Earth’s plants could be too carbon-saturated to slow global warming by century’s end

Rick Docksai in Science Recorder: Earth’s plant life puts a damper on global warming for now, but researchers do not expect this to last. In a study published this week in the Proceedings of the National Academy of Sciences, they explain that while plants’ photosynthesis process ingests huge concentrations of carbon dioxide from the air, the plants can only retain so much and will tap out by century’s end as human civilization’s carbon dioxide pollution continues to rise.

The study assumes that global temperatures rise another four degrees Celsius by 2100, a scenario that the UN Intergovernmental Panel on Climate Change and other climate research institutions have indicated will probably happen if the world community doesn’t make unprecedented reductions in carbon-emitting emissions in the next few years.

At that four-degree high point, plant reuptake of carbon dioxide will be most likely to flat-line. This will in turn set off a further upward spiral in greenhouse warming as atmospheric carbon dioxide levels’ rise not only continues, but accelerates.

Andrew Friend, Cambridge University environmental scientist and the study’s lead researcher, told reporters that plants’ capacity to take up carbon dioxide at all falls when temperatures get too high. So when there is a heat wave, the affected ecosystems thus release more carbon-dioxide than usual.

Europe’s summer 2003 heat wave was an example of this, Friend added—as the continent’s heat index soared, carbon dioxide levels rose, as well. They did so to such an extent, in fact, that they negated all of the carbon reuptake that the continent’s plant life had done over the previous four years....

Interior main greenhouse at the Jardin des Plantes in Paris, shot by Marie-Lan Nguyen, Wikimedia Commons, under the Creative Commons Attribution 2.5 Generic license