Climate Change Impacts in the U.S.: Sober Analysis, Cool Graphics from Patrick Michaels and Chip Knappenberger

by Marlo Lewis on January 18, 2013

in Features

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Cato Institute scholars Patrick Michaels and Chip Knappenberger have produced a layman-friendly yet thoroughly referenced draft report summarizing “the important science that is missing from Global Climate Change Impacts in the United States,” a U.S. Government document underpinning the EPA’s December 2009 endangerment rule, the foundation of all of the agency’s greenhouse gas (GHG) regulations.

Pat and Chip’s draft report, titled Addendum: Climate Change Impacts in the United States, is a sober antidote to the climate fear-mongering patronized by the Obama administration, mainstream media, the U.N., corporate rent seekers, and the green movement. Among the best features are the numerous graphics, some of which I will post here.

Taking these in no particular order, let’s begin with the scariest part of Al Gore’s “planetary emergency”: sea-level rise. Is the rate of sea-level rise dangerously accelerating? No. Over the 20th century, there was considerable decadal variation in the rate of sea-level rise but no long-term trend.

Decadal rate of sea level rise from satellites (red curve) appended to the decadal rate of global sea level rise as determined from a nine-station tide gauge network for the period 1904–2003 (blue curve) and from a 177-station tide gauge network for the period 1948–2002 (magenta). Adapted from Holgate, S.J., 2007: On the decadal rate of sea level change during the 20th century. Geophysical Research Letters, 34, doi:10.1029/2006 GL028492

The UN IPCC Fouth Assessment Report (2007) famously concluded that “most of the observed increase in global average temperature since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.” However, recent studies attribute components of the observed warming to other factors. Adding up those contributions, Pat and Chip calculate that greenhouse gas concentrations account for less than half of the observed warming since 1950.

“Observed” global average temperature anomalies from 1950–2010 (red) and “adjusted” global temperature anomalies after accounting for non-greenhouse gas influences from a cold bias in sea surface temperatures, a warm bias in land temperatures, increases in stratospheric water vapor, and revised estimates of the warming effect from black carbon aerosols (blue). The trend through the adjusted temperature anomalies is less than half the trend in the original “observed” data series. [Sources provided in footnotes 67-73 on p. 34.] 

Climate models typically overestimate actual warming, indicating that they overestimate climate sensitivity (the amount of warming resulting from a given increase in GHG concentrations).

During the 15 year period from 1997-2011, the observed rate of global warming as derived from the five major compilations of global average surface temperatures (GISS (red), NOAA (green), Hadley Center (dark blue), MSU satellite—University of Alabama version (yellow) and MSU satellite (Remote Sensing Systems version (light blue) falls out in the left-hand tail of the distribution of model projected trends of the same length (grey bars).

Is the recent Midwest drought evidence that our fuelish ways are destabilizing the climate system? No. There is no long-term trend in U.S. soil moisture such as might be correlated with the increase in atmospheric GHG concentrations.

The Palmer Drought Severity Index (PDSI) shows no trend in the area of the nation experiencing drought or excessive wetness over the period of record that begins in 1895.

In fact, throughout the U.S., soil moisture in the 20th century increased in more areas than it declined.

Source: Andreadis, K.M., and D.P. Lettenmaier, 2006: Trends in 20th century drought over the continental United States. Geophysical Research Letters, 33, L10403, doi:10.1029/2006GL025711

Okay, but as the world warms (and as urban heat islands expand), there are going to be more heat waves, and more people will die, right? Yes and no. “Mortality from heat waves declines as heat wave frequency increases, and deaths from extreme cold decline dramatically as cold air preferentially warms.” Cities with the most frequent hot weather, such as Phoenix, AZ and Tampa, FL, have virtually no heat-related mortality.

 Average heat-related mortality in U.S. urban areas has declined nationwide; subsequent research shows this trend continues into the 21st century. [Sources: Davis RE, et al., 2003. Changing Heat-Related Mortality in the United States. Environmental Health Perspectives 111, 1712–18. Kalkstein, L.S., et al., 2011. An evaluation of the progress in reducing heat-related human mortality in major U.S. cities. Natural Hazards 56, 113-129.]

