IEEE Power & Energy Magazine - January/February 2022 - 20

Changes brought about by climate change
may make weather phenomena such as the
Santa Ana winds worse.
promoting electrical flashover. Wildfire can heat powerlines,
causing the conductors to sag, which, combined with
wind, can cause conductor clashing. Wooden poles can burn
during fires, severely damaging power networks. Similarly,
aluminum conductors may melt during wildfires due to the
low melting point of aluminum (~640 °C). Fire retardants
dropped from aircraft can cause power lines to foul, limiting
their performance.
Experience tells us that wildfires are more likely to
spread in dry and warm climate conditions. Intuitively, this
leads to the hypothesis that climate change manifestations
of drought and higher temperatures could have an important
impact on wildfire activity. The nature of this impact (i.e.,
frequency of fires, size of fires, or type of fires, and so on)
on wildfire activity is less intuitive; however, the data from
reports of large destructive wildfires over the past several
decades show strong clear evidence of increased wildfire
severity and size.
Climate Change and Wildfires
Weather extremes around the globe are confirming what has
been the consensus among climate scientists: the climate
is changing. Human influence on this change is substantial
and cannot be denied. Large amounts of greenhouse gas
emissions and overexploitation of essential ecosystems have
overcome the natural resilience of the planet and are causing
changes in the climate. The latest Intergovernmental Panel on
Climate Change report (August 2021) states " it is unequivo4
r
= 0.72
p < 0.01
3
2
11
13
1972-1999
2000-2016
2017 2018
15
Mar.-Oct. VPD (hPa)
figure 3. A summer-burned area in California compared
to climate indicators. The atmospheric water VPD is used as a
proxy for drier vegetation. (Source: Williams et al.; used with
permission.)
20
ieee power & energy magazine
cal that human influence has warmed the atmosphere, ocean,
and land. Widespread and rapid changes in the atmosphere,
ocean, cryosphere, and biosphere have occurred. "
Especially in the Northern Hemisphere, climate change
is expressed through consistently higher temperatures (during
the past century, global average temperatures have risen
by about 1 °C) and extended periods of drought. In general,
weather phenomena become more extreme. While overall
rainfall has not necessarily diminished, it occurs in shorter,
more intensive events. An example is the extensive flooding
that devastated large areas of Central Europe and Southeast
Asia during the early summer of 2021. The preceding
heatwave, which produced unprecedented temperatures in
several locations across Europe (e.g., 35 °C in Ireland), completes
the picture.
Climate change results from a positive feedback loop. An
example is the temperature-induced melting of ice caps in
the polar regions. The Northern Siberian permafrost region
contains important extensions of peatland, which upon thawing
provides fuel for smoldering fires that further emit carbon
dioxide. While forest fires are, in theory, carbon-neutral
(carbon dioxide released during the fire will be reabsorbed as
the vegetation grows back), peat fires are a net contributor to
carbon emissions. It was estimated that carbon dioxide emissions
from the 1997 peatland fires in Indonesia corresponded
to up to 40% of fossil fuel emissions during the same year.
Carbon dioxide-driven climate change thus self-accelerates
and indirectly contributes to increased carbon dioxide emissions,
which in turn further accelerate climate change.
One consequence of higher average temperatures resulting
from climate change is the decrease of ambient humidity,
which causes a decrease in vegetation moisture levels.
This in turn makes the vegetation easier to ignite and burn
more intensely. Thus, climate change is likely to result in an
increase in wildfire activity.
A recent study published in the research journal Earth's
Future presented evidence confirming such a link,
identifying
an increase in the areas consumed by wildfires in
California as the atmospheric water vapor pressure deficit
(VPD-a proxy for drier vegetation) increases. The graph
in Figure 3 shows this increase, and also establishes a link
between increased VPD and climate change since higher
VPD has occurred predominantly during the past
two
decades (illustrated by the orange and red data points). Similar
trends are observed in Eurasia and Canada, especially in
the arctic and subarctic regions. The enhanced propensity to
burn could, in turn, indicate elevated risk to power networks.
january/february 2022
log10 (km2)
IEEE Power & Energy Magazine - January/February 2022

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