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Nicole Kaeding

The problems with federal highway spending are well documented. The program distorts project incentives and distributes money inefficiently. A new report from the Government Accountability Office (GAO) adds to the list of problems, detailing improper fund management within the Federal Highway Administration (FHWA).

In 2014 the highway trust fund collected $39 billion in fuel tax revenues, but spent $53 billion, creating a $14 billion deficit. This was not an isolated event. Since 2008 Congress has provided  $50 billion of general federal revenues to prop up the highway trust fund. The Congressional Budget Office estimates that the highway trust fund will require another $157 billion of general revenues by 2024.

Funds from the highway trust fund are spent by several agencies, with the bulk allocated by FHWA. In fiscal year 2013, FHWA spent $41 billion, or 80 percent, of all highway funds. Of that, $39 billion was sent to states; the majority going to road and bridge construction and improvement.

But GAO found that FHWA is poorly tracking how this money is being spent. According to GAO,  “FHWA tracks and reports aggregate obligations for its “major projects” (projects with a total cost of $500 million or more), it does not collect and report aggregate obligations for other projects, which represented nearly 88 percent of all fiscal year 2013 spending.” GAO’s analysis states that $36 billion in federal highway funding is not being properly tracked by FHWA.

Tracking this information would allow FHWA to provide greater oversight on projects, and to provide Congress and the public greater detail about spending projects and priorities. The agency could track cost growth on projects and perhaps stop cost overruns, which are common on transportation projects.

FWHA already has the technology to make these improvements. GAO notes that FHWA’s computer system already has the capability to track this data, but the agency does not feel inclined to use this capability.

Congress’ current short-term patch to the highway trust fund expires in May. FHWA’s adoption of GAO’s recommendations would allow both Congress and the agency to better control spending and lower the imbalance between spending and revenues.

Chris Edwards

The Secret Service is scandal prone. It spends excessively on foreign presidential trips, and it has agents who get in trouble with prostitutes and liquor bottles. The recent White House fence-jumping incident was a stunning failure. Despite the Service spending $1.9 billion a year, a guy with a knife jumped the fence, sprinted across the lawn, pushed open the front door, galloped through the Entrance Hall, danced across the East Room, and almost had time to sit down for a cup of tea in the Green Room.

In the wake of the incident, the head of the Secret Service resigned. But the Service is an agency within the Department of Homeland Security (DHS), and the head of DHS, Jeh Johnson, did not resign. Indeed, he said very little about it, presumably to evade responsibility. So what is the purpose of having the DHS bureaucratic superstructure on top of agencies such as the Secret Service? If DHS does not correct problems at agencies when they fester for years, and if DHS leaders do not take responsibility for agency failures, why do we need it?

A new survey of 40,000 DHS employees reported in the Washington Post finds that the department has severe management problems:

The government’s 2014 Federal Employee Viewpoint Survey portrays a Department of Homeland Security still facing debilitating morale problems that have plagued it for years but worsened during the Obama administration — and which have grown more serious since Johnson took over in December.

While the survey shows that the vast majority of DHS employees are hard-working and dedicated to their mission to protect the homeland, many say the department discourages innovation, treats employees in an arbitrary fashion and fails to recruit skilled personnel.

At the DHS Science and Technology Directorate, for example, only 21 percent of employees in this year’s survey held positive views of their leadership’s ability to “generate high levels of motivation and commitment in the workforce,’’ according to results for that division.

Since its inception, the department has been plagued by poor morale and a work environment widely seen as dysfunctional, which has contributed to an exodus of top-level officials in recent years, many of whom have been lured by private security companies.

Only 41.6 percent of DHS employees said they were satisfied with the department, down from 44.4 percent a year earlier.

In 2013, only 29.9 percent of employees department-wide had a positive view of their leaders’ ability to “generate high levels of motivation and commitment in the workforce.’’ That number plunged to 24.9 percent this year.

That’s all pretty pathetic. But this is the most stunning result from the survey: “Asked if their leaders ‘maintain high standards of honesty and integrity,’ just 39.1 percent of employees responded positively.”

The 2002 creation of DHS was a mistake. Congress should revisit its handiwork, and begin unbundling the department and closing it down. Some DHS agencies, such as the Secret Service, should be stand-alone organizations that report directly to the president. Some DHS agencies should be moved to existing departments. And some DHS agencies, including TSA, ought to be abolished.

