Tuesday, September 30, 2014

Update on Energies Special Issue

We now have nine papers published in the special issue of Energies on energy transitions and economic change and there are more to come. The latest paper is by Robert Kaufmann on the end of cheap oil and the implications for the United States and the former Soviet Union. This was one of the invited papers. The other published so far was the paper by Steve Sorrell. Also recently published is a paper by James Kahn et al. on Brazil's plans for expanding hydropower and by Rodriguez-Molina et al. on the smart grid.

Upcoming Seminars


I am giving three seminars in Europe in October and November. First up is 28th October at 1pm at the Grantham Research Institute on Climate Change at the London School of Economics. I will talk about "Energy Transitions and the Industrial Revolution." Then on 12th November at 2:15pm I will talk at the Department of Economic History at Lund University. Topic: "Energy and Economic Growth: The Stylised Facts"  - a topic that blog readers should be pretty familiar with by now.


Finally, I will be presenting at the University of Kassel in Germany on 18th November. More details to come.

Saturday, September 13, 2014

Fuel Choices in Rural Maharashtra Accepted for Publication

My paper with former masters student Jack Gregory was just accepted for publication in Biomass & Bioenergy. Jack is just starting his PhD at University of California, Davis.

This paper went through one of the more tortuous paths to publication, largely because we didn't have any sort of price data, which made the paper less interesting to economics journals. This is where we sent it: World Development (submitted 27 Jan 2012, desk reject, too narrow case study), Environment and Development Economics (referee review), Energy Policy (referee review), Energy (desk reject, too economics focused), Biomass and Bioenergy (revise and resubmit and accept). More than 2.5 years to get it published. But that's not very unusual...

Wednesday, September 10, 2014

Workshop on Research Metrics

I submitted one of the 152 responses to HEFCE's call for evidence on research metrics. BTW, my paper was just accepted by PLoS ONE :) Anyway, HEFCE and the University of Sussex are holding a one day workshop at SPRU on the potential for metrics in research assessment. Register here and see the program here. As I am in Australia, unfortunately I can't attend - I'm actually going to be in England in late October and early November - but maybe some of you can.

Tuesday, September 2, 2014

New Professorial and Research Positions at SPRU, University of Sussex


SPRU (Science Policy Research Unit) at the University of Sussex, UK is embarking on an ambitious new research strategy, focused on long-term transformative change and innovation. As part of this strategy, we are looking to recruit three dynamic, innovative and highly respected academic leaders to join the SPRU team as Professors. In addition, we are seeking to appoint two experienced research staff to join the Research Centre on Innovation and Energy Demand (CIED), led by the Sussex Energy Group at SPRU. The posts are as follows:

Professor of Energy Policy: This person will lead the Sussex Energy Group and will have an outstanding background in energy and climate policy, preferably with an emphasis on innovation and transitions.

Professor in Sustainability Transitions: This person will have an outstanding background in sustainability transitions, history of technology and/or science and technology studies.

Professor in Innovation and Evolutionary Economics: This person will have an outstanding background in evolutionary economics, economics of innovation, institutional economics, economic history and/or development economics.

Senior Fellow in Innovation and Energy Demand: This person will have a strong track record in innovation studies and/or energy and climate policy and will be expected to help shape the Centre’s research programme and design and lead research projects.

 Research Fellow in Innovation and Energy Demand: This person will have a background in innovation studies and/or energy and climate policy and will be expected to design and lead research projects and conduct empirical research.

 Full details of the jobs can be found here: http://www.sussex.ac.uk/spru/newsandevents/apps/jobs

Monday, September 1, 2014

Citation Data for Citation Prediction Paper Now Available

The data underlying my recent working paper: "High-Ranked Social Science Journal Articles Can Be Identified from Early Citation Information" are now available from the ANU Data Repository. The data set includes most journal articles in economics and political science published in 2006 and included in the Web of Science and the number of citations that received each year through 2012. There is also a worksheet with all economics articles from 1999 too. That's not mentioned in the working paper but is mentioned in the revised version of the article I just resubmitted to the journal. The journal's (PLoS ONE) data policy requires all data to be made available with DOI's if possible. This is definitely the current trend and looks like becoming the norm. For example, Energy Economics requires both data and code to be submitted prior to publication. I have mixed feelings about this. Obviously I am in favor of replicability but putting together datasets costs time and/or money and so it seems a bit unfair to force authors to make their data freely available as the price of publication.

P.S. 9th September
My paper was accepted at PLoS ONE! :)

Saturday, August 30, 2014

"Economic Growth and the Transition from Traditional to Modern Energy in Sweden" to be Published in Energy Economics

We started working on this paper when I visited Sweden in September 2010. It took a while till we were both happy with the paper. Then we submitted it to what I think is the top economic history journal. We got a revise and resubmit. I worked hard to do exactly what the referees wanted but the editor rejected the paper. I think this was a first for me. Of course, I had declined to resubmit papers in the past because I thought the chances were better elsewhere. Then we submitted to another economic history journal who gave us a revise and resubmit too. But this time we decided to not resubmit as it seemed unlikely we could please the referees. So, then I submitted the paper to Energy Economics and got a "minor revisions" and now it is accepted. This is a fairly typical story I think in terms of time taken and submissions made.

Sunday, August 17, 2014

Jakob et al. (2012) Revisited

A recent paper by Jakob et al. (2012) finds that there is decoupling between growth in energy use and growth in GDP in developed countries. The authors regress the first differences between five year period means of log per capita energy use on the same transformation of GDP per capita separately for panels of OECD and non-OECD countries. They have 21 OECD and 30 non-OECD countries between 1971 and 2010. They estimate that the elasticity in developing countries is 0.631 (standard error = 0.167) and in developed countries -0.181 (0.343).

I was curious why these results are very different from those in our stylized facts paper where we find a stable monotonic relationship between energy use and PPP GDP per capita over the 1971-2010 period for 99 countries (75 non-OECD, 24 OECD) with an elasticity of around 0.70. Obviously, Jakob et al.'s method is different, their sample is smaller, and they also use market exchange rates. So, I re-estimated their model using our dataset. I find that the elasticity in developing countries is 0.395 (0.081) and in OECD countries 0.479 (0.078). This is in line with our stylized facts results. The numbers are lower probably due to using differences and country and time fixed effects.