Is global warming spinning up ever more powerful tropical cyclones? In the Atlantic Basin, there has been no long-term trend in the accumulated cyclone energy (ACE) index (which combines the duration and intensity of each storm into a seasonal total).

Accumulated Cyclone Energy (ACE) index for the Atlantic Basin from 1851 through 2010. There is obviously no relationship to long-term temperature rise or GHG concentrations. Data available at

Nor has there been a long-term increase in ACE globally since 1970.

Global hurricane activity as measured by the ACE index has been in general decline since the early 1990s and as of 2011 was near its 40-year low. Source: Maue, R.N., 2011: Recent historically low global tropical cyclone activity. Geophysical Research Letters, 38, L14803, doi:10.1029/2011GL047711

Is global warming altering wind patterns such that more hurricanes are striking the U.S.? There has been no long-term trend in the number of hurricanes and major (category 3-5) hurricanes making landfall in the U.S.

U.S. landfalling decadal hurricane counts reached their maximum in the 1940s. Source: Blake, E.S., C.W. Landsea, and E.J. Gibney, 2011: The deadliest, costliest, and most intense United States tropical cyclones from 1851 to 2010 (and other frequently requested hurricane facts). NOAA Technical Memorandum NWS NHC-6, National Weather Service, National Hurricane Center, Miami, FL,

Okay, but apart from hurricanes, has the area of the U.S. experiencing extreme weather expanded as GHG concentrations have increased? The National Climate Data Center’s Climate Extremes Index (CEI) plots the ”fraction of the area of the United States experiencing extremes in monthly mean surface temperature, daily precipitation, and drought.” The CEI has increased since 1970 but the current weather regime “clearly resembles that of the early 20th century, long before major greenhouse gas emissions.”

Climate extreme index, not counting tropical storms and hurricanes, 1920-2010. Source: Gleason, K.L., et al., 2008: A revised U.S. Climate Extremes Index. Journal of Climate, 21, 2124-2137.

But surely, tornadoes are more frequent now than ever, and what else can explain this except the increase in GHG concentrations? Actually, it’s the ability to detect small tornadoes that has increased. If we consider just the large tornadoes (F3-F5) that have been detectable for decades, there is no trend.

Number of strong U.S. tornadoes, 1950–2011. Source: NCDC, U.S. Tornado Climatology, 7 March 2012, at, visited 11 May 2012.

But tornadoes are killing more people, right? Nope.

U.S. tornado death rate, 1900–2011. Sources: Updated from Goklany (2009a), using USBC (2011); NWS, Hazard Statistics at, accessed May 11, 2012; NWS, Storm Prediction Center, Annual U.S. Killer Tornado Statistics, at, accessed May 11, 2012.

The same holds for mortality rates and extreme weather generally:

For the U.S., the cumulative average annual deaths from extreme weather events declined by 6% from 1979–1992 to 1993–2006 (despite a 17% increase in population), while all-cause deaths increased by 14%. [Source: Goklany, I.M. 2009. Deaths and Death Rates from Extreme Weather Events: 1900-2008. Journal of American Physicians and Surgeons 14, 102-09]

Hurricane damages keep going up and up, but that’s due to the ongoing rise in population and development in coastal areas. When hurricane damage is adjusted for changes in population, wealth, and inflation, there is no long-term trend.

U.S. tropical cyclone damage adjusted for inflation, population growth and wealth, 1900-2012 [Note - I am using a more updated graph than the one appearing in Addendum. Source: Pielke et al. 2008. Normalized Hurricane Damage in the United States: 1900-2005, Natural Hazards Review, DOI: 10.1061/1527-6988, 9:1(29), updated 12/31/2012].

Okay, but warmer temperatures mean more photo-chemical smog and worse air pollution, right? Only if air pollutant emissions stay the same, but emissions have declined on average by 67% since 1980. Further declines are projected as auto fleets and capital stock are replaced by newer, cleaner models.

Despite an increasing population, energy consumption, and economic productivity, U.S. pollution emissions declined by 67% since 1980. [Source: U.S. Environmental Protection Agency, Air Trends,]

Whatever risks climate change may pose to U.S. agriculture in the future, warming historically has not been associated with reductions in crop yield.

