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

Fall and winter outlook still murky

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Seasonal weather forecasters look out to sea surface temperatures in the equatorial Pacific to get an idea of what weather patterns may bring.

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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

Global climate report for 2012 full of warning signs

Strongest climate signals coming from Arctic and extreme weather events

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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 June temps the 5th-warmest on record

Many northern hemisphere land areas reported near-record warmth

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Most areas of the globe reported temperatures running well above the 20th century average during June 2013.

By Summit Voice

FRISCO — The Globally averaged land and sea surface temperature was 1.15 degrees above the 20th century average, tying with 2006 as the fifth-warmest on record, according to the National Climatic Data Center monthly summary report released this week.

The average land-surface temperature was even warmer. At 1.89 degrees above average, it was the third-warmest June on record over the world’s land areas. Record-setting warmth was reported from many locations in northern Canada, far northwestern Russia, southern Japan, the Philippines, part of southwestern China, and central southern Africa.

The year to-date is also running hot, tied with 2003 as the seventh-warmest January to June period on record, with a combined global land and ocean average surface temperature that was 1.06 degrees above the 20th century average. Continue reading

Climate: Better El Niño forecasting ahead?

Early warning could help regional preparedness efforts

A new climate model could help project El Niño conditions a year in advance.

A new climate model could help project El Niño conditions a year in advance.

By Summit Voice

FRISCO — Forecasting the emergence of El Niño well in advance has long been a goal of climate scientists and a team of German researchers say they may have devised a model that extends the lead time to a year.

Published recently in the Proceedings of the National Academy of Sciences, their paper describes how the model uses high-quality data of air temperatures as the basis for making long-term projections about El Niño, a warm phase of a periodic Pacific Ocean cycle that affects climate and weather around the world.

“Enhancing the preparedness of people in the affected regions by providing more early-warning time is key to avoiding some of the worst effects of El Niño,” said Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research, who co-authored the paper with Josef Ludescher, of Justus-Liebig Universität Giessen. Continue reading

Global warming may drive more active La Niña pattern

Broad tree-ring record provides accurate ENSO history

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Researchers say tree ring records show that El Niño activity during the 20th century has largely been outside the range of natural variability.

By Summit Voice

Climate scientists have long suspected that global warming has an influence on the Pacific Ocean El Niño- La Niña cycle (El Niño-Southern Oscillation), but instrumental records tracking the shift between above- and below average sea surface temperatures don’t go back far enough to provide context for any recent changes in the pattern.

But scientists working at the International Pacific Research Center, University of Hawaii at Manoa say a new tree ring record extending back about 700 years has helped decipher long-term trends. The tree ring samples from both the tropics and mid-latitudes in both hemispheres support the idea that the unusually high ENSO activity in the late 20th century is a footprint of global warming said Jinbao Li, lead author of the study published online in the journal Nature Climate Change. Continue reading

Global warming: USGS study shows 20 percent decline in Rocky Mountain snow cover since 1980

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Sparse January snow across the Colorado Plateau in January 2013. Bob Berwyn photo.

Drop linked primarily with warmer spring temperatures

By Summit Voice

SUMMIT COUNTY — Long-time skiers often say that skiing was better in the good old days, and new research from the U.S. Geological Survey suggests that those claims are based on more than nostalgia — notwithstanding the occasional bumper crop of powder like in 2010-2011.

After taking an in-depth look at snowfall and temperature records, federal scientists said warmer spring temperatures since the 1980s have caused an estimated 20 percent loss of snow cover across the Rocky Mountains of western North America — especially at lower elevations where temperatures have the greatest effect. Continue reading

Climate: Does El Niño drive West Antarctic warming?

Ice cores suggest current climate is in the natural range of variability

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Climate scientists track Antarctic changes, Bob Berwyn photo.

By Summit Voice

FRISCO — Ice cores from West Antarctica spanning the last 2,000 years suggest that recent warming and glacier loss in the region is comparable to other warm periods during that span.

Most of the recent warming may be related to powerful El Niño phases in the tropical Pacific in the 1990s, said University of Washington researcher Eric Steig. The ice core record shows similar temperature spikes in the 1830s and 1940s, he said, adding that the recent warming  cannot be attributed with confidence to human-caused global warming.

Steig built on previous research showing that rapid thinning of Antarctic glaciers was accompanied by rapid warming and changes in atmospheric circulation near the coast. The new study suggests that the 1990s were not all that different from some of those earlier warm spells. Continue reading

Report: Global warming not a big factor in 2012 drought

Natural climate variability the biggest player, scientists say

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Drought conditions persist across the central part of the country.

By Bob Berwyn

SUMMIT COUNTY — Last summer’s crippling Great Plains drought can’t definitively be linked with global warming, according to a team of federal scientists from various agencies. In a new report issued this week, the researchers said the drought was probably caused by a confluence of natural climate variations that might only come together in a similar constellation once a century.

Cyclical variations in ocean temperatures — especially the combination of a cooler-than-average Pacific Ocean and a warm phase of the North Atlantic Multidecadal Oscillation may have nudged the region toward drought conditions, but those factors tend to be more of a factor in suppressing winter precipitation. Continue reading

Climate: Study looks at changing monsoon patterns

Natural climate variables so far outweigh global warming impacts

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The North American monsoon is an important climate factor in the Rocky Mountains.

By Summit Voice

SUMMIT COUNTY — The timing and amount of monsoon rains in the northern hemisphere have important economic and environmental ramifications, for example for farmers in Asia and the wildfire season in the southwestern U.S.

As a result, climate researchers have been trying to determine how the Earth’s steady warming will affect those seasonal rainfall patterns, and so far, the jury is still out. Some recent research has suggested that the timing of the North American monsoon might be delayed, while other studies have indicated that there could be an overall increase in monsoon precipitation.

In one of the latest studies, scientists with the International Pacific Research Center, University of Hawaii at Manoa, say that monsoon rainfall patterns appear to more influenced by natural long-term swings in ocean surface temperatures. The Interdecadal Pacific Oscillation or mega-El Niño-Southern Oscillation, which has lately been in a mega-La Niña or cool phase is one key factor, and shifts in the Atlantic Multidecadal Oscillation, also contributes to the intensification of monsoon rainfall. Continue reading

Colorado: No El Niño, no La Niña – what’s driving the weather?

Spring outlook trends toward warm and dry conditions

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The Madden-Julian Oscillation has played a role in Colorado weather this winter.

By Summit Voice

FRISCO — With neither El Niño or a La Niña conditions in the Pacific Ocean, long-range weather forecasters have been struggling to develop confidence in their outlook for the coming spring season — a critical time for much of the West in terms of getting some relief from drought conditions.

A wet and cool spring could at least take the edge off the drought in some areas, helping to maintain stream flows and reduce the potential for massive and dangerous wildfires. Conversely, a return to last year’s very dry and warm spring pattern would spell trouble for places like Colorado.

So if the El Niño-La Niña cycle isn’t driving the weather, what is? What we do know is that conditions over the Pacific Ocean are the key to understanding exactly what path storms will take across the western United States, and that conditions in the North Atlantic can also be a factor. Continue reading

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