Climate zones
Climate zones refer to distinct regions characterized by specific weather patterns and ecological communities, primarily determined by temperature and precipitation over extended periods. The classification of these zones is commonly based on the Köppen Climate Classification System, developed by climatologist Wladimir Köppen, which identifies five major climate types: tropical moist climates, dry climates, humid middle latitude climates, continental climates, and cold climates. Each zone exhibits unique features; for instance, tropical moist climates are found in areas with consistently high temperatures and abundant rainfall, while dry climates experience minimal precipitation and significant temperature variations.
As global warming progresses, there is concern that climate zones could drastically change, with predictions suggesting that up to 39% of the world's land surface could transition to new climate types by the end of the century. This transformation may impact heavily populated regions and critical ecosystems, including changes in biodiversity, agricultural viability, and wildlife migration patterns. For example, shifts in climate zones could lead to the northward movement of certain tree species in North America and alterations in food production areas, particularly for crops like corn. Overall, the future of climate zones remains uncertain, emphasizing the importance of understanding these dynamics in the context of ongoing climate change.
Subject Terms
Climate zones
Definition
Climate, the average weather conditions over a period of at least thirty years, is determined by various factors, the most important of which are the amount of precipitation and the temperature of the air. Climate controls the major ecological community types or biomes; that is, the climate in a given region determines the flora and fauna that will thrive in that region. In 1900, Wladimir Köppen, a German climatologist, developed what has become the most widely used system for classifying world climates. The Köppen system identifies five major climate zones: tropical moist climates (A zone), dry climates (B zone), humid middle latitude climates (C zone), continental climates (D zone), and cold climates (E zone). Köppen also used two subgroups to more specifically describe the zones.
Tropical moist climates are characterized by year-round high temperatures and large amounts of rain. Rainfall is adequate all year round, and there is no dry season. This zone is typical of northern parts of South America, Central Africa, Malaysia, Indonesia, and Papua New Guinea. The dry climate zone has little rain and a wide range of daily temperatures. There is a dry season in the summer and winter, with a mean annual temperature of 18° Celsius, as in the western United States, northern and extreme Southern Africa, parts of Central Asia, and most of Australia.
The humid middle latitude climate, or temperate zone, has hot-to-warm, dry summers and cool, wet winters, but no dry season as such. Southeastern sections of the United States and South America, westernmost Europe, and the southeast corner of China fit this category. The continental climate zone, in interior regions of large land masses such as Canada and Northern Europe and Asia, experience varied seasonal temperatures and moderate rainfall. The cold climate zone, characterized by permanent ice and ever-present tundra, occupies Greenland and the most northerly parts of Asia.
Significance for Climate Change
While acknowledging some unknowns and uncertainty, researchers predict that, if global warming caused by and other greenhouse gas (GHG) emissions continues at the rate observed in the beginning of the twenty-first century, some climate zones could disappear entirely by the end of the century, giving way to new climate zones on up to 39 percent of the world’s land surface. Major areas that could be affected are tropical highlands and polar regions. Broad strips of areas labeled tropics and at the beginning of the twenty-first century could develop new climates that do not resemble any of the zones in categories assigned in the Köppen Climate Classification System. Heavily populated areas such as the southeastern United States, southeastern Asia, parts of Africa such as its mountain ranges, the Amazonian Rainforest, and South American mountain ranges are likely to be the most severely affected.
Climate change patterns could affect ecosystems on a global scale. For example, major changes in the forests of North America could result. Four species of tree—the yellow birch, the sugar maple, the hemlock, and the beech—are expected to move northward up to 1,000 kilometers while abandoning entirely their present-day locations. Animals could also be affected. Temperature and rainfall patterns could change breeding and migration patterns.
For humans, a grave concern was global food production. One model predicted that the corn belt in North America would move northward, possibly as far as Canada, and a 2022 study suggested that by 2100, the corn belt, or the corn production area of the midwestern United States, would be unable to produce corn without large advancements in agricultural technology. Winter wheat may replace corn in parts of the corn belt. Other scientists predicted various changes over the course of the twenty-first century. The Swiss Alps could become a Mediterranean climate, with wet winters and long, dry, warm summers. The climate zone in southern Switzerland may move northward by as much as 500 kilometers. In the western Alps, the climate may come to resemble the climate in southern France.
Biodiversity in South Africa was also predicted to be affected substantially by shifting climate zones: Species extinction on a wide scale; new climate zones in up to half the country; suffering succulent karoo, a globally important arid-climate hotspot, and suffering biomes in the fynbos (a Mediterranean-climate thicket) will suffer. While the degree of this change remains speculative, availability of food could affect sub-Saharan West Africa, as vegetation zones move southward.
With continued deforestation in the Amazonian forest areas of South America, new climates will be created near the equator. Some researchers predict that mountainous areas such as those found in Peru and the Colombian Andes, as well as regions in Siberia and southern Australia, could experience the disappearance of climates completely. Devastation of critical ecosystems and changes in agricultural patterns could severely affect Australia, New Zealand, and the developing island nations of the Pacific. With so many unknown factors, it remains to be seen how climate zone changes will play out in the future.
Bibliography
Burroughs, William James. Climate Change: A Multidisciplinary Approach. 2nd ed. New York: Cambridge University Press, 2007.
Clark, Carol. “Climate Change on Course to Hit US Corn Belt Especially Hard, Study Finds.” Emory University News Center, 2 June 2022, news.emory.edu/stories/2022/06/esc‗climate‗change‗corn‗belt‗02-06-2022/story.html. Accessed 30 Jan. 2023.
"Climate Zone." National Oceanic and Atmospheric Administration, 13 June 2023, www.noaa.gov/jetstream/global/climate-zones. Accessed 13 Dec. 2024.
Diaz, Henry F., and Richard J. Murnane, eds. Climate Extremes and Society. New York: Cambridge University Press, 2008.
Ennis, Christine A., and Nancy H. Marcus. Biological Consequences of Global Climate Change. Sausalito, Calif.: University Science Books, 1996.