The target should not be 1.5°C; rather we should aim for a safe climate. James Hansen told us in 2007 that to achieve a safe climate we need to bring GHG concentrations down to 350 ppm as soon as possible. That’s CO2 equivalent, not CO2. Current CO2e is not often quoted, but would be around 500 ppm on the basis that CO2 is about 80% of total GHGs. Also we need to focus on what we are doing to the planet over centuries and millennia, not just the next 50 to 100 years.
However, the IPCC team putting the report together were not asked what the goal should be. They were asked to build a scenario for achieving the 1.5°C warming limit specified as desirable in the Paris Agreement of 2015, and to look at the impacts of a 1.5°C world as against a 2°C world. Two Degrees came out of Europe in the 1990s, achieved a general currency, then became the official goal of at the Conference of Parties of the UNFCCC in Cancun in 2010. At that time there was a move mainly by many of the island states vulnerable it inundation for a more ambitious target. Essentially the whole group at Paris agreed to try.
However, while two degrees was commonly seen as a guardrail for a safe climate even by many scientist, it was never a scientifically derived goal for a safe climate.
The IPCC Special Report on 1.5°C is important because it shows that the path to 1.5°C has a high degree of difficulty and has implications which to most will not be acceptable. It’s importance is in changing the discourse, from being seen as an achievable safe guardrail to 1.5°C as difficult to achieve and far from safe.
I’ll give a short overview, then a summary of Gavin Schmidt’s response, then address some issues under specific headings.
When the UNFCCC decided to target 1.5°C there was little scientific literature on the subject, because all the focus had been on 2°C. However, scientists got busy and, from the media release, over 6,000 scientific papers were cited in the report, from 91 authors from 40 countries.
They consider that global net human-caused emissions of carbon dioxide (CO2) would need to fall by about 45% from 2010 levels by 2030, reaching ‘net zero’ around 2050. In energy, they see perhaps 2% coming from coal and very little from gas. Oil and fuel may still be used, but there would need to be carbon sinks to offset any such usage, as well as to offset methane from livestock and any other unavoidable emissions.
They foresee some 14 to 18 million square kilometres being set aside to grow trees to absorb carbon. Australia is 7.7 million sq km.
They have plotted a range of scenarios. The best offerings give only a 50% chance of staying within 1.5°C. Other scenarios involve “overshoot”. So if we want a better chance of staying within 1.5°C, or if we overshoot, then more atmospheric carbon will have to be removed and sequestered.
- The effectiveness of such techniques [is] unproven at large scale and some may carry significant risks for sustainable development, the report notes.
- Coral reefs would decline by 70-90 percent with global warming of 1.5°C, whereas virtually all (> 99 percent) would be lost with 2°C.
To most of the original proponents of a target more ambitious than 2°C this should be unacceptable and a deal breaker.
They say, as Hurricane Michael bears down on the Florida coast, possibly the strongest ever:
- “One of the key messages that comes out very strongly from this report is that we are already seeing the consequences of 1°C of global warming through more extreme weather, rising sea levels and diminishing Arctic sea ice, among other changes,” said Panmao Zhai, Co-Chair of IPCC Working Group I.
In “among other changes” add bushfires, or wildfires as they are called elsewhere, which have appeared in the Arctic circle and California in winter.
The Climate Council’s acting CEO, Dr Martin Rice, has called a 1.5°C world “our best possible future”. I would hope that policy makers, looking at a likely 1.5°C world, might think that the impacts and risks are unacceptable and decide to target a 350 ppm world, even if that means putting the economy on a war footing.
The Climate Council has prepared The good, the bad and the ugly: Limiting temperature rise to 1.5°C to put into context what this means for Australia. I recommend the Climate Council report, while sounding a caution about burnable carbon budgets (see below). Also the Climate Council says repeatedly that continuing on our present course will produce warming up to 3°C. There is no reason at all that warming would stop at that point.
While the Summary for Policy Makers has been approved by every government, including the United States, Australia and Saudi Arabia, the authors say the science has been preserved. The full scientific report is large. I added up five chapters and got 695 pages. I can’t cope with all that, so I’ve worked mainly from secondary comments and the Summary for Policy Makers. Hence the comments of scientists like Gavin Schmidt are valuable.
