Improved scientific understanding in recent years has shown that humans are the major causes of climate change on the planet. A report released by IPCC (the UN Intergovernmental Panel on Climate Change) in 2014 reports that it is “extremely likely” that the dominant cause of global warming in the 20th Century is the influence of humans.
Human activities over the last two hundred years, since the beginning of industrialization, have caused a building up of greenhouse gases in the atmosphere, and as a result, the Greenhouse Effect (a natural phenomenon which regulates the temperature of the earth) has increased to the point where an excess of gases such as methane, carbon dioxide and nitrous oxide, amongst others, are trapping excess radiant heat against the earth, preventing it from dissapating into the atmosphere, and subsequently contributing to global warming.
Humans are significant contributors to this problem, mainly due to the need for energy. The burning of fossil fuels such as coal, oil and natural gas to produce energy in the form of electricity and for motor vehicles is essentially the major contributor to the accumulation of atmospheric greenhouse gases. Another human contribution to global warming is deforestation. Tropical rainforests are the major source of the exchange of carbon dioxide between the earth and the atmosphere, and the destruction of rainforests, particularly in Asia and South America, has removed a large amount of this interface. As these forests also form a sink for most of the world’s carbon, destruction of forests for farming, logging and development is releasing excess carbon into the atmosphere.
Mesozoic Age Fossils in California
In southern California, two layers from the Cretaceous Period – the Point Loma Formation and the Cabrillo Formation – contain rare fossils including cycads, invertebrate burrows and ammonites with attached bivalves. Other fossils found in the Cabrillo Formation include fragments of wood, corals bivalves, echinoderms and gastropods.
Few dinosaur fossils from the Mesozoic Age can be found in California, because during this period the area was covered by ocean, although some isolated fossil remains of Anklosaurus and Hadrosaurus have been discover in Cretaceous marine rock, close to the region of the Cabrillo National Monument, which is located at Point Loma, San Diego. Therefore the most likely fossils to be discovered are those of marine organisms.
Various locations in California contain fossils of marine species. The Franciscan Complex in the San Rafael Mountains in Santa Barbara County contains the only known Jurassic hydrothermal vent community of fossils. These fossil deposits are specimen rich although not very diverse and consist of the remains of vestimentiferan worms, brachiopods and gastropods. A recent discovery by Mooi and Hilton (2014 421) of a Jurassic echinoid in the Middle Fork American River drainage system of the northern Sierra Nevada, California is adding to the knowledge of the evolution of this species. Other fossils of ocean-dwelling organisms such as trilobites, ammonoids, corals, plants and invertebrates have been found in the Marble Mountains of San Bernardino County.
Works Cited
IPCC. Summary for Policymakers. In: Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press, 2014.
Little, C. T. S., Danelian, T., Herrington, R. J. and Haymon, R. M. “Early Jurassic Hydrothermal Vent Community from the Franciscan Complex, California.” Journal of Paleontology 78.3 (2004): 542-559.
Mathez, E.A. Climate Change : The Science of Global Warming and Our Energy Future. New York: Columbia University Press, 2009. Online.
Pi, R. and Hilton, R. P. “First Record and Phylogenetic Significance of a Jurassic Diadematacean Sea Urchin from California.” Journal of Paleontology 88.3 (2014): 421-433.
Peecook, B. R. and Sidor, C. A. “The First Dinosaur from Washington State and a Review of Pacific Coast Dinosaurs from North America.” PLoS One 10.5 (2015): 1-15.
Randerson, J. T. “Global warming and tropical carbon.” Nature 494.7437 (2013): 319-320.
San Bernadino County Museum. Fossils in Southern California. 2007. <http://www.sbcounty.gov/museum/exhibits/ex_unearthed_fossils.htm>.
Tweet, J. S., Santucci, V. L. and Connors, T. “Documenting the Paleontological Resources of National Park Service Areas of the Southern California Coast and Islands.” Monographs of the Western North American Naturalist 7 (2014): 68-81.
