Topic: Energy and Environment

Suffer the Little Children

But maybe think twice before taking them as authorities on complex environmental and economic matters.

The used lunch trays Emily Fox took home about four years ago from the loading dock outside her elementary school were gross, some still plastered with ketchup. Emily stacked the trays in piles of 10. She wanted to know just how many polystyrene lunch trays Piney Branch Elementary School students went through in a day.  “Three hundred and twenty-five,” said Emily, now 12…

On Friday, the Hermosa Beach City School District in Southern California started replacing foam trays with recycled paper trays once a week, thanks in part to the advocacy of Max Riley, a fourth-grader at Hermosa Valley School, and his sister Reece, a second-grader.

“No Foam Friday” will run through the end of the school year, and the siblings say they’re pushing for permanent change.

Max said he worries about the health repercussions of littering Earth with foam.

Exporting Natural Gas

Suddenly, due to improved drilling techniques, the U.S. is overflowing with natural gas, driving down domestic prices. But foreign prices remain high, which means there is an opportunity for us to export natural gas.  Unfortunately, the infrastructure does not currently exist. To transport natural gas across the ocean, you have to liquefy it first. We have the facilities to import liquefied natural gas, but not to liquefy it ourselves and export.  In order to start exporting, we need to build the appropriate facilities, which requires regulatory approval from the Energy Department. A number of applications have been made to build new facilities.

So why wouldn’t the Energy Department approve this?  Some are arguing that allowing exports would raise prices for domestic consumers and manufacturers, and this would be bad for American users of natural gas.

For more on all this, see the Washington Post here and the NY Times here.

Normally, free trade is about whether or not to allow imports, but preventing exports in an effort to help domestic interest groups is really just the same situation in reverse.  The Washington Post has a good editorial in which they argue for allowing exports.  As they put it:

USUALLY, OPPONENTS of freer trade argue that Americans shouldn’t be buying so many cheap products from abroad, sending their cash overseas. But when it comes to exporting some of this nation’s abundant supplies of natural gas, those who oppose opening up to the world turn that logic on its head — arguing, strangely, that Americans shouldn’t be trying to sell this particular product to other nations, bringing money into the country in the process. Both arguments are unconvincing, and for the same reason: When countries can buy and sell to each other, their economies do what they are best at, producing more with less and driving economic growth.

That’s well put, but let me just add one thing: Under our international trade agreements, we have promised not to restrict exports.  We can’t restrict exports just to keep domestic prices down. In fact, we have already brought a successful WTO complaint against China for doing similar things.  If we want others to play by the rules, we have to do so as well.

So, not only is allowing exports of natural gas good policy, it is what we have promised to do, and what we are demanding of others.

The Current Wisdom: ‘Dumb People’ Syndrome

The Current Wisdom is a series of monthly articles in which Patrick J. Michaels, director of the Center for the Study of Science, reviews interesting items on global warming in the scientific literature that may not have received the media attention that they deserved, or have been misinterpreted in the popular press. Occasionally — as in this edition — we examine recent global warming perceptions that are at odds with reality.

“The habitability of this planet for human beings really is at risk.”
–Al Gore, July 18, 2007

The notion that people just can’t adapt to change (and therefore that governments must regulate change) is known as “Dumb People Syndrome” (DPS).  Given the fact that the planet is “habitable” (meaning  that there large numbers of people) over a mean annual temperature range of approximately 40°C , Gore’s statement—which is about a few degrees C, at best—is quintessential DPS.  

DPS has its subtypes, such as “Dumb Farmer Syndrome”, in which there’s agricultural Armageddon as the world’s farmers fail to adapt to warming conditions.  It’s not only preposterous, it’s inconsistent with history.

Farmers aren’t dumb, and there are incentives for their supply chain—breeders, chemical manufacturers, equipment companies, etc.—to produce adaptive technologies.  Corn is already much more water-use efficient than it was, thanks to changes in genetics, tillage practices, and farm equipment.  The history of U.S. crop yield bears strong witness (Figure 1).

Figure 1. U.S. national corn and wheat yields, 1900-2012 (source: USDA National Agricultural Statistics Service).

