Some people say there is no global warming, because 1998 was a very hot year and the rate of increase since then has been smaller than projected (note not zero).
Just as the temperature varies greatly from day to day, even an average over a year isn't that robust, as you have factors such as El Nino.
What i find more useful is looking at the average over a decade. That is long enough that the average (of 3,653 days) is pretty robust.
The data is from NASA. The average global temperature is around one degree higher than 100 years ago, and since the 1970s has risen around 0.7 of a degree.
I'll deal in a later post with issues over cause and impact, but for now want to highlight that denying we have had global warming is simply not true.
As you can see 1998 was a very hot year. But not the hottest year in the last century. That was 2014 and 2015 after 10 months of data is looking to break 2014's record.
Different methods of temperature recording and different outlets all produce slightly different results (as you would expect), but the difference between them is minor compared to the very clear trend – both by decade, and annually.
Again you can have your opinions on the cause of the warming, and on how much warming there will be in the future. But the fact the world is warming is a fact, not an opinion.