Climate change, as represented by global cooling and global warming trends, is in a constant flux...the IPCC's gold-standard temperature dataset provides the empirical proof that a natural cycle of ups and downs is the reality - past, present & future.....
How much global warming (or cooling) will take place by 2050AD?
The flat-out, scientific truth is that nobody really knows. Not the IPCC. Not the climate models. Not the experts. And certainly not the green crony-facilitators, Naomi Klein and Bill McKibben (fyi...crony Al Gore just loves them to death.)
This chart plotting the IPCC's gold-standard (HC4) of global temperature trends, of past and present, reveals why it is so incredibly difficult to predict climate change, be it of short or long-term nature. Climate change is constantly happening - going from one warming acceleration to the next cooling acceleration extreme, rather rapidly.
And note, this takes place regardless of atmospheric CO2 levels (see black curve), and associated human CO2 emissions. Clearly, the skyrocketing CO2 levels since the 1950's are not responsible for such wide variance in temperature trends, since they can even be observed a century before.
In fact, based on a visual inspection, one could surmise that climate change extreme trends have lessened since the modern increase of CO2 levels.
As can be seen, shorter cooling/warming trends have been highly variable from the very start of recording instrumentally-measured "global" temperatures. The light red (12-mth) and green (60-mth) plots readily show this.
So, when did the greatest acceleration of warming trends take place? Amazingly, all the warming spikes that matched or equaled ±20°C took place (see yellow-tinted boxes) prior to the last 40 years of massive human CO2 emissions.
Regarding the 10, 20 and 30-year climate change variability, there is no question that the wild and natural extremes of the short-term always return to a rather mundane long-term variability. The dark blue, cyan and bright red plots indicate long-term climate change that is...well...pretty mundane.
Compared to a 12-month climate change extreme trend of +25.0°C reached in 1878, the 30-year trend extreme only reached a maximum of +0.72°C (during 2003) and has now been reduced to a August 2014 30-year trend of 0.61°C - and relative to the 1940's, that's a trend only eight-hundredths of a degree greater.
Conclusion: Climate change never stops. Whether short-term or long-term, global temperature trends constantly accelerate/decelerate. Human CO2 emissions have nothing to do with this extreme variability - it is a natural phenomenon that is chaotic, totally unpredictable and unstoppable. The climate change indicated by today's temperature trends is insignificantly different than the past climate change. And those are the stubborn facts.
Note: Linear temperature trends do not represent predictions (any trend today can be drastically different in the future). Excel's slope function was used to calculate the moving trends for each time span (by month) and to plot them. To calculate the trends by 2050AD, the derived slope for each month and each time-span trend was multiplied by 424 months (after August 2014, there are only 424 full months until January 1, 2050AD). HadCRUT4 global dataset and CO2 (ppm) datasets used for chart can be found here.