications for the scale and structure of energy demand will be a crucial factor, to which energy-climate models must pay far more attention. Policy relevance The dramatic growth of Chinese emissions since 2000 has become a major factor in global emission prospects and the international political agenda. Many models project rapid continued emissions growth, but an apparent halt in Chinese emissions in 2014 has amplified debate. Projections and policy need to recognise fundamental uncertainties in emission prospects, because in addition to energy/climate-specific policies, they depend on the progress in Chinese macroeconomic reforms, which are poorly represented in the models we survey. Global projections, the international process, and the design of Chinas own policies (most obviously, its national cap-and-trade system) need to cope with the possibility of continued growth to peaking in 2030 (the central commitment in Chinas Intended Nationally Determined Contribution), but must also be prepared to exploit and encourage the possibilities of low-carbon development and much earlier peaking.

Economic dimensions of the Kyoto Protocol

This chapter examines key economic issues of the Kyoto Protocol, including the strength of the overall quantified commitments. It highlights the problems with the transparency and effectiveness of the flexibility mechanisms, issues surrounding the supplementarity clause and the surplus allocations to some transition economies, and key North-South issues.

Reply to 'Interpretations of the Paris climate target'

Millar et al. reply — Our paper aimed to remain as consistent as possible with the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC AR5) definitions that have informed the United Nations Framework Convention on Climate Change (UNFCCC) negotiations. The definition of global average temperature in the Paris Agreement is undoubtedly important, and different interpretations are possible, as acknowledged in our paper. However, the Paris Agreement built on the reports of Working Group I and II1,2 of the IPCC AR5. In these reports, global temperature change was explicitly defined using the observations in the period 1850–1900 as “an approximation of preindustrial levels” (Fig. 1 of ref. 2). Climate model projections were assessed relative to 1986–2005 and then expressed relative to 1850–1900 using observed warming between these periods in the HadCRUT4 dataset3 (+ 0.61 °C). Based on the IPCCAR5-assessed4 near-term projections of a warming of 0.3–0.7 °C for the period 2016–2035 compared to 1986–2005, warming in the decade 2010–2019 is expected to be centred on 0.93 °C above 1850–1900, given forcing consistent with the representative concentration pathways and no large volcanic eruptions. Such a level of warming is consistent with the “increase of 0.85 °C [to 2012] since 1880, a good approximation for pre-industrial levels” reported in the Structured Expert Dialogue (SED)5 — dashed light blue line in Fig. 2 of Schurer et al.6 — and with the independent estimate for 2015 human-induced warming used in our paper7. Alternative definitions of global average temperature or preindustrial conditions may not be consistent with “observed impacts of climate change at 0.85 °C of warming”5 (original emphasis) in the context of which the UNFCCC longterm temperature goal was agreed — over the period 2006–2015, warming (relative to 1850–1900) in datasets that stretch back to 1850 are: 0.84 °C (HadCRUT4), 0.92 °C (HadCRUT4: Cowtan and Way) and 1.00 °C (Berkeley Earth). We aimed to remain as consistent as possible with the IPCC-AR5 definitions that have informed the UNFCCC negotiations. We therefore proposed 0.6 °C of warming above the average of the present decade as “a possible interpretation of ‘pursuing efforts to limit the temperature increase to 1.5 °C’ in light of estimated human-induced warming to date”, while also providing tables with data for 0.3–1.1 °C of additional warming to highlight the potential effects of different temperature definitions and pre-industrial reference periods for estimates of remaining budgets (refs 17,18 in Millar et al.7). The difference between model-based globally complete surface air temperature (SAT) and globally incomplete combinations of blended air and sea surface temperature observations is important for quantifying climate impacts at low-temperature thresholds. This difference is larger over the historical period than in projected future changes under ambitious mitigation. Studies of impacts of 1.5 °C of warming should indeed acknowledge this difference, but it is relatively small for ambitious mitigation scenarios expressed relative to the present decade (less than 0.05 °C — difference between dark blue and purple lines in Fig. 2 of ref. 6). In their 2017 paper, Schurer et al.8 stated that “blended observational data sets ... will probably be those used to determine whether a temperature threshold has been reached”. Our use of global SAT projections (ref. 7, Fig. 1, Tables 1 and 2) means that budget estimates for thresholds of warming beyond the present decade are actually slightly underestimated relative to budgets under a blended metric, with the same being true for the AR5 budget estimates. It is important to understand differences in the definitions of global average temperature in mitigation and climate impact studies. However, the definition of warming in the context of the Paris Agreement is not informed solely by physical geoscience considerations9,10. Our paper estimated the outstanding carbon budget consistent with limiting the increase in global average temperature above pre-industrial levels to 1.5 °C, using a definition of present-day warming consistent with government-approved assessments that directly informed the Paris Agreement, while acknowledging that other interpretations were possible. We therefore stand by the central definition of warming used in our paper and its estimate of the remaining carbon budget. ❐

