Diamond: What will global climate change bring to mankind?

For many people living around the world, the most obvious point is drought. For example, this year (20 16) is the driest year in Los Angeles where I live since meteorological records began in the19th century. Drought is harmful to agriculture.

Global climate change leads to drought. The distribution of arid areas in the world is uneven. The most seriously affected areas are North America, the Mediterranean and the Middle East, Africa, Australia's South Australia crop-growing areas and the Himalayas. Snow in the Himalayas provides a lot of water for China, Viet Nam, India, Pakistan and Bangladesh.

The second consequence of the global average warming trend is that the grain production on land is decreasing. Drought is one of the reasons, and another reason is the puzzling rise of land temperature. The decline of grain output is a problem worthy of attention, because the world population is in the process of sustained growth. In the next few decades, the population is expected to increase by 50%, and the living standard of human beings is also constantly improving. In this way, the world's food consumption has also increased. This is really a bad thing, because at present, we human beings have already had the problem of food shortage, and billions of people are still in a state of not having enough to eat.

The third consequence of the global average warming trend is that insects carrying tropical diseases are entering temperate regions. So far, some diseases caused by it include tropical Chikungunya fever which recently arrived in Italy and France, dengue fever and tick-borne diseases which recently spread in the United States, and malaria and viral encephalitis which spread all over the world.

The consequence of the global average warming trend is sea level rise. It is conservatively estimated that the average sea level rise in this century is expected to be 1 m. However, there has been a sea level rise of 23 meters before. At present, the main uncertainty involves whether the Antarctic ice sheet and Greenland ice sheet will collapse. Even if the average sea level rise is only 1 m, plus other factors such as storms and tides, many densely populated areas in the world will no longer be suitable for human habitation-such as some places on the east coast of the United States and lowlands in Bangladesh.