A common misconception among climate change deniers is that global warming has not been happening since 1998, the "warmest" year on record. In this topic I will address this one misconception, but am open to requests for future posts.

I'll start with the tl;dr version: Surface and air temperatures are only one of many places heat can go. Most heat is going to the oceans. Ocean cycles like El Nino/ La Nina contribute to short term air temperature trends. For example, 1998 was a particularly strong el nino year as large amounts of heat transferred from the ocean to atmosphere. Other local mins and maxes correspond with el nino/la nina events. When the effects of these cycles and solar and volcanic activity are factored in, the warming trend is clear and uninterrupted.

Now, for the more detailed explanation.

Many seem to focus too much on one particular indicator to jump to vast conclusions about climate change. While 1998 was hotter than the years following, the atmosphere only receives a small fraction of the heat. Most goes to the oceans. This graph shows the change in the earths total heat content, distinguishing between ocean and land/atmosphere/ice heat.

source: http://onlinelibrary.wiley.com/doi/10.1029/2011GL048794/full

Not only that, but climate models predict air temperature stagnations like we witnessed in the last decade.  These same model simulations show large intakes of heat in the deap oceans.  The earth has certainly been warming this last decade, just not specifically in the benchmark of atmospheric temperatures.  Essentially, while surface air temperatures have stagnated, the deep ocean has been accumulating massive amounts of heat.

source: http://www.nature.com/nclimate/journal/v1/n7/full/nclimate1229.html

Cool/warm ocean trends like El Nino and La Nina contribute to short term atmospheric temperatures.  1998 was a year accompanied by a particularly strong El Nino transfer of heat from the ocean.  Temperatures go up slightly in El Nino years and down slightly in La Nina.  This graph highlights these influences:

From this graph it looks like a warming trend is happening, but as I just showed natural factors like ocean cycles influence air temperatures, which are only one of many indicators of global warming.  Solar activity is also another factor that must be accounted for.  Some have claimed that past warming trends can be explained soley by solar activity.  The opposite trends of temperature and solar activity and air temperature in recent decades show this is not the case.

In order to more clearly see the human influence on warming trends, we must factor in the effects of ocean cycles, solar activity, and volvanoes.  When we do this, we very clearly see that global warming has not stopped.

source: http://iopscience.iop.org/1748-9326/6/4/044022