IPCC: Climate change is unequivocal with rapid and substantive emissions reduction required
A packed hall last thursday night (3 October) in Melbourne heard from Australian climate scientists on the latest science report from the Intergovernmental Panel on Climate Change (IPCC). I was one of four members of Climate Action Moreland who attended.
The Australian Meteorological and Oceanographic Society (AMOS) organised the free public event in Melbourne to explore the findings and significance of the latest comprehensive report on the science of climate change. It was so popular that 700 people registered to attend – the capacity of the hall, and a further 200 people enquiring had to be turned away or put on a waiting list.
The IPCC Fifth Assessment Report, IPCC Working Group 1: the Physcical Science, a review of the science of climate change, was released the previous Friday, September 27 in Stockholm Sweden. The scientific report found that the Science is now unequivocal on human caused climate change – deep and rapid cuts to carbon emissions are needed for a safe climate.
Upon publication of the report Professor Andy Pitman, Director of the ARC Centre of Excellence for Climate System Science at The University of New South Wales, and a review editor and previously a lead author on AR4 said in a comment to the Australian Science Media Centre:
“This is a bad news, and a good news story. The bad news is that the 2013 IPCC report finally puts to rest the role humans play in causing global warming. The good news is that it highlights we can still avoid 2 degrees of warming if we deeply and rapidly cut emissions of greenhouse gases. The future scale of climate change is therefore still within human control provided the global community does deeply and rapidly cut greenhouse gas emissions.”
Master of Ceremonies was environmental entrepreneur Rob Gell, who is Chairman of UNESCO Western Port Biosphere, and also Chair of Wildlife Victoria. The evening consisted of a keynote address, followed by questions posed to a panel of Australian climate scientists, some of whom were lead authors or reviewers of the report. Some questions had been gathered from twitter and facebook in the days leading up to the event, as well as questions from the audience.
Dr Scott Power, Senior Principal Research Scientist, Bureau of Meteorology and Coordinating Lead Author of Chapter 11, Fifth Assessment Report, IPCC Working Group 1, presented the keynote address which presented the major scientific conclusions and summary of the report. Watch it as a basic introduction to the report. (27’32”)
The Scientific Panel who answered questions included Dr Scott Power, as well as:
Dr Julie Arblaster
– Senior Research Scientist, Bureau of Meteorology
– Lead Author of Chapter 12, Fifth Assessment Report, IPCC Working Group 1
Professor Neville Nicholls
– Professor, School of Geography and Environmental Science, Monash University
– Past President, Australian Meteorological and Oceanographic Society
Dr Penny Whetton
– Senior Principal Research Scientist, CSIRO Marine and Atmospheric Research
– Lead Author of Chapter 25, Fifth Assessment Report, IPCC Working Group 2
Dr Malte Meinshausen
– Honorary Senior Research Fellow, University of Melbourne
– Senior Researcher, Potsdam Institute for Climate Impact Research, Germany
About 30 questions were asked including questions on: the carbon dioxide lag effect in the atmosphere, sea level rise, capacity of the ocean to continue as a CO2 sink, the problem of ocean acidification, longer term projections past 2100, impact on tropical cyclones, likelihood of increasing desertification in Australia, high risk low probability outcomes and how they are treated by the IPCC, whether reduction in short term emissions is useful, impact of 2 degrees warming on food production, whether climate change will impact on volcanic activity, Geo-engineering, adaptation and heatwaves, and emission scenarios and current (business as usual) trajectory.
The IPCC and high Risk, low probability impacts
The question asked by Dr Barrie Pittock from the audience was one of the more interesting and thought provoking ones. Barrie Pittock led the Climate Impact Group in CSIRO until his retirement in 1999. He contributed to or was a lead author of all four previous major reports of the Intergovernmental Panel on Climate Change. His question was on how the IPCC considers high risk low probability outcomes.
I asked a similar question on twitter, which wasn’t raised at the meeting, with regard to sea level rise (Read more on this on my blog: Is Climate Change causing an exponential rate of Ice sheet Mass Loss, sea level rise?)
