Within the model of equivalent grey atmosphere, this paper analyses different mechanisms of negative feedback in thermal balance of the Earth's surface, which stabilize its present thermal regime, and single mechanism of positive feedback, which is able to lead to the lost of its stability and transition to hot state similar to Venus state. A role of key greenhouse gases, i.e., СО2, H2O, CH4, and cloud aerosol in the positive feedback, as well as vaporization, photosynthesis, and cloud in the negative feedback is determined. The existence of a critical rate of increase in albedo versus temperature is obtained. If the growth rate of albedo is higher than the critical one, then the present thermal regime is single stationary and global stable state of the Earth's surface in the temperature range > 288 K.
atmosphere; carbon dioxide; thermal balance of the earth; green-house explosion