A look at the horrible crop year of 2012 is instructive. Corn yield drops about 38 bushels per acre  from what’s known as the “technological trend line.”  Because the “expected” yield—thanks to  technology—with good weather is so high (around 160 bushels/acre), that’s a drop of about 24%, which is simply unremarkable when compared to the other lousy weather years of 1901 (36%), 1947 (21%), 1983 (29%) and 1988 (30%).  Did we mention that the direct fertilization effect of atmospheric CO2  has resulted in a  corn yield increase of approximately seven per cent?

Most assessments of the impacts of climate change give some credence to DPS. Below is one of the  “Key Findings” from the report Global Climate Change Impacts in the United States produced by the U.S. Climate Change Global Change Research Program (USGCRP), which was used as a major support for  the U.S. Environmental Protections Agency’s “Endangerment Finding”  that human carbon dioxide emissions are a threat to health and welfare. According to the USGCRP:

Crop and livestock production will be increasingly challenged.

Many crops show positive responses to elevated carbon dioxide and low levels of warming, but higher levels of warming often negatively affect growth and yields. Increased pests, water stress, diseases, and weather extremes will pose adaptation challenges for crop and livestock production.

Now compare that to the corresponding “Key Finding” from our report Addendum: Global Climate Change Impacts in the United States which is an independent (from the USGCRP) assessment of the scientific literature relating to environmental changes and how they may impact U.S. agriculture:

Crop and livestock production will adapt to climate change.

There is a large body of evidence that demonstrates substantial untapped adaptability of U.S. agriculture to climate change, including crop-switching that can change the species used for livestock feed. In addition, carbon dioxide itself is likely increasing crop yields and will continue to do so in increasing increments in the future.

Another example of the DPS relates to projections of the effects  of more or stronger  heat waves on human mortality.  Everyone has heard—especially after last summer—how human use of fossil fuels to produce energy will increase the frequency and severity of killer heat waves.

Here is how the USGCRP sees it, according to the “Key Messages” from the “Human Health” chapter of their report:

Increases in the risk of illness and death related to extreme heat and heat waves are very likely.

History shows that things don’t work this way.

Why? Because people are not dumb. Instead of dying in increasing numbers as temperatures rise, people take better precautions to protect themselves from the heat.

Numerous examples of this abound, including some pioneering work that we did on the subject about 10 years ago.  We clearly demonstrated that across the U.S., people were becoming less sensitive to high temperatures, despite the fact that high temperatures were increasing. In other words, adaptation was taking place in the face of (or, perhaps even because of) rising temperatures. Adaptations include expanding use of air conditioning, increasing public awareness, and more widespread community action programs.

What was interesting  about our work is we didn’t even need global warming to drive increasing heat waves.  All we needed was economic activity that concentrates in cities.  As they grow, buildings and pavement retain the heat of the day and impede the flow of ventilating winds.  In recent years, the elevation of night temperatures here in Washington (where your tax dollars virtually guarantee economic growth),  compared to the countryside, has become truly remarkable.  But you won’t find  an increase in heat-related mortality.  Instead, there’s been a decrease.
Our research was limited to major cities across the United States. But similar findings have since been reported for other regions of the world, the most recent being the from the Czech Republic.

Czech researchers Jan Kyselý and Eva Plavcová recently published the results of their investigation of changes in heat-related impacts there from 1986 through 2009.  What they found sure wasn’t surprising to us, but surely must come as quite a shock to the fans of DPS.

Declining trends in the mortality impacts are found in spite of rising temperature trends. The finding remains unchanged if possible confounding effects of within-season acclimatization to heat and the mortality displacement effect are taken into account. Recent positive socioeconomic development, following the collapse of communism in Central and Eastern Europe in 1989, and better public awareness of heat-related risks are likely the primary causes of the declining vulnerability. The results suggest that climate change may have relatively little influence on heat-related deaths, since changes in other factors that affect vulnerability of the population are dominant instead of temperature trends. It is essential to better understand the observed nonstationarity of the temperature-mortality relationship and the role of adaptation and its limits, both physiological and technological, and to address associated uncertainties in studies dealing with climate change projections of temperature-related mortality.

Findings like these, along with our own work, caused us to conclude in our Addendum report that:

“In U.S. cities, heat-related mortality declines as heat waves become stronger and/or more frequent.”