“#askamos James Hansen thinks multi-metre sealevel rise by 2100 due to non-linear dynamic ice sheet loss is quite possible with BAU global warming of 3-6°C. There are still many scientific unknowns to model ice sheet collapse accurately. Could the IPCC AR5 process for sea level rise projections still be too conservative?”
Here is what Barrie Pittock asked: “I had trouble right from the beginning with the IPCC on communication and I think it is explicitly brought out in this report with the definitions of uncertainty.” he said, “A critical point is that climate change is a matter of risk assessment.”
He used the example of the probability of a 2 metre rise in sea level by 2100, that even if it is unlikely, it needs to be communicated. “A 1 in 10 chance or a 1 in 3 chance of something terrible happening is important and politicians and others should take note of it.” he explained.
Dr Penny Whetton from CSIRO responded to the question:
“I think Barrie expressed it very well. Neville mentioned earlier the evolution of very careful language in the IPCC. One of the down sides to that is the IPCC has tended to focus on statements that it can make confidently. As a consequence it probably doesn’t put enough emphasis on rare but possible events. That’s one of the things you always have to look at when managing risky issues, for risky issues such as this. You don’t take out fire insurance on your house because you think it is likely to burn down, you do it because it may burn down in a 1 in 100 case. It is those warmings of 5 or 6 degrees which may be treated as low liklihood according to the IPCC. What they are also saying is that they are still possible and we need to actually look at those, particularly when it comes to responses.”
The 2 Degree Limit is a political value judgement, not science
One of the few important outcomes of the 2009 Copenhagen UNFCCC meeting was there was agreement by all Governments to limit global warming to a maximum of two degrees, although small island nations in particular argue for a lower level. This was further confirmed at the meeting in Cancun in 2010, and Durban in 2011. Although we talk about the importance of a 2 degree limit, this is an arbitrary point and value judgement which the intergovernmental political process has decided upon as beyond which lies ‘dangerous’ impacts of climate change. But the science tells us we may see high impacts and tipping points crossed even below this arbitrary point.
Dr Malte Meinshausen made clear that two degrees is not the IPCC target, “There are thresholds and the more warming you have, the more surprises you have to expect, and the more impact we are going to see. In fact small island states say ‘2 degrees is too high for us. We are not going to have our islands here for another 100 years with sea level rise projected. We want to survive’ so they want a 1.5 degrees target. It is important. It is a value judgement about where do you want to stop climate change. The value judgement has been done by most of the Governments, but it is not a value judgement that can come or should come from science.”
Dr Penny Whetton, in responding to another question, made it clear that 2 degrees of global warming is too hot for coral reefs, including Australia’s Great Barrier Reef. (For more information see my blog post on Global Warming imperils coral reefs: 2 degrees warming is too hot say scientists)
Climate Adaptation and heatwaves
Climate adaptation is going to be essential, even if we mitigate and rapidly and drastically reduce emissions because of the substantial inertia in the climate system and the cumulative lag effect of carbon dioxide in the atmosphere.
I asked a question on climate adaptation and heatwaves, which wasn’t raised at the meeting. But Professor Nicholls did give a response to a question on the relative importance of climate adaptation and heatwaves. Here is my question:
#askamos Australia has just experienced its hottest 12 month period on record. Extreme heatwave events are predicted to become of longer duration and more intense as global average temperatures increase in coming decades, even if we rapidly decarbonise our society in best case scenarios.
Heatwaves also exacerbate and amplify the Urban Heat Island Effect so that the impact is magnified (Li et al 2013). This affects infrastructure (think warped train lines, power spikes), reduces work capacity (Dunne et al 2013) and increases heat stress related mortality. These are direct economic and health impacts which we experience now in our cities with climate change. (think 2009 heatwaves associated with Black Saturday bushfires, 2013 Angry Summer)
These questions are less about science more about adaptation. Prof Nicholls might like to answer:
1. What are the future projections for extreme heat events in Australian cities?
2. Are our health authorities, hospitals and mortuaries adequately prepared?
3. Are all levels of Government taking adequate measures to upgrade urban infrastructure and the urban environment for more climate resilience?
