Graham Williamson

Professor Nerilie Abram

ARC Centre of Excellence for Climate Extremes

Dear Professor,

I refer to your article, “Australia’s Angry Summer: This Is What Climate Change Looks Like”.

No doubt like most people who are drawn to your article, I am interested in solutions or effective preventative actions, especially during this tragic time, and it is in this context I refer to your article.

You state:

The catastrophic fires raging across the southern half of the continent are largely the result of rising temperatures […] Of course, unusually hot summers have happened in the past[…]

Apparently they were hotter in the past.

[…] so have bad bushfire seasons. But the link between the current extremes and anthropogenic climate change is scientifically undisputable.

The fires raging across the southern half of the Australian continent this year have so far burned through more than 5 million hectares. To put that in context, the catastrophic 2018 fire season in California saw nearly 740,000 hectares burned 

Why do you feel it is more appropriate to compare it to California fires rather than the 1851 Australian fire which also burnt out 5 million hectares?

[…]Climate change is making Australian wildfires larger and more frequent because of its effects on dryness and fire weather […] The current summer has presented the perfect storm for wildfire. Long-term climate warming, combined with years of drought, colliding with a set of climate patterns that deliver severe fire weather […] In the tropical Indian Ocean, one of the most severe positive Indian Ocean Dipole (IOD) events on record played out this year.

The unusually cold sea-surface temperatures in the eastern Indian Ocean cut off one of Australia’s critical moisture sources, adding to the ongoing drought in southern parts of the country […] Again, climate change is part of the story, because anthropogenic warming is causing positive IOD events to become stronger and more frequent […]The role of climate change in the unprecedented fires gripping Australia is also well understood by our emergency services. Sadly, though, this summer has occurred against a backdrop in which the Australian government has argued, on the world stage, to scale back our greenhouse-gas-emissions-reduction targets. Our leaders are literally fiddling while the country burns.

The fundamental question here is: are you referring to human-caused climate change or to natural climate change? In other words, are you suggesting you have scientific evidence which confirms lowering emissions will prevent or lessen bushfires? If so, could you please supply that evidence?

You further claim:

Increasing temperatures cause increased evaporation that dries the soil and fuel load. More than a decade ago, the Intergovernmental Panel on Climate Change (IPCC) concluded that ongoing anthropogenic climate change was virtually certain to increase in intensity and frequency of fires in Australia. This assessment of the science evidence has been repeated in countless reports, including the IPCC’s Climate Change and Land report, released in August 2019 […]

One of the factors driving this long-term loss of winter rainfall is the positive trend in the Southern Annular Mode (SAM). This change is causing the westerly winds that circle the Southern Ocean to shift southward toward Antarctica, causing rain-bearing winter cold fronts to pass south of the Australian continent. The role of anthropogenic climate change in driving this trend in the SAM is also clear in the science.

You cite the IPCC Climate Change 2007 report as stating “anthropogenic climate change was virtually certain to increase in intensity and frequency of fires in Australia.” Could you please state your page reference for this citation? When I examined this report I could find nothing to support your claim. According to the report:

Climate Change 2007

Australia and New Zealand

The region is already experiencing impacts from recent climate change […]Since 1950 there has been a 0.3 to 0.7°C warming in the region, with more heat waves, fewer frosts, more rain in north-western Australia and south-western New Zealand, less rain in southern and eastern Australia and north-eastern New Zealand, an increase in the intensity of Australian droughts, […]

The climate of the 21st century is virtually certain to be warmer, with changes in extreme events (medium to high confidence).

In summary, the IPCC state in their 2007 report: “Increased fire danger is likely with climate change; for example, in south-east Australia the frequency of very high and extreme fire danger days is likely to rise 4 to 25% by 2020 and 15 to 70% by 2050”

What you neglected to mention however, is that the IPCC specifically define the term ‘climate change as including natural (irreversible) climate variability. In other words, rewriting the above conclusion in accord with the intended definition utilised by the IPCC, we see the following:

Increased fire danger is likely if there are natural &/OR human induced climatic changes”.

Clearly, your assertion that the report states “anthropogenic climate change was virtually certain to increase in intensity and frequency of fires in Australia”, is contradicted by the report itself; unless of course, you can supply more evidence. 

Why did you fail to explain these facts to readers? Were you genuinely unaware of the facts?

You further cite the IPCC’s Climate Change and Land report, released in August 2019, but here again you fail to point out that the IPCC specifically includes natural climate variability and does not separate this from human induced changes when it comes to fires.

According to the report:

Technical Summary, 2019. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems

Climate change is playing an increasing role in determining wildfire regimes alongside human activity (medium confidence), with future climate variability expected to enhance the risk and severity of wildfires in many biomes such as tropical rainforests (high confidence). Fire weather seasons have lengthened globally between 1979 and 2013 (low confidence). Global land area burned has declined in recent decades, mainly due to less burning in grasslands and savannahs (high confidence). While drought remains the dominant driver of fire emissions, there has recently been increased fire activity in some tropical and temperate regions during normal to wetter than average years due to warmer temperatures that increase vegetation flammability (medium confidence). The boreal zone is also experiencing larger and more frequent fires, and this may increase under a warmer climate (medium confidence). {Cross-Chapter Box 4 in Chapter 2}

I also draw your attention to the IPCC’s assertion that “drought remains the dominant driver of fire emissions”, which again contradicts your claim that“The catastrophic fires raging across the southern half of the continent are largely the result of rising temperatures”.

The connection between droughts and fires is of particular interest since scientists have indicated that there is no reliable evidence humans are causing droughts (I recently reviewed the evidence) and, in fact, the IPCC has acknowledged that earlier claims droughts were caused by human induced climate change were false or exaggerated

Once again, however, you failed to communicate these vitally important facts to your readers. Why?

You have failed to substantiate your claim that “the link between the current extremes and anthropogenic climate change is scientifically undisputable”

If you have evidence of this could you please provide it?

I think you will agree with me, especially at this tragic time with so many people suffering, what is needed is accurate and useful information.

To this end, I look forward to a clarification, or alternatively, a retraction.

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