Tag Archives: climate sensitivity

Climate change by the numbers

In 1999 NASA lost its $125-million Mars Climate Orbiter because spacecraft engineers failed to convert from Imperial to metric measurements when exchanging vital data before the craft was launched. Numbers are important!

When Michael Le Page attempts to sort out the numbers in climate science (probably pay-walled) it’s not as straight forward as you might think. For starters we are given this image:

When ice melts, sea level rises – but how much, and how fast? Paul Nicklen/National Geographic Creative

Sorry, when floating ice melts the sea level does not rise. The caption is misleading. Continue reading Climate change by the numbers

Hansen got it right

In 1988 James Hansen gave his famous testimony to the US Senate. For the short story, go to Tamino at Open Mind. For the longer story, Gavin Schmidt at RealClimate, plus the commentary thread is best.

Hansen told the politicians that our production of greenhouse gases, principally CO2, N2O, CH4 and CFC, were warming the climate. He said temperatures would go up in the coming years: Continue reading Hansen got it right

Climate clippings 125

1. Paris climate talks won’t keep warming below the dangerous 2°C Limit

Joe Romm at Climate Progress believes the Paris climate talks should not be written off as a failure if they don’t do enough to keep warming below 2°C. He thinks the CFC ozone layer example is apt. The Montreal Protocol was concluded in 1987. Initially the protocol’s targets and timetables slowed the rate of growth of concentrations only slightly and would have still led to millions of extra cases of skin cancer by mid-century.

President Reagan endorsed the protocol, and the Senate ratified it. By the end of 1988, 29 countries and the European Economic Community — but not China or India — had ratified it. The treaty came into effect the next year. But it took many more years of negotiations, continuous strengthening of the scientific consensus, and significant concessions to developing countries before amendments to the treaty were strong enough and had enough support from both rich and poor countries to ensure that CFC concentrations in the air would be reduced.

Elsewhere 14 high-profile CEOs want to decarbonise the economy completely by 2050. They are the B Team led by Virgin founder Richard Branson. See also at The Guardian.

2. 2013 record heatwave ‘virtually impossible’ without climate change

That’s according to a new report from the Climate Council.

From The Guardian:

The country experienced its hottest day, month, season and calendar year in 2013, registering a mean temperature 1.2C above the 1961-90 average.

The Climate Council says recent studies show those heat events would have occurred only once every 12,300 years without greenhouse gas emissions from human activities.

Record hot days have doubled in Australia over the past 50 years. During the past decade heat weather records were set three times more often than cold ones.

Heatwaves across Australia are becoming hotter, lasting longer, occurring more often and starting earlier.

The ABC article has handy links to other sites.

The following graph shows the number of days each year where the Australian area-averaged daily mean temperature was above the 99th percentile for the period 1910-2013:

Hot days Australia_cropped_600

3. Two degrees by 2036

Michael Mann using an Earth energy balance model has calculated that we could reach 2°C of warming as early as 2036. To stay within the 2°C guardrail we need to limit CO2 concentrations to 405 ppm. It would be 450 ppm but for the aerosol issue. If we cease burning coal we lose the cooling effect of the crap that coal spews into the atmosphere along with CO2.

Mann has done the calculation on the basis of climate sensitivity of 3°C. Problem is, he says, that this modelling is based only on short term feedbacks.

David Spratt at Climate Code Red has done a long and thorough post based on Mann’s article. Spratt looks in some detail at the longer term climate sensitivity issue, drawing also on the work of James Hansen, Aradhna Tripati and others. Hansen found that climate sensitivity with long term feedbacks was considerably higher than 3°C; Tripati found that in the Miocene with CO2 concentrations similar to now “temperatures were ~3° to 6°C warmer and sea level was 25 to 40 meters higher than at present”.

Spratt also reminds us that 2°C warming is not safe.

4. Would turfing Abbott help climate change policy?

In short, yes, but perhaps not a lot. The conservative side of politics is still infested with climate change denialists.

