Category: La Niña

Global warming changing global precipitation patterns

Simultaneous changes in global precipitation patterns can’t be explained by natural variability


By Summit Voice

FRISCO — Scientists with Lawrence Livermore National Laboratory say unequivocally that greenhouse gases are affecting the distribution and intensity of precipitation around the world.

The new study, published Nov. 11 in the Proceedings of the National Academy of Sciences, shows how emissions of heat-trapping and ozone-depleting gases affect the distribution of precipitation through two mechanisms. Increasing temperatures are expected to make wet regions wetter and dry regions drier (thermodynamic changes); and changes in atmospheric circulation patterns will push storm tracks and subtropical dry zones toward the poles.

“Both these changes are occurring simultaneously in global precipitation and this behavior cannot be explained by natural variability alone,” said LLNL’s lead author Kate Marvel. “External influences such as the increase in greenhouse gases are responsible for the changes.” Continue reading “Global warming changing global precipitation patterns”

Climate study shows heat building up in the ocean

‘We may have underestimated the efficiency of the oceans as a storehouse for heat and energy … ‘

The heat trapped by greenhouse gases isn’t missing — it’s in the ocean. bberwyn photo.

By Summit Voice

FRISCO — There’s more evidence that the world’s ocean are taking up the heat trapped by greenhouse gases at an increasing rate, according to a new study published in Science this week.

After reconstructing Pacific Ocean temperatures from the last 10,000 years, the researchers found that the middle depths have warmed 15 times faster in the last 60 years than they did during apparent natural warming cycles in the previous 10,000 years.

“We’re experimenting by putting all this heat in the ocean without quite knowing how it’s going to come back out and affect climate,” said study coauthor Braddock Linsley, a climate scientist at Columbia University’s Lamont-Doherty Earth Observatory. “It’s not so much the magnitude of the change, but the rate of change.” Continue reading “Climate study shows heat building up in the ocean”

Climate: 6th-warmest September on record for Planet Earth

Warmer than average temperatures prevailed across much of the globe in September 2013. Graphic courtesy NCDC.

Southern hemisphere land-surface temps record warm for the month

By Summit Voice

FRISCO — For all the tweeting, squawking and general clamor from global warming deniers, you’d think the Earth was on the brink of a new ice age, but the facts show otherwise.

Once again during September, the average global temperature was near record highs, at 1.15 degrees above the 20th century average — tied with 2003 as the fourth-warmest on record.

Even without the warming effect of El Niño, the average global ocean temperature was .97 degrees above the 20th century average, tying with 2006 as the fourth-warmest on record. For the year, land and sea surface temperatures together are on pace to register as the sixth warmest on record, according to the National Climatic Data Center, which released its monthly climate update a few days late due to the shutdown. Continue reading “Climate: 6th-warmest September on record for Planet Earth”

New study shows link between Pacific sea surface temperatures and tornado patterns in the Midwestern U.S.

Cooler Pacific Ocean temps may drive tornado activity into southern U.S.

A tornado near Lakeview, Texas. Photo courtesy NOAA.
A tornado near Lakeview, Texas. Photo courtesy NOAA.

By Summit Voice

FRISCO — After studying more than 56,000 tornados, researchers at the University of Missouri say they’ve found a clear link between Pacific Ocean sea surface temperatures and the patterns of storms that spawn the violent twisters. The findings could help scientists predict the type and location of tornado activity in the U.S.

When surface sea temperatures were warmer than average, the U.S. experienced 20.3 percent more tornadoes that were rated EF-2 to EF-5 on the Enhanced Fuijta (EF) scale. (The EF scale rates the strength of tornados based on the damage they cause. The scale has six category rankings from zero to five.)

“Differences in sea temperatures influence the route of the jet stream as it passes over the Pacific and, eventually, to the United States,” said Laurel McCoy, an atmospheric science graduate student at the MU School of Natural Resources. “Tornado-producing storms usually are triggered by, and will follow, the jet stream. This helps explain why we found a rise in the number of tornadoes and a change in their location when sea temperatures fluctuated.” Continue reading “New study shows link between Pacific sea surface temperatures and tornado patterns in the Midwestern U.S.”

Climate: With no Niño — what’s a forecaster to do?

Fall and winter outlook still murky

Seasonal weather forecasters look out to sea surface temperatures in the equatorial Pacific to get an idea of what weather patterns may bring.
Without a stron El Niño or La Niña in the outlook, forecasters are not confident of projecting pronounced temperature or precipitation anomalies.

By Bob Berwyn

FRISCO — With no strong El Niño or La Niña on the horizon, forecasters are struggling even more than usual to develop seasonal outlooks for the western U.S. The periodic El Niño-La Niña cycle is a large-scale shift in the Pacific involving a complex interplay of winds, ocean currents and sea surface temperatures.

In the U.S. the warm El Niño phase is associated with wetter than average conditions in the Desert Southwest and California, and can result in below average precipitation in the Pacific Northwest.

La Niña, on the other hand, has been linked with Southwestern drought conditions and heavy precipitation in the Pacific Northwest. That persistent moist flow off the northwestern Pacific can also favor parts of Colorado with good winter snows, but the ENSO climate signal is more marginal in Colorado than in other areas. Continue reading “Climate: With no Niño — what’s a forecaster to do?”

Hurricane experts still see active season ahead

Hurricane Sandy as seen from NOAA’s GOES-13 satellite on October 28, 2012. Photo courtesy NOAA/NASA.

Warm ocean temps, strong West Africa rainy season boost chances for tropical formation

By Summit Voice

FRISCO — Federal weather experts this week reaffirmed their earlier projections of an active hurricane season in the Atlantic, with hemispheric patterns similar to those that have produced many active Atlantic hurricane seasons since 1995.

Ingredients for tropical storm formation include above-average Atlantic sea surface temperatures and a stronger rainy season in West Africa, which produces wind patterns that help turn storm systems there into tropical storms and hurricanes.

The peak of the Atlantic hurricane season is just ahead, from mid-August through mid-October. Continue reading “Hurricane experts still see active season ahead”

Global climate report for 2012 full of warning signs

Strongest climate signals coming from Arctic and extreme weather events

Many parts of the globe reported record and near-record temps in June 2013.

By Bob Berwyn

FRISCO — Some of the most compelling signs of global warming impacts continued to come from the Arctic in 2012, where sea ice extent reached a record low and Greenland experienced record surface melting last summer.

Another worrying sign is the warming in permafrost regions, where significant thawing could release a new surge of heat-trapping greenhouse gases that would intensify warming.

The average global temperature for the year was among the top-10 warmest on record, and other climate observations also are consistent with what to expect in a warming world, according to climate experts who released the 2012 State of the Climate report this week. Continue reading “Global climate report for 2012 full of warning signs”