In supplementary material, Jakob et al. report that when they use PPP GDP data from the World Development Indicators the elasticity estimates are 0.626 (0.180) and -0.353 (0.474) for non-OECD and OECD countries respectively. I would have doubted that the differences are mostly due to the different source of PPP data  - we used the Penn World Table - but our OECD sample only includes three countries omitted by Jakob et al. So, this will need further investigation.

Reference

Jakob, M., M. Haller, and R. Marschinski (2012). “Will History Repeat Itself? Economic Convergence and Convergence in Energy Use Patterns.” Energy Economics 34: 95–104.

Thursday, August 14, 2014

Revenue-Neutral Carbon Tax with Global Temperature Indexation

The Climate Colab at MIT is running a competition for innovative climate policy proposals. Richard Hobbs is a local contender in this competition. You can support his proposal or make comments here. The winner will get to fly to MIT to present their proposal to US politicians, policy makers, economists, business executives and NGOs. Richard's proposal is a revenue-neutral carbon tax meant as a policy platform for the Republicans to bring forward to the next US election. It is revenue-neutral (cutting capital gains taxes and corporate taxes) and it is temperature indexed (so if climate sceptics are right the price trends to a low level).


Monday, August 4, 2014

Online Accessibility of Scholarly Literature, and Academic Innovation

Kevin Staub presented this paper today at ANU. They download data on all papers in fifty core economics journals over the decades of the 1990s and 2000s during which academic journals gradually went online. They test the effect of the fraction of references cited in article being online on the diversity of references cited. Diversity is measured by the average citation difference between articles in the reference list. Imagine I write an article and in the reference list I cite this paper by Kevin Staub and Martin Weitzman's article on recombinant growth cited by Staub then the distance between those two articles is 1. If I also cite Paul Romer's article "The Origins of Endogenous Growth" cited by Weitzman then the distance between Staub's paper and Romer's is 2 and between Weitzman and Romer is 1. Controlling for time and journal fixed effects and some other control variables they found that there were significant increases in the share of references with distances of 3 or greater the more of the reference list was available online. This seems expected to me as people find it easier to search for literature beyond the reference lists or even the forward citations of articles they have already seen as more of the literature is searchable online.

But the paper contains another result which I found much less expected and much more interesting that I think deserves a paper of its own. They found that papers with higher average distances between items on their reference lists received higher numbers of citations 20, 30, or 40 years down the track than papers with less diverse reference lists. So, this supports the notion that papers that bring together articles that were not previously cited together are more innovative. One might expect papers with more eclectic references to be produced by less professional more dilettantish authors. Of course, these papers were all published in the fifty core economics journals, so that probably acts to filter out the more outlandish papers or papers written by "outsiders" that are doomed to be ignored.


Frank Jotzo Responds to Danny Price

Frank has an op ed in today's Australian Financial Review - responding to Danny Price's op-ed last Wednesday which I also commented on, on this blog, last week. Here is a non-paywalled version of Frank's op-ed.

Sunday, August 3, 2014

Follow Me on Twitter

I'm planning on tweeting all my blogposts from now on, so you can follow me on Twitter. My username is sterndavidi. I've had a Twitter account since 2009 but never really used it much until now.

Friday, August 1, 2014

New ANU Open Access Policy

ANU researchers are now required to submit all published research outputs to our institutional open access repository. Details of the policy are here. Material should be submitted here. Previously, this was on a voluntary basis. Holders of ARC grants would have needed to justify why outputs of their project were not available on an open access basis. As in economics we have a very strong working paper culture this seems unnecessary. But that isn't the case in other disciplines and I guess a one size fits all policy is easier to implement and enforce.

Thursday, July 31, 2014

Direct Action vs. Carbon Pricing

There was an op-ed in yesterday's Australian Financial Review by Danny Price criticising the 59 economists including me who agreed to sign a statement in favour of carbon pricing and praising direct action. First, a clarification. By signing that statement we were not endorsing the previous Labor government's Emissions Trading Scheme. We were simply endorsing some pricing mechanism on carbon. Price criticises carbon pricing because of the "cost to the broader economy of any tax". Here he seems to be referring to the tax interaction effect. Where there are existing distorting taxes,  a new tax interacts with these and increases the costs of the new tax beyond the amount of the direct costs involved with abating pollution. The advantage of a carbon tax is that the revenue from the tax can allow the government to cut existing distorting taxes and reduce of offset this effect. This is known as a "green tax reform" and was much discussed in the so-called "double dividend debate". But imposing a regulatory cap on emissions (and issuing free tradeable permits) results in the same increased costs in the presence of existing distortionary taxes. So, this is why economists generally recommend auctioning emissions trading permits rather than giving them away.* This raises revenue allowing other distortionary taxes to be cut. Direct action is effectively a cap on emissions where the government subsidizes firms reducing emissions through a reverse auction. But this uses government revenue and doesn't allow the cutting of other taxes unless the government budget is cut drastically, which doesn't look like happening. If other spending isn't cut at all then the government will have to increase the existing distortionary taxes. So, direct action is worse than a carbon tax or traded permits on this basis. However, Price says that under direct action the government only imposes one dollar of costs on the economy for every dollar spent. This seems to be incorrect.

On top of that are the problems of the incentives for firms to inflate the baseline from which they claim they will reduce emissions.

So, I'm still in favor of carbon pricing of some sort though I think there are also important problems with emissions trading schemes that only provide a very volatile short-term price signal. The article by Ottmar Edenhofer in the latest issue of Nature Climate Change discusses some of these issues.

* I've argued that the Australian scheme failed because due to objections by the Greens, not enough free permits were given away allowing the scheme to be characterised as a "huge tax". The Australian scheme was less generous than the European scheme. But any such giveaway should be a transitory policy that would be replaced by more auctioning of permits over time.

Wednesday, July 30, 2014

Environmental and Resource Economics Journals

There aren't that many field journals in environmental, resource, and energy economics in the Journal Citation Reports:

REEP and JEEM are clearly the top journals in terms of article influence scores but Ecological Economics dominates the field as measured by Eigenfactor Score or total citations because it is a much bigger journal. JEEM is also ranked 48th among economics journals by Article Influence, so this whole field is not that highly ranked.

2013 JCR Released

The 2013 edition of Journal Citation Reports has been released. I don't like the new interface that was recently introduced and it wasn't obvious how to download data easily but then I discovered there was a button at top right to download everything you had results on at that point without selecting journals individually. So, now I figured that there will be more analysis coming. Anyway, here is the report for PLoS ONE, which is the journal visitors to my blog seem most interested in :)

Yes, the journal lost ground again on all impact metrics as has been expected. It still does fairly well for a journal that publishes so many papers. I have an article under review with submission number 40332 submitted on 16th July. So, using those numbers and last year's number of published articles we get an acceptance rate of 42%, which is likely to be an underestimate if the number of articles published is still rising.

