Continuing the theme of wildfires in the Western Contiguous U.S (CONUS), we have this recent paper by Spracklen et.al.: Wildfires drive interannual variability of organic carbon aerosol in the western U.S. in summer.

Abstract: Forest wildfire area burned in the western U.S. has increased in recent decades resulting in a substantial organic carbon (OC) source with large interannual variability. We derive OC emissions from wildfires using data for area burned for 1980–2004 and ecosystem specific fuel loadings.For the period 1989–2004 we analyze OC observations in the western U.S. from the IMPROVE network and use a global chemical transport model to simulate OC concentrations. Modeled and observed OC concentrations are highly correlated when we use interannually varying fire emissions (R2 = 0.88); the correlation is smaller with climatological emissions (R2 = 0.4). We estimate that the observed increase in wildfire activity after the mid 1980s has caused mean OC concentrations in summer over the western U.S. to increase by 30% relative to 1970–1984. In the coming decades, climate change will likely cause further increases in wildfires resulting in increased OC concentrations with implications for health and visibility.

Continue Reading »

… and the sarcastic replies they probably didn’t want to hear.

precipitation++front+cloud+cold+warm

They really wanted to know about fronts. Didn’t really know if the assignment asked about warm or cold fronts. Searched both, just to be safe.

“stand an egg on its end”

Take egg. Stand on end. Duh. I already wrote that in a previous post.

how does the autumn equinox effect…

It doesn’t. No need to finish the sentence. Ahh, quit talking before you make my head explode.

stationary front hits a cold front

A stationary front is stationary. It’s impossible for it to hit anything.

housewife & green house effect

The addition of a housewife will increase your household greenhouse emissions. However, since she is probably moving from her own residence, the net greenhouse emissions will decrease, provided the old residence is sold. Therefore, the more housewives you have, the less total greenhouse gas emissions. More wives, more money. It’s a twofer, for roughly half the population.

A few days ago I wondered if there would be a correlation between temperature anomalies and wildfires (number, intensity, or some other quantitative metric). It seems intuitive enough: warmer temperatures lead to drier conditions which lead to more fires. But how would one compare these two quantities in a meaningful way? Luckily for you, someone has already done just this problem, albeit just for the Southwestern United States.

Forest Wildfire Activity Warming and Earlier Spring Increase Western U.S.

Abstract: Western United States forest wildfire activity is widely thought to have increased in recent decades, yet neither the extent of recent changes nor the degree to which climate may be driving regional changes in wildfire has been systematically documented. Much of the public and scientific discussion of changes in western United States wildfire has focused instead on the effects of 19thand 20th-century land-use history. 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 haven’t delved into this paper, but on a cursory examination it appears that my (and likely a lot of other peoples) simple hypotheses was correct: increasing temperatures lead to more wildfires.

Westerling, A.L. et al., Forest Wildfire Activity Warming and Earlier Spring Increase Western U.S., Science 313, 940 (2006). DOI: 10.1126/science.1128834

Take egg. Stand on its end. The Bad Astronomer has more details.

Since the standing an egg on end myth has something to do with celestial mechanics, and this post would be pretty short if I stopped here, I’ll talk about Milankovitch cycles as well. Weeeee.
Continue Reading »