Mother Jones in an article One of the World’s Worst Climate Villains Could Soon Be Booted From Office would clearly like to see the back of Abbott. Julie Bishop has a background of denialism, but is pragmatic and has understood from the Lima experience that our stance on climate is negatively affecting our international standing.

Turnbull stated back in 2009:

“I will not lead a party that is not as committed to effective action on climate change as I am.”

He would now, of course.

Tristan Edis looks at actions Turnbull might get away with. Giles Parkinson thinks he might rescue renewable energy and could adapt Direct Action into a baseline and credit scheme.

See also Lenore Taylor at The Guardian.

Climate sensitivity and the myth of ‘burnable carbon’

The ink is scarcely dry in the IPCC’s fifth report when it has become clear that they have badly underestimated the risks in two key areas – sea level rise and climate sensitivity. With respect to the latter, David Spratt at Climate Code Red comes to the conclusion that there is no carbon budget left, no ‘burnable carbon’ if we are looking for a safe climate.

As I said in Climate clippings 97 the fourth IPCC report in 2007 estimated that the planet will warm between 2 and 4.5°C warming in response to a doubling of the amount of CO2 in the atmosphere, with a best estimate of 3°C. This estimate was followed by a number of studies suggesting a lower sensitivity, leading the IPCC’s fifth report to extend the range to 1.5°C at the lower end and omit a best estimate entirely.

Back in May Dana Nuccitelli reported on a study by Kummer & Dessler which showed that recent studies suggesting an insensitive climate are flawed. They eliminate the lower part of the range but still converge on a value around 3°C.

Spratt now reports:

a recent paper by Sherwood, Bony et al looking at clouds and atmospheric convective mixing finds that on “the basis of the available data… the new understanding presented here pushes the likely long-term global warming towards the upper end of model ranges.” Taking “the available observations at face value,” they write, “implies a most likely climate sensitivity of about 4°C, with a lower limit of about 3°C.”

Problem is that these estimates are based on short-term feedbacks only, or what is known as Equilibrium Climate Sensitivity (ECS). Spratt says:

Paleoclimatology (study of past climates) suggests that if longer-term feedbacks of “slow” factors are taken into account, such as the decay of large ice sheets, changes in the carbon cycle (changed efficiency of carbon sinks such as permafrost and methane clathrate stores, as well as biosphere stores such as peatlands and forests), and changes in vegetation coverage and reflectivity (albedo), then the Earth’s sensitivity to a doubling of CO2 could itself be double that of the “fast” climate sensitivity predicted by most climate models, or around 6°C.

A measure of these effects for a doubling of CO2 is known as Earth System Sensitivity (ESS).

He says that “ESS is generally considered to come into play over periods from centuries to several millennia.”

If that’s how the earth system operates, that’s how we must operate.

Now in February 2013, new research on Russian cave formations measuring historic melting rates gives rise to a warning that a +1.5°C global rise in temperature compared to pre-industrial is enough to start a general permafrost melt.

Other research indicates that thaw and decay of permafrost carbon, once seriously started, is irreversible.

Rather than 2°C as a guardrail to avoid dangerous climate change, we must expect danger to occur at 1.5°C.

We are pushing the climate harder than it has been pushed in the last 65 million years. In this post I asked what does 4°C mean?

Professor John Schellnhuber, Director of the Potsdam Institute for Climate Impact Research, provides a stark assessment of the difference between a rise of two and four degrees. ‘The difference,’ he says, ‘is human civilisation. A 4°C temperature increase probably means a global [population] carrying capacity below 1 billion people’.

For a safe climate as we saw in The game is up, again quoting David Spratt:

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.

I hate to say this, but at the leading edge people are catching up with what James Hansen was saying back in 2008. Here’s a table from page 17 of the 2011 paper Earth’s Energy Imbalance and Implications where he gives four categories of climate sensitivity:

Climate sensitivity_cropped_600

The fourth doesn’t bear thinking about. Clearly he’s a dangerous man and needs to be locked up.


Climate clippings 97

Climate clippings_175 This edition contains a miscellany from the absolutely central scientific issue of climate sensitivity to adaptation in Bangladesh.

