Ch 7.2 Is our climate really changing?

Question 1

What are the evidences that our climate is changing?

Answer 1

1. Increasing global temperature.
2. Shrinking sea ice and glaciers.
3. Rising global mean sea level.
4. Change of global precipitation patterns.
5. Extreme weather events.

Question 2

Elaborate more on increasing global average temperature.

Answer 2

1. The increasing rate has become faster since the 1980s.
2. The increase rate of mean surface temperature of the Northern Hemisphere was greater than in the Southern Hemisphere. The greatest increase was found in the Arctic region, where some areas experienced a increase of 3 degrees.
3. Some parts of the ocean, particularly in the southern hemisphere, a decrease in mean surface temperature of less than 2 degrees.

Question 3

Elaborate more on shrinking arctic ice and glaciers.

Answer 3

1. The extent of Arctic sea ice has been decreasing since the late 1970s.
2. Glaciers are retreating.
3. Arctic sea ice has lost about 34% of its volume over the past two decades. It is predicted that if the ice continues to melt, the Arctic Ocean will probably be ice-free in summer by 2050.

Question 4

What are the reasons of rising global mean sea level?

Answer 4

1. Glaciers melt -> become sea water.
2. Seawater expansion. (thermal)

Question 5

Elaborate more on changes of global precipitation patterns/

Answer 5

1. Precipitation has increased over the land areas of the Northern Hemisphere in some regions, such as eastern Europe, Tropical Africa, eastern North America and some high-latitude regions in Europe, Asia and North America.
2. Some places have become drier, e.g. the Middle East, and the western parts of Australia, North America and South America.
3. There are some observed changes in the global precipitation pattern:
   - More intense rainfall.
   - Shorter duration of rainfall.
   - Precipitation falls as rain rather than snow in some higher altitude regions

Question 6

What are the impacts under such change in global precipitation?

Answer 6

1. An increase in the annual precipitation in some areas, in the form of heavy rain -> more serious and frequent flooding -> destroy people’s homes and their food stocks.
2. A decrease in the annual precipitation in some areas -> more serious and frequent drought conditions -> hindered crop growth.
3. Soil erosion would worsen, and the pace of desertification would increase, increasing the risk of food shortages.
4. Water shortages would also affect the daily lives of people there.

Question 7

Elaborate more on extreme weather events.

Answer 7

1. Heat waves have become more common.
2. More intense periods of rainfall results in a higher risk of flooding.
3. There are stronger tropical cyclones and more frequent droughts.