Tuesday, July 29, 2014

Ed Prescott to Speak at ANU

Ed Prescott (Nobel Laureate in Economics) will give the Trevor Swan Distinguished Lecture at ANU on 13th August. The lecture will be titled: Neoclassical Growth Theory: From Swan to Now. The blurb says:

"The Swan 1956 growth model is the cornerstone of secular growth theory. To broaden the model to encompass aggregate business cycle fluctuations Kydland and Prescott added an aggregate household to explain investment- savings and labor-leisure decisions. With this addition, neoclassical growth theory came into existence. Extensions of this theory have proven successful in the study of stock markets, growth miracles, prosperities and depressions, alternative tax policies, and differences in aggregate labor supply across countries and time. Deviations from the predictions of this theory are puzzles to be resolved and their resolutions have advanced neoclassical growth theory."

Unfortunately, I have to teach at that time, but I am hoping it will be recorded and some people will ask some good questions. Some of Prescott's work on growth is pretty fundamental to our current research on economic growth and economic history.

Friday, July 25, 2014

Future of Solar

At the workshop in A Toxa I attended in late June, Richard Schmalensee presented findings of a yet to be released MIT report on the "Future of Solar". This will be part of their series on the future of energy. He was skeptical of how much of a role solar can play any time soon in addressing the climate issue. It's not clear that the costs of solar can come down a lot more when most of the costs are now in the non-silicon components. There is also the issue of rare materials needed for alternatives to silicon. Then there is the intermittency / storage issue. Yes, we keep hearing about storage breakthroughs, but they aren't yet commercial products. And even when they will be they will add further huge costs to the cost of solar. There is a need for new transmission infrastructure to the renewable locations. Electricity markets may need to be reformed again to handle the intermittent new renewables effectively.  Back in April, I noted that Ottmar Edenhofer stated that there was an increasing realisation of the difficulties of integrating renewable energy on a large scale into electricity supply systems. These are some of the issues alluded to and the reason that CCS and other alternatives are getting renewed consideration.

Essential Concepts of Global Environmental Governance Now Available

This book, which I contributed an entry on the EKC to, is now available from Routledge. There are some nice blurbs from well-known people:

"This volume provides an essential glossary of critical terms and concepts in the field of international environmental politics for diplomats, analysts and students. The interdisciplinary array of expert authors provide terse and authoritative overview of the key concepts and debates that have defined the field of international environmental governance over the years. The entries carefully survey the intellectual ecosystem of the concepts applied to understanding and managing our global environmental crisis." –Peter M. Haas, Professor of Political Science, University of Massachusetts Amherst, USA

"In a truly unique way, this book helps to connect the dots and navigate between the concepts, ideas and schools of thought in global environmental policy today. As environmental issues climb higher on the global agenda, I would highly recommend this book to all who wish to better understand the insights of sustainable global governance." –Connie Hedegaard, European Union Commissioner for Climate Action

"The global community is at a crossroads in respect to addressing climate change. A solid understanding of global environmental governance empowers people to better shape positive democracy that determines a safer future. This book makes a valuable contribution to societal understanding and societal change. Those who care about the world we leave to our children should take inspiration from its many and varied contributors drawn from so many disparate but interlocking disciplines." –Christiana Figueres, Executive Secretary, United Nations Framework Convention on Climate Change 

Henriques PhD Dissertation on the Energy History of Portugal Now Available on the Web

Sofia has posted her dissertation to Academia.edu. It includes the data. She studied in Lund with Astrid Kander and is now at the University of Southern Denmark.

Thursday, July 24, 2014

Latest Journal Metrics Released

Elsevier have released the latest edition of their journal metrics - SNIP and SJR. There is also a new metric - Impact per Publication (IPP), which is just a simple three year impact factor. This time the Energy Journal has an SJR (1.533) but still no SNIP. That makes it the 120th ranked journal in economics. Energy Economics ranks 89th with an SJR of 2.025, and Resources and Energy Economics at 151st with an SJR of 1.274. There are 890 economics journals. Ecological Economics is 98th (SJR=1.91). The QJE is the top ranked economics journal (SJR=25.2), Econometrica is second (18.9), and Journal of Political Economy is third (18.5).

A Toxa Meeting Website

The website with links to recordings of all the presentations at the 6th Atlantic Workshop in A Toxa is now up. I presented our paper on modelling the emissions-income relationship using long-run growth rates. There are also a few pictures. I'm somewhere in the back row in this one:

Tuesday, July 22, 2014

Call for Papers: 2015 IAEE International Conference in Antalya

The call for papers has been released for the 38th International Conference of the IAEE in Antalya, Turkey in May 2015 (25th-27th). The conference will be held at a golf resort. Deadline for abstract submissions is 19th December.

Global Growth Rate of GDP and Energy Use

Another slide from Wednesday's opening lecture. It shows the tight correlation between the annual global economic growth rate and the growth rate of energy use. In all but one year, energy use grew more slowly than GDP implying a decline in energy intensity. That year was 2010 - the year of strong rebound growth in the global economy and energy use following the Great Recession in the US and Europe. We analysed these movements in our short 2012 paper in Nature Climate Change.

Top Twenty Carbon Emitters, Coal Consumers, and Coal Producers

Some slides from my upcoming introductory lecture for my Energy Economics course:

This slide uses CDIAC data on the top twenty countries by emission of carbon dioxide globally in 2010. Carbon dioxide emissions here include only those from fossil fuel combustion and cement production. I also have summed up the emissions from the European Union and added it as if it was a single country (as the EU negotiates as a bloc) in addition to including all its member countries in the ranking. The three big emitters stand out clearly from all the rest. Emissions are measured by mass of carbon. To get carbon dioxide multiply by 3.66.

Of course, coal use is a big driver of CO2. This chart shows how China consumers so much more coal than any other country and after the US and India, the rest look pretty inconsequential.
On the whole, coal is consumed where it is produced with two important exceptions - Indonesia and Australia - the two biggest coal exporters. China produces the overwhelming majority of the coal it uses despite large imports. The majority of Australian exports are coal for iron smelting, so-called "metalurgical coal".

Malthusian Trap

Some interesting blogposts from Nick Szabo on the Malthusian trap and the breakout to economic growth. Follow the link in the post back to previous blogposts.


