Comment pubs.acs.org/est
ES&T and the IPCC hen the Intergovernmental Panel on Climate Change publishes the Climate Mitigation report of its fifth assessment (AR5) in mid-April, it will be with a significant contribution from regular ES&T authors and with important conclusions based on research first published in this journal. Serving as a lead author of the energy chapter of this report has been my single largest time commitment over the past three years, comparable with my teaching load. I would like to reflect here on my experience. It is no secret that emissions of greenhouse gases (GHGs), and in particular of CO2 from fossil fuel combustion, have increased at a record rate over the past decade. This accelerated rise of emissions has come as a result of rapid, coal-fueled development in emerging economies and continued high emissions in industrialized countries. This trend most likely leads to a “dangerous anthropogenic interference with Earth’s climate system”, the action criterion defined in the United Nations Framework Convention on Climate Change (UNFCCC), the international law governing the global climate mitigation effort agreed upon at the Rio Earth Summit in 1992. International negotiations, unfortunately, are stymied by a game of chicken. Developing countries argue that industrialized countries must go ahead in reducing their emissions as they are responsible for most of the CO2 added by humans to the atmosphere, while industrialized countries argue that without significant effort by developing countries, climate mitigation cannot be achieved as these countries are responsible for the majority of the current emissions and virtually all of the increase in emissions over the past decade. ES&T has first published research showing that a substantial portion of emissions in developing countries serves to produce goods consumed in industrialized countries (DOI: 10.1021/ es072023k). Substantial regional differences in emissions controls among regions may lead to an increase of these “emissions embodied in trade”. Further, consuming and producing countries share responsibility for these emissions. Of course this research does not help to resolve the first-mover problem of international negotiations, but it provides scientific understanding for finding joint solutions. Understanding the evolution of GHG emissions also requires insights into the characteristics of fossil fuel resources and the technologies used to utilize these resources. While there is significant recent research on the environmental impacts of new, low-carbon energy technologies, there has been much less work on the main sources of emissions, fossil fuels. Two questions are pertinent. One, does the increasing depletion of easily accessible oil and gas lead to a substantial increase in the own-energy requirements of fuel production? The body of work on life cycle assessment of Canadian oil sands, largely published in ES&T, indicates that for that fuel, at least, GHG emissions and own-energy consumption are substantially higher than those associated with producing transportation fuels from conventional petroleum (e.g., DOI: 10.1021/es202312p and 10.1021/es1013278). A similar body of work on shale gas, however, does not yield such a clear-cut answer (e.g., DOI:
W
© 2014 American Chemical Society
10.1021/es201942m and 10.1021/es300375n). Virtually no work is available that documents the emissions associated with increased or enhanced oil recovery, that is, of efforts to pump more oil from mature fields. An important concern associated with gas and coal production is the rate of methane leakage, which has only received recent attention and where measurementsrequired to resolve conflicting emissions estimates based on engineering calculationsare largely lacking. The mainstream analysis of future mitigation efforts relies on a large family of energy scenario models, which show that increasingly radical efficiency gains in the economy and shifts in the employed energy sources (to and below zero emissions) are required to achieve a stabilization of GHG concentrations limiting global warming to 2 °C. There is, however, a much weaker basis of recent empirical research on technologies, costs, and application experiences of specific energy efficiency opportunities. Important research published in ES&T showed that material production was responsible for about half of GHG emissions from industry, analyzed the role of demand for cars, buildings, and infrastructure for the future development of these emissions, and pointed to service life-extension, recycling, and materials management as important, systemic mitigation strategies (e.g., DOI: 10.1021/es3031424, 10.1021/ es202211w). There is a particular need for published research on energy demand reduction and for the development of technological solutions and organizational models for mitigation in emerging and developing economies. Now let me turn at last to the issue which has formed the main focus of my own contribution, the assessment of mitigation options in terms of their emission reduction efficiency (in a life cycle sense), their environmental and other cobenefits and adverse trade-offs. Life cycle assessment (LCA) studies form part of the empirical basis of this work. Many studies have been published, but their value to our assessment was often limited by the poor transparency and documentation of the work. The LCA field lacks a practice of publishing the underlying inventories as data sets following a common format that would allow a reproduction or metaanalysis. In other, more fundamental sciences, the release of data sets is obligatory and repositories for such data exist. LCA studies published in ES&T were often more transparent and better documented than those of some other journals, and ES&T is now discussing a requirement of publishing inventory data. In my experience, the standards of evidence required for scientific findings to be communicated in the technical summary and the summary for policy makers of an IPCC report is very rigorous, requiring the support of multiple publications in peer-reviewed journals and a transparent exposition. ES&T has a good track-record of publishing policy-relevant findings that meet such standards of rigor, and Published: February 11, 2014 2517
dx.doi.org/10.1021/es500491j | Environ. Sci. Technol. 2014, 48, 2517−2518
Environmental Science & Technology
Comment
this is why it has had such an impact on the IPCC fifth assessment report.
■
Edgar G. Hertwich AUTHOR INFORMATION
Corresponding Author
[email protected] Notes
Views expressed in this editorial are those of the author and not necessarily the views of the ACS or the IPCC. The authors declare no competing financial interest.
2518
dx.doi.org/10.1021/es500491j | Environ. Sci. Technol. 2014, 48, 2517−2518
