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How Much Silk Can A Spider Spin in a Day? Sierra Club Knowledge Cards

Similar in subject to one of our existing Sierra Club decks, How Many?, this one takes a slightly different approach to quantifying the natural world. Focusing on meteorological forces, animal behavior (including that of humans), and other everyday phenomena, it exposes both the wonders and horrors that transpire on a daily basis.

Sample card: How many people are born worldwide in a day? Answer: According to the Population Reference Bureau in Washington, DC, as of mid-2004 about 368,000 people were coming into the world every day while around 158,000 were dying. That leaves the world with nearly 80 million additional people each year. At that rate, today's population of around 6.4 billion will rise to roughly 9.3 billion by 2050. Most of that growth will come in the developing countries of Africa and Asia. The US population is growing slightly, while Europe's, as a whole, is declining. China and India, combined, today account for more than one-third of the world's population. By 2050, India—whose population is growing at 1.7 percent per year—is expected to overtake China as the world's most populous country. On the flip side, Liberia has the world's highest infant mortality rate (15 percent), while Finland has the lowest (0.3 percent). And worldwide some 38 million people—including 25 million in Africa—are now infected with HIV/AIDS. Size: 3 1/4 x 4". Ages 10+.

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