The Truth About The World Climate
Much Ado About Tiny Temperature Trends: The possible identification of an error in the evaluation of the satellite temperature record that could turn earth's post-1979 temperature trend from a cooling to a warming diverts our attention from the more crucial tasks of trying to determine the cause of the global warming of the past century and the significance of the many direct biological impacts of atmospheric CO2 enrichment.
Volcanism: A 600-Year Influence on Temperature: A study of tree-ring densities from 380 boreal forest locations shows that large negative Northern Hemispheric temperature anomalies typically follow large volcanic eruptions, compromising our ability to unequivocally determine the effects of other climate-forcing factors that may have varied in the past or that are changing now.
Stratospheric Impacts on the Troposphere: A search of meteorological databases has revealed a number of situations where stratospheric process distortions have induced anomalies in tropospheric dynamics. This cause-and-effect relationship is not incluede in the GCMs that are currently used to predict future climate, which can only weaken their credibility in terms of making real-world representations.
Atmospheric CO2 and the Chemical Weathering of Soils: Although it is not the conclusion of the authors of this paper, the calculations and observations described in this study tend to suggest that the propensity for an increase in atmospheric CO2 to warm the earth may be much less than what is currently being predicted by state-of-the-art general circulation models of the atmosphere.
Detecting a Human Influence on Weather: Analyses of two gaseous pollutants, rainfall, and tropical cyclone windspeeds and central pressures in the northwest Atlantic Ocean all reveal weekly periodicities that would seem to be attributable to the weekly cycle of human activities on the eastern seaboard of the United States. This putative human influence on regional climate appears to be reducing the intensities of coastal tropical cyclones on weekends as compared to weekdays, while it (or something else) appears to have reduced their intensities over the 51-year period of the study.
Orbital Effects on Satellite Temperatures: Lower-troposphere satellite-derived temperature data are examined for the influence of orbital decay. When applying a correction for orbital decay, linear trends in these data change from -0.05°C per decade to +0.07°C per decade.
Effects of Atmospheric CO2 on Potato: In an Italian study of CO2 effects on potato that utilized Free-Air-CO2-Enrichment (FACE) technology, elevated CO2 enhanced net photosynthesis, total nonstructural carbohydrate concentration and yield of potato. It also induced earlier flowering and accelerated senescence, thereby reducing the time the crop was in the field.
CO2 and Plant Root Growth: In a growth chamber study of the small, fast-growing Arabidopis thaliana, it was found that a doubling of the air's CO2 content led the plants to produce more and larger roots, enhancing their capacities to acquire water and nutrients, as well as transfer more carbon to the soil in a high-CO2 world.
C4 Grass Responses to CO2: In a growth chamber study of the responses of six different species of C4 grasses to a doubling of the air's CO2 content, it was found that they all exhibited increases in the efficiencies with which they utilize water.
Global Environmental Change: Impact on Global Carbon Balance: Two recent studies exploring the effects of global warming on terrestrial carbon storage show that certain ecosystems may release CO2 to the atmosphere if the climate warms, but that the planet as a whole appears to act as a sink for CO2 under such circumstances.
CO2-Enriched Ecosystems Support Greater Animal Populations: In a study of complex food chains in minature terrestrial ecosystems maintained within the sophisticated Ecotron controlled environment facility at Silkwood Park in the UK, 15 scientists from 10 different research institutions collaborated to demonstrate that a 53% increase in the ecosystem's atmospheric CO2 concentration led to a 52% increase in the numbers of microarthropods that resided at the tops of the ecosystems food chains.
Coral Reefs: Doomed by Carbon Dioxide?: A brief review of the many problems currently faced by the world's coral reefs suggests that CO2-induced global warming should come last on a long list of concerns
Persistent Millennial-Scale Climate Oscillations: Reconstructions of sea surface temperatures throughout the Pleistocene reveal regular 4 to 4.5°C variations during times of ice sheet growth and disintegration, 3°C variations during glacial maxima, and 0.5 to 1°C variations during warm interglacials. Climatic warming such as the one being predicted to result from the widespread use of fossil fuels are just not seen, anywhere in the record, suggesting that they probably cannot happen.
Persistent Millennial-Scale Climate Oscillations of the Past Million-Plus Years: Analyses of a North Atlantic sediment core have revealed the existence of persistent millennial-scale climate oscillations similar to those of the last glacial epoch as far back in time as the early Pleistocene. None of these climate changes are believed to have been produced by atmospheric CO2 variations, suggesting that the even smaller-scale warming of the last hundred years or so has not been caused by any change in the air's CO2 content either.
The Rising Costs of Natural Disasters: Is Global Warming Responsible?: A study of trends in a number of potentially dangerous natural phenomena, along with shifts in national population and wealth density, reveals that the global warming of the past half-century is in no way responsible for the increasing economic losses incurred as a consequence of natural disasters.
