carbon dioxide


400 ppm: A Milestone that Means Everything, and Nothing

For the first time in history, the atmosphere’s concentration of CO2 has topped 400 ppm

Commentary by Michael D. Lemonick

CO2 levels have been climbing since the Industrial Revolution.

I’m not big on taking note of milestones. They’re artificial, and usually meaningless, but people get all worked up about them anyway. I don’t like to stay up late on New Year’s Eve, for example, because Dec. 31 is a purely arbitrary date. Nothing real actually begins the next day, but we all pretend otherwise. I have similar feelings about the first day of spring, the temperature reaching 100° as opposed to 99° and all sorts of other magic-sounding dates and numbers that don’t have any real significance.

But since no law says I have to be consistent, I’m going to take note of a milestone that happened some time in the past couple of months, and which was reported last week by NOAA. For the first time in recorded history, and almost certainly for much longer than that, the atmosphere’s concentration of carbon dioxide, or CO2, has nipped above 400 parts per million in at least one part of the world. Monitoring stations in Alaska, northern Europe, and Asia have all noted readings above that level during this past spring.

In one sense, this isn’t all that important. There’s no meaningful difference between 399 ppm and 400, and the current world average is more like 393. Even in the Arctic, scientists know the CO2 level will drop back below 400 this summer, as trees in the Northern Hemisphere suck carbon dioxide back out of the atmosphere (you can see the annual ups and downs as trees start growing in the spring and go into hibernation in the fall). We won’t get to a world average of 400 for several years yet.
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Cutting Emissions…With Car Insurance?

The “Pay As You Drive” approach to auto coverage could save some drivers money–and cut lots of CO2, studies say.

Los Angeles traffic (Photo: Gabriel Bouys)

Most car insurance is priced in the United States kind of like an all-you-can-eat salad bar, says Justin Horner, a transportation analyst at the Natural Resources Defense Council. You pay a set amount once or twice a year, and then you can eat one little salad, or you can totally chow down, making several trips back for more food, piles of cole slaw and jello threatening to topple from your over-filled plate. Either way, it makes no difference to your wallet.

And, of course, regardless of hunger level, it can be kind of tempting to go back again and again, just because you can.

On the other hand, if you get your salad at one of those pay-by-weight places, you’re likely to be a lot more discriminating about what’s on your plate. That’s how we buy gas, says Horner.

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The Other “Earth Day”

Photo by Reed Galin

Photo by Reed Galin

There is another “Earth Day” that’s been around for, oh, about a hundred years longer than the one we mark on April 22. It’s Arbor Day, though few people can tell you when it is. In fact, nowadays few seem to even know what it is.

Julius Sterling Morton would be crestfallen that the tradition he started shortly after the Civil War is so little remembered. The soon-to-be Secretary of Agriculture under President Grover Cleveland was a big believer in the trans formative power of trees. He reckoned that what his Nebraska farm needed were trees, to gird against both the relentless winter wind and intense summer sun. The idea caught on. When the state marked its first official Arbor Day in 1872, Cornhuskers are said to have planted a million trees (I’ve driven through Nebraska and I’m not sure where they all went).

During the Nixon administration, Arbor Day was designated as the last Friday in April, another reason why it languishes in the shadow of Earth Day. Adding to the confusion is that different states celebrate it at different times, depending on the local climate. In Florida, it’s the third Friday in January. Here in California, it’s not even a “day.” It’s a week. The calendar maintained by the Arbor Day Foundation gives the date of California’s Arbor Day as “March 7-14,” which happens to be right now.

The Arbor Day spirit endures at places like the Sacramento Tree Foundation, which has been using funds from the local utility, SMUD, to fill out the urban canopy and reduce the effect of urban heat islands. Over the past 25 years, the Foundation has orchestrated the planting of 1.25 million trees. The goal is five million. That’s a lot of trees but then it takes a lot of trees to cool down a metro area the size of Sacramento. The shade freaks at SMUD have done the math and say that to make any measurable difference in temperature, you have to add about 10% to the urban canopy.

It’s doubtful that Julius Sterling Morton had urban heat islands or carbon sequestration in mind, back in 19th century Nebraska. He was probably just trying to get out of the damn wind. But given the crucial role of trees in storing carbon and recent reports documenting trees dying off at an alarming rate throughout the West, now seems like a terrific time to exhume Arbor Day from the Tomb of the Unknown Occasion.

Global Warming a Tough Sell this Winter

October snow in upstate NYI believe they call it “the tyranny of the present.” This is the season of solidarity for climate change contrarians and global warming skeptics.

Take my brother, Chuck, who’s been digging out of his driveway in upstate New York non-stop since Halloween. After powering down the snow blower, Chuck recently explained to me that all this global warming hoopla is a conspiracy to redistribute American wealth to developing nations, under the auspices of the U.N. (which just happens to put out all those horrifying projections about climate change run amok–coincidence? You decide).

Climate change skeptics like Chuck have a lot of support for their views when the plow goes by and throws up a 6-foot wall of snow in front of their driveways and CNN switches from O.J. to avalanche coverage. Rush Limbaugh weighs in on their behalf. They even have their own convention, scheduled for March in New York. Then to cap it all off, London Telegraph columnist Christopher Booker has declared 2008 as “the year man-made global warming was disproved.” (Last time I checked, his column on this had more than 1,000 comments).

But it’s more than just the chilling effect of winter. Across much of the country (California being a notable exception), recent public polling would seem to indicate an eroding public acceptance of climate science, increasingly divided along party lines. A survey by the Pew Research Center last spring found that 71% of those surveyed accepted the basic premise of climate change but less than half believed it was related to human activity (“Republicans are increasingly skeptical,” noted Pew).