Evidence is much more compelling in  support of a “smart people” diagnosis than its opposite.  In fact, if humankind was really as dumb as the fans of DPS would have us believe, we wouldn’t be around  today to hear their doomsaying, because Homo sapiens would have been wiped out during vastly larger environmental swings (in and out of ice ages, for example) in our past,  than those expected as a consequence of the burning of fossil fuels to produce the energy that powers our world—a world in which the human life expectancy, perhaps the best measure of our level of “dumbness” or “smartness”—has more than doubled over the last century and continues to grow ever longer.

Simply put, we are not “dumb” when it comes to our survival and our ability to adapt to changing environmental conditions, but “scientific” assessments that assume otherwise most certainly are.


Davis, R.E., Knappenberger, P.C., Novicoff, W.M., Michaels, P.J., 2002. Decadal changes in heat-related human mortality in the Eastern US. Climate Research, 22, 175–184.

Davis, R.E., Knappenberger, P.C., Novicoff, W.M., Michaels, P.J.,2003a. Decadal changes in summer mortality in U.S. cities. International  Journal of Biometeorology, 47, 166–175.

Davis, R.E., Knappenberger, P.C., Michaels, P.J., Novicoff, W.M., 2003b. Changing heat-related mortality in the United States. Environmental Health Perspectives, 111, 1712–1718.

Davis, R.E., Knappenberger, P.C., Michaels, P.J., Novicoff, W.M., 2004. Seasonality of climate-human mortality relationships in US cities and impacts of climate change. Climate Research, 26, 61–76.

Jan Kyselý, j., and E. Plavcová, 2012.Declining impacts of hot spells on mortality in the Czech Republic, 1986–2009: adaptation to climate change? Climatic Change, 113, 437-453.

Climate Sensitivity Going Down

Global Science Report is a weekly feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

“Climate sensitivity” is the amount that the average global surface temperature will rise, given a doubling of the concentration of atmospheric carbon dioxide (CO2) in the atmosphere from its pre-industrial value. This metric is the key to understanding how much global warming will occur as we continue to burn fossil fuels for energy and emit the resultant CO2 into the atmosphere.

The problem is that we don’t know what the value of the climate sensitivity really is.

In its Fourth Assessment Report, released in 2007, the United Nations’ Intergovernmental Panel on Climate Change (IPCC) had this to say about the climate sensitivity:

It is likely to be in the range 2°C to 4.5°C with a best estimate of about 3.0°C, and is very unlikely to be less than 1.5°C. Values substantially higher than 4.5°C cannot be excluded…

In IPCC parlance, the term “likely” means a probability of greater than 66% and “very likely” means a greater than 90% change of occurrence. The IPCC’s 90% range for the climate sensitivity  includes values at the low end which, if proven true, would engender very little concern over our use of fossil fuels as a primary energy source, and values at the high end would generate calls for frantic efforts (which would likely fail)  to lower carbon dioxide emissions.

While there has been a lot of effort expended to better constrain estimates of sensitivity over the past several decades, little progress has been made in narrowing the range.  The IPCC’s First Assessment Report, released back in 1990, gave a range of 1.5°C to 4.5°C.  It’s not that climate science hasn’t progressed since then, but just that the advanced understanding has not led to substantially better constraints.

But what has occurred over the past several decades is that greenhouse emissions have continued to rise (in fact, half of the total anthropogenerated  carbon dioxide emissions have been since the mid-1980s), and global temperature observations have continued to be collected.  We now have much more data with which to use to try to determine the sensitivity.

While global carbon dioxide emissions continue to rise year-over-year (primarily driven by the rapid growth in developing countries such as China), global temperatures have not kept up—in fact, there has been little to no overall global temperature increase (depending upon the record used) over the past decade and a half.

That doesn’t bode well for the IPCC’s high-end temperature sensitivity estimates. The scientific literature is now starting to reflect that reality.

Never mind that Pat Michaels and I published a paper in 2002 showing that the sensitivity lies near the low side of the IPCC’s range.  This idea (and those in similar papers subsequently published by others) had largely been ignored by the “mainstream” scientists self-selected to produce the IPCC Assessments.  But new results supporting lower and tighter estimates of the climate sensitivity are now appearing with regularity,  a testament to just how strong the evidence has become, for such results had to overcome the guardians of the IPCC’s so called “consensus of scientists”, which the Climategate emails showed to be less than gentlemanly.