1. Sense about climate sensitivity

The fourth IPCC report in 2007 estimated that the planet will warm between 2 and 4.5°C warming in response to a doubling of the amount of CO2 in the atmosphere, with a best estimate of 3°C. Since then a number of studies suggested a lower sensitivity, leading the IPCC’s fifth report to extend the range to 1.5°C at the lower end and omit a best estimate entirely.

Dana Nuccitelli reports on a new paper by Kummer & Dessler which shows that recent studies suggesting an insensitive climate are flawed. Without going into the detail they converge on a value around 3°C.

2. CO2 fertilization won’t slow global warming

Some contend that increased CO2 in the atmosphere will enhance plant growth leading to an increase in soil carbon. A study of this issue found that any such gains were offset by increased microbial activity in soils. Along the way the researchers found that soil carbon was less stable than previously thought.

3. Bangladesh uncovers the crippling cost of climate change adaptation


Bangladesh has found the cost of climate change adaptation quite crippling in a new report.

They are spending $1 billion a year, 6-7% of their annual budget, on climate change adaptation. Only a quarter comes from aid.

The irony of the finding will be lost on few people: the average European citizen emits as much carbon in 11 days as the average Bangladeshi in an entire year. Yet it is the government and the people of Bangladesh who are expected to pay for the escalating costs.

Within the country it is the poor who are most severely affected.

After the report Bangladesh sees climate adaptation expenditure as central to their development.

4. Deutsche Bank rules out funding for controversial Abbot Point coal terminal

Deutsche Bank:

said it would not finance an expansion without the assurance of both the Government and UNESCO that it would not damage the Great Barrier Reef.

“We observe that there is no consensus between UNESCO and the Australian Government regarding the expansion of Abbot Point,” it said.

“Since our guidance requires such a consensus as a minimum, we would not consider a financing request.”

Thanks to John Davidson for the heads-up.

5. Onshore wind cheapest form of power

In Europe, that is
according to Portugal’s EDP, which has around 24GW of generation, of which around 8.7GW is in onshore wind.


CCGT is baseload gas.

John D has more detail at Climate Action 04.

The same article tells us that Keith DeLacy, former Qld Labor treasurer who would do just about anything to turn a buck, said on the front page of the Oz that renewables had “no place in a modern society”.

Meanwhile economist Jeffrey Sachs, advisor to UN secretary general on the Millennium Development Goals, is in Australia telling us that we can’t mine all that coal unless we invest in carbon capture and sequestration technology. We just need to get serious:

Put in real money, probably $20 to $30 billion I would say, minimum, to get scaled, serious demonstration programs working in China, in India, in Australia, in Canada, in the United States and to test the geology and the engineering of this technology.

Sachs is a man who thinks big!

6. EU’s energy strategy

Not surprisingly, the EU has been taking another look at its energy security strategy in view of the political instability to their east.

The EU imports over half the energy it consumes at a cost of more than €1 billion per day. Two-thirds of its gas is imported, with nearly a third coming from Russia. Half of that is transported via Ukraine.

Russia has already twice pulled the plug on gas supplies to Europe arriving via Ukraine, in 2006 and 2009.

The bottom line is that there will be a continued dependence on Russia for the foreseeable future:

The EU energy security strategy doesn’t look like it’ll take a rifle to that Russian bear just yet. But with a tweak to address vulnerability here and a spotlight on energy dependence there it may just help the EU avoid a mauling – and drive an ambitious EU 2030 climate and energy deal too.

Shale gas and nuclear energy are being left as options that member states can explore if they wish.

Reminder: Use this thread as an open thread on climate change.

State of the Climate, 2014

Front page_cropped

CSIRO and the BOM have released their State of the Climate 2014 report. Pretty much the same story you’ve heard before, only a bit worse.

There’s a good summary at the special BOM site, where you can download the report. Other than that Climate Citizen has perhaps the best summary.

Graham Readfearn at Planet Oz riffs off the Dorothea Mackellar theme of a “sunburnt country” of “droughts and flooding rains”.