Michael F. Cannon

Today, the Supreme Court hears a case about whether dentists and other professions should be allowed to use state licensing boards to engage in anti-competitive behavior that would be illegal if not done under the auspices of state governments. The case is North Carolina State Board of Dental Examiners v. FTC, and involves actions taken by that state’s dental board to prevent non-dentists from providing teeth-whitening services.

In the University of Pennsylvania Law Review, Cato Institute adjunct scholars David Hyman and Shirley Svorny explain:

A majority of the courts of appeals gives state licensing boards and similar entities considerable latitude to engage in anticompetitive conduct, even when that conduct would be clearly unlawful were it undertaken individually by the licensed providers that typically dominate these licensing boards…

[T]he North Carolina Board of Dental Examiners (N.C. Board) became concerned that non-dentists were providing teeth whitening services. In North Carolina, teeth-whitening was available from dentists, either in-office or in take-home form; as an over-the-counter product; and from non-dentists in salons, malls, and other locations. The version provided by dentists was more powerful and required fewer treatments, but was significantly more expensive and less convenient. In response to complaints by dentists that non-dentists were providing lower-cost teeth-whitening services, the N.C. Board sent dozens of stern letters to non-dentists, asserting that the recipients were engaged in the unlicensed practice of dentistry, ordering them to cease and desist, and, in some of the letters, raising the prospect of criminal sanctions if they did not do so. The N.C. Board also sent letters to mall owners and operators, urging them not to lease space to non-dentist providers of teeth whitening services.

The Supreme Court will decide whether the North Carolina dental board should be able to claim a “state action” exemption to federal laws against anti-competitive conduct. Hyman and Svorny argue they should not, noting that doctors, lawyers, and other professions have used government licensing to stamp out competition, to the detriment of consumers:

Other occupations provide no shortage of similar examples, whether it is states requiring hair braiders to obtain cosmetology licenses (even though the requisite training has absolutely nothing to do with hair braiding), laws prohibiting anyone other than licensed funeral directors from selling coffins, states prohibiting anyone other than veterinarians from “floating” horse teeth, or ethics rules prohibiting client poaching by music teachers. 

“Antitrust has historically focused on private restraints on competition, but publicly imposed limitations can pose greater peril,” they write, “since they are likely to be both more effective and more durable.”

Hyman and Svorny make three further recommendations for the courts:

First, in reviewing the decisions of licensing boards, courts should presume that states were not actively supervising the boards, absent compelling evidence to the contrary. Second, defendant–licensing boards should be required to present persuasive evidence of actual harm that their proposed licensing restrictions or restraints will prevent and should be required to show that private market and non-regulatory forces (including brand names, private certification, credentialing, and liability) are insufficient to ensure that occupations maintain a requisite level of quality. Finally, we argue that legislators should take steps to roll back existing licensing regimes.

Hyman signed onto an amicus brief filed by antitrust scholars. (Here are two more amicus briefs filed by public-choice economists and the Cato Institute.) Svorny argues for the complete repeal of government licensing of medical professionals, and illustrates how the market for medical-malpractice liability insurance does more to promote health care quality than licensing

(Cross-posted at Darwin’s Fool.)

David Boaz

In a brief filed to the Fifth Circuit Court of Appeals on Friday, Texas attorney general Greg Abbott says that the state’s gay marriage ban may help to reduce out-of-wedlock births:

Texas’s marriage laws are rationally related to the State’s interest in reducing unplanned out-of-wedlock births. By channeling procreative heterosexual intercourse into marriage, Texas’s marriage laws reduce unplanned out-of-wedlock births and the costs that those births impose on society. Recognizing same-sex marriage does not advance this interest because same-sex unions do not result in pregnancy.

As I’ve written before, this is a remarkably confused argument. There are costs to out-of-wedlock births. Too many children grow up without two parents and are less likely to graduate from high school, less likely to find stable jobs, and more likely to engage in crime and welfare dependency. All real problems. Which have nothing to do with bans on same-sex marriage. One thing gay couples are not doing is filling the world with fatherless children. Indeed, it’s hard to imagine that allowing more people to make the emotional and financial commitments of marriage could cause family breakdown or welfare spending.

The brief repeatedly says that “same-sex marriage fails to advance the State’s interest in reducing unplanned out-of-wedlock births.” Well, that may be true. But lots of state policies fail to advance that particular interest, from hunting licenses to corporate welfare. Presumably Abbott doesn’t oppose them because they don’t serve that particular purpose.

