Emissions Reduction Survey 2019

I again carried out a contingent valuation study of climate change using my environmental economics class as respondents. The survey was exactly as in 2018. Participants could vote yes or no on proposals to raise the Medicare levy by 0.125% or 0.25% to help fund the Emissions Reduction Fund. I designed the survey to follow the NOAA panel guidelines. I also asked the students to explain why they voted the way they did.

The results differ from 2018. Only 42% voted for a 0.125% increase in the Medicare levy, while 53% voted for a 0.25% increase. Five people voted against the smaller tax and for the larger tax. So there was quite a lot of irrational behavior where the perfect could have been the enemy of the good if one person had voted differently on the higher tax. This kind of thinking is in large part, IMO, why Australia doesn't now have a carbon price...

Of those voting no on both proposals, there were a mix of responses. Only one seemed to be saying that they couldn't afford the tax given the benefit! And that is what such a survey is supposed to measure. Others objected to the payment vehicle, by suggesting that the government should price carbon or reduce the diesel rebate etc. or borrow/print money instead. I agree with the first two of these, but again that leads here to nothing happening on the climate front if that is what you care about. Others worried about the distributional impact. That is a valid criticism of the Medicare levy proposal, which is a tax on all ones income rather than a progressive or marginal tax. One person incorrectly thought the Medicare levy was unethical, as it was a tax on healthcare. Actually, it is just an extra income tax.

Of those voting yes to the lower tax and no to the higher tax, only one mentioned the cost. The others said that the government should find other funding (borrowing?) or polluters should pay – of course in the end it is the consumer who will pay to the degree that polluters can pass on costs…

Those voting yes on both proposals all said the tax increase was affordable, so they did consider actual willingness/ability to pay.

The bottom line, is that there is a lot of behavior going on in the responses to this survey which doesn’t fit with the model of paying for a public good model where people state their honest WTP, even with a supposedly state of the art design. There is some free-riding - other people should pay or the government should borrow – and on the other hand some altruism as well as protest votes about the policy design. There is also irrational behavior represented by voting no, yes, though we probably can assume that some of these didn't understand the potential implication of voting against the lower tax rate.

Buying Emissions Reductions

This semester I am teaching environmental economics, a course I haven't taught since 2006 at RPI. Last week we covered environmental valuation. I gave my class an in-class contingent valuation survey. I tried to construct the survey according to the recommendations of the NOAA panel. Here is the text of the survey:

Emissions Reduction Fund Survey

In order to meet Australia’s international commitments under the Paris Treaty, the government is seeking to significantly expand the Emissions Reduction Fund, which pays bidders such as farmers to reduce carbon emissions. To fully meet Australia’s commitment to reduce emissions by 26-28% below 2005 levels by 2030 the government estimates that the fund needs to be expanded to $2 billion per year. The government proposes to fund this by increasing the Medicare Levy.

1. Considering other things you need to spend money, and other things the government can do with taxes do you agree to a 0.125% increase in the Medicare levy, which is equivalent to $100 per year in extra tax for someone on average wages. This is expected to only meet half of Australia’s commitment, reducing emissions to 13-14% below 2005 levels or by a cumulative 370 million tonnes by 2030.

Yes No

2. Considering other things you need to spend money, and other things the government can do with taxes do you agree to a 0.25% increase in the Medicare levy, which is equivalent to $200 per year in extra tax for someone on average wages. This is expected to meet Australia’s commitment, reducing emissions to 26-28% below 2005 levels or by a cumulative 740 million tonnes by 2030.

Yes No

3. If you said yes to either 1 or 2, why? And how did you decide on whether to agree to the 0.125% or 0.25% tax?

4. If you said no to both 1. and 2. why?

***********************************************************************************


85% voted in favour of the 0.125% Medicare tax option and 54% voted in favour of 0.25% - So both would have passed. A few people voted against 0.125 and for 0.25, so I changed their votes to for 0.125 as well as 0.25.