Monday, July 21, 2014

Big in Japan

I don't think our book will be big in Japan even, but it's nice to see a flyer for it in Japanese :)


I am now back in Canberra finally and catching up with teaching prep and looking at the books that Elgar sent us as payment :P An interesting one is The Art and Practice of Economic Research, which Shuang selected for me from Elgar's catalogue. Twenty five leading economists were asked almost exactly the same questions about various aspects of their career and worklife. It's reassuring to read that many top researchers confess to bad time management and feeling overwhelmed, for example: "What I am doing is not even feasible let alone optimal".

In other news, we have quite a few new CCEP working papers on RePEc. I hope to do a bit more blogging in the near future if only based on material from revising my energy economics lectures.

Monday, July 7, 2014

Economists Statement on Carbon Pricing

My name is included in the list of economists supporting a statement on carbon pricing released by WWF Australia. The statement is a little vague I think to maximize the number of people who would be willing to sign up. I think a price on carbon is a very useful part of a climate change policy. It can provide an incentive for finding cost-effective solutions, which otherwise might not be found. I favor a carbon tax now over emissions trading but the statement leaves that open. This seems to be where mainstream opinion is now heading.


Thursday, July 3, 2014

Help Fund a Cool Research Project



Pun intended :) A bit off the beaten path for this blog, but I did warn you it would be a random walk. Faruk Kececi is an online friend who unfortunately wasn't in Istanbul the week we visited. You can contribute money on Kickstarter.

Monday, June 30, 2014

World Congress of Environmental and Resource Economics


I am, like almost 1200 other participants, at the WCERE in Istanbul. Yesterday there was an interesting panel session on climate change with Jeffrey Sachs, Ottmar Edenhofer (who is apparently meeting the Pope today), Marianne Fay from the World Bank,  Laurence Tubiana - the new French climate change ambassador - and Carlo Carraro as chair. All the participants agreed that the new framework for climate change policy that will be established at Paris next year must make a break from previous agreements and pledges in consisting primarily of designing long-term transformation pathways rather than primarily short-term targets. Obviously, short-term steps will still be needed. The thinking behind this was best expressed by Marianne Fay. She showed a slide with a picture of the Freedom Tower in New York and a small cottage side by side. She asked: "If you wanted to build this tower, would the house on the left be a reasonable first step?" Similarly, we could ask whether shifting to natural gas is a reasonable first step to decarbonizing the economy. A long-term perspective is needed. Jeffrey Sachs made a point that spot carbon markets aren't an appropriate tool for long-term climate policy. The short-term price keeps fluctuating and there is no long-term futures market. Instead a predictably rising carbon tax is needed. Technology policies are also needed to complement the carbon price. The consensus is that this is where we should head.

Thursday, June 26, 2014

Canberra is the Best Place to Live in the World According to the OECD

Australia is the best country and the ACT is the best region in Australia. I checked the OECD website, and giving equal weight to each of the criteria the OECD ranks, the ACT is the highest scoring region in the world. Of course, that is not how most Australians see it. I met an Australian woman at JFK airport last week while waiting to take the train and she asked me where I lived. When I answered: "Canberra", she said: "Why would you do that to yourself?"


Wednesday, June 25, 2014

Follow Up on "Energy and Economic Growth: The Stylized Facts" at Econbrowser

James Hamilton has a new post on Econbrowser based partly on our paper Energy and Economic Growth: The Stylized Facts which I recently presented at the IAEE meeting in New York. I'd add that oil use has been flat in recent years but that was compensated for by increases in the use of natural gas, coal, and renewables. So, recent data don't substantially deviate from our stylized fact.



Today, I arrived at A Toxa, an island in Galicia, in the northwest of Spain. It is really beautiful here. Tomorrow the 6th Atlantic Workshop on Energy and Environmental Economics
starts here. I am giving a presentation in the final session tomorrow on our paper on modeling the emissions-income relationship using long-run growth rates.

Thursday, June 19, 2014

High-Ranked Social Science Journal Articles Can Be Identified from Early Citation Information

I have posted a new bibliometric working paper , which investigates how well we can predict future cumulative citations from the first citations received by a paper in the disciplines of economics and political science.

It is usually assumed that citations accumulate too slowly in social sciences apart from psychology to be useful for short-term research assessment. For this reason, the Australian Government’s Excellence in Research for Australia (ERA) exercise, which attempts to assess the research quality of universities in the previous 5 years, uses peer review in social science disciplines apart from psychology for this reason but uses citation analysis for psychology and all natural sciences. This peer review process seems to me to be a wasteful duplication of effort to review research outputs that have already passed through a peer review process once.

I show that, surprisingly, citations received by journal articles in the social sciences in the first one to two years after publication are strongly predictive for citations received in future years. By contrast, I show that journal impact factors are mostly useful in the year of publication and their contribution to predicting citations declines rapidly thereafter.

If it is actually possible to predict citations fairly reliably in social science disciplines, then it should also be easy to predict them in the natural sciences. This means that it should be possible to expand bibliometric analysis in research evaluation exercises to all disciplines apart from the humanities and arts. It also means that we should pay attention to the early citations received by papers when we evaluate individual academics for hiring and promotion. Impact factors are reflective of journal selectivity, which we frequently do not have easily available data on. But they only explain about 16-17% of the variation in rankings of papers six years later conditional on the citations already received in the year of publication. The latter explain 13-14% of the variation. But at the end of the year following publication, accumulated citations explain 52-53% of the variation in cumulative citations after 6 years and 73% at the end of the second year after publication.

These models could be improved by adding information on the characteristics of the articles themselves and their authors, but that was much too time consuming to do for the almost 12,000 articles in my sample.

I have submitted a copy of my paper to the HEFCE inquiry on the use of metrics in research assessment.

Energy and Economic Growth: The Animated GIF

It seems that everyone loves the animation of energy use per capita and GDP per capita that I am showing as part of my presentations on Energy and Economic Growth: The Stylized Facts. So, at James Hamilton's suggestion and with Zsuzsanna's help I have made an animated GIF of this slide sequence:

The graph is for the 99 countries that have data in both the Penn World Table (7.0) and the IEA Energy Balances. The line is the best fit log-log regression computed by Excel. As you can see the relationship between these two variables has been very stable over the last forty years globally.

