We report progress in assessing the feasibility of a new satellite-based laser-sounding instrument to measure CO2 concentrations in the lower troposphere from space. INTRODUCTION CO2 measurements from ice cores show that atmospheric CO2 concentrations are higher now than they have been in the past 400,000 years. It is becoming increasingly important to understand the nature and processes of the...

Plant gas exchange is a key process shaping global hydrological and carbon cycles and is often characterized by plant water use efficiency (WUE - the ratio of CO2 gain to water vapor loss). Plant fossil record suggests that plant adaptation to changing atmospheric CO2 involved correlated evolution of stomata density (d) and size (s), and related maximal aperture, amax . We interpreted the fossi...

Version 1 of the Community Earth SystemModel, in the configurationwhere its full carbon cycle is enabled, is introduced and documented. In this configuration, the terrestrial biogeochemical model, which includes carbon– nitrogen dynamics and is present in earlier model versions, is coupled to an ocean biogeochemical model and atmospheric CO2 tracers. The authors provide a description of the mod...

Global emissions of atmospheric CO2 and tropospheric O3 are rising and expected to impact large areas of the Earth’s forests. While CO2 stimulates net primary production, O3 reduces photosynthesis, altering plant C allocation and reducing ecosystem C storage. The effects of multiple air pollutants can alter belowground C allocation, leading to changes in the partial pressure of CO2 (pCO2) in th...

[1] The authors examine the observed relationships between large-scale climate variability and concentrations of atmospheric carbon dioxide (CO2) in the Southern Hemisphere. The results reveal that month-to-month variations in the rate of change of atmospheric CO2 at Palmer Station on the Antarctic Peninsula are significantly related to fluctuations in the dominant mode of Southern Hemisphere a...

[1] The remarkable correspondence between glacialinterglacial changes in atmospheric CO2 levels and global climate over much of the Pleistocene suggests that CO2 is also a key climate change driver. However, there is as yet no widely accepted explanation of the low glacial CO2 levels. Here I use an intermediate-complexity climate model to show that glacial cooling, acting on the rates of organi...

[1] We present ocean chemistry calculations based on ocean general circulation model simulations of atmospheric CO2 emission, stabilization of atmospheric CO2 content, and stabilization of atmospheric CO2 achieved in total or in part by injection of CO2 to the deep ocean interior. Our goal is to provide first-order results from various CO2 pathways, allowing correspondence with studies of marin...

Rising atmospheric CO2 concentrations can fertilize plant growth. The resulting increased plant uptake of CO2 could, in turn, slow increases in atmospheric CO2 levels and associated climate warming. CO2 fertilization e ects may be enhanced when water availability is low, because elevated CO2 also leads to improved plant water-use e ciency. However, CO2 fertilization e ects may be weaker when pl...

Understanding the role of atmospheric CO2 during past climate changes requires clear knowledge of how it varies in time relative to temperature. Antarctic ice cores preserve highly resolved records of atmospheric CO2 and Antarctic temperature for the past 800,000 years. Here we propose a revised relative age scale for the concentration of atmospheric CO2 and Antarctic temperature for the last d...

[1] Ahlbeck [2002] raises an important issue: Is the increase in the atmospheric concentration of CO2 [Keeling and Whorf, 2001] partially responsible for the increase in the normalized difference vegetation index (NDVI), which we report in the work of Zhou et al. [2001]? To demonstrate its effect, Ahlbeck [2002] adds the atmospheric concentration of CO2 (hereinafter referred to as CO2) to equat...