4. Are current programs in place to inform and prepare the public on extreme heat events adequate and sufficient? What more should be done?
Professor Nicholls explained we need to engage in adaptation regarding the impact of climate change on heatwaves, which will affect people especially in urban areas like Melbourne.
“I am sure adaptation is going to be part of the way we react to climate change and we already are. Since 2003 when we had a massive heatwave with massive mortality in Europe, most cities in most developed countries around the world have been developing heat wave alert systems in an attempt to make sure that doesn’t happen. Now that has benefits now even if we don’t get any further climate change. It has even more benefits in the context of global warming. Those systems, we have one in Melbourne and Victoria; there are ones under development in the rest of Australia. They are already saving lives, and they will save lots of lives, but they won’t save everyones life. It will be hot from this global warming. So adaptation is an essential tool in our weaponry against climate change but it can’t do it alone without mitigation to actually slow things down it is very very difficult for us to attack. Even in what is quite a simple area: human mortality related to heat is actually not too hard to actually think about what we can do. When you get to technical infrastructure in the context of a continuing warming planet, that is actually a much harder to adapt to. It really is difficult. If we don’t mitigate it is going to be tough.” said Professor Nicholls.
Carbon budgets and current emission trajectory
Carbon budgeting was included in this IPCC report for the first time as a major section. Dr Malte Meinshausen made the point that the first carbon budget study was actually published in 1978 and said that we can burn no more than 10 per cent of our known fossil fuel reserves without getting into trouble.
Dr Malte Meinshausen also highlighted in answer to the very last question that we are currently tracking at the largest emissions scenario.
Hottest September and hottest 12 months on record for Australia
Even though the global land surface temperatures have appeared to plateau since 1998 – a global hiatus – other measurements show global warming has continued with continued warming of the oceans, sea level rise, melting of Arctic sea ice, continued retreat of mountain glaciers. 2000 to 2010 was also the hottest decade on record.
Significantly, Australia has broken many temperature records this year with the extreme January heatwave and Angry Summer, sizzling warming into late Autumn, a relatively warm Winter, and now the hottest September on record averaged across Australia, and the hottest 12 months on record. Australia is also on track for the hottest calendar year this year.
The Bureau of Meteorology issued a Special Climate Statement updated on 13 October: Exceptionally warm late winter/early spring with unusually persistent warm conditions over the last 12 months (PDF). You can read the Climate Council analysis on this statement: ’OFF THE CHARTS – Record breaking September Heat and Climate Change’.
The BOM statement said:
Averaged over Australia, monthly maximum temperatures were 3.41 °C above average for September and monthly minimum temperatures 2.09 °C above average, combining to a monthly mean temperature 2.75 °C above average.
All of these have set new September records for Australia, with the monthly mean temperature more than a degree above the previous record. The monthly maximum and mean temperatures have also set Australian records for the largest positive temperature anomaly observed in any month. (The previous records are respectively, 3.16 °C above average in August 2009, and 2.66 °C above average in April 2005).
Some key facts from the BOM statement regarding mean temperature records for Australia from the last 12 months:
- Australia’s warmest month on record (January)
- Australia’s warmest September on record
- Australia’s largest positive monthly anomaly on record (September)
- Australia’s warmest summer on record (December 2012 to February 2013)
- Australia’s warmest January to September period on record
- Australia’s warmest 12-month period on record (broken twice, for the periods ending August and September)
- Indeed, Australia’s warmest period on record for all periods 1 to 18 months long
ending September 2013
- Two significant daily maximum temperature records were also set this year: Australia’s hottest summer day on record (7 January) and Australia’s warmest winter day on record (31 August)
Rob Gell read from the BOM statement and asked the science panel about the significance of these new records.