The Future: six drivers of global change Part 142

269 symbiosis between the larch and the tundra is thereby disrupted

Douglas Fischer and Daily Climate, "Shift in Northern Forests Could Increase Global Warming," Scientific American, March 28, 2011.

270 reproducing three generations per summer rather than one

Noah S. Diffenbaugh et al., "Global Warming Presents New Challenges for Maize Pest Management," Environmental Research Letters 3 (2008).

271 "unprecedented outbreak of the mountain pine beetle"

David A. Gabel, "Expanding Forests in the Northern Lat.i.tudes," Environmental News Network, March 23, 2011, http://www.enn.com/ecosystems/article/42501.

272 "the real culprit is water stress caused by climate change"

Justin Gillis, "With Deaths of Forests, a Loss of Key Climate Protectors," New York Times, October 1, 2011.

273 direct proportion to the rising temperatures

"More Large Forest Fires Linked to Climate Change," ScienceDaily, July 10, 2006, http://www.sciencedaily.com/releases/2006/07/060710084004.htm; Gillis, "With Deaths of Forests, a Loss of Key Climate Protectors."

274 in the trees and plants themselves

Gillis, "With Deaths of Forests, a Loss of Key Climate Protectors."

275 rather than a net "sink," withdrawing CO2 as the trees grow

Ben Bond-Lamberty et al., "Fire as the Dominant Driver of Central Canadian Boreal Forest Carbon Balance," Nature, November 1, 2007; "Wildfires Turning Northern Forests into Carbon-Dioxide Sources," CBC News, October 31, 2007, http://www.cbc.ca/news/technology/story/2007/10/31/boreal-forests.html.

276 eastern North America, Europe, the Caucasus, and Central Asia

Gabel, "Expanding Forests in the Northern Lat.i.tudes."

277 $3.7 trillion in environmental costs

Pavan Sukhdev et al., The Economics of Ecosystems and Biodiversity: Mainstreaming the Economics of Nature: A Synthesis of the Approach. Bonn: TEEB, 2010.

278 40 percent as many trees as the rest of the world put together

United Nations Food and Agriculture Organization, "State of the World's Forests 2009," 2009, http://www.fao.org/docrep/011/i0350e/i0350e00.htm.

279 required to plant at least three trees per year

"China's Hu Takes Part in Tree Planting," UPI, April 5, 2009.

280 approximately 100 million acres of new trees

Gillis, "With Deaths of Forests, a Loss of Key Climate Protectors."

281 in trees include the U.S., India, Vietnam, and Spain

United Nations Food and Agriculture Organization, "State of the World's Forests 2011."

282 compared to the rich variety supported by a healthy, multispecies primary forest

Jianchu Xu, "China's New Forests Aren't as Green as They Seem," Nature, September 21, 2011.

283 carbon sequestered in the first few feet of soil

Damian Carrington, "Desertification Is Greatest Threat to Planet, Expert Warns," Guardian, December 15, 2010.

284 10.57 percent of the Earth's land surface covered by arable land

CIA World Factbook, https://www.cia.gov/library/publications/the-world-factbook/geos/xx.html

285 health of the soil and interfere with the normal sequestration