The brief does note that same-sex marriage may very well produce other societal benefits, such as increasing household wealth or providing a stable environment for children raised by same-sex couples [or] increasing adoptions.” But the attorney general wants to hang the state’s ten-gallon hat on the point that it won’t reduce out-of-wedlock births by opposite-sex couples.

In a previous case, Judge Richard Posner declared that the states of Indiana and Wisconsin had not produced any rational basis for banning gay marriage. Attorney General Abbott seems determined to prove him right.

Steve H. Hanke

Over the last few months, the price of Brent crude oil lost over 20% of its value, dropping below $90 just yesterday and hitting its lowest level in over two years. In consequence, oil producers will no longer be able to rely on oil revenues to pay their bills. The fiscal break-even price – a metric that determines the price per barrel of oil required for a nation to balance its budget at current levels of production – puts the problem into perspective.

Using data from Bloomberg and Deutsche Bank, I prepared a chart showing the break-even prices for the world’s major oil producers and the price on Brent crude. Over the past six months, Brent crude fell far below the break-even price for eleven of the top oil producers in the world; Iran, Venezuela, Nigeria, and even Saudi Arabia can no longer finance their governments’ largess through oil revenues.

The combination of oil markets flying into a perfect storm and excessive government spending puts most of the world’s oil producers between a rock and a hard place, where they will stay for some time.

David Boaz

Dumb arguments against libertarianism are increasing, as guardians of the expansive state begin to worry that the country might actually be trending in a libertarian direction. This may not be the dumbest, but as Nick Gillespie said of a different argument two weeks ago, it’s the most recent:

‘You Ready to Step Up?’ The deadly drug war in Long Island’s Hempstead ghetto is a harrowing example of free-market, laissez-faire capitalism, with a heavy dose of TEC-9s To be fair, author Kevin Deutsch never uses the terms “laissez-faire” or “free-market” in his detailed article, so we should probably direct our disdain at Newsweek’s headline writers. Deutsch does portray the second-ranking guy in the Hempstead Crips as a businessman seeking to “recruit talent, maximize profits and expand their customer base.” But even the drug dealer gets the difference between selling prohibited substances and doing business in a free market: “We’re looking to market, sell and profit off drugs the way any business would handle their product,” Tony says. “Only our product is illegal, so more precautions need to be taken. It’s all systematic and planned, all the positions and responsibilities and assignments. All of that’s part of our business strategy. It’s usually real smooth and quiet, because that’s the best environment for us to make bank. But now, we at war, man. Ain’t nothing quiet these days.” Deutsch describes the competition between the local Crips and Bloods in terms not usually seen in articles about, say, Apple and Microsoft or Ford and Toyota: As for strategies, they seem to have settled on a war of attrition, aiming to kill or maim as many of their enemies as possible….   They’re far better armed and willing to use violence than the smaller neighborhood cliques scattered throughout Nassau County….   They’re also able to keep out other competitors through use of brute force….   It’s one of hundreds of similar conflicts being fought by Bloods and Crips sets throughout the country. These battles breed shootings, stabbings and robberies in gang-plagued, low-income neighborhoods each day.  These are, of course, just the sorts of consequences that libertarians and economists expect from prohibition. As Tim Lynch and I wrote in the Cato Handbook on Policy a decade ago,

drug prohibition creates high levels of crime. Addicts commit crimes to pay for a habit that would be easily affordable if it were legal. Police sources have estimated that as much as half the property crime in some major cities is committed by drug users. More dramatic, because drugs are illegal, participants in the drug trade cannot go to court to settle disputes, whether between buyer and seller or between rival sellers. When black-market contracts are breached, the result is often some form of violent sanction, which usually leads to retaliation and then open warfare in the streets.

Jeffrey Miron of Harvard’s economics department and Cato made similar points in his book Drug War Crimes, as have such economists as Milton Friedman and Gary Becker. Miron also noted that prohibition drives up the prices of illegal drugs, making the trade attractive to people with a high tolerance for risk. And so in that sense, it’s true that some people will usually enter the prohibited trade – in alcohol, gambling, prostitution, crack, or whatever – and will employ some techniques that are also used in normal business enterprises. As Tyler Cowen says, there are markets in everything. Given our natural propensity to truck, barter, and exchange in order to improve our own situation, we can expect people to step into any trade, prohibited or not. Better that such trade should take place legally, within the rule of law, than underground, where violence may be the only recourse in disputes.

