La Niña fizzles, making record warm global temperatures more likely

Andrew Freedman Yahoo News 9 Sep 16;

With stabilizing sea surface temperatures in the eastern tropical Pacific Ocean, climate forecasters announced Thursday that they have canceled the La Niña watch that had been in effect since April.

The diminished likelihood of a La Niña event starting this fall and lasting into the winter has ramifications far beyond the Pacific, including how the Atlantic hurricane season may evolve along with U.S. winter weather patterns.

Importantly, it also means there will not be a natural brake placed on the planet's increasing fever, fed by human-caused global warming.

La Niña events, which are characterized by cooler-than-average sea surface temperatures in the central and eastern tropical Pacific Ocean, tend to lower global average surface temperatures.

The lack of a La Niña, or even just the presence of a weak La Niña as opposed to a strong one, means the current record-long string of hottest months may continue through the end of 2016 and into next year.

El Niño and La Niña events tend to develop in the late spring and peak during the winter.

According to the latest forecast issued Wednesday by the Climate Prediction Center and the International Institute for Climate and Society (IRI), there is just a 43 percent likelihood of a La Niña developing during August, September and October.

"Overall, the combined ocean and atmosphere system continues to reflect ENSO-Neutral," the Climate Prediction Center stated in an update on Thursday.

By November, December and January, the odds of a La Niña decrease to 39 percent, with a 57 percent probability of so-called "ENSO-neutral" conditions, meaning that there is neither an El Niño or La Niña present. Some forecasters refer to this as "La Nada."

In May, the forecast for August, September and October called for a 58 percent probability of La Niña conditions.

While sea surface temperatures (SST) in the tropical Pacific Ocean are near the threshold for a La Niña event, Emily Becker of the Climate Prediction Center wrote in a blog post that computer model forecasts show that ocean temperatures are likely to rebound and stay above the threshold.

"The second step of the La Niña conditions decision process is 'do you think the SST will stay below the threshold for the next several overlapping seasons?' For now, the answer to this question is 'no,'" she wrote.

According to Becker, La Niña conditions have failed to develop because the ocean and atmosphere failed to interact in the necessary ways to fully develop such an event.

La Niña events tend to diminish the winds at high altitudes across the tropical Atlantic Ocean, which can aid the formation of tropical storms and hurricanes. Such storms tend to sputter and die when faced with powerful upper level winds, and the expectation of a weak La Niña helped lead to forecasts of an above average hurricane season.

Coming out of a record-strong El Niño event during 2015-2016, the climate has smashed longstanding temperature records. July of this year, for example, was the warmest month since temperature records began in 1880, according to the two U.S. agencies that track global temperatures: the National Oceanic and Atmospheric Administration (NOAA) and NASA.

Scientists have said that while El Niño, which is characterized by above-average ocean temperatures in the central and eastern tropical Pacific Ocean and altered weather patterns worldwide, was responsible for only a minority of that record warmth.

Instead, human-caused global warming has been the biggest player in turning up the Earth's thermostat.

If August turns out to have been the warmest such month on record, it would make it the 16th straight month to set such a milestone, which is unprecedented in NOAA's climate history.

For climate scientists, what matters is the long-term trend over decades to centuries, making monthly records much less significant compared to the steady increase in temperatures throughout the 20th and 21st centuries. The long-term record shows an unmistakable upward trend in global temperatures, with warming accelerating in the oceans and atmosphere in recent decades.

For example, climate scientists have said that it is now virtually certain that 2016 will beat 2015 for the dubious distinction of the hottest year on record.