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
Other human activities include agriculture and changes in land-use patterns. They all work to tip the Earthâs energy balance by trapping more heat. Even scientists who think human activity is the main cause of climate change don't deny that natural changes will cause temperature fluctuations on Earth. However, their argument is that in the current cycle of climate change, the impact caused by man is far greater.