13 of 14 warmest years on record occurred in 21st century – UN | Environment | theguardian.com:
Ouch. As you look at the clock, you will see that we are only 14 years into the 21st Century. Yet we have 13 of the hottest 14 years in recorded history.
You do have to take the whole of the earth into account, obviously, not just the USA, where we were ?fortunate? enough to have a exceptionally cold and blizzardy Winter. (Polar Vortex is now in our daily vernacular.)
If you are interested in the science go here to look at the 11 or 12 major indicators (based on several data sources each) that would indicate global warming. http://en.wikipedia.org/wiki/Instrumental_temperature_record
If you want a composite graphic that shows the robustness of the evidence, go here. There are several data sources overlaid in each graphic. Note that the stratosphere is decreasing (cooler), that is consistent with a depletion of the ozone layer.
The recent UN report talks about the trends in costs associated with climate effects, like typhoons. A draft report talks about $1.45T costs associated with climate change over the next decade. (See here http://www.livescience.com/43891-global-warming-economic-damage.html.)
The costs are expected to reach $70 to $100B per year for adaptation by 2050. (See here: http://www.usnews.com/opinion/articles/2014/03/31/will-the-uns-new-report-shift-the-global-warming-debate)
NASA has lots of interesting graphics, including time-series that will show the world temperature changes over the last couple hundred years. (Or just recently if you want since 1970).(The science visualization study at NASA is awesome, no mater what your interests: http://svs.gsfc.nasa.gov/Gallery/index.html or if you want to draw your own graphs based on the underlying data, go here: https://www.ncdc.noaa.gov/cag/time-series/global/globe/land_ocean/3/2/1880-2014).
As we come up on Earth Day (EarthDay.org or EarthDay in Wikipedia) the impacts of business as usual (BAS) really revolves around whether you think something should be done to be much more sustainable NOW!, in decades or in centuries to come.
The degree of urgency really depends on how much you believe in global warming, and how fast you think that warming may take place.
Look at the graphs and make your own call on this.