Monsoon ecosystems control on atmospheric CO₂ interannual variability: Inferred from a significant positive correlation between year‐to‐year changes in land precipitation and atmospheric CO₂ growth rate

Abstract

Abstract. Previously, large interannual variability were observed of atmospheric CO 2 mixing ratio at Mauna Loa Observatory, and were found to be positively correlated with the global near-surface air temperature variability, notably over E! NinoSouthern Oscillation (ENSO) cycles, and negatively correlated with global precipitation on the decadal time-scale. By contrast, here we report a significant positive correlation between the interannual variability of CO 2 growth rate and the year-to-year changes in global land precipitation. The interannual extremes •n the rate of CO 2 growth coincide with the largest year-to-year changes in precipitation over land, particularly Indian summer monsoon. We suggest that this positive correlation restilts mmnly from changes in terrestrial net ecosystem production (NEP) w•th •ncoming solar radiation' an increase of clouds concurrent with precipitation reduces seasonal N EP and causes a positive anomaly in CO: emission fi'om the terrestrial biosphere. IntroductionThe In this paper, we report our finding of a positive correlation between the interannual variability of atmospheric CO 2 and the year-to-year changes in precipitation over land. Data and restilts of analysis are described in Sections 2 and 3, respectively. A discussion of the results and conclusions are presented in Section 4.

Emissions, Concentrations, & Temperature: A Time Series Analysis

“…This temperature increase is not large enough to offset completely the effect of the SOI variable in the CO 2 equation therefore, the ENSO experiment indicates that on net, the 1982-1983 El Niño reduced atmospheric CO 2 by about 0.34 ppmv. This negative effect is consistent with analyses that suggest that ENSO events reduce the flow of carbon to the atmosphere by slowing ocean upwelling (Dettinger and Ghil, 1998;Winguth et al, 1998) or that enhanced incoming solar radiation during the early stages of an ENSO event increase carbon uptake by terrestrial vegetation (Graham et al, 2003;Yang and Wang, 2000). This reduction also is consistent with an inverse relation between ENSO and the atmospheric growth rate of CO 2 (Rayner et al, 1999;Francey et al, 1995).…”

Recent patterns and mechanisms of carbon exchange by terrestrial ecosystems

“…Globally, there appears to be a net release of carbon to the atmosphere during warm and dry years, and a net uptake during cooler years 30,38 . Recently, evidence for links between the El Nin Äo/Southern Oscillation cycle and atmospheric CO 2 have become stronger 29,30,39 .…”

Continental-Scale Partitioning of Fire Emissions During the 1997 to 2001 El Niño/La Niña Period

“…These include drought inhibition of photosynthesis (33)(34)(35)(36), warm temperature stimulation of ecosystem respiration (37-39), a combination of both (40)(41)(42), or changes in cloud induced light limitation on photosynthesis (43,44). In this study we did not address the potential impacts of climate induced variability on autotrophic respiration (37,39) or diffuse light effects on photosynthesis (43,44). The predicted magnitude of the contributions of fire emissions to CO 2 anomalies reported here is independent of these issues because it was derived from the atmospheric CO signal, with CASA providing only the timing and spatial distribution of fire emissions within each region.…”