Query: A longer and warmer growing season also has an effect, Dr. Overpeck said, as plants take up more water, further reducing stream flows.

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Climate change and agriculture <=SEP=> -RSB-   Climate change and agriculture are interrelated processes , both of which take place on a global scale . Climate change affects agriculture in a number of ways , including through changes in average temperatures , rainfall , and climate extremes ( e.g. , heat waves ) ; changes in pests and diseases ; changes in atmospheric carbon dioxide and ground-level ozone concentrations ; changes in the nutritional quality of some foods ; and changes in sea level .   Climate change is already affecting agriculture , with effects unevenly distributed across the world . Future climate change will likely negatively affect crop production in low latitude countries , while effects in northern latitudes may be positive or negative . Climate change will probably increase the risk of food insecurity for some vulnerable groups , such as the poor .   Agriculture contributes to climate change by ( 1 ) anthropogenic emissions of greenhouse gases ( GHGs ) , and ( 2 ) by the conversion of non-agricultural land ( e.g. , forests ) into agricultural land . Agriculture , forestry and land-use change contributed around 20 to 25 % to global annual emissions in 2010 .   There are a range of policies that can reduce the risk of negative climate change impacts on agriculture , and to reduce GHG emissions from the agriculture sector .

List of ecoregions in North America (CEC) <=SEP=> This list of ecoregions of North America provides an overview of North American ecoregions designated by the Commission for Environmental Cooperation ( CEC ) in its North American Environmental Atlas . It should not be confused with Wikipedia articles based on the classification system developed by the World Wildlife Fund , such as List of ecoregions ( WWF ) and Lists of ecoregions by country .   The commission was established in 1994 by the member states of Canada , Mexico , and the United States to address regional environmental concerns under the North American Agreement on Environmental Cooperation ( NAAEC ) , the environmental side accord to the North American Free Trade Agreement ( NAFTA ) . The Commission 's 1997 report , Ecological Regions of North America , provides a framework that may be used by government agencies , non-governmental organizations , and academic researchers as a basis for risk analysis , resource management , and environmental study of the continent 's ecosystems . Ecoregions may be identified by similarities in geology , physiography , vegetation , climate soils , land use , wildlife distributions , and hydrology .   The classification system has four levels . Only the first three levels are shown on this list . `` Level I '' divides North America into 15 broad ecoregions . `` Level II '' subdivides the continent into 52 smaller ecoregions . `` Level III '' subdivides those regions again into 182 ecoregions . `` Level IV '' is a further subdivision of Level III ecoregions . Level IV mapping is still underway but is complete across most of the United States . For an example of Level IV data , see List of ecoregions in Oregon and the associated articles .

Season creep <=SEP=> In phenology , season creep is observed changes in the timing of the seasons , such as earlier indications of spring widely observed in temperate areas across the Northern Hemisphere .  Phenological records analyzed by climate scientists have shown significant temporal trends in the observed time of seasonal events ,  from the end of the 20th century and continuing into the 21st century . In Europe , season creep has been associated with the arrival of spring moving up by approximately one week in a recent 30-year period .  Other studies have put the rate of season creep measured by plant phenology in the range of 2 -- 3 days per decade advancement in spring , and 0.3 -- 1.6 days per decade delay in autumn , over the past 30 -- 80 years .   Observable changes in nature related to season creep include birds laying their eggs earlier and buds appearing on some trees in late winter . In addition to advanced budding , flowering trees have been blooming earlier , for example the culturally important cherry blossoms in Japan ,  and Washington , D.C.  Northern hardwood forests have been trending toward leafing out sooner , and retaining their green canopies longer .  The agricultural growing season has also expanded by 10 -- 20 days over the last few decades .   The effects of season creep have been noted by non-scientists as well , including gardeners who have advanced their spring planting times ,  and experimented with plantings of less hardy warmer climate varieties of non-native plants . While summer growing seasons are expanding , winters are getting warmer and shorter , resulting in reduced winter ice cover on bodies of water ,  earlier ice-out ,  earlier melt water flows ,  and earlier spring lake level peaks .  Some spring events , or `` phenophases '' , have become intermittent or unobservable ; for example , bodies of water that once froze regularly most winters now freeze less frequently ,  and formerly migratory birds are now seen year-round in some areas .