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GEO-6 Regional Assessment for North America


and Hirsch 2007). Based on the Montréal Process criteria and indicators applied at the sub-state level, this report led the county government to shift its focus from encouraging additional development in peri-urban areas—with its higher costs of providing public utilities and education—to re- developing existing urban areas.


Many of the existing urban areas were first developed over a century ago and in recent decades had experienced economic and social declines—increasing numbers of rundown and vacant buildings. But these developed areas had intact infrastructure—transportation and public utilities, shopping areas, and education and medical facilities.


Reinvesting


in existing areas, including updating infrastructure, can enhance quality of life and renew economic development at lower cost than fostering more peri-urban development.


The WUI issue presents both land-use and land-cover challenges. In many settings where homes are built in what was formerly productive forest, much of the tree cover is retained because it adds value to the developed property. A proportion of the ecological services, such as sequestering atmospheric carbon or regulating water supply and quality, that the trees formerly provided in forestland continue to be provided by the remaining trees in the newly developed areas. Quantifying changes in ecosystem services resulting from land-use changes remains difficult and not well- understood. Scientific advances on these questions are needed so policy makers can better understand the effects of their development decisions.


2.2.5 Climate change interactions with agriculture and forest land uses


Crops grown in North America are critical for food supplies domestically and around the world. Canadian and US farmers produce more than one-third of the maize and soybeans grown globally, they have over one-third of the global wheat export markets, and they produce nearly one-third of global roundwood harvests. Extreme conditions of temperature and precipitation and the frequency and intensity of other climate-related events have significant impacts on crop yields in North America (Figure 2.2.9).


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The 1993 flood affected over 1 million km2 and caused USD


15 billion in damages; half of that was the value of crops lost that year (NOAA 1994). As California enters the fourth year of a drought and millions of hectares in Saskatchewan and Manitoba go unseeded due to excess moisture or flooding (AAFC 2015), there is a growing sense of climate change- induced fragility in North America. The increasing incidence of extreme events and erratic seasonality is exacerbating the adverse impacts of climate change.


Forests are not immune to climate changes either. Evidence is already clear in forest inventories that some tree species are “on the move” (see US Forest Atlas). Iverson et al. (2007) found that the species range of nearly half the 134 eastern species modeled will move, some up to 800 km northeasterly in the hottest scenario and highest emissions trajectory. The models suggest a retreat of the spruce-fir zone and an advance of the southern oaks and pines. In reaction to these scientific findings, foresters are already planting some species normally found in warmer places farther north than ever before. Further, natural stand conditions are changing, resulting in species changes—disappearing in some areas and emerging in other places where they haven’t been previously. Finally, the past three decades of wildfire history clearly demonstrate that conditions are different today than before 1980. Fire seasons are longer and more land area is burning despite the valiant efforts of wildfire fighters.


More detailed discussion on regional impacts, vulnerability and


adaptation to climate change, including in the


agricultural sector, is found in Section 2.8 of this assessment (see Climate change). Climate change mitigation responses related to sustainable land management, including crop production and forest management practice, can be found in Chapter 3.


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