At Radio National’s PM Mark Colvin interviewed CSIRO’s Dr Penny Whetton.

At The Conversation Professor Neville Nicholls emphasises rising heatwaves and fires. Sophie Vorrath has more at RenewEconomy.

I’ll comment on a few sundry aspects.

Level of greenhouse gases

We are told that the global mean for CO2 in 2013 was 395 ppm, or “likely the highest level in at least 2 million years”. Back in the 2012 report the figure of 390 ppm for 2011 was described as “a level unprecedented in the past 800,000 years”. David Spratt at Climate Code Red added a corrective addendum “that should be 15 million years.”

Spratt referenced the work of Aradhna Tripati:

The last time carbon dioxide levels were apparently as high as they are today — and were sustained at those levels — global temperatures were 5 to 10 degrees Fahrenheit [DS: 3 to 6 degrees Celsius] higher than they are today, the sea level was approximately 75 to 120 feet [BB: 23 to 36 metres] higher than today, there was no permanent sea ice cap in the Arctic and very little ice on Antarctica and Greenland.

I’m amazed at how often these reports understate the gravity of the situation, presumably for fear of being written off as alarmist.

The report usefully adds the other main greenhouse gases to give a CO2 equivalence figure:


Please note the nitrous oxide and synthetic greenhouse gases are given in parts per billion.

In terms of CO2 equivalence we are now the 480 ppm. We should be red alerts everywhere and an emergency meeting of the G20, or something. The sad fact is that no policy agenda adopted by a political party has aspired to a safe climate. In fact the Garnaut Report and the Clean Energy Future Package legislated by Labor, the Greens and the indies, only ever aspired to 450 or 550 ppm CO2e. James Hansen in nominating 350 ppm as an initial target was very clear that this needed to assume net zero for the other greenhouse gases. What we are committed to now is a very unsafe climate as the effects play out in the short, mid and longer term.

Abbott was going to leave climate change off the forthcoming G20 agenda for Brisbane until the Americans complained.

Prospective temperature increases

Temperatures are projected to rise by 0.6 to 1.5°C by 2030 compared to the climate of 1980 to 1999. Warming by 2070 is projected to be 1.0 to 2.5°C for low greenhouse gas emissions and 2.2 to 5.0°C for high emissions.

We’ll achieve the upper bound if we continue as we are; the lower bound lacks credibility. To the ranges given we need to add 0.6°C in order to obtain the values for change since pre-industrial.

Again, we are clearly heading for dangerous climate change.

At time of writing there was a short piece in New Scientist citing three recent studies which indicate that climate sensitivity may have been under-estimated. Drew Shindell of NASA GISS:

“Sensitivity is not down at the low end,” Shindell says. “We can’t take any solace from warming being slower of late.”

That means we must cut our emissions fast, he says, or the planet could warm by 6°C by 2100.

Warming of 4°C is usually given as the level where civilisation as we know it comes into play. For Australia in a 4°C world, see Gabrielle Kuiper at Climate Code Red.

Hot days and heat waves

This graph shows the incidence of days in a year when the temperature is in the hottest 1% relative to 1910-2013:


Graham Readfearn points out:

Starting from 1910 when Australia’s records start, it took 31 years for the country to rack up 28 days hot enough to fall into that top one per cent.

2013, however, managed to deliver this same number of extremely hot days in a single year.

Precipitation changes

The following map shows the rainfall variation in deciles since 1995-1996 for the northern wet season of October to April:


The next map shows the rainfall variation in deciles since 1995-1996 for the southern wet season of April to November:


I believe that Sydney, which has dominant autumn/early winter rainfall, sits on the border between the summer and winter rainfall zones.

Clear patterns of change are becoming obvious. Apart from southern areas there is distinct drying in large tracts of Queensland, especially in winter.

This is disturbing:

The reduction in rainfall is amplified in streamflow in our rivers and streams. In the far southwest, streamflow has declined by more than 50 per cent since the mid-1970s. In the far southeast, streamflow during the 1997–2009 Millennium Drought was around half the long-term average.

