Sometimes it is necessary to ask difficult questions about even our most sacrosanct ideas.
My op-ed in the New York Times: http://www.nytimes.com/2014/09/20/opinion/to-save-the-planet-dont-plant-trees.html
Professor Ken Caldeira’s similar op-ed published in 2007:
The primary key to solving the global climate problem is the transformation of our energy system into one that does not use the sky as a waste dump for our greenhouse gas pollution.
Land-use change effects a redistribution of carbon among land, ocean, and atmosphere reservoirs while fossil fuel emission adds carbon to these combined reservoirs. The long-term climatic effects of these two processes are very different. A primary reason for wanting to avoid human-induced climate change is to protect natural ecosystems. Protecting natural ecosystems is an important goal, regardless of their climate effects.
SCIENTIFIC PUBLICATIONS THAT SUPPORT ALL OF THE STATEMENTS IN MY OP-ED:
1. The world’s forests generously mop up about a quarter of the global fossil-fuel carbon emissions every year.
Chapter 6 from latest IPCC AR5 WG1 report (PDF
LeQuere et al., Global Carbon Budget 2013
, Earth. Syst. Sci. Data.
, 6, 235-263, 2013.
LeQuere et al., Trends in the sources and sinks of carbon dioxide
, Nat. Geo.
, 2, 831-836, 2009.
2. The dark color of trees means that they absorb more of the sun’s energy and make the planet’s global surface temperature warmer.
Betts, Offset of the potential carbon sink from boreal forestation by decreases in surface albedo
, 408, 187-190, 2000.
Lee et al., Observed increase in local cooling effect of deforestation at higher latitudes
, 479, 384-387, doi:10.1038/nature10588, 2011.
Rotenberg and Yakir, Contribution of Semi-Arid Forests to the Climate System
, Science, 327, 2010.
3. Their conclusion is that planting trees in the tropics would lead to cooling, but in colder regions, it would cause warming.
Bala et al., Combined climate and carbon-cycle effects of large-scale deforestation
, Proc. Natl. Acad. Sci.
, 104, 6550-6555, 2007.
Jackson et al., Protecting climate with forests
, Environ. Res. Lett.
, 3 doi:10.1088/1748-9326/3/4/044006, 2008.
Anderson et al., Biophysical considerations in forestry for climate protection
, Front. Ecol. Environ.
, 9, 174-182, 2011.
Davin and de Noblet-Ducoudre, Climatic Impact of Global-Scale Deforestation: Radiative versus Nonradiative Processes
, Journal of Climate
, 23, 97-112, 2010.
4. In order to grow food, humans have changed about 50 percent of Earth’s surface area from native forests and grasslands to crops and pasture.
Hurtt et al., Harmonization of land-use scenarios for the period 1500-2100: 600 years of global gridded annual land-use transitions, wood harvest, and resulting secondary lands
, Clim. Change
, 109, 117-161, 2011.
Vitousek et al., Human domination of Earth’s ecosystems
, 277, 494-499, 1997.
5. There is no scientific consensus on whether the historical cropland expansion has caused overall global warming or cooling.
Chapter 8 from latest IPCC AR5 WG1 report (http://www.climatechange2013.org/images/report/WG1AR5_Chapter08_FINAL.pdf
Brovkin et al., Role of land cover changes for atmospheric CO2 increase and climate change during the last 150 years
, Glob. Chang. Biol.
, 10, 1253-1266, 2004.
Pongratz et al., Biogeophysical versus biogeochemical climate response to historical anthropogenic land cover change
, Geophys. Res. Lett.
, 37, 2010.
6. Chemical reactions with tree volatiles in the air act to increase two powerful greenhouse gases, methane and ozone, and form tiny particles that can change clouds...changes in tree volatiles have effects on the global climate on a similar scale to changes in the Earth’s surface color and carbon storage capacity.
Arneth et al., From biota to chemistry and climate: towards a comprehensive description of trace gas exchange between the biosphere and atmosphere, Biogeosciences
, 291, 121-149, 2010. (PDF
Carslaw et al., A review of natural aerosol interactions and feedbacks within the Earth system
, Atmos. Chem. Phys.
, 10, 1701-1737, 2010.
Unger, Human land-use-driven reduction of forest volatiles cools global climate
, Nat. Clim. Chang.
, doi:10.1038/nclimate2347, 2014.
7. Even if all photosynthesis on the planet were shut down, the oxygen content of the atmosphere would change by less than 1 percent. Oxygen levels in the air have remained at a constant 20 percent for the last 400 million years, primarily regulated by the Earth’s geological processes.
Introduction to Atmospheric Chemistry by D. J. Jacob, Princeton University, Press, Chapter 6 Geochemical Cycles (PDF
) Section 6.4 The Oxygen Cycle.