Help with a geogrpahy project.. what was global warming like in the past?
John H’s timescales are way off, glacial periods last ~100,000 years, interglacial last 12 to as long as 25 thousand years. Those ice cores he talks of actually show Co2 moving between 180ppm and 300ppm for the last 500,000 years. No elephants in England, Mammoths which are related but died out soon after man appeared in Europe, same with lion, which can easily survive in cool climates they could be found in Europe as late as the Roman periods but were hunted to extinction. As for shells and fossils on mountain tops, sorry that has more to do with geology than sea level, mountains are, for the most part, made by land mass collision that push land up, the fossils and shells just go for the ride. As for the actual causes of past natural climate change the current cycle of glacials started around 2.5 million years ago the likely trigger the separation of Antarctica and South America allowing the Antarctic current to form which cooled Antarctica and over millions of years it became roughly
In the recent past there have been a number of high level meeting called to address the impacts of human activity on the environment. The most serious of these impacts is global warming. Over the years man has engaged in activities that have led to the depletion of the ozone layer and a high concentration in greenhouse gases in the atmosphere. These greenhouse gases retain heat from the sun and cause a general rise in the temperature of the earth’s surface. Global warming is thus the rise in the temperature of the earth’s surface due to heat retained by greenhouse gases in the atmosphere.
Depends how far into the past you want to go – if you go into the very distant past i.e. 100,000 years or more, then global warming was (and STILL IS) a naturally occuring event – approx every 4,000 – 7,000 years. Ice bores taken from the South Pole indicate that CO2 was prevalent on many occasions over the millenia. In the UK, in the East Anglia region, elephants, lions and other animals more known to us now to live in hot climates like Africa were well established. Cambridge University museums back this up with the findings of fossils of these animals all over the East Anglia region. You could also connect with the fact that shells and fossils of fish have been found on mountain tops and peaks – proving that water levels were higher in the past. Coming more up to date, you are correct that aeroplanes were not as common but the more important factor is the manufacturing processes used in countries like India and China – they do not have emission controls as stringent as most western c
Prior to the last century or so, there was global warming and cooling due to natural cycles and forcings related primarily to changes in solar input (wobbles in the orbit, sunspot cycles, and so on). It was usually fairly slow (something on the order of a degree every couple of centuries). Global warming in the past century, however, is both more rapid than most historical warming, and not explainable by any of the known natural cycles.
