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Volume 3 Number 2:  15 January 2000

Editorial
The Climatological Challenge of Airborne Dust: In our previous editorial (Vol. 3, No. 1: Questions, Questions, Questions ...), we illustrated the paucity of our knowledge of the intricacies of the many different ways by which clouds may (or may not) influence climate, particularly within the context of rising atmospheric CO2 concentrations.  We now indicate the degree to which another airborne substance falls within this same category of limited understanding: atmospheric dust.

Subject Index Summaries

Acclimation

Aerosols

Agriculture

Aircraft Effects

Air Pollution

Albedo

Alpine Ecosystems

Animals
     Birds
     Earthworms
     Herbivores
     Insects
     Life Span
     Range Expansion

Antioxidants

Aquatic Plants

Arthropods

Biodiversity
     Among Genotypes
     C3 Plants vs. C4 Plants
     Fungi
     General
     N-Fixers vs. Non-N-Fixers
     Weeds vs. Non-Weeds

Journal Reviews
Storminess Signals in Long-Term Sea Level Data: Analyses of one hundred years of sea level data from several monitoring stations in northwest Europe suggest that there has been no significant trend in storminess there over the past century.

Adding to Our Knowledge of the Global-Ocean Biophysical Thermostat: New investigations and a review of previous studies reveal a number of new ways by which interrelated biological and physical processes in ocean surface waters tend to moderate climate change, especially independently-induced global warming.

Signs of One of the "Living Thermostats" that Moderate Climate Change: An eleven-year study of airborne particulates at the northernmost manned site in the world reveals the presence of sulfur compounds of biogenic origin that are produced in greater abundance in warmer years and have a tendency to reduce the warming that spurs their production.

Evidence Mounts for Oceanic Control of Hemispheric Warming and Cooling: An analysis of oceanic sediment core data from various parts of the world suggests that changes in the strength of the planetary thermohaline circulatory system that may be induced by events in the North Atlantic have the capacity to induce rapid climate changes in both the Northern and Southern Hemisphere.  Observed climate changes of the past clearly bear this cause-specific signature, which is vastly different from what would be expected from CO2-induced climate change.

Volcanoes As Agents of Climate Change: This paper examines a number of issues related to the linking of various climatic perturbations to volcanic eruptions, noting how easy it is to go astray in assuming that the former phenomena are the result of the latter.

Response of a Sub-Tropical Tree to Elevated CO2 and Temperature: Schima superba seedlings grown for six months at an atmospheric CO2 concentration of 720 ppm and an optimal day/night temperature regime exhibited higher rates of photosynthesis and greater dry matter accumulation than seedlings grown at 360 ppm.  When grown at an elevated day/night temperature regime, CO2-enriched seedlings displayed even greater enhancements and absolute values for these parameters than control seedlings exposed to the same growth temperature treatment, indicating that elevated CO2 shifted the optimal growth temperature for this species upward.

Effects of Elevated CO2 and Nitrogen Deposition on Spruce Needle Quality and Consumption by Nun Moths: Three years of atmospheric CO2 enrichment reduced needle quality of seven-year-old spruce trees by increasing needle starch, tannin, and phenolic concentrations, while reducing needle water and nitrogen contents.  After placing nun moth larvae on current-year needles, it was demonstrated that less foliage was consumed under elevated CO2 conditions than at ambient CO2.  Consequently, larvae feeding upon CO2-enriched leaves obtained less total nitrogen, displayed reduced relative growth rates, and achieved only two-thirds the biomass of larvae feeding upon ambiently-grown needles.  Thus, the current widespread defoliation caused by nun moth larvae should decline as the air's CO2 content rises.

Effects of Elevated CO2 and Nitrogen on Heather and its Consumption by a Winter Moth: Heather plants grown for 20 months in open-top chambers receiving atmospheric CO2 concentrations of 600 ppm exhibited significantly greater water-use efficiencies than control plants exposed to 350 ppm CO2.  Although elevated CO2 enhanced photosynthetic rates by up to 30%, it did not alter foliar C:N ratios or total phenolic contents.  Thus, it was not surprising that larvae of the winter moth Operophtera brumata failed to display any changes in their growth rates, development, or pupal weights after feeding upon CO2-enriched foliage for nearly one month.  Thus, it is not likely that the rising CO2 content of the air will lead to increased outbreaks of this winter moth upon this host, as often is generically predicted in the popular media.

Effects of Elevated CO2 on Biomass and Competition in Irish Grasslands: Four-species mixed grassland ecosystems exposed to atmospheric CO2 concentrations of 700 ppm for eight months exhibited a 26% increase in community biomass relative to that of ecosystems fumigated with air of ambient CO2 concentration.  In addition, even though some species were more responsive than others to atmospheric CO2 enrichment, elevated CO2 did not significantly alter community composition.  Thus, elevated CO2 preserved grassland ecosystem biodiversity.

Response of C3 and C4 Weeds to Herbicide Applications at Elevated CO2: Atmospheric CO2 enrichment stimulated the photosynthesis and growth of the C3 weed Chenopodium album, but not the C4 weed Amaranthus retroflexus.  After treating both types of weeds with the chemical herbicide glyphosate, it was determined that elevated CO2 did not alter the tolerance of the C4 weed to the herbicide, but slightly increased the tolerance of the C3 weed.