The Atmosphere and Climate Modeling - Introduction to Carbon Capture and Sequestration - page 60

Figure 2.4.1 Temperature anomalies for the period Jan-Nov 2012
Deviations of average global temperature across land and ocean surfaces for January-
November compared to a 30-year average (1981-2010). This period was the eighth
warmest on record, at 0.59°C (1.06°F) above the 20 th century average. 2012 surpassed
2011 as the warmest La Niña year since at least 1950, according to NOAA's Climate
Prediction Center. Figure from National Climatic Data Center [2.3].
hockey stick is the suggestion that our current temperatures are outside
the “normal” range. The fl uctuations are large, in particular as the older
temperature data are not as reliable as the data we can obtain now, cre-
ating signifi cant uncertainty in the data. This uncertainty raises the ques-
tion of whether the observed heating of the planet is real. And, if it is real,
what is the cause? The scientifi c reaction to uncertainty is, of course, to
ask if we can fi nd other data that would support or contradict this
hypothesis. At this point, it is important to mention that there has histori-
cally been a large scientifi c debate about whether climate change is real
or not. The outcome of this debate has been a large number of different
experiments all aimed at testing the hypothesis of global warming. As a
result of these tests, the scientifi c consensus is now that climate change
is real and that it is caused by human activity. Let's look at some of these
tests and data and how they have borne out these hypotheses.