The Acid Rain Scam

Acid rain became an “issue” in 1980 when Congress passed the Acid Deposition Act.  After a ten year study, National Acidic Precipitation Assessment Program reported that there wasn’t much of a problem with acid rain.  The first report was rejected and Congress went ahead and amended the Clean Air Act to mandate SO2 and NOx emissions.  These emissions have been substantially reduced at a cost of several billion dollars per year.  Chump change relative to the potential costs of Kyoto/Copenhagen schemes.

According to the EPA the Acid Rain Program has made significant progress…

Air Quality: Emission reductions achieved under the ARP have led to improvements in air quality with significant benefits to human health.

  • Between 1989-1991 and 2006-2008 average ambient sulfate concentrations have decreased by 38 percent in the Mid-Atlantic, 44 percent in the Midwest, 43 percent in the Northeast, and 28 percent in the Southeast.

Figure 1: Trends in Electricity Generation, Fossil Energy Use, Prices, and Emissions from the Electric Power Industry, 1990-2008

But… The reduction of SO2 and NOx emissions has had no clear affect on the pH of rainwater.   Here’s a link to an interactive map of the National Atmospheric Deposition Program…

National Atmospheric Deposition Program Interactive Map

Click on a station, select “Trend Plots”, then select “Field pH” or “Lab pH” and look at the actual data.

In some parts of the country, the pH is stable, in some parts it’s gently falling, in other parts it’s gently rising.  Most stations exhibit little or no change in slope over the measurement period, which in many cases goes back to the late 1970’s.

I downloaded all of the annual data from the National Atmospheric Deposition Program and calculated an annual average rainwater pH for the USA…

Annual Average Rainwater pH (USA) 1978-2008

Rainwater was not becoming more acidic prior to the initiation of the EPA’s Acid Rain Program in 1990.  The pH of rainwater was actually rising (becoming less acidic) prior to the EPA’s efforts to fight acid rain.  The really crazy thing is that the pH has been rising more slowly since the EPA started to fight acid rain!

Rain is supposed to be acidic.  The pH of rain in a pristine environment, free from pollution (including volcanoes) is normally about 5.6.  Most of the lakes which were showcased as acid rain victims were naturally acidic and had been acidic since well before mankind ever burned his first lump of coal.

Rather than being a global problem, anthropogenic acid rain was a localized problem in parts of Northern Europe which was relatively easily fixed.

The costs of reducing SO2 and NOx emissions haven’t been that awful… And the reductions did lead to some beneficial incremental environmental effects… But… No acid rain crisis ever existed.


In response to Professor Gutow’s comment: I downloaded a single station from upstate NY with data back to 1979, NY08 Aurora Research Farm…

The pH was already increasing before the EPA initiated its Acid Rain Program (ARP)…

Even more significantly, the SO4 concentration was already in decline. Based on the pre-1990 trend, SO4 would have declined to its current level without ARP, albeit 5 years later…


11 Responses to “The Acid Rain Scam”

  1. Fish Says:

    As a geophysicist, I really enjoy reading your site. Your data analysis is concise and easy to understand. Have you seen the TED 2010 video of Bill Gates on climate change, his ‘equations’ make my head want to explode.

    • David Middleton Says:

      I haven’t seen it… I’ll have to check it out. Although, my head will explode if I hear “Stefan-Boltzmann” many more times. I’ll bet that I’ve read hundreds of blog posts and articles in which some physicist has said that Stefan-Boltzmann or some other radiative forcing equation proves that CO2 is driving climate change… Yet all of the observational data prior to about 1980 proves that CO2 can’t drive climate change.

      I haven’t done the math, but wouldn’t the Henderson-Hasselbalch equation say that the rising level of atmospheric CO2 since 1980 should be causing rain to become more acidic?

      The “funny” thing about equations, is that mathematically sound ones can still yield the wrong answer.

      I don’t know how many times I’ve seen dry holes drilled on very sound geophysical models that failed to properly integrate the geology.

  2. Global Warming, er, Climate Disruption, and My Kid « NooneOfAnyImport's Blog Says:

    […] and environmentalism generally.  We talked about how, when I was a kid, I was scared of acid rain killing all our trees and plants and […]

  3. Jonathan Gutow Says:

    If you are going to make statements suggesting that the trend of increasing pH decelerated after 1990, you should look at the data first. I chose a random site in NY. Prior to 1990 the pH was oscillating between 4.1 and 4.2 (maybe trending slightly upwards). After 1990 it began to trend significantly upwards. In 2010 (last available data) the pH was about 4.9. This single example clearly contradicts your statement. Note also that it is inappropriate to look at the whole US. The meaningful data is for locations downwind of coal fired power plants, which were the main emitters of NOx and SO2 gases. Thus almost all the acid deposition occurs in places located in the Northeast US.

    Go to
    select: NTN, Concentration, Lab pH (or Field pH) and compare 1994 to 2009 for a clear picture of what has happened and where the acid deposition occurs.

    • David Middleton Says:

      Professor Gutow,

      Thank you for taking the time to read and comment on my blog post.

      How does a single station refute the average of all of the stations?

      Even in your example, the pH was already rising before the initiation of the EPA’s Acid Rain Program in 1990. (See addendum).

      • Jonathan Gutow Says:

        You are missing the point about how acid rain is distributed. Acid rain occurs when acid forming compounds such as NOx and SO2 mix with water in the clouds to form acidic rain drops. This only occurs in locations where NOx and SO2 are produced upwind (to the west in general) of the location of the precipitation. Most coal fired power plants (the major source of SO2) are located in the Midwest. This means that acid rain caused by them occurs mostly in New York and the Mid Atlantic states which are east of the power plants. If you look at the maps provided of the distribution of acid deposition, you will see that the acidity of the rain began to reduce significantly in these regions after the laws were changed.
        By averaging over the whole US you are masking the trends in the regions of the country that are affected by NOx and SO2 emissions.

  4. Patrick Jak (netherlands) Says:

    Maybe a small detail. PH is of course a logarithmic scale…if you would rework the data to (milli)moles H+ per litre you would find that the change in H+ concentration after 1990 is an order of magnitude smaller than the change before 1990.

  5. Norman Bates Says:

    You people are crazy. Acid Rain is real they have scientific evidence for it

  6. Tony Says:

    Enjoyed the article, was thinking about acid rain as I was watching the beautiful blue sky get hazed out by Chem debris! Haven’t heard much about acid rain or the hole in the ozone since grade school.. over 20 years!

  7. chaamjamal Says:

    No evidence that acid rain acidified lakes in the Adirondacks and killed trees on Camel’s Hump Mountain.

  8. ingenieurs marocains Says:

    هيئة المهندسين التجمعيين – corps des ingenieurs du parti du RNI

    corps des ingenieurs du parti du RNI

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