Global Warming - Why a few degrees temperature rise matters?

When scientists predict that the Earth’s atmosphere will get much warmer because of global warming, some people expect to hear that the temperature will get 10, 20, or 30 degrees warmer. Some have visions of sitting in a hot, steamy sauna, melting away. So, when climate scientists predict a temperature rise of 2–11.5°F (1.1–6.4°C), they are inclined to ask what the big deal is about global warming. It is just a few degrees, right?
Look at it this way: During the Earth’s last ice age, the Earth was only about 6.7–10°F (4–6°C) cooler than it is today. Although it may not seem like much, these few degrees were responsible for blanketing huge areas of the Earth in thick layers of ice. It had such an impact on ecosystems that some animal species became extinct.

Thus, although a few degrees may seem trivial, the Earth’s climate is so sensitive that those few degrees can make a big difference. Scientists have already proven that temperatures are rising, making it something people cannot ignore now or in the future.

The more people learn about the effects of global warming and how it can affect ecosystems worldwide, the more that can and must be done to slow down the changes. Society has progressed to a point where avoiding global warming is no longer an option, but learning how to slow it down, adapt, and have each person learn to do their part are important pieces of any solution.

Today is the time for action, and people can make a difference. It is key to understand the following:
Updates on Global Warming: 

Nov 16, 2010
U.S. and British meteorologists have reported that the earth's troposphere is also heating up along with the surface due to global warming. Troposphere is the very first layer of atmosphere above the surface where weather related events occur. The revealing has been done based on data of troposphere temperature recording for the last four decades.

Nov 25, 2010
A new research by two NASA scientists have found that lakes are warming up faster than the other ecosystems on earth. Satellite data was collected over the past 25 years and 104 large inland lakes were observed during the period for maintaining the temperature records. The study revealed that the average temperature of these lakes have risen over 1.1° C since 1985. The temperature rise of atmosphere during that time period was 2.5 times less than the rise in temperature of lakes.