The most common arguments set forth by skeptics are pretty well summarized in this letter we got from William McKillop, a resource economist now retired from the U.C. system. I present McKillop’s comments without annotation, except for one, which you’ll find at the end of his remarks, below. As always, I invite your comments.


Human Activity May Not Be The Main Cause Of Global Warming

  • It is possible that human activity may not be the main cause of global warming.
  • Humans are responsible for only 2% to 5% of total carbon dioxide emissions and less than two-tenths of one percent (0.2%) of total greenhouse gases emitted into the atmosphere each year.
  • Higher temperatures increase non-human emissions of carbon dioxide from plant-life and the sea
  • Recent reductions in sunspots on the solar surface suggest that we may be entering into a cooling period
  • More than 17,000 scientists of diverse backgrounds signed the Oregon Petition against the Kyoto Protocol because they saw “no compelling evidence that humans are causing discernible climate change.”
  • The Kyoto Protocol would cost the U.S. economy $100 to $200 billion per year, as estimated by the Clinton Department of Energy.
  • Kyoto would restrain temperature increases by less than one degree and delay global warming by only six years.
  • Kyoto was rejected by the U.S. Senate 95-0.

It is legitimate to recognize that global warming is taking place and will cause significant problems. And few in the U.S. will deny that we should decrease our dependence on oil from the Middle East. But some persons think it is heresy to disagree with the view that human activity may not be the main cause of global warming rather than factors such as change in solar activity and change in the earth’s orbit and tilt. Some of them appear to be confused. They do not seem to understand that the debate is not about the fact that global warming is taking place but rather about its major cause. Some believe, based on a review of 928 studies that there is no controversy that human activity is causing global warming. They seem not to realize that only 2 percent of the 928 studies wholly endorsed that claim and that there were 11,000 studies on the subject that were not examined.

One should also be careful in studying findings of the United Nations Intergovernmental Panel on Climate Change (IPCC). A University of Auckland [New Zealand] paper by C.R. de Freitas says “The UN IPCC’s voice to the public, press and policy makers regarding climate science is through summaries; in particular, the brief, politically approved “Summaries for Policymakers” (SPM), which have become notorious for their bias, tendency to overstate problems and penchant for simplifying and dramatizing scientific speculation”. Nor should one be swayed by the fact that a large number of scientists contributed to the preparation of the IPCC report. In 2000, Professor S. Fred Singer testified to the U.S. Senate that more than 17,000 scientists of diverse backgrounds signed the Oregon Institute of Science and Medicine Petition against the Kyoto Protocol because they saw “no compelling evidence that humans are causing discernible climate change.”

Modeling of the causes of global warming requires use of a comprehensive data series and a complete and logical set of explanatory variables. A proper analysis should use a data set that includes the whole of the twentieth century and not just the last few decades. Also, it should include as explanatory variables, measures of solar activity and indicators of the earth’s orbit and tilt. Carbon dioxide concentration by itself is an inadequate explanatory variable, especially in view of the fact that higher temperatures increase non-human emissions of carbon dioxide from plant-life and the sea.

Persons who are eager to place predominant blame on mankind for global warming often specialize in personal attacks on those who have an opposing view. For example, they promulgate smears that dissenting scientists are bribed by energy producers such as “Big Oil”. People who want to know the facts should seriously study websites such as,, and

For a broad overview they should read “The politics of global warming,” an interview of the Canadian climatologist, Dr. Tim Ball, in the February 10, 2007 Pittsburgh, PA Tribune. They should be dismissive of attempts by entities with a political agenda to smear Dr. Ball and others. Persons with a background in science should read the critique of the climate change modeling process by Meyer (A Skeptical Layman’s Guide to anthropogenic global warming); and “Environmental Effects of Increased Atmospheric Carbon Dioxide” by Robinson and Soon. Persons with a background in science and economics should read the scathing analysis of the IPCC and Stern report by a British panel of fourteen independent expert scientists and economists at They should consider whether it is wise to impose huge costs on consumers by adopting the Kyoto Protocol for very little gain. [Kyoto would cost the U.S. economy $100 to $200 billion per year, as estimated by the Clinton Department of Energy, and restrain temperature increases by less than one degree. That is equivalent to delaying global warming by only six years]. Kyoto was rejected by the U.S. Senate 95-0.

They should pay particular attention to the chart on the Friends of Science home page which shows a close relationship between temperature anomaly and the length of sunspot cycles, but a very weak relationship between temperature anomaly and concentration of carbon dioxide. Recent reductions in sunspots on the solar surface suggest that we may be entering into a cooling period. And, in his movie, even Al Gore seems to be aware that tilt of the Northern Hemisphere towards the sun leads to global warming because of its greater land mass. The Geocraft website explains the effect of cyclical eccentricities in the earth’s rotation and orbit.

Furthermore, on the basis of U.S. Department of Energy data, J. DuHamel in his paper, Climate Change in Perspective, noted “that humans are responsible for 2% to 5% of total CO2 emissions. Carbon dioxide constitutes about 3% to 4% of total greenhouse gases by volume; therefore anthropogenic CO2 represents less than two-tenths of one percent (0.2%) of total greenhouse gases emitted into the atmosphere each year”.


Editor’s Note: McKillop makes reference to the Oregon Institute of Science and Medicine Petition, first circulated in 1998. This is often cited by climate change skeptics, including the chairman of General Motors. Others, however, including the National Academy of Sciences, have called this petition drive and its bona fides into serious question. Likewise the climate science credentials of Arthur B. Robinson & Willie Soon, whose paper is also cited here, have been similarly challenged.

Photo by Chuck Miller: October snow in Pierrepont Manor, NY