"Unprecedented" Pacific Trade Wind Strengthening And Pacific Cooling Amplified By Atlantic Warming


This image from a new paper published in Nature Climate Changes shows the relationship between temperature anomalies in the Atlantic (red) and Pacific (blue) as shown in the top panel with anomalies in atmospheric pressure at sea level (SLP) and trade winds strengths as shown in the bottom panel  - where the detrended zonal surface wind velocity anomalies is the black line; and the 11-month running mean of the detrended Atlantic/Pacific SLP anomaly difference is the cyan line. The authors - from the University of Hawaii and from the University of New South Wales - state: "An unprecedented strengthening of Pacific trade winds since the late 1990s has caused widespread climate perturbations, including rapid sea-level rise in the western tropical Pacific, strengthening of Indo-Pacific ocean currents, and an increased uptake of heat in the equatorial Pacific thermocline. The corresponding intensification of the atmospheric Walker circulation is also associated with sea surface cooling in the eastern Pacific, which has been identified as one of the contributors to the current pause in global surface warming". Image courtesy: the authors and Nature Climate Change. Story here.



Satellite Data Shows Global Temperature Anomaly For July Is Flat Indicating Recent Surge Peaked


Latest satellite data show that global average temperatures for the lower troposphere were essentially flat in July compared with June indicating that the surge in temperatures seen over the first few months of 2014 has peaked. Global average temperature anomalies for July 2014 have been calculated for the lower troposphere using satellite data by the University of Alabama in Huntsville (UAH) and US firm Remote Sensing Systems (RSS). UAH's Version 5.6 global satellite-measured average lower tropospheric temperature (LT) anomaly for July 2014 is +0.31C making July 2014 the fifth warmest July in the 36 year old satellite dataset. This is in line with the +0.30C reported in June. Meanwhile RSS's Version 3.3 Global Land And Sea average lower troposphere temperature anomaly for June 2014 is +0.35C, which is in line with its June anomaly of +0.34C. These results indicate that temperatures may have peaked after rising sharply earlier this year. Image courtesy: Dr Roy Spencer. Full story here.



Paper Suggests Antarctic Sea Ice Growth May Have Been Overestimated Due To Satellite Data Error


New research suggests that Antarctic sea ice may not have grown as fast as thought in the past. A team of scientists say a previously unseen processing error in satellite data led to an apparent jump in Southern Hemisphere sea ice extent of around 200,000 square kilometers back in 1991. For comparison, total Antarctic sea ice extent growth since 1990 has now amounted to around 1 million square kilometers.  Satellite observations suggest that sea ice cover in the Antarctic is expanding – albeit at a moderate rate – and that sea ice extent has reached record highs in recent years – most recently at the end of June. The mystery over what has caused the Southern Hemisphere sea ice cover to increase in a warming world has puzzled scientists since the trend was first spotted. Image shows a tabular iceberg surrounded by sea ice in the Antarctic and is courtesy of Eva Nowatzki, distributed via imaggeo.egu.eu. Story here.





Global Warming Pause Is No More Than A Natural Variation Says Statistical Study Of Historic Data


Statistical analysis of average global temperatures between 1998 and 2013 shows that the slowdown in global warming during this period is consistent with natural variations in temperature, according to research by McGill University physics professor Shaun Lovejoy. In a paper published this month in Geophysical Research Letters, Lovejoy concludes that a natural cooling fluctuation during this period largely masked the warming effects of a continued increase in man-made emissions of carbon dioxide and other greenhouse gases. The new study applies a statistical methodology developed by the McGill researcher in a previous paper, published in April which ruled out, with more than 99% certainty, the possibility that global warming in the industrial era is just a natural fluctuation in the earth’s climate. In his new paper, Lovejoy applies the same approach to the 15-year period after 1998, known as the Pause, during which globally averaged temperatures remained high by historical standards, but were somewhat below most predictions generated by the complex computer models used by scientists to estimate the effects of greenhouse-gas emissions. This graphic, from the paper and courtesy of the authors and GRL, shows that the pattern seen in the Pause is in line with variations that occur historically every 20 to 50 years where as the warming pattern seen over the majority of the period of the industrial era, if natural, would be the kind of pattern seen only once in thousands of years. Full story here.