The Monthly - Joëlle Gergis
The latest science is alarming, even for climate scientists
Dr Joëlle Gergis is an award-winning climate scientist and writer from the Australian National University.
She is an internationally recognised expert in Australian and Southern Hemisphere climate variability and change based in the Australian Research Council (ARC) Centre of Excellence for Climate Extremes.
Her research focuses on providing a long-term historical context for assessing recently observed climate variability and extremes.
In August 2018 she was appointed to the Climate Council, Australia's leading independent body providing expert advice to the Australian public on climate change and policy.
Her book, Sunburnt Country: The future and history of climate change in Australia, is now available through Melbourne University Publishing. |
In June, I delivered a keynote presentation on Australia’s
vulnerability to climate change and our policy challenges at the annual
meeting of the Australian Meteorological and Oceanographic Society, the
main conference for those working in the climate science community. I
saw it as an opportunity to summarise the post-election political and
scientific reality we now face.
As one of the dozen or so Australian lead authors on the United
Nations Intergovernmental Panel on Climate Change’s (IPCC) sixth
assessment report, currently underway, I have a deep appreciation of the
speed and severity of climate change unfolding across the planet. Last
year I was also appointed as one of the scientific advisers to the
Climate Council, Australia’s leading independent body providing expert
advice to the public on climate science and policy. In short, I am in
the confronting position of being one of the few Australians who sees
the terrifying reality of the climate crisis.
Preparing for this talk I experienced something gut-wrenching. It was
the realisation that there is now nowhere to hide from the terrible
truth.
The last time this happened to me, I was visiting my father in
hospital following emergency surgery for a massive brain haemorrhage. As
he lay unconscious in intensive care, I examined his CT scan with one
of the attending surgeons who gently explained that the dark patch
covering nearly a quarter of the image of his brain was a pool of blood.
Although they had done their best to drain the area and stem the
bleeding, the catastrophic nature of the damage was undeniable. The
brutality of the evidence was clear – the full weight of it sent my
stomach into freefall.
The results coming out of the climate science community at the moment are, even for experts, similarly alarming.
One common metric used to investigate the effects of global warming
is known as “equilibrium climate sensitivity”, defined as the full
amount of global surface warming that will eventually occur in response
to a doubling of atmospheric CO2 concentrations compared to
pre-industrial times. It’s sometimes referred to as the holy grail of
climate science because it helps quantify the specific risks posed to
human society as the planet continues to warm.
We know that CO2 concentrations have risen from pre-industrial levels
of 280 parts per million (ppm) to approximately 410 ppm today, the
highest recorded in at least three million years. Without major
mitigation efforts, we are likely to reach 560 ppm by around 2060.
When the IPCC’s fifth assessment report was published in 2013, it
estimated that such a doubling of CO2 was likely to produce warming
within the range of 1.5 to 4.5°C as the Earth reaches a new equilibrium.
However, preliminary estimates calculated from the latest global
climate models (being used in the current IPCC assessment, due out in
2021) are far higher than with the previous generation of models. Early
reports are predicting that a doubling of CO2 may in fact produce
between 2.8 and 5.8°C of warming. Incredibly, at least eight of the
latest models produced by leading research centres in the United States,
the United Kingdom, Canada and France are showing climate sensitivity
of 5°C or warmer.
When these results were first released at a climate modelling
workshop in March this year, a flurry of panicked emails from my IPCC
colleagues flooded my inbox. What if the models are right? Has the Earth
already crossed some kind of tipping point? Are we experiencing abrupt
climate change right now?
The model runs aren’t all available yet, but when many of the most
advanced models in the world are independently reproducing the same
disturbing results, it’s hard not to worry.
When the UN’s Paris Agreement was adopted in December 2015, it
defined a specific goal: to keep global warming to well below 2°C and as
close as possible to 1.5°C above pre-industrial levels (defined as the
climate conditions experienced during the 1850–1900 period). While
admirable in intent, the agreement did not impose legally binding limits
on signatory nations and contained no enforcement mechanisms. Instead,
each country committed to publicly disclosed Nationally Determined
Contributions (NDCs) to reduce emissions. In essence, it is up to each
nation to act in the public interest.
Even achieving the most ambitious goal of 1.5°C will see the further
destruction of between 70 and 90 per cent of reef-building corals
compared to today, according to the IPCC’s “Special Report on Global
Warming of 1.5°C”, released last October. With 2°C of warming, a
staggering 99 per cent of tropical coral reefs disappear. An entire
component of the Earth’s biosphere – our planetary life support system –
would be eliminated. The knock-on effects on the 25 per cent of all
marine life that depends on coral reefs would be profound and
immeasurable.
So how is the Paris Agreement actually panning out?
