Page 95 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

THEhumanDENOMINATOR 2 Solar Energy and the Seasons
SOLAR ENERGY/SEASONS HUMANS
• Solar energy drives Earth systems.
• Solar wind affects satellites, spacecraft, communication systems, and power grids on Earth.
• Seasonal change is the foundation of many human societies; it determines rhythm of life and food resources.
HUMANS SOLAR ENERGY/SEASONS
• Climate change affects timing of the seasons. Changing tempera- ture and rainfall patterns mean that spring is coming earlier and fall is starting later. Prolonged summer temperatures heat water bodies, promote early thawing and later refreezing of seasonal ice cover, alter animal migrations, shift vegetation patterns to higher latitudes—virtually all ecosystems on Earth are affected.
2b
2a
Solar energy drives Earth systems, including winds, ocean currents, weather, and living ecosystems. [NASA/JSC.]
During coronal mass ejections (CMEs) and other solar storms, International Space Station astronauts take cover in sheltered areas of the spacecraft. [NASA/SDO.]
2c
Seasonal shifts in subtropical high pressure in Africa are leading to decreased rainfall. Drought tolerant maize is one development that will help farmers adapt to climate change. [Philimon- Bulawayao/Reuters.]
2e
2d
Timing of last spring frost and first fall frost 1895–2011
Positive values show frost occurred later in
that
the year
Spring frost
Long-term
average
Fall frost
Negative values show that
frost occurred earlier in the year
As summers get longer in Alaska, moose migrations no longer coincide with the hunting seasons of native people, who depend on the meat. Shifting animal migrations and vegetation patterns will
affect ecosystems across the globe. [Steve Bower/Shutterstock.]
6 4 2 0
–2 –4 –6
Data are for the contiguous United States. The overall trend is toward a longer growing season, with a longer fall and an earlier spring. [EPA, data courtesy K.E. Kunkel 2012; www.epa.gov/climatechange/ indicators.]
ISSUES FOR THE 21ST CENTURY
1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020
Year
• Ongoing climate change will continue to alter Earth systems. Societies will need to adapt their resource base as timing of seasonal patterns changes.
59
Deviation from average (days)