NASA released the July global temp data this evening. The last 7 months are the warmest January – July on record. The thermometer record goes back to 1880. Before 1880 there are proxies for temperature. Tree rings and ice cores for example. These proxies (See Oldest Ice Core Recovered from Greenland) indicate we are very possibly in the warmest period in at least one thousand years.
The temperature anomalies map shows that the higher latitudes are continuing to warm the fastest. This comes on the 30th anniversary of a now famous paper by Wally Broecker back in 1980. Broecker predicted in 1975 that the slight cooling trend of the 1970’s would reverse itself and a significant warming trend would begin due to increasing greenhouse gases. The blog Real Climate (written by several climate experts) has details on this. You can also read the paper for yourself.
July 2010 was the warmest July on the record for the Northern Hemisphere as well.