Gavin Schmidt’s response
Gavin Schmidt at RealClimate says of the IPCC Special Report on 1.5°C that responding to climate change is far more like a marathon than a sprint. He addresses directly the question Can we avoid going through 1.5°C?:
- So my answer is… no.
Gavin Schmidt is:
a climate modeller at the NASA Goddard Institute for Space Studies and Earth Institute at Columbia University in New York and is interested in modeling past, present and future climate. He works on developing and improving coupled climate models and, in particular, is interested in how their results can be compared to paleoclimatic proxy data. (Emphasis added)
Schmidt had been second-in-charge to James Hansen for at NASA GISS for many years, and has taken over the top job now that Hansen has moved on.
Schmidt says there are many issues related to the feasibility question of which physical climate-related issues are only one.
The basic issue is that the effort to reduce emissions sufficiently to never get past 1.5ºC would require a global effort to decarbonize starting immediately that would dwarf current efforts or pledges. This seems unlikely (IMO).
He says that if you want to stabilize CO2 then near-term reductions in carbon emissions by ~70% are required.
If you want to stabilize temperature, then even further (net) reductions are required.
If you want to stabilize sea level, then temperature drops would be required.
I think it is not appreciated that 1.5°C is a really big deal. Schmidt says it is a third of an ice age unit, that is, the amount of warming from the depths of the last ice age 20,000 years ago to the mid-19th Century.
From this I get the message that what is suggested is not enough to stabilise the climate.
What the IPCC report left out
Bob Ward, who is policy and communications director at the ESRC Centre for Climate Change Economics and Policy at the London School of Economics and Political Science, looks at what the IPCC left out in The IPCC global warming report spares politicians the worst details. He points out that the “summary of the report was approved line by line by governments, including the US, Australia and Saudi Arabia”. The governments, not the scientists. What they leave out includes:
- any mention the potential for human populations to migrate and be displaced as a result, hence the notion of climate change as a national security “threat multiplier”, which could increase the chances of political instability and conflict.
- important information about “tipping points” in the climate system, beyond which impacts become unstoppable, irreversible or accelerate.
- any mention of other important thresholds that might, for instance, halt the Gulf Stream in the Atlantic, or cause shifts in the occurrence of the monsoons in Africa and Asia.
There is a distinct possibility that scientists left out material that might be politically unacceptable.
When will the earth reach 1.5°C?
Tamino at Open Mind explains that the question depends on where you start from and which data series you use. He starts from 1900, or the more exactly the average of 1890 to 1909, and gets this:
Then points out that if you use Cowtan & Way you have a third less burnable carbon in your carbon budget than if you use HadCRUT4, which omits the Arctic (the fastest-warming region on earth).
In an earlier post he uses a trend line from 1970, and finds that the different data sets again vary, but roughly the answer is 2040, which is what the IPCC says.
However, David Spratt cites research by Benjamin Henley
and Andrew King showing that the 1.5°C target could be reached by between 2026 and 2031 depending on the phases of the Interdecadal Pacific Oscillation (IPO).
The difference here is that the IPCC follows the pack, whereas Spratt cites quality recent research. There is a risk that the new research is right. However, policy makers will blithely ignore it until it is incorporated perhaps in the next IPCC report years down the track.
Is there a carbon budget remaining for 1.5°C?
I addressed this issue in June 2014 in the post The game is up where I cited David Spratt and found evidence to support him. Spratt said:
We have to come to terms with two key facts: practically speaking, there is no longer a “carbon budget” for burning fossil fuels while still achieving a two-degree Celsius (2°C) future; and the 2°C cap is now known to be dangerously too high.
In Spratt’s commentary on the IPCC report before publication IPCC’s political fix on 1.5°C will undermine its credibility, he writes:
“We have no carbon budget left for the 1.5°C target and the opportunity for holding to 2°C is rapidly fading unless the world starts cutting emissions hard right now,” says Prof Michael Mann. Prof. Stefan Rahmstorf of Germany’s Potsdam University considers that we are now “in a kind of climate emergency” and that at least 1.5°C is “locked in”. (“Locked in” means that the warming will occur for the present level of emissions in the absence of large-scale carbon drawdown and/or solar radiation management.) Three other senior Australian scientists to whom I have spoken agree with the 1.5°C figure articulated by Mann and Rahmstorf. Some think it is likely to be somewhat higher.
