Scientists have observed rises in average temperatures since the late 19th century. Scientists call this rise in temperature global warming.
Scientists have created climate models that predict a significant rise in temperatures.
Scientists believe carbon dioxide released by humans is causing global warming in the Earths atmosphere and oceans and that climate change is causing the polar icecaps to melt and sea levels to rise.
Critics such as myself dispute the credibility of climate scientists and reject that humans are the main cause of global warming and that temperatures will continue to rise.
Carbon dioxide most definitely increases global temperature. This is well accepted. But carbon dioxide has a diminishing returns kind of effect. If Carbon dioxide were doubled, and just its effects were measured, temperatures would rise less than 1 degree Celsius. The models that suggest 3-5 degrees Celsius temperature rise do so assuming warming is a positive feedback, meaning, that if carbon dioxide causes the globe to warm, things like water vapor will make it warm much more.
But if there is neutral or a negative feedback doubling carbon dioxide will continue to make the temperature rise slightly, but the lack of positive feedbacks will mean the end result is much easier to manage and there is little to be worried about.
In November 2009 and November 2011 e-mails of climate scientists were hacked and released online which revealed disagreement among scientists over climate models.
Recent scientific research shows that global warming in the atmosphere has slowed but has increased in the oceans due to carbon dioxide which is also causing Ocean acidification.
Climate anomalies related to each other from large distances is called teleconnection. An example of teleconnection is the warm oceanic phase El Niño and the cool oceanic phase La Niña.
By this definition, we are still in the ice age that began 2.6 million years ago at the start of the Pleistocene epoch, because the Greenland, Arctic, and Antarctic ice sheets still exist.
Within the ice ages (or at least within the current one), more temperate and more severe periods occur. The colder periods are called glacial periods, the warmer periods interglacials, such as the Eemian Stage.
The Earth is currently in the Holocene epoch interglacial.
Ice core records show that before the Holocene there was global warming after the end of the last ice age and cooling periods, but climate changes became more regional at the start of the Younger Dryas. During the transition from last glacial to holocene, the Huelmo/Mascardi Cold Reversal in the Southern Hemisphere began before the Younger Dryas, and the maximum warmth flowed south to north from 11,000 to 7,000 years ago. It appears that this was influenced by the residual glacial ice remaining in the Northern Hemisphere until the later date.
Glacial events are caused by what is called Milankovitch cycles which are orbital movements that effect the Earths climate.
I think more research needs to be done into how carbon dioxide affects the Earths atmosphere and oceans and what impact it has on the climate.
References:
Pearce, W. (30 July 2013) Are climate sceptics the real champions of the scientific method? Retreved from http://www.theguardian.com/science/political-science/2013/jul/30/climate-sceptics-scientific-method
Jowit, J. & Hickman, L. (23 November 2011) Climate scientists defend work in wake of new leak of hacked emails Retreved from http://www.theguardian.com/environment/2011/nov/23/climate-scientists-hacked-emails-uea
Pearce, F. (9 February 2010) Hockey stick graph took pride of place in IPCC report, despite doubts Retreved from http://www.theguardian.com/environment/2010/feb/09/hockey-stick-graph-ipcc-report
George, A. (8 June 2001) Breaking the ice Retreved from http://www.theguardian.com/science/2001/jun/28/physicalsciences.highereducation
Roberts, A. (30 September 2012) Humans may notice a chill in the air
Retreved from http://www.theguardian.com/environment/2012/sep/30/ice-age-human-survival-alice-roberts
