What are the manifestations of ubiquitous climate anomalies?

Researchers from Harvard University and other American universities have calculated the date when spring comes every year for more than 50 years. Comparing the global climate records from 1850 to 1950 provided by the University of East Anglia, they found that spring was about two days earlier. The researchers said that the reason for this situation is still unclear, but it is suspected that it is related to climate warming caused by human activities.

It is found that not only the arrival time of spring is advanced, but also the start time of other three seasons and the highest temperature period of each year are advanced.

Alexander stine, a graduate student at the University of California, Berkeley, who participated in the research, said that in the northern hemisphere, for example, the starting time of the four seasons from 1850 to 1950 has not changed much, and the hottest day of the year is around July 2 1. In contrast, the maximum temperature from 1954 to 2007 was advanced by 1.7 days on average.

"During the period of 100 (1850 ~ 1950), the seasons naturally change. Later, with the increase of the global average temperature, the time of the four seasons changed greatly. " Sting said.

In addition to the early replacement of seasons, researchers also found that in the past 50 years, the temperature difference between winter and summer has been shrinking, and the temperature in winter has risen faster than that in summer.

The results show that in non-equatorial areas, the land temperature has increased by 65438 0.8℃ in winter and 65438 0℃ in summer in recent 50 years. The temperature of the ocean changes less than that of the land.

"The start time of all seasons has been advanced and the temperature has risen," said Sting.

Some biologists also found that in the past 50 years, some natural phenomena, such as blooming flowers, bird migration, melting snow and sea ice, also occurred earlier.

Scientists believe that the early appearance of these phenomena shows that the earth's climate is warming, which leads to the monthly temperature increase.

In addition to the advance of the season, there will be weather conditions that are completely inconsistent with the local climate characteristics in some places. On September 3, 2008, a rare heavy snow fell in a village more than 200 kilometers northwest of Nairobi, Kenya. When residents got up in the morning, they found that the grass was covered with ice and snow overnight. Many villagers have never seen snow in their lives. Some people picked up ice cubes to cool off the heat, while others took the opportunity to have snowball fights.

The place that experienced this snow is located in the Great Rift Valley of East Africa. There used to be hail, but it never snowed Some experts pointed out that the local area was still a forest 20 years ago, and it is estimated that sudden climate change is related to excessive felling of trees.

Affected by global warming, precipitation in some places will decrease. In March, 2007, the National Weather Service announced that Los Angeles was affected by global warming, the urban climate was abnormal, and the rainfall was greatly reduced. The National Weather Service said in a statement that the rainfall in downtown Los Angeles was only 6 1 .47mm from July, 2006 to the time of issuing the statement, which was 220.95mm less than the rainfall in the same period in normal years and the lowest rainfall on record.

In addition to the decrease in rainfall, Los Angeles was hit by a rare high temperature in the summer of 2006, which killed more than 65,438+000 people. In the winter of the same year, the cold current swept through Los Angeles, which has always been warm as spring, causing great damage to crops.

William Patzert, an American climatologist, pointed out that this extremely hot, extremely cold and extremely dry abnormal climate is closely related to global warming. He said that in previous years, the Pacific Ocean was affected by the El Ni? o phenomenon, and the sea water was warmer, which eased the cold air flow from the north. However, in the winter of 2006, the El Ni? o phenomenon did not have much impact on the Los Angeles area, so a cold air flow from the polar regions affected the climate in this area.