A relação entre o aquecimento e os incêndios

Minho

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Comente:

"O aumento de 1 ºC na temperatura nos últimos 15 anos fez multiplicar por 4 o número de incêndios que se registam anualmente no Oeste Americano."

in 60 Minutos, Sic Notícias (03.11.2007)


Fantástico! Essa também foi do Al-Gore??

Frases soltas não dizem nada... Era bom ver as tabelas das temperaturas, precipitação e área ardida nos últimos 15 anos no Oeste Americano...
 

Mário Barros

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Se calhar multiplicaram-se por 4 os madeireiros que querem madeira devido ao crescimento economico...Mas de facto os Estados Unidos e partes da Asia são os unicos que estão a aquecer o resto do mundo está ou estabilizado ou a arrefecer.

Isso é frase para ajudar a acentar melhor na cabeça das pessoas uma certa teoria.
 

Vince

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Já agora, ainda sobre a mesma temática, a Carbon Balance and Management publicou ontem um estudo sobre as emissões de CO2 provocados pelos incêndios nos EUA, e chegaram à conclusão que estes grandes incêndios como os que ocorreram recentemente nos EUA libertam tanto CO2 para a atmosfera como todo o transporte automóvel durante um ano nalguns estados americanos.

Major wildfires boost carbon dioxide
With last week's disastrous California wildfires still smoldering, here's some unsettling new research that was just released today: Intense wildfires can emit as much carbon dioxide into the atmosphere as vehicles in some U.S. states, a study reports. Typically, carbon dioxide emissions from wildfires are about 5% of the man-made total in the USA. But during major fires in the West and Southeast, the proportion of fire contributions to carbon-dioxide emissions can increase dramatically.

Christine Wiedinmyer of the National Center for Atmospheric Research and Jason Neff of the University of Colorado conducted the study. The authors report: "A striking implication of very large wildfires is that a severe fire season lasting only one or two months can release as much carbon as the annual emissions from the entire transportation or energy sector of an individual state."

The additional carbon dioxide from wildfires also could complicate carbon-emissions monitoring and climate modeling. Wiedinmyer warns, "There is a significant potential for additional net release of carbon from the forests of the USA due to changing fire dynamics in the coming decades." A 2006 study noted that the number and size of large wildfires in the West have increased dramatically in the past two decades.

The new study is published today in the online journal Carbon Balance and Management.
http://blogs.usatoday.com/weather/2007/11/major-wildfires.html

Background
Fires emit significant amounts of CO2 to the atmosphere. These emissions, however, are highly variable in both space and time. Additionally, CO2 emissions estimates from fires are very uncertain. The combination of high spatial and temporal variability and substantial uncertainty associated with fire CO2 emissions can be problematic to efforts to develop remote sensing, monitoring, and inverse modeling techniques to quantify carbon fluxes at the continental scale. Policy and carbon management decisions based on atmospheric sampling/modeling techniques must account for the impact of fire CO2 emissions; a task that may prove very difficult for the foreseeable future. This paper addresses the variability of CO2 emissions from fires across the US, how these emissions compare to anthropogenic emissions of CO2 and Net Primary Productivity, and the potential implications for monitoring programs and policy development.
Results

Average annual CO2 emissions from fires in the lower 48 (LOWER48) states from 2002-2006 are estimated to be 213 (+/- 50 std. dev.) Tg CO2 yr-1 and 80 (+/- 89 std. dev.) Tg CO2 yr-1 in Alaska. These estimates have significant interannual and spatial variability. Needleleaf forests in the Southeastern US and the Western US are the dominant source regions for US fire CO2 emissions. Very high emission years typically coincide with droughts, and climatic variability is a major driver of the high interannual and spatial variation in fire emissions. The amount of CO2 emitted from fires in the US is equivalent to 4-6% of anthropogenic emissions at the continental scale and, at the state-level, fire emissions of CO2 can, in some cases, exceed annual emissions of CO2 from fossil fuel usage.

Conclusions
The CO2 released from fires, overall, is a small fraction of the estimated average annual Net Primary Productivity and, unlike fossil fuel CO2 emissions, the pulsed emissions of CO2 during fires are partially counterbalanced by uptake of CO2 by regrowing vegetation in the decades following fire. Changes in fire severity and frequency can, however, lead to net changes in atmospheric CO2 and the short-term impacts of fire emissions on monitoring, modeling, and carbon management policy are substantial.
http://www.cbmjournal.com/content/2/1/10