Reasons for voting for both:


• $200 not much, willing to do more than just pay that tax 
• We should meet the target
 
• Tax is low compared to other taxes - can reduce government spending on health in future
 
• Can improve my health
 
• Benefit is much greater than cost to me
 
• I pay low tax as I'm retired, so can pay more
 
• I'm willing to pay so Australia can meet commitment
 
• Only $17 a month
 
• Tax is small
 
• Because reducing emissions is the most important environmental issue
 
 

Reasons for voting for 0.125 but against 0.25:


• Can afford 0.125 but not 0.25
• Government can cover the rest with other measures like incentives
 
 

Reasons for voting against both:


• There are other ways to reduce emissions - give incentives to firms rather than tax the middle class... 
• Government should tax firms
• Don't believe in emissions reduction fund because it is inefficient

• I prefer to spend my money rather than pay tax and reduction in emissions is not very big for tax paid


Mostly the reasons for voting for both are ones we would want to see if we are really measuring WTP - can afford to pay and it is a big issue. Those thinking it will increase their personal health or reduce health spending were made to think about health by the payment vehicle. I chose the Medicare Levy as the payment vehicle as the Australian government has a track record of increasing the Medicare Levy for all kinds of things, like repairing flood damage in Brisbane!
 I chose the emissions reduction fund because it actually exists and actually buys emissions reductions.

Most people who voted for 0.125% but against 0.25% have valid reasons - they can't afford the higher tax. However, one person said the government should cover the rest by other means. So that person may really be willing to pay 0.25% if the government won't do that.


When we get to the people who voted against both tax rates, most are against the policy vehicle rather than not being willing to pay for climate change mitigation. So, from the point of view of measuring WTP these votes would result in an under estimate. These "protest votes" are a big problem for CVM. Only one person said they weren't willing to pay anything given the bang for the buck.

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.

Economic Growth and Particulate Pollution Concentrations in China

A new working paper coauthored with Donglan Zha, who is visiting the Crawford School, which will be published in a special issue of Environmental Economics and Policy Studies. Our paper tries to explain recent changes in PM 2.5 and PM 10 particulate pollution in 50 Chinese cities using new measures of ambient air quality that the Chinese government has published only since the beginning of 2013. These data are not comparable to earlier official statistics and we believe are more reliable. We use our recently developed model that relates the rate of change of pollution to the growth of the economy and other factors as well as also estimating the traditional environmental Kuznets curve (EKC) model.

Though the environmental Kuznets curve (EKC) was originally developed to model the ambient concentrations of pollutants, most subsequent applications have focused on pollution emissions. Yet, it would seem more likely that economic growth could eventually reduce the concentrations of local pollutants than emissions. This is the first application of our new model to such concentration data.

The data show that there isn't much correlation between the growth rate of GDP between 2013 and 2014 and the growth rate of PM 2.5 pollution over the same period:

What is obvious is that pollution fell sharply from 2013 to 2014, as almost all the data points have negative pollution growth. We have to be really cautious in interpreting a two year sample. Subsequent events suggest that this trend did not continue in 2015.

In fact, the simple linear relationship between these variables is negative, though statistically insignificant. The traditional EKC model and its growth rate equivalent both have a U shape curve - the effect of growth is negative at lower income per capita levels and positive at high ones. But the (imprecisely estimated, so not statistically significant) turning point fro PM 2.5 is way out of sample at more than RMB 400k.* So, growth has a negative effect on pollution in the relevant range. When we add the initial levels of income per capita and pollution concentrations to the growth rates regression equation the turning point is in-sample and statistically significant. The initial level of pollution has a negative and highly statistically significant effect. So, there is "beta convergence" - cities with initially high pollution concentrations, reduced their level of pollution faster than cleaner cities did.

So what does all this mean? These results are very different than those we found for emissions of CO2, total GHGs, and sulfur dioxide. In all those cases, we found that growth had a positive and quite large effect on emissions. In some cases, the effect was close to 1:1. Of course, we should be cautious about interpreting this small Chinese data set. But our soon to be released research on global PM 2.5 concentrations, will again show that the effect of growth is smaller for these data than it is for the key pollution emissions data. This confirms early research that suggested that pollution concentrations turn down before emissions do, though it doesn't seem to support the traditional EKC interpretation of the data.

BTW, it is really important in this research to use the actual population of cities and not just the registered population (with hukou). If you divide the local GDP by the registered population you can get very inflated estimates of GDP per capita for cities like Shenzhen.

* The turning point is in-sample for PM 10.

Arik Levinson Seminar 24 February at ANU

Arik Levinson will be presenting at the Arndt Corden Seminar at 2pm on 24th February (Seminar Room B in the Coombs Building). The Freakonomics Radio Show just did a podcast on the paper which he is going to be presenting.