Wednesday, June 18, 2014

World Energy Use Increased 2.3% in 2013

The annual BP Statistical Review was just released. It shows that world energy use increased by 2.3% in 2013. According to the IMF, the world economy grew 3% in 2013. World population is growing at about 1.1% p.a. Therefore, there was a 1.2% increase in per capita energy use for a 1.9% increase in GDP per capita - a ratio of 0.63 - which is a little below our stylized fact that energy use tends to increase by 0.7% for a 1% increase in GDP.

Tuesday, June 17, 2014

Environment and Development Economics is 20 Years Old

And there is a special issue to celebrate. You can find the introductory article from the editors here. One of my tasks as a post-doc at University of York was helping my boss, Charles Perrings, with the administrative tasks for the new journal like sending invitation letters to the editorial board members. It's also 20 years since I got my PhD - my defence was in April 1994 - I started the post-doc at York as an "ABD" in September 1993. Time flies!

Right now I'm at the IAEE meeting in New York City, will be going on to the Atlantic Workshop in Spain next week and the World Congresss of Environmental and Resource Economics in Istanbul the following week. Not surprisingly, the main talk here is about shale oil and gas and their implications. Flying over Pennsylvania on Sunday I saw quite a few drilling sites...

Saturday, June 7, 2014

Friday, June 6, 2014

The Environmental Kuznets Curve: A Primer

I've updated my article on the environmental Kuznets curve that appeared in the Encyclopedia of Energy in 2004. The revised version will be available as part of Elsevier's Online Reference Database: Earth Systems and Environmental Sciences. I've also posted a working paper version of the article titled: The Environmental Kuznets Curve: A Primer. Despite all the papers that have been published on the topic in the past ten years, I don't think my main messages have changed much. Increases in income tend to increase emissions per capita but time related and other effects can reduce emissions. On the other hand concentrations of some local pollutants are reduced by income increases. The section on theory is a bit more optimistic than I was in 2004 but I think there is still opportunity to develop a comprehensive theory of how income and emissions evolve. I also write in the conclusions that recently developed econometric methods have also only been applied to analyze a couple of well-known pollutants. Therefore, I expect that in coming years this will continue to be an active area of research interest. The emerging issue of how emissions evolve over the business cycle is also likely to be an area of expanding research.



Thursday, June 5, 2014

Energy and Economic Growth: The Stylized Facts

I contributed an article to the IAEE Energy Forum as part of their report on the New York City conference of IAEE. The topic of our paper that I will present in New York on 16th June is "Energy and Economic Growth: The Stylized Facts". The full paper is available as part of the conference proceedings. This has been a project under development for a while, being the subject of my "foundation seminar" (=inaugural lecture) here at Crawford School. Things progressed further once Zsuzsanna Cserekylei put a consistent dataset together for the 1971-2010 period and did the analysis. Then Mar Rubio contributed historical data and analysis. Anyway, this is the text of our article:

What overall patterns, or stylized facts, characterize the relationship between economic growth and energy use both across countries and over time? Energy economists and economic historians have investigated these issues, but existing research has either looked at how energy use and economic development vary across countries at one point in time or how they evolve over time in individual countries or groups of countries. Researchers have not linked together the cross-sectional and time series behaviors despite their obvious dependence on each other.

We investigate the links between the time and cross-sectional (or income per capita) dimensions using two datasets. One is a dataset for 99 countries from 1971 to 2010 that uses IEA and Penn World Table data. The other comprises historical data for the U.S. and a number of European and Latin American countries that extends back to 1800 for the U.S. and some Northern European countries and to later dates in the 19th and early 20th century for the other countries.

In recent years, economic historians, including one of the authors of this paper, Mar Rubio, have been working to reconstruct the energy history of many countries in Europe and the Americas for the years before the Second World War. Some of the historical data we use was prepared for the recently published Power to the People, authored by Astrid Kander, Paolo Malanima, and Paul Warde and published by Princeton University Press. Mar Rubio collaborated with Kander et al. on the Spanish data for that volume and led a team that developed historical data for Latin America. Though these data are obviously much more uncertain than those for recent years, they can provide insights into the long-run relationship between energy and economic development.

Our key finding from the recent data is that there has been a fairly stable relationship between countries’ GDP per capita measured in purchasing power parity adjusted Dollars and their per capita energy use over the last 40 years. A 1% increase in income per capita across countries is associated with a 0.7% increase in per capita energy use. This implies that energy intensity (energy use/GDP) is lower in richer countries and that on average a 1% increase in income per capita is associated with a 0.3% decrease in energy intensity.

The relationship is also stable in the sense that the average energy use per capita associated with any given level of income per capita has not changed over the four decades. This means that the typical country only managed to reduce its energy intensity by increasing its income per capita. A different way of looking at the same data is to compare countries’ average GDP per capita growth rate from 1971 to 2010 to the rate of change in their energy intensity over the same period. This relationship is shown in Figure 1:


The graph shows that higher rates of economic growth are associated with higher rates of decline in energy intensity. The graph also shows that if a country’s economic growth was zero then not only did its energy intensity not decline, but actually it increased on average.

Figure 1 also indicates that there are many countries where energy intensity rose despite economic growth. Our second main finding is that there was convergence in energy intensity over time and that the countries whose energy intensity rose typically had low energy intensity at the beginning of the period. Countries that were very energy intensive typically saw declines in energy intensity. There is now a tighter relationship between income and energy use than there was forty years ago.

In other words, though there has been some degree of “decoupling” of energy and growth in some formerly energy intensive economies, this has not been the common experience. Rather, there has been a homogenization, with countries increasingly resembling each other, while energy intensity globally has declined, but not by enough to reduce energy use.

This picture is borne out in the historical data too. Figure 2 shows the evolution of energy intensity and income over the last two centuries for four representative countries. Energy intensity appears to have declined the most in the United States, which was the most energy intensive economy in the 19th Century. On the other hand, energy intensity has been fairly stable in Spain, which was a very low energy intensity economy in the 19th Century. These time-paths are superimposed on the global distribution of energy intensity and income in 2010. This shows that in the past the United States was more energy intensive for its income level than any countries are today but that in the last few decades it has ceased to be remarkable in that way. On the other hand, the time paths of Sweden, Brazil, and Spain are mostly within the present day energy intensity distribution.


Our paper in the online proceedings also covers other regularities in the data. Specifically, there is some evidence that the share of energy in costs declines over time. But this “stylized fact” is still more of a prediction than a proven regularity. As is well known, the quality of energy increases over time and with income as countries have transitioned from traditional biomass, to fossil fuels, to primary electricity over time. We also find that the energy/capital ratio, which is an alternative to energy intensity as an indicator of overall energy efficiency, behaves somewhat similarly to energy intensity.

