Deke Arndt at the National Climatic Data Center (NCDC) has a recent blog post at Climate.gov which provides some perspective on temperatures around the globe in 2014 to date and what it means for the yearly temperature record. The post points out that the globe has already set several temperature records this year and that if we continue on this path, we might observe the warmest year ever in recorded weather observations.
This report is based on surface weather records, which cover temperatures near the earth’s surface and primarily over land, although NCDC has accounted for this in their calculation of the global temperature. If you follow satellite temperature records, you will know that the satellites record a slightly different story. Satellites measure average temperatures over a depth of the atmosphere from the ground to 8 kilometers high. They have the advantage of being able to cover the entire globe, including over the oceans, but because they measure such a deep layer of the atmosphere, may not reflect conditions at the ground where we live. Satellite temperatures also show that the global atmosphere is rising, but at a slower rate that is attributed to cooling in the higher part of the atmosphere which reduces the overall trend.