When the government bans the use and sale of a substance, and imprisons hundreds of thousands of people in an attempt to enforce that prohibition, that’s not “laissez-faire, free-market capitalism.” Duh. 

Ted Galen Carpenter

Beijing’s behavior on the international stage over the past few months has been surprisingly restrained—in marked contrast to an earlier, lengthy period of assertive, if not abrasive, conduct toward its neighbors. Not too long ago, policymakers in the United States and throughout East Asia were alarmed by China’s initiatives. Beijing’s territorial claims in the South China Sea were breathtakingly broad, leading to nasty incidents with the Philippines, Vietnam, and other nations.  Even worse were the confrontations between China and Japan over islands in the East China Sea, along with Beijing’s unilateral proclamation of an extensive Air Defense Identification Zone in that same area, which led to a surge of tensions with Japan, South Korea, and the United States.

Two developments illustrate the new, less confrontational trend in China’s policy. One is Beijing’s concerted diplomatic courtship of such countries as South Korea, Vietnam, and Sri Lanka. As I discuss in a recent article in China-U.S. Focus, even such longstanding rivals as Japan and India have been recipients of this Chinese “charm offensive.” 

The other sign of uncharacteristic restraint is Beijing’s handling of the ongoing pro-democracy demonstrations in Hong Kong. True, there are indications that the Chinese government may have organized and paid for counterdemonstrators to confront and harass democracy activists.  But, at least to this point, there is no indication that Xi Jinping’s government intends to intervene directly with its security forces, much less trigger a bloodbath reminiscent of the 1989 Tiananmen Square massacre. Instead, Beijing has allowed its appointed authorities in Hong Kong to manage the turbulence.  

That is a smart move because the United States and the nations of East Asia are closely watching how the Chinese government handles the democratic ferment in Hong Kong. Taiwan is an especially interested spectator, and if Beijing wants to preserve the possibility of the island’s eventual return to the Chinese fold, a brutal crackdown in Hong Kong would doom those hopes for a generation or more. Conversely, the toleration of even limited moves toward free elections for Hong Kong’s leadership would increase the chances of seducing Taiwan regarding the desirability of gradual re-unification. It appears that Xi and his associates may understand that.

Of course, further developments bear close watching, since they could move quickly in an undesirable direction. It is possible that Beijing’s more conciliatory stance toward its Asian neighbors and its restraint regarding Hong Kong is merely a temporary tactical shift, and that we will soon see a return to a bold, confrontational approach. But if the current restraint instead is the harbinger of a more cautious, cooperative policy over the long term on geopolitical issues, China would become easier to accommodate as a rising great power. That would be good for the peace and security of East Asia and for harmonious relations between Beijing and Washington.

Tim Lynch

Last Week Tonight with John Oliver: Civil Forfeiture (HBO)

For related Cato scholarship, go here.

Chris Edwards

Kansas Gov. Sam Brownback (R) has become a punching bag for liberal pundits. They particularly dislike his tax reforms, which they say are causing a state budget disaster. Nicole Kaeding and I awarded Brownback an “A” on our “Fiscal Report Card.” So let’s take a look at how liberal and libertarian views on Governor Brownback differ.

John Judis at the New Republic writes, “the heart of his program consisted of drastic tax cuts for the wealthy…”

Brownback did sign into law large tax cuts, but that is a good thing. Legislation in 2012 replaced income tax rates of 3.5, 6.25, and 6.45 percent with lower rates of 3.0 and 4.9 percent, while substantially increasing the standard deduction. Those cuts provided savings for taxpayers at all income levels, not just the wealthy. 

Judis continues, “Brownback’s tax cuts had produced a staggering loss in revenue—$687 million, or nearly 11 percent.” Tax Foundation shows the revenue effects of 2012 and 2013 tax legislation here. Judis gets the numbers about right, but I don’t think that magnitude of revenue change is “staggering.” In 2011, Gov. Dan Malloy (D) increased overall Connecticut taxes about 15 percent. That same year, Gov. Pat Quinn (D) increased overall Illinois taxes about 25 percent—now that is “staggering.” (Details on both increases here).