Figure 1 shows the estimates of the climate sensitivity from five research papers that have appeared in the past two years, including the recent contributions from Ring et al. (2012) and van Hateren (2012)—both of which put the central estimate of the climate sensitivity at 2°C or lower, values which are at or beneath the IPCC’s  current “likely” range.

Figure 1. Climate sensitivity estimates from new research published in the past two years (colored), compared with the range given in the IPCC Fourth Assessment Report (black). The arrows indicate the 5 to 95% confidence bounds for each estimate along with the mean (vertical line) where available. Ring et al. (2012) present four estimates of the climate sensitivity and the red box encompasses those estimates.  The right-hand side of the IPCC range is dotted to indicate that the IPCC does not actually state the value for the upper 95% confidence bound of their estimate. The thick gray line represents the IPCC’s “likely” range.

The IPCC is scheduled to release its Fifth Assessment Report in 2013.  We’ll see whether these new, lower, and more constrained estimates of climate sensitivity  that are increasing populating the literature result in a modification of the IPCC estimates, or whether the IPCC authors manage to wave  them all away (or simply ignore them, as was the case with our 2002 paper).

Regardless of how the IPCC ultimately assesses climate science in 2013, the fact of the matter is that there is growing evidence that anthropogenic climate change from the burning of fossil fuels is not going to turn out to be as much as climate alarmists have made it out to be.


Annan, J.D., and J.C. Hargreaves, 2011. On the genera­tion and interpretation of probabilistic estimates of climate sensitivity. Climatic Change, 104, 324-436.

Lindzen, R.S., and Y-S. Choi, 2011. On the observational determination of climate sensitivity and its implica­tions. Asia-Pacific Journal of Atmospheric Sciences, 47, 377-390.

Michaels, P.J., P.C. Knappenberger, O.W. Frauenfeld, and R.E. Davis, 2002. Revised 21st century temperature predictions. Climate Research, 23, 1-9.

Ring, M.J., et al., 2012. Causes of the global warming observed since the 19th century. Atmospheric and Climate Sciences, 2, 401-415, doi:10.4236/acs.2012.24035.

Schmittner, A., et al., 2011. Climate sensitivity estimat­ed from temperature reconstructions of the Last Glacial Maximum, Science, 334, 1385-1388, doi: 10.1126/science.1203513.

Solomon, S., et al., (eds.), 2007. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, 996pp.

van Hateren, J.H., 2012. A fractal climate response function can simulate global average temperature trends of the modern era and the past millennium. Climate Dynamics, doi:10.1007/s00382-012-1375-3.

Ah, the Sweet Smell of Lukewarm Success

Three years ago the climate world was set ablaze by the release of thousands of “Climategate” emails from the server at the University of  East Anglia.  The ruling climate establishment, which I now call “hotheads”, showed itself threatening editors of journals who dared publish my papers, and engaged in a wide variety of other shady and nefarious practices.

I didn’t realize until the Climategate circus that my view on climate change had generated a moniker.  I was branded—accurately—a “lukewarmer”, meaning that my synthesis of climate behavior is that global warming is real, and caused in part by people. It is also exaggerated, both in magnitude and effect. My new Center studies why this occurs, and finds similar dynamics operating across many fields of federally-sponsored science.

Apparently this view is getting, as is said here in Swamp-By-the-Potomac, “traction”.

My evidence comes from no less a media icon than Bill Maher, writing about me and my sidekick Chip Knappenberger here at Cato, specifically concluding, “they are winning”.

Thank you Bill, and no I won’t go on your show.

Fact check:  Maher doesn’t realize that my company is closed and World Climate Report has migrated and evolved into Global Science Report, featured weekly on this blog.

Straw Men

Global Science Report is a weekly feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

Lawrence Livermore National Laboratory’s Benjamin Santer and his mentor, Tom Wigley, of the National Center for Atmospheric Research seem, well, a little obsessed over Cato’s Pat Michaels.  First, Santer threatened to “beat the cr&p out of him”, and then Wigley tried to foment a cabal to “re-assess” his doctoral dissertation, under grounds that were completely, unalterably, and demonstrably 100 percent false.

