Blood group: An inherited feature on the surface of the red blood cells. A series of related blood types constitutes a blood group system, such as the Rh or ABO system. The frequencies of the ABO and Rh blood types vary from population to population.lood group: An inherited feature on the surface of the red blood cells. A series of related blood types constitutes a blood group system, such as the Rh or ABO system. The frequencies of the ABO and Rh blood types vary from population to population.
October 22, 2009. Running time 1:26. Climate scientists explain why theyâre sure the primary cause of global climate change today is increasing human emission of greenhouse gases â mainly carbon dioxide. Skip to main content
Natural Causes of Climate Change. Milankovitch cycles over the past 1 000 000 years. Source: Global Warming Art. The Milankovitch Theory explains the 3 cyclical changes in Earthâs orbit and tilt that cause the climate fluctuations that occur over tens of thousands of years to hundreds of thousands of years.