Future theoretical models of the relationship between energy use and economic development will need to take these stylized facts into account and make sure that their predictions match the facts. The stylized facts might also be useful for developing simple business as usual energy use scenarios.

Asia and the Pacific Policy Society

The Asia and the Pacific Policy Society is an academic society set up in association with Crawford School's flagship journal, Asia and the Pacific Policy Studies. Joining the society is free.

Sunday, June 1, 2014

First Issue of JAERE is Out

The first issue of the new Journal of the Association of Environmental and Resource Economics has now been published. A mix of different topics and some big names, though not as many as one might expect for the first issue of a new journal.

The Relationship Between per Capita Energy Use and Income per Capita Has Been Very Stable

First preview of the paper that I will be presenting at the IAEE meeting in New York in a couple of weeks. Using Penn World Table 7 data for GDP per capita and IEA data for energy use, we (me, Zsuzsanna Csereklyei and Mar Rubio) found that the relationship between energy use per capita and income per capita has been very stable from 1971 to 2010 for a group of 99 countries. I've prepared an animation that shows this relationship. Just click through the pages in the pdf to see what happens as countries have grown (or not) over time.

Thursday, May 29, 2014

Elsevier Article Usage Dashboards and Tips for Early Career Researchers

The new article usage dashboards are a nice feature of Elsevier journals. Here is the dashboard for my 2013 article in Energy Economics:

It's interesting to see where our paper is being downloaded. China is in the lead. Obviously there are a lot of downloads in Sweden and Australia as the authors are Swedish and Australian and the data is Swedish. Also, there are a lot of downloads in Turkey, which has a lot of researchers in energy economics.

There is also a link in the Dashboard to a page with lots of useful guides for early career researchers. Some of the advice will also be useful for more senior researchers looking to get greater impact from their publications.

Reforming IPCC Communications

The IPCC is currently discussing whether to change its approach to publications and communications in future years. We (Frank Jotzo and I) were asked about our opinions as former lead authors by the people in the relevant government departments here. It seems to make sense to have more of a continuous reporting model given the capability of the web. Perhaps each chapter could be updated one at a time on an ongoing cycle or even a Wikipedia style format could be adopted. On the other hand, the large septennial assessment reports do generate a big media splash for a few days when they are released, which the continuous communication format would not. If assessment reports are continued, then maybe they should all be released simultaneously, or each Working Group release its report 2 years apart. The 5th assessment report cycle saw WG1 release its report in September 2013 and then WG2 and WG3 released their reports two weeks apart in April 2013, which was somewhat confusing. We also thought that the IPCC plenary should be less prescriptive about the contents of each chapter including sub-sections and what should be in each subsection.

COIN in the UK have released a short report with some more radical suggestions. In particular, they think the IPCC should do human interest stories that are more suitable for most media outlets and use social media more effectively.

Wednesday, May 28, 2014

Australian Energy Intensity Decomposition

This post is based on part of a presentation that I gave yesterday in a short course here in at ANU. Australia has improved its energy intensity over recent decades but the gains have been quite small. My research suggests that adjusted for industrial structure etc. Australia is relatively energy inefficient compared to other developing countries. The following graph removes all these other factors, resulting in a measure of "pure" energy efficiency:


A declining trend implies increasing energy efficiency. I advised Muhammad Shahiduzzaman on his PhD research at the University of Southern Queensland. Subsequently, he published a paper in Energy Policy on decomposing Australian energy intensity. The following graph from the paper shows the effects of structural change at two levels of aggregation on Australian energy intensity:


The shift between the larger sectors helped reduce energy intensity but the shifts between smaller categories of industries tended to increase energy intensity. Real intensity is the residual energy intensity once the structural effects are removed. The Australian Bureau of Resource and Energy Economics has also carried out research on energy intensity trends and decomposition. The following graph shows the decomposition for the transport sector in Petajoules:


The activity effect here is the energy use increase due to increased passenger and tonne kilometres for passenger and freight transport respectively. Structural change - shifts between road, rail, air etc. contributed very little. There was a substantial efficiency improvement but it was outweighed by the large increase in activity resulting in a substantial increase in energy use in the sector. The final graph in this post, shows the decomposition for the residential sector in Australia:

In this decomposition, the activity effect is the increase in energy use due to increased  population. The BREE researchers defined the structural effect as due to larger houses, smaller households etc. I think it is debateable as to whether this should be considered structural change rather than change in the level of activity. In any case the efficiency improvement is of the same order as either the activity or structural effect and so energy use increased here too.

Tuesday, May 27, 2014

Modeling the Emissions-Income Relationship Using Long-Run Growth Rates

We have a working paper out on a new way of modelling the relationship between emissions and GDP per capita, a literature that has been dominated for more than two decades by the environmental Kuznets curve (EKC) approach. I presented an early version of this paper at the AARES conference at Port Macquarie in February. I will also be presenting it at the 6th Atlantic Workshop in A Toxa, Spain in late June and then at the World Congress of Environmental and Resource Economics in Istanbul a few days later.

The paper emerged from our work on Chapter 5 of the recently released Working Group III volume of the IPCC 5th Assessment Report. Reyer Gerlagh, who was one of the coordinating lead authors on my chapter drew up a version of the following graph and asked me if it would be suitable for the section I was writing on economic growth and emissions:

 

I liked this graph so much that I said we should write a paper about it, which we have now completed. Rather than compare the levels of emissions and GDP per capita as is usually done in the EKC literature, the graph compares the average growth rates of these two variables over a 40 year period (1971-2010). We can see that faster economic growth is associated with faster carbon emissions growth but that there is also a lot of variation around this main trend in the data. The further "southeast" a bubble is, the faster emissions per dollar of GDP (emissions intensity) declined in that country. As you can see China (the big red circle) and the US the big blue circle both had rapid declines in emissions intensity. But emissions intensity also rose in many countries and it is not immediately obvious how it relates to development status.*

One of the nice things about using growth rates rather than levels of variables is that it avoids several econometric problems that have plagued this literature. First and foremost is the issue of unit roots and non-linear functions of unit roots raised by Martin Wagner. Differencing the variables removes that issue, but using long-run growth rates focuses attention on long-run behavior, whereas using first differences would focus on the short-run. Then there is the issue of time effects raised by Vollebergh et al. We think our approach does a good job there too. The constant in a regression of emissions growth rates on income growth rates represents the rate of emissions growth if there were no economic growth. We think this is a good definition of a time effect. The paper discusses further econometric issues.