Environmental & Resource Economics Acceptance Rate 2013

Just got an e-mail from the journal noting that they got just over 600 submissions in 2013. They have already reached that level at this point of 2014. Back in 2004 they got less than 200 submissions. This is a common trend at many journals including Ecological Economics, where I am an associate editor. The email from ERE also notes that their impact factor is now 1.7 and this too has risen over time (0.6 in 2005). One of the reasons for that is the increased coverage of economics journals in the Journal Citation Reports. The number covered doubled in the last decade and that increases the opportunity to get cited in outlets covered by the JCR. One thing, ERE don't report on is their acceptance rate, but it is easy to calculate. According to the JCR they published 83 articles in 2013. Therefore, the acceptance rate is 13%.

I previously reported that the acceptance rate at ERE was 21%. So, this is a big drop. This is also a common trend.

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.

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...

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.

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.

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.

House Prices and Wind Farms

House prices within 2km of UK wind farms reduced by 5-6%.

Port Macquarie Conference Paper Now on the Web

Our paper from the Port Macquarie AARES Conference is now on the web. We plan to have an updated and extended version of the paper on the web as a formal working paper in the next week or so. I'll write up a discussion about the paper then.

World Congress of Environmental and Resource Economics 2014

The European Association of Environmental and Resource Economics (EAERE) and the US based Association of Environmental and Resource Economics hold a joint meeting every four years called The World Congress of Environmental and Resource Economics. 2014's meeting will be in Istanbul from 28 June to 2 July. The deadline for submission of sessions is 1 December 2013 and for individual papers 15 January 2014. Submissions are peer reviewed. Details of submission requirements are yet to be released.

I was at the first of these World Congresses in Venice in 1998. But I haven't been to one since. I've always wanted to visit Turkey, but the nearest I've got is Istanbul airport this year in June. So, this looks like a good opportunity.

Travel Cost Study: Lake Nakuru National Park, Kenya

I was interested to see a working paper on pricing Lake Nakuru National Park, which I recently visited.  They find that the revenue maximizing price for foreign visitors is $1500 compared to a fee of $75 currently. It is hard to imagine it could be this high given the existence of substitutes, though obviously some foreign visitors would be able to pay it. For comparison our whole trip for four days to Lake Nakuru and Maasai Mara cost less per person than than this suggested entrance fee for one day at one national park.

What Happened to the US Sulfur Emissions Market?

An interesting paper from Schmalensee and Stavins on the market for sulfur emissions in the US. This market is often cited as an example of the success of environmental economics and specifically cap and trade and I have used it as that in my teaching in the past. But what has happened more recently? The authors describe it as "ironic". After a period of relative stability often cited as a great success, the price of permits first sky-rocketed and then collapsed:



Essentially, the George W. Bush administration tried to tighten the cap on emissions significantly pushing the price up. In reaction EPA said they'd reconsider starting the collapse in price and then the courts overturned the new regulations. Then a couple of years ago the Obama administration then proposed state based emissions caps and limited interstate trading couple of years ago the market stopped trading entirely.

Schmalensee and Stavins still think that the program was a success if "ironic". I think this shows just how volatile emissions trading programs are and the likelihood of changes being made in response to price spikes that threaten or destroy the program. I think that the volatility of the European Union carbon trading market tells a similar story and increasingly shows that carbon taxes are the way to go. I used to be in favor of emissions trading due to the supposed certainty it would give on emissions reductions but real world experience shows that this could be a case of the perfect being the enemy of the possible.

New Citation Analysis of Environmental and Ecological Economics

A new citation analysis of environmental and ecological economics has just been published in Ecological Economics. The authors are Andreas Hoepner, Benjamin Kant, Bert Scholtens, and Pei-Shan Yu. It follows up on our papers on influential articles in the field (Costanza et al., 2004; Ma and Stern, 2006) by analyzing articles from 2000-2009. The main characteristics of their research design are:

1. They only look at citations to articles published between 2000 and 2009 in a group of 14 environmental and resource economics journals including Ecological Economics.

2. The main indicator is citations per annum which gives recently published papers much more weight than in most traditional rankings.

3. They distribute citations to authors and institutions on a fractional basis - so each author of our 2004 paper would only get 20% of the citations.

The results are interesting but different to what you might expect. Costanza ends up being ranked 61st in the field as all the above features count against him. C. C. Lee ends up in the 1st position in the ranking. Papers and authors associated with ecosystem services and payments for them are highly ranked which does make sense.

