On Monday, the Intergovernmental Panel on Climate Change released the second part of its Fifth Assessment Report. This second section attempts to summarise the research available on the likely impacts of human-induced climate change.
This builds on the first section of the Assessment Report, released back in September, which detailed our understanding of how the physical climate (temperature, rainfall, sea level, etc) is likely to change with increasing greenhouse gas emissions.
Unfortunately, the Summary for Policy Makers released today is not all that helpful to anyone trying to get a concrete understanding of what we might be in for if we don’t get our act together to take this problem seriously. Instead it leaves us with somewhat vague descriptions of what might or might not happen depending on what humans might do to either:
- lower emissions; or
The report is very far from alarmist, in fact a politician that reads it is likely to be left wondering what they need to do.
Why is the report so vague?
Assessing impacts starts to go beyond the hard physics and into the realms of biology which is still reasonably precise, but also the very messy study of human society. That’s because the impacts of climate change depend quite heavily on how humans respond to likely risks and the IPCC deliberately avoids making any assumption as to what humanity might do.
We might actually act to lower emissions or some miracle technology could come along so temperature rise isn’t particularly big.
And the consequences of temperature rise can be reduced through adaptation. So increased sea level and increased severity of flooding and storm surges aren’t that big a problem if your cities are located in areas that are elevated above land vulnerable to inundation and wave erosion, and where barriers are erected to counter such events. Likewise bushfires aren’t much of a problem if your house is built in areas away from forests or is highly resistant to catching fire. In addition even if agricultural yields suffer in places like the tropics and Australia, they could be somewhat offset by improvements in Russia and Canada.
If we were to reduce emissions to keep temperature rise to around 2 degrees above pre-industrial and planned sensibly to prevent urban development in areas exposed to risks from climate change, and allowed freer migration of people from vulnerable regions, then things probably wouldn’t be so bad.
Yet, are we actually on track to do such a thing? And if not, what is the future we’re headed for?
The IPCC’s Summary for Policy Makers released today doesn’t answer these two questions particularly clearly.
As an illustration, the report provides the following chart that attempts to summarise its overall assessment of how climate change would impact on five key areas of analysis. As you get to 4 degrees most things are in the red or even purple, meaning “high” to “very high” risks. But the reader is not all that well enlightened by the Summary for Policy Makers as to whether or not 4 degrees is a likely outcome, and what “high” to “very high” risk would mean for a particular country’s people.
Source: IPCC Fifth Assessment Report – Working Group II Summary for Policy Makers
Yet the thing is that the International Energy Agency’s forecast of energy usage based on current policies suggests we run a very high probability of a 4 degree rise.
If a 4 degree rise were to transpire, then in Australia the current available evidence suggest the following is likely:
– Unique and threatened systems (essentially cover natural biological ecosystems) ... say goodbye to the Great Barrier Reef and also the ski season and associated alpine habitat.
– Extreme weather events ... days of extreme heat would be very common over summer for large sections of Australia’s population (For Melbourne 1 in 5 days and Adelaide 2 in 5 days would be over 40 degrees) with all that entails for heat stress, bushfires, general liveability, additional power system infrastructure, and productivity of construction activity. Flooding events would also in all probability be particularly severe, requiring upgrades of major infrastructure to manage.
– Distribution of impacts ... Neighbours to our north with heavy dependence on agricultural subsistence would see large loss of agricultural yields required for basic survival, forcing people to emigrate resulting in serious stress for Australia’s border controls (unless relaxed). Also run-off in the Murray-Darling Basin is likely to decline such that irrigated agriculture is projected to decline by 90 per cent by 2100.
– Large-scale singular events ... Irreversible melting of the Greenland ice sheet and a 7m rise in sea level becomes likely, although it would unfold over several centuries.
And how do we perform on adapting to control for the negative impacts of climate change?
– Queensland and NSW state governments have relaxed planning policies that helped to guide development away from areas exposed to climate change impacts. For an example of what’s occurred see this article, How NSW will burn homeowners with its sea-level deception, by Climate Risk’s Karl Mallon.
– The Federal Government wants to amend legislation to remove a requirement for Infrastructure Australia to consider climate change impacts.
– The Federal Government has decided to move away from reforms to farmer drought assistance that would encourage them to withdraw from unsustainable regions.
There will no doubt be some extremely useful insights available from the detailed technical chapters of the IPCC’s Working Group II report. Unfortunately in trying to cover off on all possible scenarios, the Summary for Policy Makers becomes heavily compromised in what useful guidance it ultimately provides for policy makers and the media and general public.