According to the Fifth Scientific Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), the global average surface temperature has been on a rising trend for more than 100 years from 1880 to 2012. By the 1980s, the rate of temperature increase was even greater Significant. 1983 to 2012 is the hottest 30 years in the past 1400 years.
During this period, the land warming faster than the ocean, warming in high latitudes faster than in low latitudes. In particular, Wang Huijun mentioned the plateau region, where there is snow cover all year round. Due to the feedback of ice and snow, the warming trend in the plateau region is also stronger. The situation on the plateau resembles the polar.
However, since climate warming was put forward, voices of doubt have never stopped. Especially in recent years, scientists who challenged the theory of climate change think so far the global climate has not warmed up for more than ten years or is called "Hiatus." This is also an important factual basis that the 16 global scientists jointly challenged the question of global warming in 2012.
"The global average temperature has indeed reached a plateau after reaching a high value in 1998." Wang Huijun acknowledged that temperature has slowed in the past decade or so, "but the so-called climate change is focused on decades and centuries of scale Rather than the decisive change in the interannual timeline, with a focus on the global average. "In fact, the last 15 years are still the warmest 15 years in a century. The long-term warming trend cannot be stopped.
However, the greenhouse gas emitted by mankind is still increasing. What is the reason for the global average temperature to go flat?
Wang Huijun explained that more than 90% of the energy of the solar shortwave radiation accepted by the real earth system has entered the ocean. Studies have shown that seawater is much larger than the heat capacity of the atmosphere, upper marine energy storage is increasing, and to some extent digesting the amount of heat absorbed as a result of greenhouse gas increases.
In addition, the Pacific Decadal Oscillatory (PDO) will generate annual interdecadal fluctuations in the atmosphere. Since 2000, PDO has shifted into a negative phase, which has alleviated the temperature increase.
Wang also mentioned that some scientists predict that PDO may turn positive from 2030 to 2035. By that time, interdecadal warming may increase the greenhouse gas pressure together with the climate system and climate warming will become even more violent.
Not the will of the people for the transfer?
Since the formation of the earth's climate, the world has experienced different periods of climate change. This has also led some scientists to hold a view that the long-term history of the Earth's climate shows that alternating cold and warm cycles are not transferred from human will. Therefore, it seems that it should not be unduly attributable to humans.
In response, Wang Huijun pointed out that human activities, especially greenhouse gases lead to climate warming and a series of corresponding climate change is determined by rigorous physics and other scientific laws, not a guess, not just the results of the statistical model.
The energy source of the earth system is the shortwave radiation of the sun. Most of it reaches the ground after passing through the atmosphere, and eventually, the part reaching the ground eventually returns to space in the form of longwave radiation. This explains why, from the ground to the troposphere, the temperature is higher and lower. Because the energy that heats the atmosphere actually comes from the surface.
However, it has been calculated that the amount of heat reaching the ground is not equal to the amount of heat exiting the top of the atmosphere after the true reflection.
In fact, long-wave radiation trapped is absorbed by the greenhouse gases in the atmosphere, especially carbon dioxide and water vapor.
Ozone is also a greenhouse gas, which is very important. "Without them in the atmosphere, the annual average temperature in the world will drop by more than 30 degrees now," Wang said.
"However, as the amount of greenhouse gases increases, the amount of heat removed from the top of the atmosphere decreases, warming the greenhouse effect and contributing to global warming."
The latest IPCC report also pointed out that the conclusion that climate change is mainly caused by human activities is more than 95% credible.
Of course, in the long run, periodic fluctuations in the orbit of the earth around the sun, volcanic activity, and solar activity will also have an impact on the Earth's climate system.
Let the climate change go its own way?
In the opinion of some people, the trend of contemporary climate change has not gone beyond the historical climate change. Humans can let it be.
However, precisely because of human civilization, climate change has become highly sensitive.
"It is very difficult for humans and many animals and plants to adapt to the drastic climate change in the short term. In particular, such severe climate change will be accompanied by extreme weather, frequent climate events, and disasters." Wang Huijun said that if the global warming Unchecked, will have a major impact on human society and the environment, many of which may be negative.
