The Week That Was
August 24, 2002

1. TRYING TO CORRECT MISCONCEPTIONS IN THE NY TIMES ABOUT OIL PRICES. Tom Friedman (NYT 7/31) has it just backwards when he states: "If prices skyrocket because of a war in the Persian Gulf, Venezuela, Iran, Nigeria and others will cut back their output and keep prices high to milk the moment for all it's worth."







2. Astrophysicist connects Supernovae, cosmic rays, meteorites, and ice ages
(See Physical Review Letters, 29 July 2002.)

New research suggests that ice age epochs on the earth may result from our solar system's trek through the spiral arms of the Milky Way. Nir Shaviv (, +972-54-738555), of the University of Toronto and Jerusalem's Hebrew University bases this hypothesis on correlations he has found between apparent changes in the flux of cosmic rays reaching the earth and geological evidence for major ice ages in the past billion years. Galactic spiral arms are not permanent, rigid fixtures; rather they are transient and result from density ripples traveling around the galaxy. Many massive stars form in the wake of the density waves and later explode as supernovae, which are a primary source of cosmic rays. It seems reasonable to expect our planet to receive more cosmic rays when it is near the supernovae in a major spiral arm. If there is a connection between cosmic-ray flux and climate, past ice ages should correlate with the solar system's location relative to the traveling spiral arms.

One of the challenges in making the climatic connection is finding records of cosmic ray flux over past eons. Shaviv deduced the earth's exposure to cosmic rays by considering the cosmic-ray exposure of 42 iron meteorites. The meteorite record seems to indicate that the cosmic-ray flux varies with a period of about 143 million years, which correlates well with both the geological records of ice age epochs and the solar system's location relative to the spiral arms. Our current position in the minor Orion spiral arm should lead to cosmic ray fluxes about half of what we would receive in a major spiral arm. Shaviv's model places us in the wake of a major ice age epoch, and is consistent with the global temperatures that we are now experiencing. Shaviv points out that the weakest link in his proposal is uncertainties in the extent and timing of glacial periods indicative of ice-age epochs, and that further geological research is necessary to confirm that galactic spiral-arms effect our climate. (Nir J. Shaviv, Physical Review Letters, 29 July 2002.)

The main result of Shaviv's work is that the variations of the GCR flux, as predicted from the galactic model and as observed from the Iron meteorites, is in sync with the occurrence of ice-age epochs (IAE) on Earth. The agreement is both in period and in phase: (1) The observed period of the occurrence of ice-age epochs on Earth is 145+/-10 Myr (compared with 143 +/- 10 Myrs for the Cosmic ray flux variations), (2) The mid point of the ice-age epochs is predicted to lag by 31 +/- 8 Myr and observed to lag by 33 +/- 20 Myr.

This can be seen in the following graph:


3. Cosmic Rays Help Resolve Climate Change Puzzle

Fangqun Yu, a research associate with the Atmospheric Sciences Research Center at the State University of New York-Albany, has shown that cosmic rays may have height-dependent effects on Earth's cloudiness. Yu's National Science Foundation supported study is published in the July 2002 issue of the American Geophysical Union's "Journal of Geophysical Research-Space Physics."

[High clouds generally reflect sunlight while lower clouds tend to retain surface energy. Both effects are well known to science and both have significant effects on global temperatures.]

[A cosmic ray is a high-speed particle - either an atomic nucleus or an electron - that travels throughout the Milky Way Galaxy, including the solar system. Some of these particles originate from the Sun, but most come from sources outside the solar system and are known as galactic cosmic rays. These tiny charged particles bombard all planets with varying frequency depending on solar wind intensity]

Yu investigated the dependence of the production rate of cloud condensation nuclei (CCN) on galactic cosmic ray (GCR) ionization rate at different altitudes. Yu's primary studies indicate that an increase in GCR ionization rate leads to an increase in CN production in the lower troposphere (>680 mbar), but a decrease in CCN production in the upper troposphere (<440 mbar).