So it’s no surprise that they have just published—two years after the fact—what they consider to be a rejoinder to Michaels’ 2010 testimony to the Subcommittee on Energy and Environment of the Committee on Science and Technology of the United States House of Representatives.  There’s about as much real substance here as there was in Wigley’s very ill-informed (and seemingly actionable, if Michaels didn’t have a day job here at Cato) campaign against his doctorate.

It’s just been published in the journal Climate Dynamics.  This is technically peer-reviewed, but, judging from the climategate emails and the serial paper trail of threatening journal editors (say, by writing to the University administrations where they worked) as well as the less than high quality contents of the actual paper, it makes you wonder just how critical the reviewers actually were.

In their paper, Wigley and Santer wrote:

Michaels’ 2010 Congressional testimony…is in conflict with the results presented here. This testimony makes the claims that “…greenhouse-related warming is clearly below the mean of relevant forecasts by IPCC”, and that “… the Finding of Endangerment from greenhouse gases by the Environmental Protection Agency is based on a very dubious and critical assumption”. The “assumption” referred to here is the IPCC statement that is the primary focus of the present paper, i.e., the statement that most of the warming since 1950 is very likely due to the human-caused increase in greenhouse gas concentrations.

Regarding Michaels’ statement that “…greenhouse-related warming is clearly below the mean of relevant forecasts by IPCC” Wigley and Santer argued that:

Roughly half of these [IPCC climate model] simulations did not consider the cooling effect of indirect aerosol forcing, so the results, on average, would be biased towards trends that are warmer than observed even if the models were perfect (cf. Santer et al. 2011).

So the climate models are biased to producing more warming than is observed? Isn’t that what Michaels said? These guys just won’t take “yes” for an answer.

And in fact, the reference in the above quote to “Santer et al. 2011” is a paper published by Santer and Wigley (and 15 others) that finds:

The multi-model average [lower atmospheric temperature] trend is always larger than the average observed [lower atmospheric temperature] trend…[a]s the trend fitting period increases…average observed trends are increasingly more unusual with respect to the multi-model distribution of forced trends.

That says what you think it says! Model temperature trends are always higher than the observed temperature trends and that over longer periods (i.e., more robust analysis) the model/observed discrepancy grows. Here is the relevant figure from that paper.

Figure 1. A comparison between modeled and observed trends in the average temperature of the lower atmosphere, for periods ranging from 10 to 32 years (during the period 1979 through 2010). The yellow is the 5-95 percentile range of individual model projections, the green is the model average, the red and blue are the average of the observations, as compiled by Remote Sensing Systems and University of Alabama in Huntsville respectively (adapted from Santer et al., 2011).

Their own analysis supports Michaels’ contention, which they somehow say is wrong.  Beats me.

In fact, their picture looks an awful lot like the one that Michaels used in his testimony (Figure 2).

Figure 2. Range of climate model probabilities of surface temperature trends (gray shading) overlaid with the observed surface temperature trend from the Climate Research Unit (blue line) (data through September 2010).

It’s worth noting that Michaels’ was the first presenter of this type of chart several years ago.  In fact, Wigley reviewed a paper it was in, helped get the editor to kill it, and then, with Santer, published something mighty similar.  How strange for someone they are arguing is wrong.

It goes on.

They then take exception with Michaels’ statement to Congress that the IPCC’s central finding that “[m]ost of the observed increase in global average temperatures since the mid-twentieth century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations” is “dubious.”

Wigley and Santer spill a lot of ink over the concept that in the absence of everything else, that the potential warming from anthropogenic greenhouse gases is likely greater than the observed warming. Michaels didn’t say that it wasn’t. In fact, most people believe this as true.

Michaels was concerned about the observed warming not some hypothetical, unrealizable (and therefore unverifiable) change. After all, it is the actual warming that the environment largely responds to. So when assessing the accuracy of the IPCC statement on observed warming, it is therefore appropriate to divide it up between various elements as he did.