Carbon Brief looks at why the IPCC expanded the carbon budget to 10 years of emissions at current rates from the three years of IPCC5.
You can choose your experts. I would have a lot of faith in Rahmstorf and Mann.
Sea level rise
If we look at my old favourite of sea level rise, the IPCC press release says that:
- by 2100, global sea level rise would be 10 cm lower with global warming of 1.5°C compared with 2°C.
From the Summary for Policymakers, Section B, p.10:
- Model-based projections of global mean sea level rise (relative to 1986-2005) suggest an indicative range of 0.26 to 0.77 m by 2100 for 1.5°C global warming, 0.1 m (0.04-0.16 m) less than for a global warming of 2°C (medium confidence).
Then we have a warning:
Sea level rise will continue beyond 2100 even if global warming is limited to 1.5°C in the 21st century (high confidence). Marine ice sheet instability in Antarctica and/or irreversible loss of the Greenland ice sheet could result in multi-metre rise in sea level over hundreds to thousands of years. These instabilities could be triggered around 1.5°C to 2°C of global warming (medium confidence).
They gesture to ice sheet decay, but then put then give us scenarios that put us in harm’s way, an outcome, I think caused because of the political nature of the context in which the paper was written.
The last interglacial, the Eemian, was reached about 120,000 years ago with CO2 emissions of only 300 ppm. Back then the sea was 6-9 metres higher than now. We have already left the Eemian behind us and are in territory back in the mid-Pliocene, about 3 million years ago, and seem to be heading for the mid Miocene, about 15 million years ago.
See also this graph from a paper by James Hansen and some other scientists with established reputations – Young people’s burden: requirement of negative CO2 emission:
David Spratt in this article says:
- By 1.5°C, a sea-level rise of many metres, and perhaps tens of metres will have been locked into the system. In past climates, carbon dioxide levels of around 400 ppm (which we exceed three years ago) have been associated with sea levels around 25 metres above the present. And six years ago, Prof. Kenneth G. Miller notes that “the natural state of the Earth with present carbon dioxide levels is one with sea levels about 20 meters higher than at present”.
In Scoping sea long-term level rise I posted David Archer’s 2006 graph:
From this graph we can readily see that when 10-12°C gives you close to 200 metres of sea level change each degree means a lot. Remember Gavin Schmidt said 1.5°C amounts to a third of an ice age unit, the amount of warming from the depths of the last ice age 20,000 years ago to the mid-19th Century.
Can the climate be stabilised at 1.5°C
This hinges on the phenomenon of ‘tipping points’. Graham Readfearn has recently posted a piece Earth’s climate monsters could be unleashed as temperatures rise.
Then there was the “Hothouse Earth” paper, which received widespread publicity recently – Trajectories of the Earth System in the Anthropocene.
I plan to do a post on this shortly, but the loss of Arctic sea ice, the potential instability of the Greenland and West Antarctic ice sheets, plus methane from permafrost and ocean clathrates comprise neglected factors within the IPCC scenarios.
In this discussion from the Climate Matters series Scientific Reticence: A Threat to Humanity and Nature with James Hansen, Pam Pearson and Philip Duffy, Pearson says that according to the best information, which last November is likely more recent than the IPCC process, the threshold for the irreversible melting of the Greenland ice sheet is a warming of 1.6°C. That’s 6-7 metres of SLR. However, if Greenland goes, so does West Antarctica (5-6 metres), land-based ice (1 metre) and a slice of East Antarctica.
Hansen says if you want to arrest ice sheet decay once it has started in earnest, you will need temperatures lower than pre-industrial.
Phillip Duffy, CEO at Woods Hole, said that land GHGs stored in northern permafrost lands amounts to three times what has been put into the atmosphere during the industrial era. He said that it is starting to go, but is not included at all in climate models. This alone, leaving aside other tipping points, casts serious doubt on whether it is possible to stabilise the temperature at 1.5°C.
Here’s David Spratt again:
Coauthor of the recent “hothouse” paper, Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research, says: “What we do not know yet is whether the climate system can be safely ‘parked’ near 2°C above pre-industrial levels, as the Paris Agreement envisages. Or if it will, once pushed so far, slip down the slope towards a hothouse planet. Research must assess this risk as soon as possible.”