Climate Fluctuations on Mount Kenya: A sediment core from a high-altitude lake in East Africa reveals a 3,000-year temperature record that includes a 4°C warming over a short 300-year time interval.
Plant Exudate Utilization by Soil Microbes Under Elevated CO2: Perennial ryegrass grown in sand and soil microcosms for 21 days at an atmospheric CO2 concentration of 720 ppm displayed tremendous increases in plant dry weight relative to plants grown at 450 ppm atmospheric CO2. In soil microcosms, elevated CO2 increased the numbers of culturable bacteria, fungi, and yeast, indicating that increased carbon exudation from the roots of plants grown in elevated CO2 can maintain or increase soil microbial biodiversity.
Fungal Response to Elevated CO2 and Nutrients in Five Grassland Species: Four months of atmospheric CO2 enrichment increased the percent root colonization by arbuscular mycorrhizal fungi in five plant species common to the mediterranean annual grasslands of California, while it only increased colonization by non-mycorrhizal fungi in two species.
Effects of Elevated CO2 on Carbon Allocation of Fungi: The growth of Gutierrezia sarothrae shrubs in elevated CO2 for four months resulted in increased carbon allocation to arbuscular mycorrhizal fungi associated with its roots. This carbon was invested in different morphological structures depending on soil nitrogen availability.
Effects of Atmospheric CO2 on Soil Biota: Poplar tree cuttings that received atmospheric CO2 enrichment for five months increased soil carbon inputs by increasing root biomass and fine root production. In turn, this led to increases in the local protozoan population and greater microarthropod associations with fine roots relative to observations made at ambient CO2. Although elevated CO2 increased mycorrhizal masses only in the presence of high soil nitrogen, the authors believed that this would not affect the ability of fungi to metabolize additional soil carbon inputs resulting from CO2-induced root growth in poplar tree cuttings.
Fungal Species Affect Plant Biodiversity: Total plant biomass varied for three plants common to a European calcareous grassland with different single AMF species or equal proportions of four different AMF species, indicating that AMF species diversity can potentially determine plant community diversity.
Something Old, Something New: As we commence a new year of work at the Center for the Study of Carbon Dioxide and Global Change, we thought we would reflect on a few of the major science stories we covered in 1998, as well as speculate on where the science of CO2 and global change is likely to take us in 1999.
There is a Human Influence on Climate: A study of temperatures in large industrial cities in India suggests that the cooling influence of urban-produced particulate matter is over-powering natural warming and urban heat island effects.
There isn't a Human Influence on Climate: Proxy temperature data for Scandinavia reveal that summer temperatures there have oscillated throughout the last 10,000 years in apparent response to changes in solar irradiation.
The Natural Variability of Climate: A 500-year global climate model simulation suggests that natural variability within the actual climate system may explain nearly all global temperature fluctuations over the past millennium.
Warmer Temperatures at Lower CO2 Concentrations: Proxy temperature and precipitation data from a lake-sediment core in Morocco indicate that both winter and summer temperatures there were "4°C warmer than the present" at a time when earth's atmospheric carbon dioxide concentration was approximately 100 ppm less than it is today.
Effects of Elevated CO2 on Fungal Infection of an Annual California Grass: Four months of atmospheric CO2 enrichment in open-top chambers increased percent arbuscular infection of roots and the infection intensity of all but the youngest roots of Bromus hordeaceus, despite the fact that percent root length colonized remained unaffected.
Effects of Elevated CO2 on Fungi: In a literature review of arbuscular mycorrhizal fungi responses to atmospheric CO2 enrichment, the authors determined that when increased root colonization occurs in response to elevated CO2, it acts synergistically with the elevated CO2 to increase plant growth.
Interactive Effects of CO2 and Fungi on Sagebrush: In a study of sagebrush plants inoculated with four different species of fungi, it was found that a doubling of the air's CO2 content significantly enhanced the development of fungal structures that facilitate internal and external nutrient transfer, which led to a 35% increase in sagebrush root biomass, thereby significantly increasing its prospects for survival in nutrient-poor environments and during periods of drought.
Interactive Effects of CO2 and Mycorrhiza on a Perennial Herb: In a three-month study of Plantago lanceolata plants inoculated with mycorrhizal fungi, it was found that a 54% increase in the air's CO2 content significantly enhanced root development and fungal colonization of roots. This stimulation, in turn, led to greater uptake of mineralized phosphorous, which played a major role in enhancing total biomass production in plants grown in elevated CO2.
Effects of CO2 on Microbial Community Structure: Six or 18 weeks of atmospheric CO2 enrichment did not affect rhizosphere microbial community structures of ryegrass or wheat microcosms, indicating that the increasing CO2 content of the air will maintain soil microbial biodiversity beneath these species.