U.S. Cotton, corn and wheat yields, 1866–2010 [Source: National Agricultural Statistics Service, QuickStats 1.0 (2010), available at by_Subject/index.php?sector=CROPS, downloaded December 26, 2010]

Remember the U.N. Environment Program’s (UNEP) November 2005 prediction that there would be as many as 50 million climate refugees by 2010? Not only did those displaced populations fail to materialize, some of the areas UNEP supposed would be hardest hit by climate change impacts experienced rapid population increases. Something similar is going on right here in the USA. Decade by decade, millions of Americans vote with their feet to live in warmer climates.

U.S census data show that the largest percent increases in population are in the relatively dry and hot Pacific Southwest, the moist and hot southeast Texas, and the Florida peninsula.

But ‘everybody knows’ that global warming is the worst threat facing humanity. Okay then explain this: Why do U.S. (and global) population, per capita income, and life expectancy keep rising along with carbon dioxide emissions?

U.S. carbon dioxide emissions, population, GDP per capita (affluence) and life expectancy at birth, 1900-2009. [Source: Goklany, I.M. 2009. Have increases in population, affluence and technology worsened human and environmental well-being? The Electronic Journal of Sustainable Development 1(3), updated using the Statistical Abstract of the United States 2011, and National Vital Statistics Report 59 (4): 1; CDIAC (2010); GGDC (2010)]

Well, that should be enough to whet your appetite to read Addendum. I’ll conclude this post by reproducing the draft report’s ”key findings.”

Key Findings:

  1. Climate change is unequivocal, and human activity plays some part in it. There are two periods of warming in the 20th century that are statistically indistinguishable in magnitude. The first had little if any relation to changes in atmospheric carbon dioxide, while the second has characteristics that are consistent in part with a changed greenhouse effect. (p. 17)
  2. Climate change has occurred and will occur in the United States. U.S. temperature and precipitation have changed significantly over some states since the modern record began in 1895. Some changes, such as the amelioration of severe winter cold in the northern Great Plains, are highly consistent with a changed greenhouse effect. (pp. 38–56, 187–92)
  3. Impacts of observed climate change have little national significance. There is no significant long-term change in U.S. economic output that can be attributed to climate change. The slow nature of climate progression results in de facto adaptation, as can be seen with sea level changes on the East Coast. (pp. 48–49, 79–81, 155–58, 173–74)
  4. Climate change will affect water resources. Long-term paleoclimatic studies show that severe and extensive droughts have occurred repeatedly throughout the Great Plains and the West. These will occur in the future, with or without human-induced climate change. Infrastructure planners would be well-advised to take them into account. (pp. 57–71)
  5. 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. (pp. 102–18)
  6. Sea level rise caused by global warming is easily adapted to. Much of the densely populated East Coast has experienced sea level rises in the 20th century that are more than twice those caused by global warming, with obvious adaptation. The mean projections from the United Nations will likely be associated with similar adaptation. (pp. 173–74)
  7. Life expectancy and wealth are likely to continue to increase. There is little relationship between climate and life expectancy and wealth. Even under the most dire climate scenarios, people will be much wealthier and healthier in the year 2100 than they are today. (pp. 139–45, 158–61)
  8. Climate change is a minor overlay on U.S. society. People voluntarily expose themselves to climate changes throughout their lives that are much larger and more sudden than those expected from greenhouse gases. The migration of U.S. population from the cold North and East to the much warmer South and West is an example. Global markets exist to allocate resources that fluctuate with the weather and climate. (pp. 154–69)
  9. Species and ecosystems will change with or without climate change. There is little doubt that some ecosystems, such as the desert West, have been changing with climate, while others, such as cold marine fisheries, move with little obvious relationship to climate. (pp. 119–38, 208)
  10. Policies enacted by the developed world will have little effect on global temperature. Even if every nation that has obligations under the Kyoto Protocol agreed to reduce emissions over 80 percent, there would be little or no detectable effect on climate in the policy-relevant timeframe, because emissions from these countries will be dwarfed in coming decades by the total emissions from China, India, and the developing world. (pp. 28, 211)

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