The end of coal
Graham Readfearn has looked at the end of the fossil fuel era in IPCC Report Says 1.5C Climate Target Is Reachable, But Only With Rapid Fossil Fuel Phase Out:
- Four scenarios are modeled in the report that reflect different strategies governments could take to deliver “no or low overshoot” of the 1.5°C target.
Within these scenarios, by 2030 coal use would need to drop between 25 percent and 60 percent compared to 2010. By 2050, coal use drops between 73 and 97 percent.
Dr. Joeri Rogelj, of the International Institute for Applied Systems Analysis in Austria and a coordinator of the IPCC report chapter looking at pathways to cut emissions, told DeSmog: “The report provides quite clear messages for fossil fuels in a 1.5°C world, but also highlights that the future out to 2050 looks differently for the various types of fossil fuels.
“For coal the picture is the clearest. It is reduced 75 to 95 percent from 2010 levels across the entire economy and fully phased out from producing electricity.”
He said by 2050, renewables would need to generate between 70 and 85 percent of global electricity to meet a 1.5°C target.
“Oil use is reduced consistently across most of 1.5°C scenarios, about a 30 to 80 percent reduction from 2010 levels in 2050. Depending on how gas is used and how successful carbon capture and storage (CCS) is, natural gas use is reduced by more than 50 percent or stays roughly similar to 2010 levels.”
Climate change moves to the centre of politics
With all its limitations the IPPC report is a giant wake-up call. The LNP Coalition has been forced into overt inanities. Labor has taken the high ground, but their aim of 45% reductions in emissions is also manifestly inadequate.
The Greens may be in a position to exercise leverage after the next election. We’ll have to see how that works out.
Last election climate change was avoided by Labor because they knew it would produce a Turnbull rant, the mother of all scare campaigns, about blackouts caused by ideological frolics by South Australia with renewable energy causing blackouts, rather than a dirty big storm.
Last Monday Ben Potter wrote an article in the AFR Labor, Coalition square off in Great Barrier Reef election:
- Australia faces a climate change election on the fate of the Great Barrier Reef after a landmark report warned that coral reefs would be destroyed by global warming of 2 degrees Celsius.
Labor’s acting energy spokeswoman Penny Wong laid down the gauntlet on Monday, doubling down on Labor’s 45 per cent emissions reduction target and accusing the Morrison government of having “absolved themselves from any responsibility in tackling climate change”.
Of gas Potter says:
- Renewable energy would supply 70-85 per cent of electricity, and gas – another strong export industry for Australia – would supply 8 per cent of electricity when coupled with carbon capture and storage (CCS). CCS has been demonstrated technically but its cost is prohibitive and no commercial rollouts on existing thermal power stations have resulted from trials conducted in the US, Canada, Australia and China.
This opens the opportunity for discussion of other forms of firming wind and solar, such as pumped hydro. However, the discourse is moving away from gas as being the answer.
This graph shows the impacts of 1.5°C and 2°C in the Australian context:
This one highlights the policy choices:
Remember, the following graph represents our Department of Environment’s representation of current government policy:
Now we have the BCA (Business Council of Australia) saying that if government can’t do energy policy, business will go it alone:
Finally, the Energy Security Board, those “experts” who came up with the NEG (National Energy Guarantee) appear to be joining the rebellion.
The Coalsheviks are becoming isolated. Surely Scott Morrison will realise that is not a good place to be politically, unless the lights are on but no-one is home in the top room.
Update: The Guardian has come up with the following graphic in a number of articles, including this one, showing increasing risk in relation to warming:
It’s derived from the IPCC report, although not presented in exactly the same way. Anyone looking at that would conclude that we are entering a new phase of climate now which leaves behind the Goldilocks era of the Holocene.
The IPCC takes the average of the 1850 –1900 period as the baseline, then takes current warming as the observed global mean
surface temperature (GMST) for the decade 2006 – 2015. On this basis current warming is 0.87°C.
Hansen et al in Global Temperature in 2017 use the 1880 – 1920 period as a starting point, mainly because comprehensive global measurements are not available before 1880.
They use a linear trend line from 1970, when temperatures seriously started heading north. This gives them warming of +1.07°C at the end of 2017. The year 2017 itself was +1.17°C, the second highest ever with NASA GISS, with the last three years above the trendline. The 2017 result caused concern, because it followed two strong El Niño years and would normally be expected to fall below trend. So the trend may be quickening, time will tell.
Here’s the Hansen graph: