Climate shifts may spur big rise in wildfires

Climate shifts may spur big rise in wildfires

22 June 2012

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 USA Latest computerized climate models predict sharp rise in fires in southwest

This year’s frightening fire season in Rim Country may become the new normal, according to several recent attempts to predict how the ongoing warming trend will affect wildfire season in the Southwest.

The most recent evidence involves a compilation of 16 different computerized climate models, which predicts a sharp rise in major wildfires in the American Southwest in the next 30 years, according to the study published in Ecosphere. The explosion in wildfires has driven the U.S. Forest Service’s budget for fighting fires to $1.5 billion annually.

Studies have already shown that since 1970 the number of wildfires in the Southwest has increased four-fold and the acreage burned has increased six-fold. Last summer, Arizona suffered the biggest wildfire in history in the White Mountains. This summer, the biggest wildfire in New Mexico’s history continues to burn just over the Arizona border.

The climate models show almost all agree on more and worse wildfires in the Southwest due to an inexorable warming trend most scientists attribute to a steep rise in greenhouse gases in the atmosphere. However, the increased heat in the atmosphere in the short run may actually increase rainfall in the rain forests and have an unpredictable impact on roughly half of the planet for the next 30 years.

“In the long run, we found what most fear — increasing fire activity across large areas of the planet,” said lead author Mark Moritz of the University of California at Berkeley. “But the speed and extent to which some of these changes may happen is surprising.”

Another recent study found a complex relationship between fire and weather patterns, based on detailed fire data collected from 1916 to 2003 in 19 different ecosystems types, including both ponderosa pine and pinyon juniper forests, the two dominant ecosystem types in Rim Country.

The study confirmed the strong link between high temperatures and increased fire size and intensity. However, the scenario played out differently in some habitats. For instance, in western shrub and grasslands, fires increased when wet years caused a big increase in growth followed by dry years that turned the new grass and shrubs to tinder. The relationship between high temperatures and increased wildfires was more direct in woodlands and other habitats like those that dominate Rim Country, according to the study by researchers from the U.S. Forest Service and University of Washington researchers published in the journal Ecological Applications.

With Rim Country rainfall so far this year about one-third of normal, the U.S. Weather Service predicted a hot, dry week — with temperatures locally rising into the high 90s. The forecast includes a small chance of rain this weekend, with many firefighters praying for an early onset to the monsoon season.

So far the mid-term forecasts remain mixed on whether Rim Country can expect its normal, drenching rains in July and August. Some early indications offer hope for a wetter-than-normal winter, based on sea surface temperatures in the Pacific.

However, most of the mid- to long-range forecasts suggest the bone dry springs of the past several years could well become the norm, extending the peak of the fire season once confined to June all the way into April.

Meanwhile, the scientific consensus on the impact of a steady rise in greenhouse gases like carbon dioxide in the atmosphere continues to strengthen.

This spring, monitoring stations in the Arctic revealed that carbon dioxide levels in the atmosphere have hit more than 400 parts per million, the highest level on record. In recent years, the global average for carbon dioxide has risen from 350 ppm to 395 ppm.

Before the industrial age, the carbon dioxide levels stood at an estimated 275 ppm, according to the National Oceanic and Atmospheric Administrations’ Earth System Research Lab in Boulder, Colo.

The last time carbon dioxide levels hit 400 was some 80,000 years ago. In that case, scientist think an outpouring of volcanic activity accounted for the spike.

The International Energy Agency this year announced that global carbon dioxide emissions from fossil fuels hit a record 34.8 billion tons in 2011, up 3.2 percent from the previous year.

Skeptics concerning the link between carbon dioxide levels and temperature increases abound, although the overwhelming majority of climate scientists now accept the link.

NOAA concluded that the period from 2000 to 2009 represented the warmest decade on record. Last month had the second warmest combined land-ocean temperature for May since global record keeping began in 1880, placing second to 2010. Both the land and water temperatures for the Northern Hemisphere set a record in May as well, averaging 1.53 degrees above average. Globally, land surface temperatures were 2.18 degrees above average for the month — the all-time warmest May on record.

The rise in temperatures was especially pronounced in the Arctic and Greenland, with temperature increases as much as 9 degrees above normal. The trend has accelerated the melting of the ice caps, especially the massive sheet of ice over Greenland. Scientists worry that a thaw of the permafrost could release a massive dose of carbon dioxide into the atmosphere.

The ice sheet encasing Greenland is one or two miles thick in places — enough water to raise sea levels globally by 24 feet.

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