In 2017, we reached 1°C of warming above global pre-industrial
conditions. According to the UN Environment Programme’s “Emissions Gap
Report”, released in November 2018, current unconditional NDCs will see
global average temperature rise by 2.9 to 3.4°C above pre-industrial
levels by the end of this century.
To restrict warming to 2°C above pre-industrial levels, the world
needs to triple its current emission reduction pledges. If that’s not
bad enough, to restrict global warming to 1.5°C, global ambition needs
to increase fivefold.
Meanwhile, the Australian federal government has a target of reducing
emissions by 26 to 28 per cent below 2005 levels by 2030, which experts
believe is more aligned with global warming of 3 to 4°C. Despite Prime
Minister Scott Morrison’s claim that we will meet our Paris Agreement
commitments “in a canter”, the UNEP report clearly identifies Australia
as one of the G20 nations that will fall short of achieving its already
inadequate NDCs by 2030.
Even with the 1°C of warming we’ve already experienced, 50 per cent
of the Great Barrier Reef is dead. We are witnessing catastrophic
ecosystem collapse of the largest living organism on the planet. As I
share this horrifying information with audiences around the country, I
often pause to allow people to try and really take that information in.
Increasingly after my speaking events, I catch myself unexpectedly
weeping in my hotel room or on flights home. Every now and then, the
reality of what the science is saying manages to thaw the emotionally
frozen part of myself I need to maintain to do my job. In those moments,
what surfaces is pure grief. It’s the only feeling that comes close to
the pain I felt processing the severity of my dad’s brain injury. Being
willing to acknowledge the arrival of the point of no return is an act
of bravery.
But these days my grief is rapidly being superseded by rage.
Volcanically explosive rage. Because in the very same IPCC report that
outlines the details of the impending apocalypse, the climate science
community clearly stated that limiting warming to 1.5°C is geophysically
possible.
Past emissions alone are unlikely to raise global average
temperatures to 1.5°C above pre-industrial levels. The IPCC report
states that any further warming beyond the 1°C already recorded would
likely be less than 0.5°C over the next 20 to 30 years, if all
anthropogenic greenhouse gas emissions were reduced to zero immediately.
That is, if we act urgently, it is technically feasible to turn things
around. The only thing missing is strong global policy.
Although the very foundation of human civilisation is at stake, the
world is on track to seriously overshoot our UN targets. Worse still,
global carbon emissions are still rising. In response, scientists are
prioritising research on how the planet has responded during other warm
periods in the Earth’s history.
The most comprehensive summary of conditions experienced during past
warm periods in the Earth’s recent history was published in June 2018 in
one of our leading journals,
Nature Geoscience, by 59 leading
experts from 17 countries. The report concluded that warming of between
1.5 and 2°C in the past was enough to see significant shifts in climate
zones, and land and aquatic ecosystems “spatially reorganize”.
These changes triggered substantial long-term melting of ice in
Greenland and Antarctica, unleashing 6 to 13 metres of global sea-level
rise lasting thousands of years.
Examining the Earth’s climatic past tells us that even between 1.5
and 2°C of warming sees the world reconfigure in ways that people don’t
yet appreciate. All bets are off between 3 and 4°C, where we are
currently headed. Parts of Australia will become uninhabitable, as other
areas of our country become increasingly ravaged by extreme weather
events.
This year the Australian Meteorological and Oceanographic Society’s
annual conference was held in Darwin, where the infamous Cyclone Tracy
struck on Christmas Day in 1974, virtually demolishing the entire city.
More than 70 per cent of the city’s buildings, including 80 per cent of
its houses, were destroyed. Seventy-one people were killed and most of
the 48,000 residents made homeless. Conditions were so dire that around
36,000 people were evacuated, many by military aircraft. It was a
disaster of monumental proportions.
As I collated this information for my presentation, it became clear
to me that Cyclone Tracy is a warning. Without major action, we will see
tropical cyclones drifting into areas on the southern edge of current
cyclone zones, into places such as south-east Queensland and northern
New South Wales, where infrastructure is not ready to cope with cyclonic
conditions.
These areas currently house more than 3.6 million people; we simply aren’t prepared for what is upon us.
There is a very rational reason why Australian schoolkids are now
taking to the streets – the immensity of what is at stake is truly
staggering. Staying silent about this planetary emergency no longer
feels like an option for me either. Given how disconnected policy is
from scientific reality in this country, an urgent and pragmatic
national conversation is now essential. Other-wise, living on a destabilised planet is the terrible truth that we will all face.
As a climate scientist at this fraught point in our history, the most
helpful thing I can offer is the same professionalism that the doctor
displayed late that night in Dad’s intensive-care ward. A clear-eyed and
compassionate look at the facts.
We still have time to try and avert the scale of the disaster, but we
must respond as we would in an emergency. The question is, can we
muster the best of our humanity in time?
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