Climate expert: Human influence is the main cause of global warming and needs continuous attention.

654381October 5, the Nobel Prize in Physics was announced. Half of the prizes were awarded to Syukuro Manabe, a Japanese meteorologist in the United States, and Klaus Hasselman, a German oceanographer and climate modeler, for their "reliable prediction of the physical modeling, quantitative variability and global warming of the earth's climate".

In 1960s, Syukuro Manabe developed a numerical model that can reproduce and predict the earth's climate on the computer according to the laws of physics, which clearly proved the correlation between the increase of CO2 concentration in the atmosphere and the increase of the earth's surface temperature for the first time.

Klaus Hasselmann created a model linking weather and climate, and his "fingerprint method" is still used to prove that the rise of atmospheric temperature is due to CO2 emitted by human beings.

Now, more and more studies have confirmed that human influence is the main cause of global warming, and global warming has affected and continues to affect human socio-economic development, health, population migration, food security, water resources and terrestrial and marine ecosystems.

Research methods and tools

In attribution analysis, observation results are used as standard (benchmark) fingerprints, and simulation results of global climate models under various compulsions are used as fingerprints that need to be compared. Compared with the observation results, the simulation results are the closest to the observation results, and the corresponding compulsion is the main reason.

One of the main tools of fingerprint attribution analysis is the global climate model. At present, the main means is to compare the earth system models (CMIP5, CMIP6) in the fifth and sixth stages of the plan.

Compared with the observation, it shows that the current global climate model has a good ability to simulate the average value, anomaly value and trend of various global variables, and the simulation effect of extreme events has also been significantly improved.

In the fingerprint method used for attribution analysis, the standard (benchmark) fingerprint is observation data, including actual global observation data, reanalysis data with a large number of variables in the global multi-layer fine grid processed by global climate model, and proxy data.

The spatial scale of observation data involves a global scale, using tens of thousands of observation stations; The time scale is different, generally 50~75 years.

It should be pointed out that there are some differences in the observation results given by global observation data from different sources, and it is necessary to judge the consistency of various observation results.

Considering that the total change of a variable in the five circles of the earth system can be decomposed into: changes caused by natural compulsion+changes caused by human influence+changes within the earth system.

Attribution analysis is to find out the proportion of changes caused by human influence in the total changes. If the proportion is relatively large, it is considered that the overall reason for the change is mainly human influence.

The time scale of attribution analysis of human influence is generally several years to a hundred years. Through the attribution analysis, it is concluded that the role of human influence needs to be tested.

It is necessary to give credibility in attribution analysis, and IPCC reports generally adopt the possibility grading standard of attribution analysis, which is a quantitative standard of statistical analysis.

Possibility test is mainly used to judge the reliability of various observation data and the possible attribution of human influence.

The IPCC report also adopts the qualitative judgment standard (i.e. credibility), and makes qualitative grading judgment according to the degree of consistency and expert evaluation.

Human influence has led to global

Evidence of surface temperature warming

For a long time, the study of global warming has mainly used the global annual average surface temperature as a measure to test the role of human influence in various compulsions. In the past 10 years, it has gradually developed to test a wider range of temperature-related indicators.

0 1

Human influence is almost certainly the main cause of global warming in the last century, especially in the last 50 years.

Global warming was observed in 20 19 years (1. 1. 1), but the global climate model thinks that the global warming is caused by human influence 1.0, that is, 90% of the observed global warming is caused by human influence.

Observing the global temperature in 20 10-20 19 years, compared with 1850- 1900 years, it is very likely to increase 1.0~ 1.3. Most global climate models consider human influence, which leads to global warming of 0.8 ~ 1.

02

The observed warm day/warm night frequency increases, and the intensity is warmer, while the cold day/Leng Ye frequency decreases and slows down. However, most models consider the influence of human beings and get characteristics consistent with observation.

03

The observed heat wave/warm period has increased in frequency, intensity and duration. Most climate models consider the human influence and confirm that it is very likely to cause the enhancement and increase of heat wave and warm period on a global scale.

A record-breaking high temperature increase was observed, and a record-breaking high temperature increase was also detected considering the influence of human beings in the global climate model.

04

The observation frequency, intensity and duration of cold wave/cold period are reduced. However, most models get the characteristics consistent with the observation by considering the human influence, and the observed severe cold intensity decreases. The global model also confirms its leading role by considering human influence.

05

Taking the global daily extreme maximum temperature on land as an example, it is found that it is more likely to encounter extreme high temperature in the 1990s than in the 1960s. According to the global climate model, all the forcing forces are reduced to 17 years, while the human impact is 16 years.

Human influence has led to global

More evidence of five rings warming

Because the five circles cover a wide range of fields, what is given here is only computable, closely related to the public and highly reliable evidence of variables and phenomena.

0 1

Global warming caused by human influence is not only the warming of the surface temperature, but also the warming of the global lower atmosphere for several kilometers, while the land surface temperature is getting lower and the ocean surface water temperature is getting lower.

Taking the ocean heat capacity as an example, it was observed that the ocean heat capacity of 0 ~ 0 ~ 700m increased obviously from 1850 to 20 17, and the multi-model simulation showed that human influence accounted for about 65%.

02

The influence of human beings leads to the warming and expansion of seawater, which leads to the rise of sea level.

The multi-model simulation confirmed that the global sea level rose by 0. 19 m on average from 1900 to 20 18, which was probably caused by human influence. From 1950 to 2005, 87% of the global sea level thermal expansion from 0 to 0~700 m was caused by human influence; From 65438 to 0970-2005, 70% of the sea level rise caused by ice melting and thermal expansion was affected by human activities.

03

Human influence has accelerated the melting of sea ice, especially the Arctic Ocean, and accelerated the melting of land ice such as Greenland ice sheet and glacier.

In September, the sea ice in the Arctic Ocean decreased obviously. In the multi-climate model simulation, the combination of natural forcing and internal variability of the climate system is less than 42%, while human influence accounts for about 58%.

04

The human influence leads to the acceleration of the melting of land snow and permafrost.

Multi-model simulation shows that since 1950, the spring snow in the northern hemisphere is probably the main reason to reduce human impact.

05

The increase of CO2 emitted by human causes the ocean to absorb more CO2, which leads to the increase of ocean acidity.

06

Man-made influence leads to the increase of surface humidity. Since 1950, precipitation in high latitudes and tropical areas has increased, and the intensity of global land heavy precipitation events has increased.

07

Human influence has caused the global land frost period to be shortened, the growing period to be prolonged and the flowering period to be advanced.

08

Some variables closely related to the public, such as the increase in intensity and frequency of droughts, floods and strong tropical cyclones in some areas, have not been fully proved to be related to human influence.

It can be observed that in recent 40 years, the number of strong tropical cyclones in the global sea area has increased, and the reliability of human impact is low.

09

It is observed that some regional disasters occur jointly, such as heat wave and drought, flood and low temperature at the same time, and its relationship with human influence is still under study.

conclusion

At present, there are dozens of models of the earth system. Because of their different horizontal and vertical resolutions and different parameterization schemes for many physical, chemical and biological processes, the simulation results of several models are inconsistent or divergent, which reduces the reliability of some evidence.

In addition, some variables in the five spheres of the earth system lack sufficient observation data, which also affects the development of global climate models.

With the deepening of the understanding of earth system science, the development of computing technology, the application of artificial intelligence, the development of earth system models and more advanced tools, more evidence of global warming caused by human influence will be obtained.

After 265438+ 1920s, if the greenhouse gases emitted by human beings continue to increase, the corresponding phenomena such as global warming caused by human influence need further study.