In recent years, extreme snowstorms have occurred in winter in Western Europe, North America, Japan, and northeast China. Wang Huijun said these unusual weather and climate events are closely linked to the Arctic and global warming.
From the atmospheric circulation theory of variation to explain, under normal circumstances, the Arctic is cold, while the mid-latitudes are relatively warm, so there is a meridional gradient of temperature. The existence of this gradient allows the westerly jet stream to be maintained while the atmospheric fluctuations are transmitted along the westerly jet stream.
Because of the strong Arctic warming, the meridional gradient of temperature is weakened and the westerly jet stream weakened. The meridional direction of the atmospheric circulation is increased. As the meridionality is weakened and the latitude weaker, the cold air will more easily burst from north to south, resulting in unusually cold air and more snowstorms in these areas.
In addition, according to quantitative statistics, global land and sea ice glaciers, Greenland's land ice sheets reduce the amount of ice, are closely linked to global warming.
In a recent article in the journal Nature, a new study from Harvard University, which recalibrated baseline data on sea level changes, found that sea-level rise accelerated over the past two decades could be more severe than previously thought.
This is both strong evidence of global warming and one of the most important direct consequences it generates.
The melting of sea ice and ice sheet will lead to the rise of sea level and directly affect the survival of small island nation. The melting of mountain glaciers will change the terrestrial water cycle. Due to spring ice and frequent spring floods, the glacier will have less effect on the entire water cycle, resulting in a Series of disasters happen.
However, Wang Huijun mentioned that people are less concerned about the rapid decline in Arctic sea ice, especially in the autumn of 2007 and 2012, narrowing the scope is very obvious, which is also inextricably linked with the winter in Western Europe and North America.
Interestingly, Wang Huijun also recently found that the increase of haze in the eastern part of China may also be related to the decrease of Arctic sea ice. He said that in the long run, interannual variations of haze in winter in northern China, Huanghuai River and a part of the middle and lower reaches of the Yangtze River have a certain inverse relationship with the interannual variation of Arctic sea ice in autumn.
"On the one hand, the amount of pollutants we emit is on the increase, and on the other hand, the reduction of sea ice makes meteorological conditions not conducive to the spread of pollutants." Wang believes that it may play a role in fueling the situation.
Predict the future facing challenges
Climate change will have a great impact on the social, economic, living and ecological environment of all countries. Therefore, a more reliable prediction of how the climate changes in the future will become a hot issue for the climatologist community.
The so-called climate prediction is based on the changing laws of the climate system and is established by using increasingly complex climate models and high-performance computers for the numerical solution to predict the future long-term climate system.
Such forecasts include changes in temperature, changes in humidity, sea level rise, changes in rainfall, changes in rivers, changes in the frequency of tropical cyclones and other extreme weather events, and more.
A climate system model is a basic tool for predicting climate change. The climate system is composed of the atmosphere, biosphere, hydrosphere, cryosphere, and lithosphere. Therefore, the climate system model needs to include complex mathematical physics modules that describe these spheres, The modules can be combined in different ways to meet the needs of different studies, to simulate past and present Earth's climate systems, and to predict and predict climate change.
Of course, there are still many imperfections in the simulation of the past and current climate models in the climate system model, which cause great uncertainty in forecasting and predicting the future climate.
At present, scientists are working on the development of the Earth system model coupled with the system model of the climate system and the system of the biogeochemistry, as well as the high-resolution climate system model so that a more scientific and reliable simulation and prediction of global climate and environmental changes can be achieved.
It can be seen that it is still a huge challenge to predict the future climate.
Summary: The latest data show that in 2014 the global temperature hit a record high. The global average temperature is 14.6 degrees Celsius, 0.69 degrees Celsius above the 20th-century average. Chinese Academy of Sciences, Chinese Society of Meteorology, Wang Hui jun on the issue of global warming made the latest answer.