[In the lower troposphere the ionization rate is low and the H2SO4 concentration is relatively high; the particle formation is limited by ionization rate and an increase in ionization rate leads to an increase in nucleation. In the upper troposphere the ionization rate is very high and the H2SO4 concentration is relatively low; the particle formation is limited by H2SO4 concentration and an increase in ionization rate inhibit the nucleation by reducing the lifetime of ion clusters. The average change of CCN production as the ionization rate increases is small in the middle troposphere (440-680 mbar).]

We can expect that the correlation between GCR changes and global cloud cover (if any) should be positive for low cloud, negative for high cloud, and weak for the middle cloud. In addition to the reported positive correlation between GCR variations and low cloudiness, Yu's analyses of ISCCP D2 IR cloud data further reveal that high cloudiness may be anticorrelated with GCR variations -- if volcano and El Nino impacts are excluded. During a solar cycle the absolute change of high and low cloud amounts is opposite in sign but similar in magnitude (_1.5-2%). The fluctuations of middle cloud anomalies are small compared to those of low clouds, and no obvious correlation exists between middle cloudiness and GCR variations.

Therefore the observed different correlations between GCR variations and low, middle, and high cloud anomalies seem to be consistent with the predicted dependence of CN production on GCR variations at different altitudes. Such a consistency suggests that solar activity might actually affect global cloudiness by modulating GCR fluxes.

[Meanwhile, considering the limit of cloud-cover data available and uncertainties in the volcano and El Nino impacts, Yu emphasizes that his conclusions (especially with regard to the existence of anticorrelation between high cloudiness and cosmic ray variations) are not definitive.]

Since cloudiness is critical to the Earth radiation budget, opposite systematic variations of low and high clouds associated with solar activity, if confirmed, may represent an important mechanism to amplify the effect of solar variability on Earth's climate.

Yu speculates that the decrease in GCR intensity during the last two decades might have led to a decrease in global mean low-cloud amount and an increase in high-cloud amount, which might have warmed the Earth's surface and cooled the low troposphere. He thus suggests that may reconcile the apparent differences in global mean temperature trends over the last two decades at Earth's surface (rapidly warming, as recorded by thermometers) and in the lowest 8 km of atmosphere (little if any warming, as monitored by satellites and balloons).

In addition to their possible influence on particle nucleation rate and CCN abundance, GCR variations may also affect global electric circuit and electro scavenging [e.g., Tinsley, 2000, 2001] that will change cloud properties. On the other hand, the UV-induced changes in stratospheric ozone and heating rate alter the atmospheric circulation, energy transport and the lower atmosphere temperature [e.g., Haigh, 1996, 1999; Shindell et al., 1999] and thus may also influence the cloud properties. It is important to understand the relative contributions of different mechanisms (hypotheses) to the natural variability of the cloud properties under different atmospheric conditions (or at different altitudes/latitudes).


SEPP Comment: As you know, I have been a strong supporter of solar influence on climate change on a decadal time scale, esp. after the convincing data published by Neff (Nature 2001)

I have kept an open mind on the mechanism. My book Hot Talk, Cold Science gives some preference to the Svensmark (galactic) Cosmic-Ray-Cloudiness hypothesis, but mentions also the possibility of ozone changes affecting tropospheric circulation (Haigh) and the ionospheric electric-circuit hypothesis (Tinsley).

It seems to me now that the matter may at last be settled in favor of Svensmark -- although it does not exclude the other hypotheses. Nir Shaviv has shown (PRL 2002) that GCR are the likely cause of climate change on a time scale of 100 my. Fangqun Yu (JGR 2002) has demonstrated a mechanism whereby GCR can affect low-altitude cloudiness.

What we need now, it seems to me, is an additional demonstration. I propose we look at climate changes during periods of geomagnetic field reversal. When the Earth's dipole field goes through zero, we have a global increase in GCR-caused ionization density at all geomagnetic latitudes, producing low-altitude cloudiness wherever there is sufficient water vapor. The general outcome should be a cooling but its geographic distribution may be rather complicated.


