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Article From an email blog ClimateChange Weekly. www.heartland.org/subscribe.html
The gist is that as CO2 increases global plant growth, the more CO2 is consumed by the increased biomass.
Greening Planet May Hit Paris Agreement Goals
New research published in Global Change Biology finds the greening effect of rising atmospheric carbon dioxide concentrations is much greater than had been previously believed. The authors, an international team of scientists from research institutes and universities in Australia, France, New Zealand, and Sweden, used a biophysical model and observational data to calculate global primary productivity (GPP), the net change in standing vegetation per year, and to project future GPP using climate model forecasts.
The study found there has been a 30 percent increase in global photosynthesis from increased carbon dioxide levels since 1900. This is almost double the 17 ± 4 percent found in previous estimates of the fertilization effect of rising carbon dioxide, estimates which failed to consider the full range of factors affecting and limiting carbon dioxide uptake. Looking forward, the GPP should increase by 47 percent in response to a doubling of carbon dioxide concentrations above preindustrial levels.
Discussing the research, climate scientist Pat Michaels noted the plant growth enhancement calculated in this paper was 300 percent larger than the amount forecast in the IPCC’s 2013 report. In addition, Michaels points out, the estimates of global greening developed in this paper match satellite-observed changes in leaf-area index described in prior research.
As a result of the carbon dioxide fertilization effect, under low‐emission scenario climate model projections the land carbon sink will top 174 billion additional tons of carbon dioxide captured by the Earth from 2006 through 2099, 57 billion tons more than previous estimates of the fertilization effect, the researchers conclude. If this is correct, the carbon-dioxide-induced greening will remove enough atmospheric carbon dioxide over a 100 year period to cancel out 17 full years’ worth of carbon-dioxide emissions at the current rate of discharge.
All other things being equal, if carbon dioxide is driving temperature increases, the global greening forecast in this paper should by itself keep global temperatures below the 2°C warming increase established as the goal under the 2015 Paris climate agreement.
SOURCE: Climate etc.; Competitive Enterprise Institute; Global Change Biology