Here's the problem with CO2 and temperature today: We don't have immediate feedback - there is an approximately 40 year lag between the time CO2 is emitted and when it is reflected on the thermometer.
Because of this, there appears to be a disconnect between people telling us that we need to stop emitting CO2 and people looking at the thermometer and saying accurately that we're only worrying about 1 degree.
The reason science is warning us to limit emissions is because the one or so degree temperature rise we're seeing today - along with the slight sea level rise, massive glacier and Arctic ice loss, and extreme weather events - is based on emissions up to about 1970. We haven't yet seen the emissions from 1970 to 2013 on the thermometer, in the sea level, or in the weather.
How much CO2 are we talking about?
From 1751 through 1970, we emitted a total of 115,738 million metric tons (MMT) of carbon. That's the carbon that resulted in the slightly higher global average temperature, floods/droughts/superstorms, and dramatic ice loss we're seeing today.
From 1971 through 2010, we emitted a total of 245,201 MMT of carbon into the atmosphere. That's in addition to the 115,738 MMT already present. If the heating and effects are linear, by 2050 we should expect to see at least twice the warming we've seen so far, twice the amounts of floods, droughts, superstorms, and sea level rise that we've already seen.
http://earthobservatory.nasa.gov/Featur ... /page2.php
http://www.ipcc.ch/publications_and_dat ... ns3-2.html
The CO2 we've dumped so far has caused warming. That has warmed the land, water, and lower atmosphere. That has increased evaporation (today's atmosphere holds about 4% more water vapor). Water vapor is a greenhouse gas as well: the heating from CO2 triggers the addition of more water vapor which increases the warming.
The warming so far has been affecting the polar regions much more dramatically than the equator - Alaska has gotten warmer than Florida. The northern regions of this planet have a lot of permafrost - permanently frozen ground. The permafrost is melting. That's releasing natural methane (generated when organic matter decomposes without oxygen). Methane is a greenhouse gas that is about 25 times stronger than CO2.
More warming melts more permafrost which releases more methane which causes more warming which causes more evaporation from the land and water which increases the amount of water vapor in the air which increases warming - and the heating cycle continues faster and faster. At some point, the reinforcement from methane and water vapor can become stronger than the CO2 signal that started the warming cycle - and the warming may continue uncontrolled even if we reduce our carbon emissions to zero.
Today we can still do something to help. Once we reach the tipping point, there's nothing we can do but strap ourselves in, watch, and scream.
edits...fixed spelling, acronym, added chart and references
You do not have the required permissions to view the files attached to this post.