We did not publish a ranking of authors as part of our 2004 and 2006 papers but we did calculate them. So here are the rankings based on number of citations between 1994 and 2003 in articles published in Ecological Economics:



The full pdf is here. A peculiarity of this ranking is that all citations are assigned to the first author due to the limitations of the Web of Science database at the time. Despite this, it seems fairly plausible to me.

For JEEM, we came up with the following ranking:



Full list here.

Completed a Choice Modeling Survey

This week, I was a respondent to a choice modeling survey for the first time. The purpose of the survey was to find out about reliability of supply of water, electricity, gas etc. So this was something that I as a consumer have a lot of knowledge about and a lot of interest in and it is a clear private market. So all the criticisms about environmental valuation don't apply here. Choice modeling is often used to obtain environmental valuations and I think it is superior to other approaches in that application.

The online survey gave us eight different scenarios of possible packages with varying prices and utility reliability that we could pick from. Each scenario had three different packages - our current service plus two alternatives. Each alternative had around 10 different characteristics. I've always wondered whether survey respondents could handle that and thought that you just need to give each respondent one choice set and survey more people. I was just overwhelmed with information.



I chose the current package in every case. Partly because of the information overload but also because saving $50-$400 a year on my utility bill is just not worth it to me to suffer from multiple power cuts each year and the like, which is what the trade-offs were about. Even when I lived in East Jerusalem in the 1980s as an undergrad student we didn't have that many power cuts (Troy, NY was almost as bad :)). So I'm thinking the results of this survey will be pretty insensitive to price except for the more extreme scenarios at low incomes. $400 is a big deal to someone on $30,000 a year (Australian full time minimum wage), but $50 isn't for someone on $60,000 (average wages).

Being a social science researcher myself I always feel sympathetic to people carrying out surveys and often do them. But I get really annoyed when a surveyer has me on the phone for more than a quarter of an hour asking endless questions or when an online survey turns out to have tens of pages of questions. Why do people design surveys like this that are going to either have less patient people drop out of or refuse to respond or just give random answers to either from impatience or choice fatigue?

Carlos Lopez

I just heard from Carlos Lopez, who recently got his PhD from Rensselaer in economics. I was his advisor for a year when he started at RPI, before I left for Australia. He is now working at the Instituto Nacional de Ecologia in Mexico doing research on integrated management of water basins. He also runs a blog in Spanish with some friends, which covers issues in environment and economics among other topics. I'm adding to the list of blogs here.

Musings on Ecological vs. Environmental Economics

One way of distinguishing between environmental and ecological economics is that environmental economics has a focus on price while ecological economics has a focus on quantity. Environmental economics focuses on market failures as the main determinant of environmental problems. Seen in terms of externalities, the problem is incorrect prices and the solution is implementing the right prices. In many cases these prices must be determined through research, hence the huge emphasis on valuation. Ecological economics sees environmental problems as being primarily problems of scale – that the scale of exploitation of natural resources and the production of wastes are both too large relative to the Earth’s carrying capacity. Therefore, ecological economists are more likely to analyze economic-ecologic systems in terms of quantities of flows of materials and energy. Tools of analysis include energy return on investment and the ecological footprint – both quantity rather than price indicators. Ecological economics focuses primarily on sustainability – equitable distribution of resources over time, while environmental economics focuses on efficiency – ensuring that marginal costs and benefits of activities are equal.

How much overlap is there between ecological economics as actually practiced and the mainstream economic field of environmental and resource economics? Ma and Stern (2006) addressed this issue by analyzing the content and citation patterns of the leading journals in each field – Ecological Economics and the Journal of Environmental Economics and Management (JEEM). They found that there is a significant overlap between the two fields at the journal level — the two journals cite similar journals. The main differences are that ecological economics tends to cite (but not be cited by) general natural science journals more often than environmental economics does, environmental economics cites more heavily from journals rather than other publications, and citations in environmental economics are more concentrated on particular journals and individual publications. However, there is much less similarity at the level of individual articles. Nonmarket valuation articles dominate the articles cited in papers published in JEEM while green accounting, sustainability, and the environmental Kuznets curve are all prominent topics in Ecological Economics. Michael Hanemann was the most cited author in JEEM, while Robert Costanza was the most cited author in Ecological Economics.

Over time, however, there has been a convergence between mainstream environmental and resource economics and ecological economics. This can be seen in the trends over time in topics covered in journal articles with a greater number of mainstream valuation articles published in Ecological Economics [Castro e Silva and Teixeira] and mainstream papers increasingly include more realistic biophysical features.