Historically, the temperature of the earth has been changing. Why should we panic about global warming?

First of all, the global average temperature is not higher than it is now. Simply put, it is the spatial scale of global warming in the Tang Dynasty.

Different temperatures, the corresponding global warming period in the Tang Dynasty was not universal, and the temperature experienced many times around 600-900 AD.

Temperature fluctuation can only be caused by the temperature increase in some periods from the Yellow River Basin to the Yangtze River Basin in the Tang Dynasty, while the temperature increase in some periods.

It is believed that this may be due to the change of atmospheric fluctuation pattern to enhance the summer monsoon, while other parts of the world such as Europe are in this period.

In 600-800, it experienced a relatively cool period.

The latest recognized connection from the post-AD era to the pre-industrial revolution era.

The global warming period (in fact, mainly in the northern hemisphere) is the medieval warming period around A.D., corresponding to the late Tang Dynasty.

During the Southern Song Dynasty, the temperature in Europe, Greenland and North America was generally higher than the average level in the 20th century, such as Asia.

There are also warm and humid records in northeastern Japan, but what about the climate in other parts of the world, especially in the southern hemisphere?

There is no complete conclusion. Antarctica and some parts of the tropical Pacific show opposite cooling phenomena, and some studies also believe that

After the medieval warm period, it did not exist on a global scale.

First of all, it may be more like a hemisphere seesaw caused by ocean current changes and atmospheric fluctuations.

Effect. It is not accurate to attribute all the' prosperous times' of rapid population growth in history to the agricultural harvest brought about by global warming.

The popular statement that global warming was much higher during the Han and Tang dynasties is subjective and inaccurate, so we can compare it.

Different versions of maps are popular on the Internet, and it is not consistent whether it is cold or warm at the same time. The main basis may come from some historical records.

A record of the period, phenology or species distribution of weather events and seasonal series. For example, when the river was frozen, it snowed several times in Chang 'an in the Tang Dynasty.

These results can not accurately explain global cooling or warming, but only regional cooling or warming, and many of them are mixed.

Mechanical weather events cannot fully reflect the details of climate change at that time.

On the other hand, according to the record of phenology, as well as in-thing.

The boundary of species distribution can only infer global climate change at a certain level, which has strong limitations, and these influencing factors are more complicated.

Many, the results are not necessarily accurate, such as the phenology of Rosaceae plants in early spring (such as apricot flowers, peach blossoms, cherry blossoms) and other opening dates, which is traditionally recognized.

Because the higher the temperature, the earlier the flowers bloom, and these plants themselves need to be cold, that is, they can only bloom after a certain low temperature in winter, such as

If the first two months of a year are unusually warm and cold from late winter to early spring, the overall temperature is still above average, which will also lead to.

It blooms very late.

Second, on the contrary, if the first two months are unusually cold and the temperature is high in early spring, the mode of below-average temperature will be advanced.

Flowering and phenology are not only related to temperature, but also to seasonal lag. In addition, regarding species distribution, plum and orange in Tang Dynasty.

Chang 'an can grow oranges, so it means that the climate at that time was much warmer than now, which is also inaccurate. These may also be planted in specific places.

The microclimate environment can't be completely regarded as a climate response, and the northern boundary of plum blossom distribution is not as south as it was then, and the north is as big as Beijing.

There are even plum trees planted in the local area, and some subtropical evergreen trees such as citrus and osmanthus can be planted in Xi 'an urban area, but the soil and precipitation are not limited.

Can be used for large-scale commercial production.

Besides temperature, there are precipitation, annual temperature difference, soil environment and high vegetation coverage.

And so on, can also change the northern boundary of species distribution, citrus, plum and camellia limit their distribution in northern China.

Elements, such as the climate at a specific stage, due to the change of monsoon atmospheric circulation mode, lead to more precipitation and slower temperature in annual range.

During this period, the annual average temperature also decreased (2 degrees in summer and 1 degree in winter), showing a slight cooling trend.

The northern boundary of the lower distribution can still move northward.

Third, according to some historical records, the world's relatively warm and cold climate is circulating on the Internet.

Cold and warm maps are subjective and cannot reflect the details of climate change, so they are not really accurate. Will be completely warm and prosperous.

Taken together, it is not accurate, but there is a positive correlation between the warming pattern and monsoon intensity in some parts of East Asia, but it is not entirely like this.

Here you are. The so-called global temperature level during the Han and Tang Dynasties was not warmer than it is now.

At present, in the post-industrial revolution era, especially in the decades after 80 years, the global average surface temperature is warming and the climate is changing.

In the history of observation, it is indeed global.

Moreover, the global carbon dioxide concentration has increased for decades to nearly a hundred years.

100 ppm (279 ppm-421ppm) may exceed the highest value in geological history140,000 years, from the North Pole to the South Pole, from the ocean to.

Almost all the land is warming, and the middle and high latitudes in the Arctic and Northern Hemisphere have the largest warming range. At present, the global average temperature has been higher than that of pre-industrial leather.

Life age is high 1.2- 1.3 degrees. The Tang Dynasty (600-900) estimated that the global temperature range was below 0.5-above 0.8 (0 is roughly19th century).

Ji average level), the probability of higher than now is lower.

4. These scenarios are updates of a set of scenarios used in the past ten years, including a controversial extreme scenario: to 2 100,

The temperature will be about 5 degrees Celsius higher than the pre-industrial level. For more than a decade, this scenario has occupied an important position in climate research, but criticism

Critics accuse it of being misleading because it contains unrealistic coal consumption: by 2 100, coal consumption will increase by about 5.

Time magazine. However, many researchers ignore this criticism and think that as long as people understand its basic assumptions and limitations.

Such a high carbon row

The scenery still has its value. For example, a large amount of methane released by permafrost in the Arctic may be similar to the massive use of fossil fuels.

Effect.

"We try to understand risks, not predict the future." Donald said that he is an atmospheric scientist at the University of Illinois at Urbana-Champaign.

Wuebbles said. Wuebbles is the main work of the first volume of the latest national climate assessment in the United States released on 20 17.

Who? The purpose of these scenarios is not simply to predict emissions, but to study different degrees and types of climate warming.

What impact will the mode of economic development have?

These scenarios can be used by different researchers: economists can study policies according to them.

Ben, ecologists use them to predict changes in the global ecosystem.

"This is not a science fiction story," said an environmental health researcher at the University of Washington and co-chair of the committee that developed the new climate scenario.

Christie Eby said, "We need these modeling results to understand the consequences of our choices. Now we have the ability.

Try to do this. "