A weird property of pure water may make the global climate much more sensitive to greenhouse gas increases than IPCC and other climate change models have predicted. Pure water in clouds may cool far below the freezing point without freezing. Weird supercooled water clouds may amplify the effects of growing levels of greenhouse gases making global warming more severe. Punch hole clouds, shown in the title image are supercooled altocumulus water clouds that have holes where aircraft triggered ice formation and cloud level precipitation.
The behavior of clouds and water vapor have long been known to cause the largest uncertainties in physical models of the atmosphere. Water vapor is a powerful greenhouse gas that amplifies the effects of greenhouse gas increases directly caused by human activities. When vapor cools to form clouds, some clouds reflect heat back to space. Other clouds trap heat, increasing the warming effects of greenhouse gases. Both the height and the composition of clouds are involved in how they affect climate. Climate scientists have just discovered, based on detailed study of satellite images, that heat trapping water clouds are more abundant, and reflective ice clouds less abundant at intermediate cloud levels than in the IPCC’s climate models. The recent discovery of more water vapor at intermediate levels and this discovery of more water and less ice in intermediate level clouds means that climate models have seriously underestimated the amount of warming caused by increasing levels of greenhouse gases. news.yale.edu/...
Based on the new cloud study a doubling of CO2 levels will cause a maximum global warming of 9.5ºF (5.3C) , seriously higher than 8.2ºF (4.6C) maximum warming calculated without these new data.
Recent research has finally begun to explain why water forms weird supercooled clouds. Liquid pure water in clouds may have a rigid pentagonal or hexagonal structure at the smallest scales that does not link up in space to form solid crystals. This very fine structure of pure liquids may affect the global heat balance by stabilizing heat trapping water clouds that are formed at subfreezing temperatures.