[Vision2020] Western U.S. Forest Wildfire Activity

[lfalen]

Ted
Whether published in "Science" or not there are a few things missing. I think that 1934 was hoitter than it is now. Wheather it was dryer or not I don't know. These fire were predominatly the result of arson. The extent of the fires we exacerbated by the dense underbrush that resulltd from environmetalist not allowing it to be cleared out.
Roger
-----Original message-----
From: "Ted Moffett" starbliss at gmail.com
Date: Wed, 24 Oct 2007 13:45:27 -0700
To: "Bruce and Jean Livingston" jeanlivingston at turbonet.com
Subject: Re: [Vision2020] Western U.S. Forest Wildfire Activity

> All-
> 
> Regarding the ongoing Southern California fires, and the very important
> issue of Western US fire potential (especially in Idaho) and causes in
> general, the following fact and science based sources are critical.
> 
> Read about the record drought and heat waves for Southern California (both
> this year), coupled with the findings from the research on Western USA
> fires, in the Science magazine article below, co-authored by the scientist,
> Thomas Swetnam (University of Arizona), who I referenced at the start of
> this thread, who was interviewed on CBS 60 Minutes last weekend on the
> subject of wild land fire, with astonishing timing, given the explosion in
> the Southern California fires that occurred immediately after:
> 
> http://www.terradaily.com/reports/Western_US_States_Swelter_Under_Record_Heatwave_999.html
> 
> *Parched California has driest 'rainy season' on record*
> 
> Los Angeles (AFP) July 1 - Los Angeles suffered through the driest rainy
> season on record in 2007, marking the least amount of precipitation here in
> the 130 years
> 
> http://www.noaanews.noaa.gov/stories2007/s2838.htm
> 
> In Los Angeles, the lack of rainfall led to the driest water-year to date
> for the city since records began in 1877. From July 1, 2006, through the end
> of March, downtown Los Angeles had received only 2.47 inches of rain, almost
> one foot below the normal amount of rainfall for the period.
> 
> In the West, where mountain snowpack is relied upon to supply water needs
> throughout the region, below-average rain and snowfall have become
> increasingly common. In only two of the past nine years has snowpack on
> April 1 been at or above the long-term average in at least half the region.
> --------------
> 
> For those who wish to skip most of the Science magazine article, here is a
> critical finding of their research, indicating human land use is not the
> cause of the documented increase (note not the cause of the "increase," not
> that humans do not start fires) in Western USA fires in recent decades:
> 
> http://www.sciencemag.org/cgi/content/full/313/5789/940
> 
> We compiled a comprehensive database of large wildfires in western United
> States forests since 1970 and compared it with hydroclimatic and
> land-surface data. Here, we show that large wildfire activity increased
> suddenly and markedly in the mid-1980s, with higher large-wildfire
> frequency, longer wildfire durations, and longer wildfire seasons. The greatest
> increases occurred in mid-elevation, Northern Rockies forests, where
> land-use histories have relatively little effect on fire risks and are
> strongly associated with increased spring and summer temperatures and an
> earlier spring snowmelt.
> --------------------
> 
> I will excerpt a few more paragraphs from this article:
> 
> 
> *Science* 18 August 2006:
> Vol. 313. no. 5789, pp. 940 - 943
> DOI: 10.1126/science.1128834
>  Prev <http://www.sciencemag.org/cgi/content/short/313/5789/936> | Table of
> Contents <http://www.sciencemag.org/content/vol313/issue5789/index.dtl> |
> Next <http://www.sciencemag.org/cgi/content/short/313/5789/944>
> Research Articles Warming and Earlier Spring Increase Western U.S. Forest
> Wildfire Activity *A. L.
> Westerling,1,2*<http://www.sciencemag.org/cgi/content/full/313/5789/940#COR1>
> H.
> G. Hidalgo,1 D. R. Cayan,1,3 T. W. Swetnam4 *
> 
> http://www.sciencemag.org/cgi/content/full/313/5789/940
> 
> We compiled a comprehensive database of large wildfires in western United
> States forests since 1970 and compared it with hydroclimatic and
> land-surface data. Here, we show that large wildfire activity increased
> suddenly and markedly in the mid-1980s, with higher large-wildfire
> frequency, longer wildfire durations, and longer wildfire seasons. The greatest
> increases occurred in mid-elevation, Northern Rockies forests, where
> land-use histories have relatively little effect on fire risks and are
> strongly associated with increased spring and summer temperatures and an
> earlier spring snowmelt.
> ------
> 
> Snow carries over a substantial portion of the winter precipitation that
> falls in western mountains, releasing it more gradually in late spring and
> early summer, providing an important contribution to spring and summer soil
> moisture (*35*<http://www.sciencemag.org/cgi/content/full/313/5789/940#REF35>).
> An earlier snowmelt can lead to an earlier, longer dry season, providing
> greater opportunities for large fires due both to the longer period in which
> ignitions could potentially occur and to the greater drying of soils and
> vegetation. Consequently, it is not surprising that the incidence of
> wildfires is strongly associated with snowmelt timing.
> 
> Changes in spring and summer temperatures associated with an early spring
> snowmelt come in the context of a marked trend over the period of analysis.
> Regionally averaged spring and summer temperatures for 1987 to 2003 were
> 0.87°C higher than those for 1970 to 1986. Spring and summer temperatures for
> 1987 to 2003 were the warmest since the start of the record in 1895, with 6
> years in the 90th percentile—the most for any 17-year period since the start
> of the record in 1895 through 2003—whereas only 1 year in the preceding 17
> years ranked in the 90th percentile. Likewise, 73% of early years since 1970
> occurred in 1987 to 2003 (Fig.
> 1<http://www.sciencemag.org/cgi/content/full/313/5789/940#FIG1>
> ).
> 
> --------
> 
> If the average length and intensity of summer drought increases in the
> Northern Rockies and mountains elsewhere in the western United States, an
> increased frequency of large wildfires will lead to changes in forest
> composition and reduced tree densities, thus affecting carbon pools. Current
> estimates indicate that western U.S. forests are responsible for 20 to 40%
> of total U.S. carbon sequestration
> (*38*<http://www.sciencemag.org/cgi/content/full/313/5789/940#REF38>,
> *39* <http://www.sciencemag.org/cgi/content/full/313/5789/940#REF39>). If
> wildfire trends continue, at least initially, this biomass burning will
> result in carbon release, suggesting that the forests of the western United
> States may become a source of increased atmospheric carbon dioxide rather
> than a sink, even under a relatively modest temperature-increase scenario (*
> 38* <http://www.sciencemag.org/cgi/content/full/313/5789/940#REF38>,
> *39*<http://www.sciencemag.org/cgi/content/full/313/5789/940#REF39>).
> Moreover, a recent study has shown that warmer, longer growing seasons lead
> to reduced CO2 uptake in high-elevation forests, particularly during
> droughts (*40*<http://www.sciencemag.org/cgi/content/full/313/5789/940#REF40>).
> Hence, the projected regional warming and consequent increase in wildfire
> activity in the western United States is likely to magnify the threats to
> human communities and ecosystems, and substantially increase the management
> challenges in restoring forests and reducing greenhouse gas emissions.
> 
> ------
> 
> Vision2020 Post: Ted Moffett
> 
>