While there’s a lot of gory detail in this discussion (see here, for more ), one thing that I think we all should be able to agree on is that it is physically impossible for something (like the emissions of anthropogenic greenhouse gases) to be responsible for causing more than 100% of what has been observed, and that such statements like this one from Wigley and Santer’s paper,

Here, the probability that the model-estimated GHG component of warming is greater than the entire observed trend (i.e., not just greater than ‘‘most’’ of the observed warming) is about 93%.

is something other than science, because one surely cannot find something that nature will not reveal.

The bottom line here is that in their paper, Wigley and Santer seem to place more import on the attack of Pat Michaels, than they do on the actual logic behind it.


Santer,  B. D., C. Mears, C. Doutriaux, P. Caldwell, P.J. Gleckler , T.M.L. Wigley, S. Solomon, N.P. Gillett, D. Ivanova D, T.R. Karl, J.R. Lanzante, G.A. Meehl, P.A. Stott, K.E. Taylor, P.W. Thorne, M.F. Wehner, F.J. Wentz, 2011. Separating signal and noise in atmospheric temperature changes: the importance of timescale. Journal of Geophysical Research116, D22105. doi:10.1029/2011JD016263

Wigley, T.M.L., and B.D. Santer, 2012. A probabilistic quantification of the anthropogenic component of twentieth century global warming. Climate Dynamics, doi: 10.1007/s00382-012-1585-8

Carbon Tax Follies

Global Science Report is a weekly feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”

There seems to be a noticeable murmur around town about a carbon tax—a tax on the amount of carbon dioxide that is released upon generating a unit of energy. Since fossil fuels—coal, oil, natural gas—are both the source of over 75% of our energy production and emitters of carbon dioxide when producing that energy, a carbon tax insures that the price of everything goes up.

There is one and only one justification for a carbon tax—an attempt to influence the future course of the earth’s climate (or, as some people prefer, to mitigate anthropogenic climate change) by trying to force down the emissions of the most abundant human-generated greenhouse gas.

But of all the things that a carbon tax will do (raise prices, increase bureaucracy, elect Tea Partiers, etc), mitigating anthropogenic climate change in any meaningful manner is not one of them.

The annual carbon dioxide emissions from the U.S., currently about 5,500 million metric tons per year, only contributes roughly 0.003°C/per year of warming pressure on global temperatures (see here for a handy way of making that calculation). So the best that a carbon tax could ever hope to achieve, climatically, would be to prevent this amount of warming each year by completely eliminating all carbon dioxide emissions from the U.S.

If we went to zero emissions tomorrow,  the carbon tax would prevent about 0.26°C of global temperature rise by the year 2100. According to the latest projections from the Intergovernmental Panel on Climate Change (IPCC), the projected temperature rise by the end of the century ranges from about 1.1 to 6.4°C, with a business-as-usual rise of around 3°C (put me down for 1.6° until then, unless nature is being a blatant liar).  The “mitigated” rise is proportional to the expected temperature rise. A carbon tax enacted today that is immediately and completely successful at eliminating all U.S. CO2 emission would lower rise in temperature expected by the end of the century around 10%.  This amount is small, of little consequence, and in fact will be difficult to detect.

It is also not going to happen.  We only have the capacity to produce about 30% of our electricity from non-carbon emitting fuel sources (primarily nuclear and hydroelectric). So it will take time, and probably a lot of time (many decades) before our energy needs could possibly be met without emitting CO2 into the atmosphere.  And of course, as time ticks by before eliminating or at least appreciably reducing  our emissions, the amount of global warming saved by such action declines (and become less and less consequential), as does the justification for the carbon tax.

I am just in the early stage of this analysis, so the numbers above are a bit rough (but conservative). In the future I hope to produce a menu of emissions reductions/climate savings options—but one without prices.  That way the policymakers will see what they are going to be getting for whatever price they decide to assign. So too will the general public. And what they will all see is that whatever level of carbon tax they decide upon,  they will get a lot of climate nothing  for a lot of financial something.

The best thing would be for policymakers to just leave well enough alone, for on their own, carbon dioxide emissions in the U.S. have been declining for more than a decade (and in fact are pushing levels of the early 1990s, And even if such a reduction doesn’t result in any scientifically detectable climate impacts, at least it hasn’t cost us anything.