Tag Archives: greenhouse gas emissions

Hindering the Hothouse

It’s been over a year since I posted on climate issues (last post here after Trump’s withdrawal from the Paris Agreement). A recent study by a group of scientists warned that even if the carbon emission reductions called for in the Paris Agreement are met, there is a risk of Earth entering “Hothouse Earth” conditions. A “Hothouse Earth” climate will in the long term stabilize at a global average of 4-5°C higher than pre-industrial temperatures with sea level 10-60 m higher than today according to the scientists.

Human emissions of greenhouse gas are not the sole determinant of temperature on Earth. Our study suggests that human-induced global warming of 2°C may trigger other Earth system processes, often called “feedbacks”, that can drive further warming – even if we stop emitting greenhouse gases,” says lead author Will Steffen from the Australian National University and Stockholm Resilience Centre, adding that “avoiding this scenario requires a redirection of human actions from exploitation to stewardship of the Earth system”.

The best-selling author of “Sapiens” and “Homo Deus”, Yuval Noah Harari, makes the observation that “the hand of the market is blind as well as invisible, and left to its own devices, it may fail to do anything at all about the threat of global warming or the dangerous potential of artificial intelligence”. This is one of the themes he returns vigorously to in his new book “21 Lessons for the 21st Century”, a collection of previously published essays.

It is therefore heartening to see such an influential and intelligent financial professional as Jeremy Grantham of GMO pushing the issue as an important one for investors to consider in our daily activities. This talk from Grantham and the accommodating presentation are well worth spending some time on. His arguments are articulated further in this August GMO white paper, The Race of Our Lives Revisited, an update on his 2013 paper.

Grantham states that “the truth is we’ve wasted 40 or 50 years since the basic fact about manmade serious climate damage became known” and “we’re moving so slowly that by the time we’ve fully decarbonized our economy, the world will have heated up by 2.5ºC to 3ºC, and a great deal of damage will have been done”.

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Grantham highlights the declining costs of alternative energy like solar and wind and the advances made in battery costs. Notwithstanding these advances, progress is too slow, as the graphs below show.

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Depressingly Grantham concludes that “in all probability we will reach our 2ºC target by 2050, and we will be fighting tooth and nail – with any luck, with carbon taxes and an improved attitude – to keep it below 3ºC by 2100”. Compounding the climate issue is continued population growth, declining agricultural productivity and increased soil erosion.

Like Harari, Grantham argues that “the greatest deficiency of capitalism is its complete inability to deal with any of these things that we are talking about even though it can handle the millions of more mundane factors that go into producing a workable economy, far better than planned economies”. Grantham makes a passionate argument for investors to divest themselves of negative climate impact firms, such as the oil producers, and to do more in our personal lives to promote green changes, like buying electric cars.

In the absence of real political leadership in our world, which looks likely to continue for some years yet as the populist and nationalistic political dead end we are currently travelling on plays out, voting with our actions seems the only thing we can do. As Grantham concludes, we all need to “get to it”.

The imperfect art of climate change modelling

The completed Group I report from the 5th Intergovernmental Panel on Climate Change (IPCC) assessment was published in January (see previous post on summary report in September). One of the few definite statements made in the report was that “global mean temperatures will continue to rise over the 21st century if greenhouse gas (GHG) emissions continue unabat­ed”. How we measure the impact of such changes is therefore incredibly important. A recent article in the FT by Robin Harding on the topic which highlighted the shortcomings of models used to assess the impact of climate change therefore caught my attention.

The article referred to two academic papers, one by Robert Pindyck and another by Nicholas Stern, which contained damning criticism of models that integrate climate and economic models, so called integrated assessment models (IAM).

Pindyck states that “IAM based analyses of climate policy create a perception of knowledge and precision, but that perception is illusory and misleading”. Stern also criticizes IAMs stating that “assumptions built into the economic modelling on growth, damages and risks, come close to assuming directly that the impacts and costs will be modest and close to excluding the possibility of catastrophic outcomes”.

These comments remind me of Paul Wilmott, the influential English quant, who included in his Modeller’s Hippocratic Oath the following: “I will remember that I didn’t make the world, and it doesn’t satisfy my equations” (see Quotes section of this website for more quotes on models).

In his paper, Pindyck characterised the IAMs currently used into 6 core components as the graphic below illustrates.

click to enlargeIntegrated Assessment Models

Pindyck highlights a number of the main elements of IAMs which involve a considerable amount of arbitrary choice, including climate sensitivity, the damage and social welfare (utility) functions. He cites important feedback loops in climates as difficult, if not impossible, to determine. Although there has been some good work in specific areas like agriculture, Pindyck is particularly critical on the damage functions, saying many are essentially made up. The final piece on social utility and the rate of time preference are essentially policy parameter which are open to political forces and therefore subject to considerable variability (& that’s a polite way of putting it).

