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Volume 3 Number 13:  1 July 2000

Editorial
There Has Been Little Net Global Warming Over the Past 70 Years: In our last issue's editorial we described a body of evidence that strongly suggests that the near-surface air temperature of the planet has not warmed for the past two decades.  We now present additional evidence that strongly suggests that the earth has not warmed for at least the past 70 years.

Journal Reviews
The Coming Mega-Drought: It's already happened!: A tree-ring-based reconstruction of the Palmer Drought Severity Index over large portions of North America reveals the existence of a mammoth 16th century "megadrought" that far exceeded the United States Dust Bowl drought of the 1930s.

Yet Another Climate Model Flip-Flop: A state-of-the-art climate model predicts an entirely new response of the global ocean's thermohaline circulation to greenhouse climate forcing, completing a full circle of change in historical climate model predictions.

Yes, Virginia, There Really Was a Medieval Warm Period … And a Little Ice Age Too … Even in South America!: A review of the climatic history of the central region of Argentina over the past millennium begins in the midst of the Medieval Warm Period and proceeds through the two major pulses of the Little Ice Age.  As is almost always the case, the warm period appears to have been much preferred to the cold period.

Six Thousand Years of Chinese Climate: A 6000-year record of plant cellulose delta 18O derived from a peat bog in China reveals the existence of a warmer-than-present period between AD 1100 and 1200, corresponding to the Medieval Warm Period of Europe.  Comparison of the delta 18O record with a previously-published Delta 14C record derived from tree-rings showed that the temperature of this part of China had been forced mainly by solar variability over the entire 6000-year record.

El Niños and Global Warming: A review of potential influences of global warming on the behavior of El Niños comes up with no firm answers because the subject is so complex.  This conclusion calls into question the popular tendency to ascribe all manner of dire El Niño-mediated consequences to mankind's continued usage of CO2-emitting fossil fuels.  The tortuous linkage cannot as yet be established with even a modicum of certainty.

Antarctic Plants Thrive in Warmer Temperatures: A study of the growth response of the only two vascular plant species to be found on Antarctica demonstrates that they love warmer temperatures, manifesting this fact via large increases in leaf numbers, area and biomass in response to experimentally-induced increases in air temperature.

Why Are We Living Longer?: In a study of G7-country mortality over the period 1950-1994, it was found that "in every country over this period, mortality at each age has declined exponentially at a roughly constant rate."  Other research indicates that "the extended length of life in old age is mainly due to better health."  We describe why one possible cause of this phenomenon may be the ongoing rise in the air's CO2 content.

CO2 Enhances Plant Production of Cancer-Fighting Substances: A 75% increase in the air's CO2 concentration has been demonstrated to produce a 75% increase in the amounts of five plant constituents proven to be effective in fighting a number of human maladies, including leukemia, ovary sarcoma, melanoma, and brain, colon, lung and renal cancers, as well as Japanese encephalitis and yellow, dengue, Punta Tora and Rift Valley fevers.

Effects of Elevated CO2 on Insect Herbivores: After one year of differential CO2 exposure, scrub-oak communities exposed to an atmospheric CO2 concentration of 700 ppm contained lower densities and numbers of herbivorous leaf miners on foliage than communities fumigated with ambient CO2 concentrations.  Although CO2 enrichment reduced leaf nitrogen contents, causing leaf miners to increase their consumption of foliage, herbivore mortality was four-fold greater in CO2-enriched communities due to enhanced predation by various wasp species that naturally feed upon them.  Thus, if applicable to agricultural ecosystems, these results suggest that future increases in the air's CO2 content will reduce crop damage by leaf miner herbivory, thereby increasing crop production, yield, and economic gains.

Direct Effects of Elevated CO2 on Dark Respiration in Rice: Dark respiration rates in rice decreased with increasing nighttime CO2 concentrations, regardless of daytime CO2 growth concentrations, at nighttime air temperatures greater than 21°C.  Consequently, in the future it is likely that rising CO2 levels will reduce dark respiration rates in rice, thus increasing total net carbon retention, which should facilitate increased biomass production.