Brian Soden, Professor of Atmospheric Science at the Rosenstiel School in Miami, emphasized that the human-caused increase in water vapor in the upper troposphere is not the result of direct human activity. The increase in the concentration of water vapor in the atmosphere is caused by a response to global warming caused by human activity, primarily due to the increase in CO2 caused by the burning of fossil fuels.
“Because water vapor concentrations increase as temperatures rise, this human-induced warming triggers a ‘reverse’ mechanism that causes water vapor concentrations to increase,” Soden said. “Because water vapor itself is a very strong greenhouse gas, the increase in water vapor concentration in the atmosphere increases carbon dioxide-induced warming. Our study confirms the presence of this key ‘reverse’ mechanism, which is a critical component of global warming…”
This graph shows the dependence of the maximum concentration of water vapor in the air depending on the air temperature.
The higher the air temperature, the more water can dissolve in the air.
As the concentration of water vapor increases, the greenhouse effect increases, which leads to a further increase in air temperature.
In automation, such a mechanism is called “positive reverse relation”.
If water vapor plays a key role in global warming, which increases water evaporation, which in turn leads to an increase in water vapor concentration, could this “reverse” mechanism get out of control?
Brian Soden explains, “Fortunately, the ‘reverse’ mechanism is not strong enough to push the climate toward unlimited warming, but it is hypothesized that such a greenhouse effect occurred on Venus and caused a very large temperature increase.
Currently, the average temperature of the Earth’s surface is 14.8° C.
The average temperature of the Earth’s surface is understood as a value calculated on the basis of adding data from the entire globe and dividing by the number of points in which the measurement was made. Fluctuations depending on the time of the year do not exceed 2 ° C.
The sensitivity of the climate system is the increase in the average surface air temperature when the concentration of CO2 in the atmosphere doubles. At the end of the 19th century, Swedish scientist Svante Arrhenius said that a doubling of CO2 could lead to a 5-6°C increase in the global average temperature. In the late 1970s, scientists predicted that a concentration of 560 ppm CO2 in the atmosphere would increase the temperature by about 4°C, a prediction that has remained unchanged until now.
Global temperatures may be more sensitive to increases in atmospheric carbon dioxide (CO2) than previously thought. According to the researchers, this may prevent the Paris Climate Agreement’s goals of holding the temperature rise in check.
An international group of scientists believes that the effect of CO2 on global warming was previously underestimated. Over the past 10,000 years, the concentration of this gas in the atmosphere was almost constant at 280 ppm (particles per million, parts per million). However, with the beginning of the industrial revolution, including active mining, the amount of carbon dioxide molecules in the atmosphere has increased dramatically. Over the past three decades, CO2 concentrations have increased by 45% and are now 412 ppm.
The new work was published in the scientific journal Geophysical Research Letters, the study will form the basis of the sixth assessment report on climate change of the Intergovernmental Panel on Climate Change (IPCC). The authors note that more data and computing power have become available to the scientific community over the past few years, so their predictions more accurately reflect current climate trends.
The conclusions of the new study are based on the evaluation of 27 climate models. According to some of the proposed scenarios, a doubling of the concentration of carbon dioxide in the atmosphere will lead to an increase of the global temperature not by 3°C, as previously thought, but by 4-5°C. Mark Zelinka of the Ernest Lawrence Livermore National Laboratory in California is convinced that with such a development the world community will not be able to achieve the goals of the Paris Agreement, which stipulates keeping the global temperature at 1.5-2°C.
Russian experts about the discovery
“The scientists’ findings suggest that in the new models, the sensitivity of temperature to increasing CO2 is higher than in the models of previous generations, and this is due to the new parameterizations (descriptions of processes) in clouds,” Vladimir Semenov, head of the climatology laboratory of the Institute of Geography of the Russian Academy of Sciences, explained to Plus-one.ru. – This may indicate both that the global temperature really increases with the growth of CO2, and that the new parameterizations are not entirely adequate and need additional verification. In general, according to the expert, scientists have not made revolutionary conclusions, as the predicted temperature increase by the end of the 21st century remains within the uncertainty of the results (scatter of values for different models) in about the same range – from 2 to 5°C. “That is, there has been no qualitative change in the predicted temperature increase,” the expert said. – The range of uncertainty has just slightly widened.
Alexei Kokorin, head of WWF Russia’s Climate and Energy program, holds the same opinion. All calculations by climate scientists have always contained some degree of uncertainty,” he says. – The IPCC has already prepared five reports, and as technologies develop and more data become available, scientists’ forecasts are becoming more accurate and more detailed.”.
Alexey Kokorin reminded that in the fifth assessment report, which came out in 2013, scientists from the IPCC proposed four representative concentration trajectories (RCPs) that describe different scenarios of climate change depending on the increase in aggregate CO2 emissions into the atmosphere. Under the first, most optimistic and least likely scenario, RTC2.6, by 2100 CO2 concentrations would be 421 ppm and global temperatures would rise between 0.3 and 1.7°C compared to 1986-2005. Under the two most credible and likely scenarios, RTC4.5 and RTC6.0, CO2 concentrations would rise to 538 ppm and 670 ppm, and temperatures would rise in the ranges of 1.1-2.6°C and 1.4-3.1°C, respectively. Under the fourth and most pessimistic scenario, RTC8.5, CO2 would rise to 936 ppm and temperatures would rise in the range of 2.6-4.8°C. “The truth, as previously thought, lies somewhere in the middle – between RTK4.5 and RTK6.0,” says Alexei Kokorin. – However, according to the new findings of scientists, the sensitivity of the climate to a doubling of carbon dioxide in the atmosphere may be somewhat higher.”
The leading researcher of the Main Geophysical Observatory named after A. I. Voyeikov, climatologist Andrei Kiselev, also believes the work is based on the best climate models available today. At the same time, it contains a large number of uncertainties, and it should be considered rather as a signal calling for further research in this direction.
“The climate system is very large and inertial, with a huge, essentially infinite, number of interconnections, many of which we are still not even aware of,” the expert explained to Plus-one.ru. – And what we observe is the result of the interaction of all these connections. For example, changes in temperature affect the quantitative and qualitative composition of the atmosphere, while the composition of the atmosphere also affects the temperature; an increase in temperature causes an increase in evaporation from water surfaces, which increases the intensity of cloud formation, and so on.
Climate models, he said, show what will be the trend of changes in meteorological parameters (temperature, precipitation and others) under a situation developing under one or another scenario. “I emphasize the trend, not the forecast of what will happen, for example, in 2023, because we can better or worse predict greenhouse gas emissions, but we do not know, say, how intense will be the volcanic activity, which largely depends on the state of the climate system, – said the expert. – So the models help us understand how the state of the environment is most likely to change under various human impacts, but we have to take into account that circumstances can make adjustments.
The question is: “Do current mathematical models of Earth’s climate account for the role of water vapor in global warming? Should we start thinking of the solution of global warming in a comprehensive way?”