Could be that we’ll increasingly have to rely on damaging floods to fill our dams.


There’s more, of course, including the prospect of losing our reef ecosystems.

Climate change is upon us.

Climate clippings 58

Methane worries

A team of Russian research scientists have been surveying the seabed of the East Siberian Arctic Shelf off northern Russia for nearly 20 years.

In an exclusive interview with The Independent, Igor Semiletov, of the Far Eastern branch of the Russian Academy of Sciences, said that he has never before witnessed the scale and force of the methane being released from beneath the Arctic seabed.

“Earlier we found torch-like structures like this but they were only tens of metres in diameter. This is the first time that we’ve found continuous, powerful and impressive seeping structures, more than 1,000 metres in diameter. It’s amazing,” Dr Semiletov said. “I was most impressed by the sheer scale and high density of the plumes. Over a relatively small area we found more than 100, but over a wider area there should be thousands of them.”

I realise this has been linked to three times in the previous thread, but it’s important and not everyone reads the comments threads.

A separate study has found that the methane stored in permafrost is three times larger than earlier estimates. It could release 1.7-5.2 times more carbon than previously thought, depending how rapidly the world warms.

In a cautionary note here, James Hansen reckons we are forcing the system 20,000 times faster than commonly happened through natural caused in the past 50 million years. Continue reading Climate clippings 58

Climate clippings 42

Climate sensitivity

James Wright at Skeptical Science has constructed a summary of some recent work done by James Hansen and colleagues. Climate sensitivity is the temperature change caused by a doubling of CO2. In this post I referred to a paper by Hansen et al, Earth’s energy imbalance and implications. Wright is working from a paper by Hansen and Sato entitled Paleoclimate implications for human-made climate change which contains much of the same material, including Table 1 on p16.

The bottom line goes like this:

The exact value of climate sensitivity depends on which feedbacks you include, the climate state you start with, and what timescale you’re interested in. While the Earth has ice sheets the total climate sensitivity to CO2 is up to 8°C: 1.2°C direct warming, 1.8°C from fast feedbacks, 1°C from greenhouse gas feedbacks, and nearly 4°C from ice albedo feedbacks. The slow feedbacks have historically occurred over centuries to millennia, but could become significant this century. Including CO2 itself as a feedback would make climate sensitivity even higher, except for the weathering feedback which operates on a geologic timescale. (Emphasis mine)

CO2 alone, not CO2e, of 450ppm is likely to give us an ice-free planet – eventually.

I take it that the stability we’ve had during the Holocene is unusual. Upset the balance with a bit of the trace gas CO2 and the system can go wild. Continue reading Climate clippings 42

Immodest perturbation

Incurious and Unread in this comment talked about a “modest perturbation” and positive and negative feedbacks:

I can’t help feel that Gaia is letting us down here. It seems that we keep on getting positive feedback effects on the climate rather than negative feedback.

That seems kind of odd. As I understand it, the climate has been fairly stable pre-AGW, which suggests that negative feedback effects dominated. We have what seems to me (probably in my ignorance) a modest perturbation and suddenly we are envisaging positive feedback and an uncontrollable excursion to a new Venusian equilibrium.

Is it just that it is the positive feedback stories which hit the headlines, or is there some underlying reason why there are more positive feedback than negative feedback effects?

First up, it’s forcings that change the temperature positively or negatively. Forcings are amplified by feedbacks, positive and negative. For a stable climate the net effect of forcings and feedbacks should be zero, they should cancel each other out. Continue reading Immodest perturbation

Quantifying the negative feedback of vegetation

On another thread, John Michelmore has been telling us about an article by Lahouari Bounoua et al (behind the paywall) which finds that the enhanced effect of CO2 on plant growth provides a cooling feedback, so that doubling current CO2 to 780ppm would only cause a temperature increase of 1.64C. Hence we can all relax in relation to global warming mitigation. There’s no need to panic.

Here’s the Science Daily summary.

Continue reading Quantifying the negative feedback of vegetation