The important thing with tax cuts is that politicians need to match them with spending cuts so they are sustainable. Brownback has been frugal on spending, but it is true that Kansas needs further budget reforms so that future spending growth matches projected revenues. However, that restraint will be beneficial, as it will encourage policymakers to trim low-value programs in the budget.

Paul Krugman slammed Brownback’s tax cuts, saying, “the state’s budget has plunged deep into deficit, provoking a Moody’s downgrade of its debt.”

One problem with that assessment is that state budgets don’t really “plunge deep into deficit” like the federal budget does. Nearly all states must legally balance their general funds. They often cheat a bit with accounting maneuvers, but they generally get it done.

This recent report from the Kansas Policy Institute (KPI) shows how modest budget changes in Kansas can close the gap between projected future revenues and spending. If Brownback is reelected, he will need to trim spending to match his reduced revenues because the Kansas governor is required to submit balanced budgets. By contrast, the federal government has no balanced budget requirement, and it is federal politicians who have “plunged deep into deficit” in recent years, ironically with Krugman’s strong support.

Krugman is right that the Kansas credit rating has been downgraded, which is certainly bad for the budget. Let’s explore the issue with this chart from Pew. Notice that the ratings are somewhat fluid, with occasional upgrades and downgrades. After the chart was published, S&P downgraded Kansas from AA+ to AA, but the state has lots of company in that lower category.

Nonetheless, Kansas policymakers should roll up their shirtsleeves and begin trimming spending to regain the AA+ rating. Looking at KPI’s “medium” revenue estimate (Table 12), Kansas will need to trim at least 5 percent from spending by 2019 to match revenues, which does not sound too difficult to me.

Brownback’s critics are trying to make the larger point that state tax cuts should be avoided because they lead to low credit ratings. But looking at the Pew chart, there is no obvious relationship between major tax changes and the ratings. Two states that passed large tax hikes in recent years—California and Illinois—have the lowest ratings. And two states that passed large tax cuts in recent years—North Carolina and Indiana—have the highest rating.

For more on recent state tax cuts and increases, see the governor’s report card. For other commentary on the Kansas tax cuts, see Will Upton here and Amity Shlaes here

Dalibor Rohac

The award of the Nobel Peace Prize to the Indian activist Kailash Satyarthi is bound to attract public attention to the problem of child labor. In 1980, Satyarthi founded the Bachpan Bachao Andolan, or “Save the Childhood Movement,” focused on fighting child labor and human trafficking, as well as bonded labor.

Child labor is widespread in developing countries, concentrating often in the agricultural sector where working conditions are particularly dire. Because of the gravity of the problem, it is necessary to be extremely careful in devising solutions. As is often the case, the fix to child labor that most people would think of instinctively—namely, to ban it—could do more harm than good. As another Nobel laureate, Paul Krugman, wrote in a New York Times opinion piece in 2001,

In 1993, child workers in Bangladesh were found to be producing clothing for Wal-Mart, and Senator Tom Harkin proposed legislation banning imports from countries employing underage workers. The direct result was that Bangladeshi textile factories stopped employing children. But did the children go back to school? Did they return to happy homes? Not according to Oxfam, which found that the displaced child workers ended up in even worse jobs, or on the streets—and that a significant number were forced into prostitution.

There are no quick and easy answers to the problem of child labor, especially in poor countries where educational opportunities are limited and where bans on child labor simply displace children into less desirable, illegal, and more dangerous occupations. To end child labor, the currently underdeveloped countries must create economic opportunities that would reduce or eliminate the reliance of many, particularly poorer, families on income from the work of their children. In a recent Cato Economic Development Bulletin, the economist Benjamin Powell argues that

The main reason children do not work in wealthy countries is precisely because they are wealthy. The relationship between child labor and income is striking. Using the same World Bank data on child labor participation rates we can observe how child labor varies with per capita income. Figure 2 divides countries into five groups based on their level of per capita income adjusted for purchasing power parity. In the richest two-fifths of countries, all of whose incomes exceed $12,000 in 2010 dollars, child labor is virtually nonexistent.

 

[…]

The thought of children laboring in sweatshops is repulsive. But that does not mean we can simply think with our hearts and not our heads. Families who send their children to work in sweatshops do so because they are poor and it is the best available alternative open to them. The vast majority of children employed in countries with sweatshops work in lower-productivity sectors than manufacturing. Passing trade sanctions or other laws that take away the option of children working in sweatshops only limits their options further and throws them into worse alternatives. Luckily, as families escape poverty, child labor declines. As countries become rich, child labor virtually disappears. The answer for how to cure child labor lies in the process of economic growth—a process in which sweatshops play an important role.

