Wednesday, October 12, 2016
Global warming doubles size of forest fires in US West, study finds
This is just more rubbishy modelling. They have got no way of knowing what part of forest fire activity is attributable to anthropogenic global warming -- unless they use the old formula "post hoc ergo propter hoc" -- which is both a scientific and a logical fallacy. It does appear that there is some correlation between fire incidence and global temperature but we must remember what is just about the first law of statistics: Correlation is not causation. I would think the correlation could be amply explained by the steadily increasing Greenie influence on forestry. Greenie resistance to back-burning is by far the biggest producer of catastrophic fires. I append the journal abstract to the summary below
Global warming has caused the area affected by forest fires in the western United States to double over the last 30 years – and the problem will continue to get worse until the trees start to run out, according to new research.
Higher air temperatures dry out vegetation, making it more prone to combust, as witnessed with increasing ferocity in states like California and Oregon.
While some parts of the world will get wetter as the climate warms, fires have been increasing in places like the Amazon, Indonesia and Canada's boreal forests.
Climate scientists had predicted wildfires would increase in places, but the new study, funded in part by Nasa, is one of the first to quantify the effect.
One of the researchers, Professor Park Williams, a bio-climatologist at Columbia University, said: “No matter how hard we try, the fires are going to keep getting bigger, and the reason is really clear.
“Climate is really running the show in terms of what burns. We should be getting ready for bigger fire years than those familiar to previous generations.”
An extra 4.2 million hectares of forest fires – about 16,000 square miles, the same area as Denmark – were estimated to have been caused by human-induced climate change between 1984 and 2015, according to a paper in the journal Proceedings of the National Academy of Sciences.
This increase nearly doubled the area that would have burned if the temperature had not risen, the researchers found.
Eventually the fires will be so extreme that the remaining forests are too fragmented for flames to spread easily between them.
“There's no hint we're even getting close to that yet. I'd expect increases to proceed exponentially for at least the next few decades,” Professor Williams said.
While the world’s average temperature has risen by one degree Celsius since pre-industrial times, the increase within forests in the US West has been sharper. Since 1970, temperatures have gone up there by 1.5C – and this increase is expected to continue.
Warmer air can hold more moisture, so water is sucked out of plants, dead vegetation and the soil, creating tinder dry conditions.
Impact of anthropogenic climate change on wildfire across western US forests
By John T. Abatzoglou and A. Park Williams
Increased forest fire activity across the western continental United States (US) in recent decades has likely been enabled by a number of factors, including the legacy of fire suppression and human settlement, natural climate variability, and human-caused climate change. We use modeled climate projections to estimate the contribution of anthropogenic climate change to observed increases in eight fuel aridity metrics and forest fire area across the western United States. Anthropogenic increases in temperature and vapor pressure deficit significantly enhanced fuel aridity across western US forests over the past several decades and, during 2000–2015, contributed to 75% more forested area experiencing high (>1 σ) fire-season fuel aridity and an average of nine additional days per year of high fire potential. Anthropogenic climate change accounted for ∼55% of observed increases in fuel aridity from 1979 to 2015 across western US forests, highlighting both anthropogenic climate change and natural climate variability as important contributors to increased wildfire potential in recent decades. We estimate that human-caused climate change contributed to an additional 4.2 million ha of forest fire area during 1984–2015, nearly doubling the forest fire area expected in its absence. Natural climate variability will continue to alternate between modulating and compounding anthropogenic increases in fuel aridity, but anthropogenic climate change has emerged as a driver of increased forest fire activity and should continue to do so while fuels are not limiting.