Page 338 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

THEhumanDENOMINATOR 10 Climate Regions
CLIMATES HUMANS
• Climates affect many facets of human society, including agriculture, water availability, and natural hazards such as floods, droughts, and heat waves.
HUMANS CLIMATES
• Anthropogenic climate change is altering Earth systems that affect that temperature and moisture, and therefore climate.
10a In the Eurasian Arctic tundra, 30 years of warming temperatures have allowed
willow and alder shrubs to grow into small trees. New research from the southern parts of this region shows that the shrubs, formerly about 1 m
in height, now reach over 2 m.
This trend may lead to changes in regional albedo as trees darken the landscape and cause more sunlight to be absorbed. [AlxYago/Shutterstock.]
10c
As the tropics expand poleward, storm systems shift toward the midlatitudes, and the subtropics become drier. Drought in Texas has devastated crops; in this photo, a farmer surveys his cotton field in 2011. Under normal conditions, plants should be at knee height but here they have barely broken through the soil surface. The drought has also affected beef production and lowered reservoir levels, cutting off irrigation water for rice crops–with millions of dollars lost. [Scott Olsen/Getty Images.]
ISSUES FOR THE 21ST CENTURY
10b
Dengue fever, carried by the Aedes aegypti mosquito, is one of several diseases that are spreading into new areas as climatic conditions change. Dengue has spread into previously unaffected parts of India, and into Nepal and Bhutan. North America is not a risk area for dengue according to the World Health Organisation, but the Public Health Agency of Canada advises that travelers to risk areas should protect themselves from mosquito bites.
[Nigel Cattlin/Alamy.]
• Human-caused global warming is driving a poleward shift of the boundaries of climate regions.
geosystemsconnection
Collectively, the climate regions presented in Chapter 10 provide a synthesis of the systems studied in Chapters 2 through 9 of Geosystems. Climate classification categories are portraits of the interplay between solar insolation, moisture, and weather conditions that determine climates, and their associated ecosystems. Next, we move to the last chapter of Part II, where we survey and explain the many facets of climate change now underway. We examine the method scientists use to assess past climates and natural climate variability. We also look at present changes in atmospheric composition that are raising global temperatures, with associated effects on all Earth systems.
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