NASA says that the world is warming and that March was the third warmest month on record. Other measures say that the world's temperature peaked a decade ago and has been either steady or in a slight decline. What's going on? The computer industry web site the Register has a detailed study of this question here. You should read it but I'm going to summarize it anyway.
First, NASA has been fudging its figures. They have been altering historic measures with a bias to warming (older measurements have been adjusted down, recent ones up). They have not documented why this is being done but the result is that the world looks warmer that before the adjustments.
Next, of the three groups attempting to measure the earth's temperature, only NASA uses ground-based stations. This is an acceptable measure as long as you have sufficient stations to cover the planet. They don't. North America, Europe and Asia are covered pretty well but South America and Australia have huge gaps. Most of Africa is not included and only tiny bits of Antarctica are measured. Even in North America, Canada is somehow missed. Then there are the oceans which are mainly ignored. Funny thing about the areas that NASA is monitoring, according to the other measures, NASA is mainly measuring temperature in places that are getting hotter. They managed to miss the parts of the globe that are cooling (the majority of the globe).
The Register didn't speculate on how this happened but I will. Most of the areas being measured are industrialized. That makes it easier to place a measuring station but it also opens the station to false readings from urban heat islands. NASA is supposed to be compensating for this but this is a tough calculation to get right.
Finally, NASA used a known cold period as its baseline. This adds a few of degrees of apparent warming. Had they chosen the the warm period in the 1930s then their maps might be showing cooling rather than warming.
All of this calls NASA's ethics into question. The figures come from the Jet Propulsion Lab which is run by James Hansen. Hansen is the man who first introduced the concept of global warming to the world and is, by any measure, a biased source. Regardless, NASA keeps on producing figures showing warming and the news media reports them without mentioning the conflict.