4. Absence of contrails increases diurnal temperature range

Clouds formed by the water vapor in the exhaust from jet planes have a small but significant effect on daily temperatures, a new study confirms. The grounding of commercial flights for three days after last September's terrorist attacks in the United States gave David Travis at the University of Wisconsin-Whitewater and colleagues a chance they never thought they'd have: to study the true impact that contrails from jet engines have on our climate1

Despite a wealth of experiments, it had been virtually impossible to gauge the effect of contrails because air traffic, particularly over regions such as Europe and North America, never stopped. Until 11 September 2001, that is. Contrails left high in the atmosphere spread out into cirrus-like clouds under the right atmospheric conditions. Natural cirrus clouds - thin layers of wispy water vapor that often resemble fish scales - trap heat being reflected from the ground and, to a lesser extent, reflect some of the Sun's rays.

Travis's team compared the average daily high and low temperatures over North America from 11 to 14 September 2001, with climatic records from 1977 to 2000, matching the weather over those three days with similar weather in September from historical records.
They found that the difference between daily high and nightly low temperatures in the absence of contrails was more than 1 oC greater than in the presence of contrails. Comparing the three-day grounding period with the three days immediately before and after, the impact was even larger - about 1.8 oC.

The researchers suggest that in regions with crowded skies, contrails work just like artificial cirrus clouds, preventing days from getting too hot by reflecting the Sun's rays, and keeping nights warmer by trapping the Earth's heat. Averaged over the globe, which is largely free of air traffic, the effect is negligible. "But locally, contrails are equally as significant as greenhouse gases," says Carleton.

The discovery is important, "especially when you consider that air traffic is expected to increase at about five per cent a year". But making use of the information by incorporating it into climate models, for example, will be difficult. Little is known about what conditions lead to contrail formation, how long they last, and whether they affect more than just temperature.


1Travis, D. J., Carleton, A. M & Lauritsen, R. G. Contrails reduce daily temperature range. Nature, 418, 601, (2002).


SEPP Comment: No great surprise here. One would expect high clouds with appreciable albedo to lower day temp and raise night temp. The increase in air travel (see Singer , HTCS p.54) thus might account for the reported decreasing trend (Kukla, Karl) in the diurnal temp range.

The tricky problem is invisible cirrus; will it produce a warming or cooling trend (see, e.g., S.F. Singer. "Re-Analysis of the Nuclear Winter Phenomenon." Meteorology and Atmospheric Physics 38: 228-239 (1988)


5. Activists upset when no link is found between breast cancer and pollution

Scientists have been trying to prove a link between such factors as cigarette smoke, chemicals and electromagnetic fields near power lines to incidences of breast cancer. But they have never been able to come up with a "smoking gun" cause.

Most recently, an $8 million National Cancer Institute study failed to prove a link between certain pesticides, exhaust fumes or cigarette smoke to breast cancer among Long Island women. Researchers called the study "very, very conclusive" in its finding that smokers, for example, did not have more breast cancer than nonsmokers.

Similarly, a study published in the New England Journal of Medicine in 1997, involving 32,826 nurses, found no evidence that DDT and PCBs increase the risk of breast cancer. In 1998, a Harvard study published in The Journal of the National Cancer Institute found no link between exposure to chemicals and breast cancer.

These and other studies haven't dissuaded women who are certain the links are out there. Their attitude continues to be that a lot more studies need to be done. But many scientists are coming to the conclusion that more studies would be unproductive and there is a need to move on to other lines of work.

Source: Gina Kolata, "Looking for the Link," New York Times,
August 11, 2002. As quoted by the NCPA, Dallas


6. UV Water Treatment Verified by EPA:

EPA's recent verification of an ultraviolet (UV) radiation technology to destroy viruses in drinking water could lead to far greater use of the purification technique in North America, according to BNA's Daily Environment Report. The stamp of approval by EPA's Environmental Technology Verification Program basically verifies a manufacturer's claims and means that water systems are more likely to buy the technology. EPA gave this specific approval to the Canadian firm Trojan Technologies Inc. for a UV-based system for larger water treatment systems that claimed to inactivate contaminants including cryptosporidium and giardia. There are currently 431 large-scale water treatment facilities using UV worldwide, only seven of which are in the United States.



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