25 July 2020 | New Scientist | 43T
HE bush fires that engulfed parts
of Australia earlier this year were
nothing short of apocalyptic. More
recently, a record-breaking heatwave has hit
Siberia, causing a thaw in the permafrost that
contributed to one of Russia’s worst ever oil
spills. But were these disasters caused by
climate change?
For a long time, scientists have said that we
can’t pin any single extreme weather event
on our greenhouse gas emissions. That is still
true, but in recent years, researchers have
become far better at estimating how much
more probable any given “natural” disaster
was made by human-caused global warming.
This work is called extreme event
attribution, and it involves comparisons
between real observations of weather events
and computer simulations of a world with
and without the roughly 1°C hike in
temperatures caused by humanity so far.
Run the simulations thousands of times
and you can calculate the odds of the event
occurring in both scenarios. So you can say,
for example, that the drought conditions thatAdam Vaughan: How do you describe
your job to people?
Friederike Otto: I’m trying to answer the
question of whether, and to what extent,
man-made climate change altered the
likelihood and intensity of recent extreme
weather events. The data-processing aspect
of that is a very small part of my work. Most
of my day-to-day work is thinking about the
most appropriate data sources to use for
these kinds of studies, or which models
should be used, or how we can test the
models better to see whether they are able
to reliably simulate the weather event.What developments have moved your field
along? Is the progress purely down to better
data and more computing power?
Actually, the big advance has been that
we have realised how important it is to
understand what question you’re asking.
You can define a heatwave as unusually high
summer temperatures over three months,
and you will find that climate change made
it orders of magnitude more likely. But youwere responsible for the Australian bush
fires were made at least 30 per cent more
likely by climate change. Or that human-
induced global warming made the rise in
temperatures that have been seen in Siberia
over the past few months at least 600 times
more likely.
Friederike Otto at the University of Oxford,
who led the team behind the rapid-response
studies that made both of these estimations,
is at the vanguard of the field. As co-founder
of the World Weather Attribution project,
she has been pivotal in recent work that has
significantly sped up the process.
Attribution already occurs in a matter of
weeks, but soon it could happen within days.
And Otto thinks that a change of this sort
could have a profound effect on efforts to
strong-arm governments into tougher
action on carbon emissions. What’s more,
attribution could even soon be used as
evidence in legal cases in which people
affected by extreme weather make claims
for damages against governments or
RO fossil fuel companies.
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