Patrick J. Michaels and Paul C. "Chip" Knappenberger

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.”

A new paper overturns old suppositions regarding volcanoes, tree-rings, and climate sensitivity.

According to a 2012 press release accompanying a paper published in the journal Nature Geoscience, a research team led by Penn State’s Dr. Michael Mann concluded that the cooling influence of historical volcanic eruptions was underrepresented by tree-ring reconstructions of the earth’s temperature.

This, the press release went on to tell us, had potential implications when trying to determine the earth’s equilibrium climate sensitivity (ECS)—i.e., how much the global average surface temperature will rise as a result of a doubling of the atmosphere’s pre-industrial concentration of carbon dioxide. While most recent studies place the ECS noticeably less than earlier studies (including those most heavily relied upon by the U.N.’s Intergovernmental Panel on Climate Change (IPCC) and thus the U.S. Obama Administration), the 2012 Mann study was an exception. It implied that many existing determinations of the ESC were underestimates.

From the press release:

“Scientists look at the past response of the climate to natural factors like volcanoes to better understand how sensitive Earth’s climate might be to the human impact of increasing greenhouse gas concentrations,” said Mann. “Our findings suggest that past studies using tree-ring data to infer this sensitivity have likely underestimated it.”

Fast forward to today.

Appearing on-line in the journal Geophysical Research Letters (and sans press release) is a paper led by Penn State’s Martin Tingley that examined how the temperature response from volcanic inferred from tree-rings compared with that of observations. Tinsley’s team concluded that tree-ring based temperature proxies overestimated the temperature response caused by large volcanic eruptions. Instead of responding only to the cooler temperatures, the tree rings also included signals from reduced light availability (from the shading effect of volcanic aerosols) and the two effects together produced a signal greater than what would have been produced by cooler temperatures alone. This is basically the opposite of what Mann and colleagues concluded.

In an article posted to the website RealClimate back in 2012 touting his team’s findings, Mann took time to point out the “wider implication” of his findings:

Finally it is worth discussing the potential wider implication of these findings. Climate scientists use the past response of the climate to natural factors like volcanoes to better understand how sensitive Earth’s climate might be to the human impact of increasing greenhouse gas concentrations, e.g. to estimate the equilibrium sensitivity of the climate to CO2 doubling i.e. the warming expected for an increase in radiative forcing equivalent to doubling of CO2 concentrations. Hegerl et al (2006) for example used comparisons during the pre-industrial of EBM simulations and proxy temperature reconstructions based entirely or partially on tree-ring data to estimate the equilibrium 2xCO2 climate sensitivity, arguing for a substantially lower 5%-95% range of 1.5–6.2C than found in several previous studies. The primary radiative forcing during the pre-industrial period, however, is that provided by volcanic forcing. Our findings therefore suggest that such studies, because of the underestimate of the response to volcanic forcing in the underlying data, may well have underestimated the true climate sensitivity.

It will be interesting to see if accounting for the potential biases identified in this study leads to an upward revision in the estimated sensitivity range. Our study, in this regard, once again only puts forward a hypothesis. It will be up to other researchers, in further work, to assess the validity and potential implications of this hypothesis.

Based on the new results of Team Tingley, it seems that Mann’s hypothesis is wrong. Using tree ring temperature proxies would overestimate the climate sensitivity.

“It will be interesting to see” if this is recognized over at RealClimate.

But regardless, there is no escaping the fact that the Tingley study provides additional evidence that the earth’s climate sensitivity to human greenhouse gas emissions is likely less than advertised by the UN IPCC and the Obama Administration. The direct result being that headlong pursuit of carbon dioxide emissions limits should be reconsidered in light of this and other scientific literature.

References:

Mann, M. E., Fuentes, J.D., and S. Rutherford, 2012. Underestimation of volcanic cooling in tree-ring-based reconstructions of hemispheric temperatures, Nature Geoscience,5, 202-205.

Tingley, M. P., Stine, A.R., and P. Huybers, 2014. Temperature reconstrictions from tree-ring densities overestimate volcanic cooling. Geophysical Research Letters, doi:10.1002/2014GL061268.

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