TeacherTECH - January 24, 2006
Notes to accompany the presentation. Please note that some of the information and comments within these notes are not necessarily the views of experts, but are limited to my own general observations about the subject.
Why worry about a few degrees of temperature change?
After all, we endure much larger temperature swings every day. How can a few degrees of change be worth disrupting our lives in a big way?
Even if average global temepratures were to increase by just a few degrees Celsius over the next century, that's a big change for Earth. By comparison with other planets, the Earth's normal range of temperature variation is remarkably narrow, mostly above the freezing point of water and below the boiling point of water. That's part of the reason that larger life forms can persist on Earth.
According to the National Academy of Sciences (2005), average temperatures are expected to increase by 2.5-10.4 degrees Fahrenheit.
Think of the effort it takes to warm the air in your home on a chilly day. Then think of cranking up the thermostat up so that the entire globe warms by a few degrees, not just the air but also the sea surface. The temperature change at the sea surface may be more more modest, but the actual energy involved may be more because it takes much more energy to change the temperature of water than air.
All that extra energy rattling around the lower atmosphere and sea surface can do a lot. What work does that energy do?
It moves the air in winds and fuels the motion of storms and hurricanes. This degree of change may be increasing the average intensity of hurricanes. Will we bear the loss of life and property associated with more events like Hurricane Katrina?
It causes ice to melt. When a winter storm passes, it usually leaves snow at high elevations and rain at lower elevations, because of naturally cooler at higher elevations. If average air temperature increases, it will still be cooler at even higher elevations, but the snowline would rise. More water will melt and be lost as runoff instead of being stored as ice. More ice will melt earlier in the spring, leaving less to runoff later in the year. This may cause serious water shortages across the world. These are the predictions of Scripps scientists Tim Barnett and Jennifer Adam, and Dennis Lettenmaier of the University of Washington.
It forces living things to either adapt to changing local environmental conditions, move or perish. In a general way, it shifts climatic zones poleward and upward. Living things used to tropical areas may move poleward, including diseases and pests. Organisms living at the highest elevation would have nowhere to go. Few organisms are so adaptable that they can live in many kinds of conditions.
Not that it's entirely analogous, but what happens to the functioning of your own body when temperatures vary from the usual 98.6 or so degrees Fahrenheit? Many animals cannot regulate their body temperature and their physiology may not be able to tolerate temperature changes. Living things whether plant or animal constitute food. If some living things move or perish, many may starve as a consequence. Our own crops may be affected.
©2006 by Earthguide at Scripps Institution of Oceanography.