The other nice thing about using growth rates is that we can test the three main leading approaches to modelling the emissions-income relationship in a single framework:


In this equation all variables are in logs and "hats" (or more elegantly circumflex accents) indicate growth rates. On the lefthand side is the emissions per capita growth rate. As mentioned above the constant, alpha, represents the time effect. G-hat is the growth rate of GDP capita. The estimate of beta(1), therefore, tests the IPAT theory that growth causes increases in impacts. The term beta(2)*G(i) tests the EKC theory. This is because if beta(2) is negative then beyond a certain income level (the "turning point") more growth reduces emissions rather than increases emissions. The other main approach to modelling emissions growth has been the convergence approach, including the Green Solow Model of Brock and Taylor. We test this with the fourth term in the regression, which is the level of emissions intensity in the first year of the sample. If delta is negative, then countries with high initial emissions intensities saw more rapid decline in emissions. We also test for any effect of the level of GDP (gamma*G(i)) and for various other exogenous variables including fossil fuel endowments, legal origin, and climate.

It turns out that for both carbon and sulfur dioxide the effect of growth is very significant and close to a one to one effect. For sulfur there is a significant time effect - emissions fell by about 1.2% a year for a typical country when there was no economic growth. The convergence effect is also highly significant and probably explains a lot of the reduction in emissions intensity in both China and the US. But there is no environmental Kuznets curve effect in the full sample estimates.** While there is a marginally significant coefficient for one dataset, all the turning points are far out of sample and insignificant.

The environmental Kuznets curve has become so iconic that it often appears in introductory environmental economics textbooks. It probably is valid as a stylized fact for urban air pollution concentrations but it's not a good model of emissions of either carbon dioxide or sulfur emissions. We're hoping that the figure of the growth effect above and this one of emissions convergence:

might replace it.

* The blue circles are the developed countries that were members of the OECD in 1990. Orange is "economies in transition"  - Eastern Europe and the former Soviet Union. The other colors are the developing regions in Asia, Latin America, and the Middle East and North Africa.

** When we split the sample into two periods we find a very significant coefficient for sulfur in the second period, but the turning point is at $38k and is not statistically significant.


Saturday, May 24, 2014

Is Piketty's Work Flawed by Computational Errors Too?

The Financial Times claims that, like the work by Reinhart and Rogoff on debt and growth, Piketty's research on changes in inequality over time is also beset by computational errors. Though the theoretical component of Piketty's book has been controversial but as the article says, the critics have still praised the historical research. The biggest differences seem to be in estimates of wealth inequality in Britain in recent decades. The data the FT correspondent provides shows no increase in concentration in wealth in the top 1% and top 10% in the UK in recent decades. That would weaken Piketty's conclusions overall, but it doesn't seem it destroys them. Piketty's response is here.

Friday, May 23, 2014

Unionization in Australian Universities


After seeing that Alison Booth's paper from the Quarterly Journal of Economics was the most downloaded paper from ResearchGate at Crawford this week, I was curious what fraction of employees at Australian universities belonged to the National Tertiary Education Union. Apparently NTEU has 26,000 members. It also seems that there are 113,000 employees in the university sector. On that basis the unionization rate would be only 23%. Of course, quite a lot of those are casuals or PhD students working as lecturer A etc.* But the total number of full-time staff is 86,000. That implies 30%. Also there were 67,933 staff on continuing contracts. If the latter is the real target market for the union then the rate is 38%. Based on this, social custom doesn't work well in the university sector to overcoming free-riding. Let me know if any of my assumptions are wrong as this is the first time I've ever looked at this issue.

* There were 41,730 academics at levels B and above, but the union also represents non-academic staff.

Thursday, May 22, 2014

Regional Kaya Identities

As well as the global Kaya identity, Chapter 5 of the WGIII IPCC report also includes regional Kaya identity graphs:


OECD-90 are the countries that were members of the OECD in 1990 and are considered to be the "developed countries" for the purpose of this study. Economies in Transition are the former Soviet Union and formerly centrally planned Eastern European economies. The remaining countries are the developing world and are split into three geographic regions.

We drew the graph for each region with the same y-axis scale so that the huge differences in growth rates between regions would be more apparent. GDP per capita grew by far more in (developing) Asia than anywhere else and grew least in the Middle East and North Africa. But emissions grew the second most in the latter region mainly because population grew fastest in that region but also because, unlike other regions, energy intensity rose over time. Emissions growth was also quite strong in Latin America because energy intensity did not decline much there. Both these regions had low energy intensity at the beginning of the period. The global pattern in changes in energy intensity reflects convergence across countries in energy intensity.

Tuesday, May 20, 2014

The Global Kaya Identity

Another post on our chapter in the recently released Working Group III IPCC report, Chapter 5. I previously posted on what got left out of the final edition of the Summary for Policymakers and on the key messages from the whole report.

A key feature of our chapter is that we organized it around the idea of the Kaya Identity, which is an extension of the famous IPAT identity to explain changes in carbon emissions:


or in terms of formulae:


Sections of our chapter deal with each of the terms in the identity. It's important to understand that the identity is not really a causal relationship. A 1% increase in GDP per capita might be associated with less than a 1% increase in carbon emissions if energy intensity for example declines as a result of the increase in income. This seems to be the case in fact as our upcoming research will show. Still, it is a useful accounting framework for understanding the factors driving change. If the other terms in the identity are held constant then a 1% increase in any of the right hand side factors increases emissions by 1%.

In the technical summary we use the Kaya identity to decompose the changes in global energy related carbon dioxide emissions for each of the last four decades:


The bars show that reductions in energy intensity have contributed to the slowing in growth in carbon emissions. However, this has been overwhelmed by the increase in population and income per capita. This exercise made me much more aware of how important population growth has been in driving emissions growth over the last 40 years. In the most recent decade, though, income per capita growth became the most important factor and emissions growth accelerated to a record level.

13 Years On Our Book Becomes an E-Book!

The book was published in 2001 but the conference it is based on was held in Boston in 1996! Anyway, the e-book is now online and the introductory chapter is open access.

