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Global warming spells trouble for fish populations in desert rivers of the Southwest

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Dwindling precipitation in the Southwest spells trouble for native fish. bberwyn photo.

Study shows significant loss of fish habitat by mid-century

Staff Report

FRISCO — Big sections of vulnerable stream habitat for native fish in the Southwest are likely to disappear by mid-century as global warming causes stream flows to dwindle.

By 2050, stream-drying events could increase by 17 percent, and the number of zero-flow days could go up by 27 percent in the Verde River Basin, affecting species like speckled dace (Rhinichthys osculus), roundtail chub (Gila robusta) and Sonora sucker (Catostomus insignis).

The drying trend will fragment aquatic habitat, hampering feeding and spawning. Some populations that are already isolated may very well disappear, said Ohio State University researcher Kristin Jaeger, an assistant professor at the School of Environment and Natural Resources. Continue reading

Major Colorado River players announce conservation push

Near critical shortages in California prompt action

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Heading downstream … bberwyn photo.

By Summit Voice

FRISCO — With Colorado River water supplies disappearing at a dizzying rate, and with a thirsty — and politically mighty — California parched by drought, the biggest water users at the table said this week they’ll invest $11 million to try and conserve significant amounts of water across all sectors, including including agricultural, municipal and industrial uses.

The Central Arizona Project, Denver Water, The Metropolitan Water District of Southern California and Southern Nevada Water Authority all signed on to what is being presented as a landmark water conservation agreement aimed at demonstrating “the viability of cooperative, voluntary compensated measures,” according to a press release from Denver Water. Continue reading

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Groundwater depletion threatens sustainability of Colorado River

Satellite data suggests more than 75 percent of water loss in drought-stricken basin is from groundwater pumping

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A new study quantifies groundwater depletion in the Colorado River Basin. Map courtesy U.S. Bureau of Reclamation.

By Summit Voice

FRISCO — Groundwater pumping is a huge factor in the Colorado River Basin water equation, California-based researchers said this week, announcing the results of satellite study that for the first time quantifies how groundwater contributes to the water needs of western states.

Along with surface diversions and pipelines, water users in the basin are also unsustainably depleting underground aquifers. For example, mountain resort towns in  Colorado tap underground water from headwaters streams like Tenmile Creek and the Blue River for municipal use.

The new study found that more than 75 percent of the water loss in the drought-stricken Colorado River Basin since late 2004 came from underground resources. The extent of groundwater loss may pose a greater threat to the water supply of the western United States than previously thought, the researchers concluded. Continue reading

Climate: Utah tree-ring study shows severity of historic megadroughts

Luminosity.

Old Douglas firs can help reveal historic climate cycles.

Recent dry spells not so bad compared to past centuries

Staff Report

FRISCO — A tree-ring reconstruction of Utah’s climate going back to 1429 shows that the state has experienced several mega-droughts in past centuries that would be life-changing if they happen again, according to Brigham Young University professor Matthew Bekker.

The worst drought of the modern era, the 1930s Dust Bowl, barely ranks on the top 10 list of droughts in that 500-year span,” Bekker said. The findings reinforce similar studies for the Colorado River Basin. Continue reading

Environment: Is the Amazon rainforest near a tipping point?

A NASA photo taken from the International Space Station shows sunlight glinting off the Amazon River.

A NASA photo taken from the International Space Station shows sunlight glinting off the Amazon River.

Drought the main driver of destructive fires

By Staff Report

FRISCO — Longer droughts, land-use changes and wildfires may  be pushing parts of the Amazon rainforest toward an ecological tipping point, a team of scientists said after analyzing the effects of fire in a series of study plots.

The changes may abruptly increase tree mortality and change vegetation over large areas, the researchers said, pointing out that current Amazon forest models don’t include the impacts of wildfires. As a result, projections of future forest health tend to underestimate the amount of tree death and overestimate overall forest health, said Dr. Michael Coe, of the Woods Hole Research Center. Continue reading

Climate: Warmer temps to drive spread of drought

State officials hope to be well-prepared for the next inevitable drought in Colorado.

Drought is expected to expand the southwestern U.S. and other regions.

Evaporation seen as huge factor in climate calculations

Staff Report

FRISCO — Increasing global temperatures will drive drought expansion regardless of precipitation in some cases, as more moisture evaporates from soils.

An increase in evaporative drying means that even regions expected to get more rain, including important wheat, corn and rice belts in the western United States and southeastern China, will be at risk of drought. The study excludes Antarctica.

The new study models the effects of both changing rainfall and evaporation rates on future drought, estimating that 12 percent of land will be subject to drought by 2100 through rainfall changes alone; but the drying will spread to 30 percent of land if higher evaporation rates from the added energy and humidity in the atmosphere is considered.

Continue reading

Climate: Scientists study link between tropical belt expansion and multi-decadal oceanic circulation patterns

Long-term Pacific Ocean cycles could be driving SW drought

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What’s the role of natural climate variability in Southwestern droughts?

Staff Report

FRISCO — If you’re ready to blame drought in the southwestern U.S. on global warming, it might be time to rethink that conclusion.

According to scientists with the University of California, Riverside, dry conditions in the region may be linked with an expansion of the Earth’s tropical belt during the past few decades. And that expansion is likely driven by multi-decadal sea surface temperature variability in the Pacific Ocean, according to the new study. Other explanations for this widening have been proposed, including radiative forcing due to greenhouse gas increase and stratospheric ozone depletion. Continue reading

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