Author Correction: Emission budgets and pathways consistent with limiting warming to 1.5 °C

In the version of this Article originally published, a coding error resulted in the erroneous inclusion of a subset of RCP4.5 and RCP8.5 simulations in the sets used for RCP2.6 and RCP6, respectively, leading to an incorrect depiction of the data of the latter two sets in Fig. 1b and RCP2.6 in Table 2. This coding error has now been corrected. The graphic and quantitative changes in the corrected Fig. 1b and Table 2 are contrasted with the originally published display items below. The core conclusions of the paper are not affected, but some numerical values and statements have also been updated as a result; these are listed below. All these errors have now been corrected in the online versions of this Article.

One farewell and many welcomes

It is with a mix of pride, sadness, and pleasure that I am standing down as Editor-in-Chief of Climate Policy at the end of 2016, some 16 years after establishing and launching the journal with its first issue in January 2001. Pride, because in that period Climate Policy has developed and matured to occupy a unique niche, and become one of the leading journals of climate change policy research. We launched the journal to fulfil a clear need. Tackling climate change is a challenge of immense complexity, and successful responses would require analysis that could span scientific, technological, economic, social, and political considerations at many levels, from local to global. Moreover, given the complexity, it was vital that policy learns from experience, from critical analysis of what has been tried, what has worked, what has failed, and what lessons to draw – something which governments or other policy makers themselves were often reluctant to encourage. For research in which policy was both our laboratory and our target, the findings required a journal that reached well beyond the traditional, often barely recognized, boundaries of disciplinary silos and purely academic communities. That did not fit well with the increasingly rigid structures of most journal publishers. We were grateful that one did take on the idea in principle to launch the journal, but its processes proved unable to adapt to what we needed (e.g. regarding timeliness and the need for sometimes shorter pieces with focused contributions to live policy debates); after the founding contracts ended after three years, the entire Editorial Board resigned. The publishers eventually put the journal up for sale, and Earthscan – a relatively small but successful specialist publisher – acquired Climate Policy on the condition that I and most of the editorial board resumed our roles. Under Earthscan, with co-investment from the fledgling international research network Climate Strategies, the journal prospered and grew with an increasingly clear and rising profile. We have been fortunate indeed that when Taylor and Francis bought up Earthscan, their team, led by Rod Cookson and Andrew Kelly, have understood, continued, and supported our vision. Issue publication over the years has risen from four to six and, this year, to eight regular issues, plus two funded Special Supplements. From the academic perspective, the (journal citation-based) Impact Factor has increased substantially, last year reaching 1.98. This is despite the intrinsic difficulty of such metrics for journals that are interdisciplinary, and oriented towards analysing and informing public policy as much as advancing academic theory. For researchers both seeking to understand and hoping to influence policy, particularly internationally, Climate Policy has become the essential ‘go to’ journal. Attempting to evaluate policy relevance is problematic, and historically has tended to hinge on a few particular articles which become a focus of policy debate or action. Some such cases have underlined that publishing for policy impact requires peer review procedures to be more, not less, robust than for standard academic journals. In one notable case, we were approached twice in different ways to probe the legitimacy of an article which had been cited by the US government as the prime intellectual justification for an important government regulation. Being able to point to the extensive records of four separate peer reviews, none of which had any institutional connection with the article authors, was vital. But as any academic knows, a few examples do not amount to a robust metric. The emergence of the Altmetric indicator of mentions outside the academic sphere is thus hugely welcome. Like any single metric, it is imperfect and does

The ‘Dark Matter’ in the Search for Sustainable Growth: Energy, Innovation and the Financially Paradoxical Role of Climate Confidence

Theories of economic growth have long recognised that innovation is a key but poorly understood force — the ‘residual’ of neoclassical growth models. These models have no representation of intermediate goods, or of the factors that generate and diffuse innovations, including learning-by-doing and scale economies; they are thus unable to picture how a suite of economic and institutional changes triggers waves of long-term economic progress, which in practice has been the long-term historical pattern. The absence of finance in these models is particularly problematic. The centrality of financial structures to understanding patterns of economic growth is acute concerning policies to shape efficiency, innovation and infrastructure in ways compatible with energy and climate security, since these require substantial upfront investment. However, uncertainty and a lack of confidence deter such investment. Environmental policy could reduce risk and thereby shape ultimately profitable investments. The paper outlines deep relationships between energy/carbon-related finance and wider debates about financial systems after the crisis. The paper finally proposes an agenda for future research towards alternatives to classical growth models, intended to address some of their limitations.