Thursday, May 1, 2014

Submissions to AJARE Way Up, Acceptance Rate Way Down

Really interesting data from the editors of the Australian Journal of Agricultural and Resource Economics. It's unusual to see time series stretching back 15 years of submissions, acceptances, articles published etc. for a journal. The page budget today is slightly higher than in 1999 but less than what it was in 2000. The number of articles published though actually doubled. But submissions tripled. In the last year half of new submissions have been desk rejected.

Wednesday, April 30, 2014

First Invited Paper Published in Energies Special Issue

I am the editor of a special issue of the open access journal Energies. The special issue is on energy transitions and economic change. I'm happy to announce that the first paper that I invited for the special issue has now already been published. It is by Steve Sorrell and is on the rebound effect.
The first contributed paper has also been published. Others are still in the peer review process and a few we also already rejected.

The model for these special issues is that the editor invites a number of people to contribute papers and there is also a general call for contributions. The journal is publishing papers as they are ready but you can still submit papers up to the 15th July deadline.


Saturday, April 26, 2014

Natural Resources and Economic Growth

Carlo Carraro, Marianne Fay, and Marzio Galeotti call for mainstream macroeconomics textbooks to talk about the role of natural resources in economic growth and development. This is something that ecological economists have been calling for 25 years plus. But it is good to see more people getting on board. I wonder though how much consensus there is on what we should teach students about this.

Summary by Policymakers

Robert Stavins comments on his blog that given the outcome of the IPCC SPM approval meeting in Berlin the report should be called the "Summary by Policymakers" rather than the "Summary for Policymakers". For more commentary on the process see my article in The Conversation and this commentary in Science.

Thursday, April 24, 2014

New Article in The Conversation

Michael Hopkins, an editor at The Conversation, suggested I follow up my blogpost on the IPCC 'censorship' controversy with a piece in The Conversation. That article is out today. The censorship story has also been picked up on by Science magazine.

If you are wondering whether to contribute to sites like The Conversation, I think it is well worth it, though it is a bit more work than I usually put into a blogpost. My blogpost last Thursday on the censorship issue has received 210 hits so far according to Google. People who just navigated to my home page rather than selecting the article title aren't counted, but probably don't amount to a huge number of additional views. Our 13th April article in The Conversation has got 4720 hits so far and my previous two articles there have gotten 1681 and 1859 hits each. Three of my blogposts have exceeded those numbers (11-13000 hits) and they are all about PLoS ONE and impact factors. My next best blogpost is this one with 1666 hits. Typical numbers are in the low hundreds if I'm lucky. So, I can get much more reach on a site like The Conversation than a typical post on my blog about my own research achieves. Of course, not all stories are going to be suitable for sites like these, but it's worth thinking about what might be suitable.

Tuesday, April 22, 2014

More Debate on the Little Ice Age

Back in 2010, I discussed a paper by Kelly and O Grada on the Little Ice Age. Or rather, on the lack of a Little Ice Age. Commenters on the thread including O Grada have pointed out that that debate has made some progress in the last few years. The authors published a paper in the Journal of Interdisciplinary History, which was part of a special issue on the topic. Now, they have followed up with a response to their critics' articles from the special issue.


Thursday, April 17, 2014

Chapter 5 and the Summary for Policy Makers

Chapter 5 was one of the main chapters of the Working Group III 5th Assessment Report at the centre of the controversy this week on so-called censorship of the Summary for Policy Makers (SPM). The SPM is an executive summary of the report for the IPCC member governments. Those member governments get to dictate what points from the underlying report get included in this summary and how they are "spun". However, there is also a Technical Summary that is written entirely by the researchers responsible for the main report. The material from Chapter 5 that was in the draft SPM but eliminated in the plenary meeting in Berlin referred to emissions from specific groups of countries. This blogpost provides a quick overview of the deleted figures, some of which are still in  the Technical Summary.

The first graph breaks down emissions by broad global regions:

The developed countries are represented by the members of the OECD as it stood in 1990 (since then Mexico, Korea, Czech Republic etc. have joined). Eastern Europe and the former Soviet Union are designated "Economies in Transition" and the developing world is broken down into Asia (importantly including China and India), Latin America, and the Middle East and Africa. The left-hand panel shows emissions year by year since the Industrial Revolution and also breaks them down into energy and industrial and land use related emissions. The former continue to increase but the latter appear to have peaked. Since the 1970s, the majority of growth in energy and industrial emissions has come from developing countries and particularly Asia. In an attempt to better represent the historical responsibilities of each group of countries the right-hand panel shows the cumulative historical emissions of greenhouse gases by region.* China and particularly India have campaigned to get historical contributions to global warming better-acknowledged. But the results of our analysis show that less than half of the cumulative emissions now come from the developed countries as a whole (more when only energy and industrial emissions are considered). This, presumably, isn't the message that developing country delegates wanted to see.

The next controversial figure breaks down total and per capita greenhouse gas emissions by country income groups:


The leftmost panel shows total emissions which increased everywhere due to population growth. But they particularly increased in upper middle income countries (which includes China). The total emissions from this group are now almost equal to that from the high income countries. On a per capita basis, emissions were flat in the developed world and declining in the poorest countries (as emissions from land use declined). They rose in the middle income countries. The figure does, however, also show that in all developing country groups per capita emissions remain much below those in the developed countries.

The final deleted figure deals with emissions embodied in trade:


Looking at the emissions generated in producing imports and exports, the developed countries and economies in transition ("Annex B") import more "embodied" emissions than they export. The opposite is true of the developing countries ("Non Annex B"). Emissions that include the net emissions embodied in trade are termed "consumption emissions" in contrast to the "production emissions" that are the total emissions emitted within a country and are the usual way of calculating emissions.** These numbers are derived using input-output modelling. The results are often used to argue that developed countries have reduced their emissions by offshoring production to developing countries, which is a controversial question. But properly answering this question is more complicated than this. They are also used to claim that developed countries are responsible for their consumption emissions rather than their production emissions. But both importers and exporters gain from this trade. Because of these controversies I can understand the decision to drop the discussion and figure from the SPM.

* These do not directly correspond to the amounts of gases in the atmosphere. A large fraction of annual carbon dioxide emissions are absorbed by the ocean, vegetation etc. and methane only survives for an average of 11 years in the atmosphere before being oxidised to carbon dioxide and water. So, I am not very enthusiastic about treating cumulative emissions of carbon dioxide equivalent greenhouse gases as an indicator of historical responsibility.

** Economists would usually use the term "production emissions" to refer to emissions from production activities  and "consumption emissions" to refer to emissions by consumers. This initially caused some communication problems among researchers from different disciplines in our chapter team.