According to data released by NASA and NOAA this month, June 2011 ranked among the top 10 warmest Junes on record: NASA recorded the 8th warmest June in its dataset; NOAA recorded the 7th warmest June in its dataset. The two agencies have slightly different analysis techniques, which actually helps to reinforce the results from each other.
June’s global average temperatures were 0.50°C above normal (1951-1980), according to NASA. The warmest regions on Earth are exactly where climate models have been projecting the most warmth to occur for years: high latitudes (think Arctic & Antarctic Circles). The past three months have a +0.49°C temperature anomaly. And the latest 12-month period (Jul 2010 – Jun 2011) had a +0.52°C temperature anomaly. Additionally, the March-April-May period of 2011 tied for the 7th warmest on record.
According to NOAA, June’s global average temperatures were 0.58°C (1.04°F) above the 20th century mean of 15.5°C (59.9°F). NOAA’s global temperature anomaly map reinforces the message: high latitudes are warming at a faster rate than the mid- or low-latitudes. The extreme warmth over Siberia is especially worrisome due to the vast methane reserves locked into the tundra and under the seabed near the region. Methane is a stronger greenhouse gas than carbon dioxide, the leading cause of the warmth we’re now witnessing.
These placements high on the list of recorded temperatures come at a time when the recent strong La Nina is coming to an end (which means anomalously cool Pacific waters return to normal temperatures), and when solar irradiance remains at relatively low levels as the most recent solar cycle continues to ramp up. Recall that a favorite talking point of Deniers is the sun remains the only important component of climate system drivers. This has been proven false, as 2010, tied for the warmest year on record with 2005, occurred when solar output was at its most recent minimum. Humans have become the dominant forcing mechanism – a role that doesn’t look likely to end within the next 50-100 years.
Many future Junes will have the opportunity to pass this year’s values. That’s because the overwhelming majority of heat that has been absorbed in the climate system has been stored in the world’s oceans:
That heat will eventually be released into the atmosphere, making the surface warmer and warmer year after year, decade after decade. Right now, the atmosphere is being affected by heat that was absorbed by the ocean 50-100 years ago. The heat absorbed from 1980-current won’t really impact conditions until 2030-2060. The heat wave impacting the U.S. this year? That will likely become commonplace by mid-century. Think about what kind of extreme weather conditions will occur then.