Friday, March 11, 2016

Economic Growth and Global Particulate Pollution Concentrations

I have just posted another working paper in the Trends and Drivers series, this time coauthored with recent Crawford masters student Jeremy van Dijk.

Particulate pollution, especially PM2.5, is thought to be the form of pollution with the most serious human health impacts. It is estimated that PM2.5 exposure causes 3.1 million deaths a year, globally, and any level above zero is deemed unsafe, i.e. there is no threshold above zero below which negative health effects do not occur. Black carbon is an important fraction of PM2.5 pollution that may contribute significantly to anthropogenic radiative forcing and, therefore, there may be significant co-benefits to reducing its concentration. In our paper, we use recently developed population-weighted estimates of national average concentrations of PM2.5 pollution that are available from the World Bank Development Indicators. These combine satellite and ground based observations.

Though the environmental Kuznets curve (EKC) was originally developed to model the ambient concentrations of pollutants, most subsequent applications focused on pollution emissions. Yet, previous research suggests that it is more likely that economic growth could eventually reduce the concentrations of local pollutants than emissions. We examine the role of income, convergence, and time related factors in explaining changes in PM2.5 pollution in a global panel of 158 countries between 1990 and 2010. We find that economic growth has positive but relatively small effects, time effects are also small but larger in wealthier and formerly centrally planned economies, and, for our main dataset, convergence effects are small and not statistically significant.

Crucially, when we control for other relevant variables, even for this particulate pollution concentration data there is no environmental Kuznets curve, if what we mean by that is that environmental impacts decline with increasing income once a given in sample level of income is passed - the turning point.

The following graph shows the relationship between the average growth rates over 20 years of particulate pollution concentrations and per capita GDP:

The two big circles are of course China and India where both GDP and particulate pollution grew strongly. We can see that there is a positive relationship between these two growth rates, especially when we focus on the larger countries. The main econometric estimate in the paper shows that a 1% increase in the rate of economic growth is associated with a 0.2% increase in the growth rate of particulate pollution. This is much weaker than the effects we found for emissions of carbon and sulfur dioxides. The estimated income turning point is $66k with a large standard error. On the other hand, when we estimate a model without the control variables, we obtain a turning point of only $3.3k with a standard error of only $1.2k. To check the robustness of this result, we estimate models with other data sets and time periods. These yield quite similar results.

We conclude that growth has smaller effects on the concentrations of particulate pollution than it does on emissions of carbon or sulfur. However, the EKC model does not appear to apply here either, casting further doubt on its general usefulness.

Thursday, March 3, 2016

My Submission to Stern Review of the REF

The Stern Review of the REF (Research Excellence Framework) is the latest British government review of research assessment in the UK, following on from the Metric Tide assessment. I have just made a submission to the enquiry. My main comment in response to the first question (1. What changes to existing processes could more efficiently or more accurately assess the outputs, impacts and contexts of research in order to allocate QR? Should the definition of impact be broadened or refined? Is there scope for more or different use of metrics in any areas?) follows:

"I think that there is substantial scope for using bibliometrics in the conduct of the REF. In Australia the Australian Research Council uses metrics to assess natural science disciplines and psychology. Research that I have conducted with my coauthor, Stephan Bruns, shows that this approach could be extended to economics and probably political science and perhaps other social sciences. We have written a working paper presenting our results that is currently under review by Scientometrics.

The paper shows that university rankings in economics based on long-run citation counts can be easily predicted using early citations. The rank correlation between universities' cumulative citations received over ten years for economics articles published in 2003 and 2004 and citations received in 2003 to 2004 alone is 0.91 in the UK and 0.82 in Australia. We compare these citation-based university rankings with the rankings of the 2008 Research Assessment Exercise in the UK and the 2010 Excellence in Research assessment in Australia. Rank correlations are quite strong but there are differences between rankings based on this type of peer review and rankings based on citation counts. However, if assessors are willing to consider citation analysis to assess some disciplines as is the case for the natural sciences and psychology in Australia there seems no reason to not include economics in this set.

Previously, I published a paper, published in PLoS One showing that the predictability of citations at the article level is similar in economics and political science. This supports the view that metrics based research assessment can cover both economics and political science in addition to the natural sciences and economics.

I believe the REF review should seriously consider these findings in producing recommendations for a lighter touch future REF."

I also made briefer responses to some of their other questions. In particular:

5. How might the REF be further refined or used by Government to incentivise constructive and creative behaviours such as promoting interdisciplinary research, collaboration between universities, and/or collaboration between universities and other public or private sector

"A major issue with the REF and the ERA in Australia is the pigeon-holing of research into disciplines, which might not match well the nature of the research conducted. This clearly will discourage publication in interdisciplinary venues that may not be as respected by mainstream reviewers. The situation is less acute in Australia where a single output can be allocated across different assessment disciplines, but I still think that assessment by pure disciplinary panels discourages interdisciplinary work in Australia. So, I imagine this is exacerbated in the UK.

7. In your view how does the REF process influence the development of academic disciplines or impact upon other areas of scholarly activity relative to other factors? What changes would create or sustain positive influences in the future?

Johnston et al. (2014) show that the total number of economics students has increased in UK more rapidly than the total number of all students, but the number of departments offering economics degrees has declined, particularly in post-1992 universities. Also, the number of universities submitting to the REF under economics has declined sharply with only 3 post-1992 universities submitting in the latest round. This suggests that the REF has driven a concentration of economics research in the more elite universities in the UK.

Johnston, J., Reeves, A. and Talbot, S. (2014). ‘Has economics become an elite subject for elite UK universities?’ Oxford Review of Education, vol. 40(5), pp. 590-609.