Back when I was reading about the IPCC scenarios and what they included in this post, I thought “uh-oh, reforestation and afforestation, no one told us!”. As far as I know, though, the IPCC scenarios only include GHG based (I don’t know if they include other GHGs besides carbon), but not landscape changes that influence climate.
Here’s one 2000 paper by Betts of the UK on this topic. This paper is one of those that covers the whole world, uses remote sensing, uses a variety of datasets, makes a variety of assumptions, and may not relate well to more local studies, or even observations. For example, on soils like the Hayman, green trees vs bare soil post-fire may well impact albedo.. how much, is another question. Perhaps there are more recent and/or more local papers on this?
Still, it raises an interesting point. If you want to move from the general idea of afforestation (or changing crop back to forest lands, e.g. the Williamette Valley) how would the potential carbon sequestration and landscape change relate to each other? In the 2003 Marland et al. paper cited below (coauthored by several forest scientists), the authors consider a more holistic form of accounting for climate impacts beyond carbon.
It might even be appropriate to think of carbon management in the biosphere in terms of adjustment factors, or suitability factors, that capture other objectives of land surface change as well as carbon sequestration. These could include carbon leakage, other impacts on climate, ecosystem composition and structure, other impacts on hydrology and the environment, sustainability, and social and cultural objectives. Although this paper discusses changes in land surface entirely within the context of climate change, it is clear that changes in land surface have important considerations within other social and environmental contexts and within other international conventions. The Kyoto Protocol, for example, specifically notes that achieving mitigation objectives for climate change should be accomplished while
taking into account “relevant international environmental agreements; promotion of sustainable forest management practices;” and promotion of sustainable development. Relevant international agreements include the UN Convention on Biological Diversity, the UN Convention to Combat Desertification, and the Ramsar Convention on Wetlands (
IPCC, 2000 , p. 114). Alternatives for carbon management, whether protection of existing ecosystems or encouragement of more carbon intensive ecosystems, can have particularly important implications for biodiversity (Huston and Marland, 2003).To fully consider the climatic effect of changing land surface and/or managing carbon stocks in the biosphere would require complex modeling of the interactions between the atmosphere and the land surface, Option 4. An international consensus would need to consider climate impacts that are both global and regional (multinational) in scale. Effects on the climate system could be expressed in quantifiable energy units such as joule or watt/m2 , perhaps normalized for the area affected (
Pielke et al., 2002 ). Both increases and decreases in energy flows would be recognized as impacts on the larger system. Such an accounting system could be equally rigorous, but would inevitably be more complex, than the evolving system based on tons of carbon equivalent.
I wrote one of the leaders in the field, Roger Pielke, Sr. and asked for a set of papers that would be helpful for readers to introduce them to this topic area. So here they are.they are accessible without a firewall (others are on his research website -https://cires.colorado.edu/research/research-groups/roger-pielke-sr-group)
Pielke Sr., R.A., R. Mahmood, and C. McAlpine, 2016: Land’s complex role in climate change. Physics Today, 69(11), 40. https://pielkeclimatesci.files.wordpress.com/2016/11/r-384.pdf
Mahmood, R., R.A. Pielke Sr., T.R. Loveland, and C.A. McAlpine, 2016: Climate relevant land use and land cover change policies. Bull. Amer. Meteor. Soc. 195-202,
http://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-14-00221.1
Marland, G., R.A. Pielke, Sr., M. Apps, R. Avissar, R.A. Betts, K.J. Davis, P.C. Frumhoff, S.T. Jackson, L. Joyce, P. Kauppi, J. Katzenberger, K.G. MacDicken, R. Neilson, J.O. Niles, D. dutta S. Niyogi, R.J. Norby, N. Pena, N. Sampson, and Y. Xue, 2003: The climatic impacts of land surface change and carbon management, and the
implications for climate-change mitigation policy. Climate Policy, 3, 149-157. http://pielkeclimatesci.wordpress.com/files/2009/10/r-267.pdf
Mahmood, R., R.A. Pielke Sr., K. Hubbard, D. Niyogi, P. Dirmeyer, C. McAlpine, A. Carleton, R. Hale, S. Gameda, A. Beltrán-Przekurat, B. Baker, R. McNider, D. Legates, J. Shepherd, J. Du, P. Blanken, O.Frauenfeld, U. Nair, S. Fall, 2013: Land cover changes and their biogeophysical effects on climate. Int. J. Climatol., DOI:
10.1002/joc.3736. http://pielkeclimatesci.files.wordpress.com/2013/07/r-374.pdf
Hossain, F., and R.A. Pielke Sr., 2012: A two-way street. Intl. Water Power & Dam Construction, 64:11, 26-28. http://pielkeclimatesci.files.wordpress.com/2012/11/r-373.pdf
Hossain, F., J. Arnold, E. Beighley, C. Brown, S. Burian, J. Chen, S.Madadgar, A. Mitra, D. Niyogi, R.A. Pielke Sr., V. Tidwell, and D. Wegner, 2015: Local-to-regional landscape drivers of extreme weather and climate: Implications for water infrastructure resilience. J. Hydrol. Eng., 10.1061/(ASCE)HE.1943-5584.0001210 , 02515002.
https://pielkeclimatesci.files.wordpress.com/2015/04/r-380.pdf”
If you’re interested in this topic, you can also sign up for Dr. Pielke’s Twitter feed. There’s an interesting current study on the effects of irrigation in Nebraska going on right now.
There is more to climate change than CO2 emissions. For example, there has been “…a staggering increase in surface solar radiation of the order of ∼20% over the last decade.” — “Cleaner air: Brightening the Pollution Perspective?” by Colin O’Dowd, Darius Ceburnis, Aditya Vaishya, S. Gerard Jennings, and Eoin Moran, Proceedings of Nucleation and Atmospheric Aerosols: 19th International Conference, June 2013, Fort Collins, Colorado.
A 2004 article in The Christian Science Monitor (Feb 5, 2004), “A Parking Lot Effect?” discusses a study by Dr. Eugenia Kalnay, a University of Maryland researcher.
“[A]ccording to Dr. Kalnay’s study, published in the journal Nature last spring, urbanization, agriculture, and other human changes to landscapes in the US – quite aside from CO2 – account for as much as 40 percent of the temperature rise over the past 40 years – much larger than previously believed. That could make it a contender for CO2’s crown.”
The paper is “Impact of urbanization and land-use change on climate,” Nature, May 29, 2003, https://www.nature.com/articles/nature01675
Keep in mind that albedo is not very sensitive to moderate levels of land use change except toward the poles where long-term snow cover is replaced with dark vegetation.
This meas that:
i) changing from crops to forest at the 45th parallel might not cause a big change in albedo; and
ii) afforestation in the high boreal forest does cause a big change in albedo, so the climate benefits of increasing carbon storage in such forests is probably erased by changes in albedo.