how hot is the earth?
Published on Nov 25, 2015
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how hot is the earth?
Has there ever been an Ice Age in the past?
Photo by NASA Goddard Photo and Video
*Global temperatures rise and fall. Over past one hundred years, stadistics reveal a pattern of increasing temperatures. Does this indicate a long-term trend of global warming?
Photo by Abri_Beluga
Geological evidence for ice ages comes in various forms, including rock scouring and scratching, glacial moraines, drumlins, valley cutting, and the deposition of till or tillites and glacial erratics. Successive glaciations tend to distort and erase the geological evidence, making it difficult to interpret.
Photo by wili_hybrid
The chemical evidence mainly consists of variations in the ratios of isotopes in fossils present in sediments and sedimentary rocks and ocean sediment cores. For the most recent glacial periods ice cores provide climate proxies from their ice, and atmospheric samples from included bubbles of air.
Photo by Piero...
The paleontological evidence consists of changes in the geographical distribution of fossils. During a glacial period cold-adapted organisms spread into lower latitudes, and organisms that prefer warmer conditions become extinct or are squeezed into lower latitudes. This evidence is also difficult to interpret because it requires sequences of sediments covering a long period of time, over a wide range of latitudes and which are easily correlated.
Photo by Grant MacDonald
