30 percent of human-caused emissions of carbon dioxide—a strong greenhouse gas—and are therefore considered to play a crucial role in mitigating the speed and magnitude of climate change. However, a new study that combines future climate model projections, historic tree-ring records across the entire continent of North America, and how the growth rates of trees may respond to a higher concentration of carbon dioxide in the atmosphere has shown that the mitigation effect of forests will likely be much smaller in the future than previously suggested. The study by scientists at the University of Arizona in Tucson is the first to reveal the possible impact of a changing climate on the growth rate of trees across all of North America, in other words, how their growth changes over time and in response to shifting environmental conditions. The result are detailed forecast maps for the entire North American continent that reveal how forest growth will be impacted by climate change. The team was startled to find no evidence for a greenhouse-gas absorbing process called the boreal greening effect in their simulations. Boreal greening refers to the assumption that trees in high latitudes, where colder temperatures limit growth, should benefit from warmer temperatures and higher concentrations of carbon dioxide in the atmosphere and, as a result, "green" under the effects of climate change. In turn, these thriving boreal forests should be able to scrub more carbon dioxide from the atmosphere, so goes the idea, dampening climate change. http://phys.org/news/2016-07-north-american-forests-climate.html
In a recent Science article, researchers also report that the type of fungus normally associated with particular trees - there are two basic large categories - determines whether it can take advantage of higher CO2 concentrations to grow faster. Almost all trees have some more or less significant symbiotic or commensal fungi associated with them, they are taxonomically specific, some aid increased uptake of CO2 and others don't. The species that don't have the right fungi will not respond to extra CO2 with much extra growth unless the need met (extra Nitrogen) is met otherwise. Be interesting to see if there's a link between -say - ability to tolerate drought and the fungi that do or do not abet CO2 uptake increases.
It seems that algae and other cryptogams are going to be key to carbon sequestration. Read more at: http://phys.org/news/2012-06-algae-lichens-mosses-huge-amounts.html#jCp Some companies are planning to create large algae blooms in the oceans and get carbon credits in return.
