The focus of the article is the negative changes which can be expected in the world's glaciers associated with possible “greenhouse”; warming of the climate. It examines the mechanisms of the instability of marine ice sheets, which may lead to their catastrophic collapse and to a rise in sea level of 5–7 m over the next few decades. Calculations have been made concerning the extreme regimes of mountain glaciers in temperate and subtropical latitudes, which would involve a sharply negative mass balance (up to ‐3 to ‐5 m per year); this regime will lead to a rapid disappearance of these glaciers.