What a Global Warming Report
The report was published by the Intergovernmental Group of Experts on
Intergovernmental Group of Experts onClimate Change was founded in 1988 to produce reports on climate change. Its goal is to stabilize the concentration of greenhouse gases in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.
Who is to blame for global warming
In the new report, the authors make a clear conclusion that the main and indisputable cause of global warming is human activity.
In the last decade, the average temperatureThe earth was 1.09 degrees higher than in the second half of the 19th century, and man is directly responsible for a fraction of 1.07 degrees - only 0.02 degrees are due to natural causes.
If we take the current level, then we will choose the available emission for one and a half degrees in 15 years, and for two degrees - in 30 or 35 years.
Alexey Eliseev, one of the authors of the report from Moscow State University and the Institute of Atmospheric Physics.
How global warming develops
According to the report, there is now as much carbon dioxide in the atmosphere as there has not been in the last 2 million years, and nitrous oxide - 800 thousand years.
It is also confirmed that the past five years have been the hottest in the history of meteorological observations, and the sea level is now rising three times faster than at the beginning of the 20th century.
Each of the past four decades has been warmer than the last and any other in 170 years. The climate is changing in all regions.
In order to prevent globalchanges, large amounts of greenhouse gas emissions need to be drastically reduced. It would be possible to stabilize the global temperature in 20–30 years, but in any case it will rise at least until the middle of the 21st century.
According to the best-case scenario, by the endcentury, on average it will be warmer than now. To achieve this, greenhouse gas emissions must be no more than what is absorbed by ecosystems and through technology, although so far such technologies only exist in prototype form
But if emissions do not decrease, but, on the contrary, increase significantly, then it may become warmer by more than three degrees or more.
Five scenarios for the development of events:
- Carbon dioxide emissions will begin to decline and disappear completely shortly after 2050.
- Emissions will reach zero by 2075.
- The amount of emissions will not change in the next 50 years, after which it will begin to decline.
- Emissions will continue to increase and will double by 2100.
- Emissions will increase rapidly and will double by 2050.
The authors of the report analyzed all fivescenarios and came to the conclusion that in all five cases by 2040 the global temperature will rise by 1.5 degrees, and the warming in the Arctic and Antarctic will occur faster than on the planet on average. In the fifth scenario, by 2050, ice in Arctic waters in September will become an extremely rare phenomenon.
In the most positive development of events, an increasetemperatures will cease after 2050; if the second option occurs, then the temperature will rise by 1.8 degrees only by 2100 and the obligations under the Paris Agreement will also be fulfilled. Under the three most negative scenarios, temperatures will continue to increase and could rise to 4.4 degrees by 2100.
How to understand that global warming is really happening
To convince all doubters,The authors explain that global warming is not only an increase in temperatures; in this process, climate variability is also increasing. Therefore, sudden frosts, heavy rains or drought are all the result of global warming.
The water cycle is increasing on the planet and changingits spatial characteristics. Because of this, powerful downpours are pouring in some places, while drought is increasingly common in others. In high latitudes, most likely, precipitation will be even more, and in the subtropics - less. The higher the global temperature rises, the more often extreme weather will be set.
Already, rare temperature phenomena are happening2.8 times more often than in the pre-industrial era, and when the average temperature exceeds the values of the end of the 19th century reaches 1.5 degrees, they will occur 4.1 times more often.
Irreversible influence on the climate
The report lists processes that are notIt will be possible to reverse it even after centuries, and possibly millennia. The oceans will continue to warm up, acidify and lose oxygen, and sea levels will rise.
Permafrost will melt and release even more carbon into the atmosphere.
For people, the most critical is the rise in sea level. It would seem that from 1902 to 2018 it increased by 20 cm, but it will continue to grow, grow, grow, and we will not do anything about it.
Olga Zolina, author of the report from the Institute of Oceanology of the Russian Academy of Sciences and the Alpine University of Grenoble
Ocean level rise
World sea levels are predicted to riseexperts, it will not stop in any case: even in the most positive of scenarios, it will increase relative to the level of 1900 by about 0.3 meters by 2100 and by 0.5 meters by 2150.
In a negative scenario, by the end of the centurythe water level will rise by almost a meter. In the same way, in all the considered scenarios, experts came to the conclusion that humanity will not be able to stop the melting of glaciers at the planet's poles and on mountain peaks - in the coming centuries it can only be slowed down.
Comparison with previous 2014 report
The 2014 report consists of working group reports and conclusions.
For 2014, the report considered four scenarios in which the concentration of greenhouse gases will reach by 2100:
- 421 ppm (RCP2.6), it implies that greenhouse gas emissions will peak between 2010 and 2020, followed by a decline.
- 538 ppm (RCP4.5), it was thought to peak emissions around 2040
- 670 ppm (RCP6.0), in this scenario the peak should have been in 2080.
- 936 ppm (RCP 8.5), and this one assumed emissions would continue to rise for a century
- Ocean
It is the rise in temperature and the increasethe acidity of the ocean speaks of global climate change (see Fig. 1). The temperature of the near-surface air layer is only the most noticeable, but not the main numerical parameter.
- Number of hazardous events
The main problem is precisely in dangeroushydrometeorological phenomena. The Report shows a closer relationship between the anthropogenic enhancement of the greenhouse effect and an increase in the frequency and intensity of abnormally hot periods and anomalous precipitation, including monsoon ones.
- Freshwater scarcity (droughts), sea level rise and floods
These are three already very definitely calculatedclimate disasters caused by human impact on the climate system. Moreover, the "climate" here in most cases is superimposed on the wrong economic activity.
- Damage increases with global temperature rise
Every degree of increase in the global averagenear-surface air temperatures reduce renewable water resources in water-scarce regions by 20%, and also increases the percentage of the world's population suffering from water shortages by 7%.
- Damage depends on future scenarios of emission dynamics
The future is uncertain.It can develop according to different scenarios. In particular, by the end of the 21st century, under the scenario of maximum concentration growth, the number of people suffering from severe floods will be 3 times more than under the minimum scenario.
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