The point about damage functions is an interesting one as these are also key determinants in the catastrophe vendor models widely used in the insurance sector. As a previous post on Florida highlighted, even these specific and commercially developed models result in varying outputs.

One example of IAMs directly influencing current policymakers is those used by the Interagency Working Group (IWG) which under the Obama administration is the entity that determines the social cost of carbon (SCC), defined as the net present damage done by emitting a marginal ton of CO2 equivalent (CO2e), used in regulating industries such as the petrochemical sector. Many IAMs are available (the sector even has its own journal – The Integrated Assessment Journal!) and the IWG relies on three of the oldest and most well know; the Dynamic Integrated Climate and Economy (DICE) model, the Policy Analysis of the Greenhouse Effect (PAGE) model, and the fun sounding Climate Framework for Uncertainty, Negotiation, and Distribution (FUND) model.

The first IWG paper in 2010 included an exhibit, reproduced below, summarizing the economic impact of raising temperatures based upon the 3 models.

click to enlargeClimate Change & Impact on GDP IWG SCC 2010

To be fair to the IWG, they do highlight that “underlying the three IAMs selected for this exercise are a number of simplifying assumptions and judgments reflecting the various modelers’ best attempts to synthesize the available scientific and economic research characterizing these relationships”.

The IWG released an updated paper in 2013 whereby revised SCC estimates were presented based upon a number of amendments to the underlying models. Included in these changes are revisions to damage functions and to climate sensitivity assumptions. The results of the changes on average and 95th percentile SCC estimates, at varying discount rates (which are obviously key determinants to the SCC given the long term nature of the impacts), can be clearly seen in the graph below.

click to enlargeSocial Cost of Carbon IWG 2010 vrs 2013

Given the magnitude of the SCC changes, it is not surprising that critics of the charges, including vested interests such as petrochemical lobbyists, are highlighting the uncertainty in IAMs as a counter against the charges. The climate change deniers love any opportunity to discredit the science as they demonstrated so ably with the 4th IPCC assessment. The goal has to be to improve modelling as a risk management tool that results in sensible preventative measures. Pindyck emphasises that his criticisms should not be an excuse for inaction. He believes we should follow a risk management approach focused on the risk of catastrophe with models updated as more information emerges and uses the threat of nuclear oblivion during the Cold War as a parallel. He argues that “one can think of a GHG abatement policy as a form of insurance: society would be paying for a guarantee that a low-probability catastrophe will not occur (or is less likely)”. Stern too advises that our focus should be on potential extreme damage and that the economic community need to refocus and combine current insights where “an examination and modelling of ways in which disruption and decline can occur”.

Whilst I was looking into this subject, I took the time to look over the completed 5th assessment report from the IPCC. First, it is important to stress that the IPCC acknowledge the array of uncertainties in predicting climate change. They state the obvious in that “the nonlinear and chaotic nature of the climate system imposes natu­ral limits on the extent to which skilful predictions of climate statistics may be made”. They assert that the use of multiple scenarios and models is the best way we have for determining “a wide range of possible future evolutions of the Earth’s climate”. They also accept that “predicting socioeconomic development is arguably even more difficult than predicting the evolution of a physical system”.

The report uses a variety of terms in its findings which I summarised in a previous post and reproduce below.

click to enlargeIPCC uncertainty

Under the medium term prediction section (Chapter 11) which covers the period 2016 to 2035 relative to the reference period 1986 to 2005, a number of the notable predictions include:

  • The projected change in global mean surface air temperature will likely be in the range 0.3 to 0.7°C (medium confidence).
  • It is more likely than not that the mean global mean surface air temperature for the period 2016–2035 will be more than 1°C above the mean for 1850–1900, and very unlikely that it will be more than 1.5°C above the 1850–1900 mean (medium confidence).
  • Zonal mean precipitation will very likely increase in high and some of the mid-latitudes, and will more likely than not decrease in the subtropics. The frequency and intensity of heavy precipitation events over land will likely increase on average in the near term (this trend will not be apparent in all regions).
  • It is very likely that globally averaged surface and vertically averaged ocean temperatures will increase in the near term. It is likely that there will be increases in salinity in the tropical and (especially) subtropical Atlantic, and decreases in the western tropical Pacific over the next few decades.
  • In most land regions the frequency of warm days and warm nights will likely increase in the next decades, while that of cold days and cold nights will decrease.
  • There is low confidence in basin-scale projections of changes in the intensity and frequency of tropical cyclones (TCs) in all basins to the mid-21st century and there is low confidence in near-term projections for increased TC intensity in the North Atlantic.

The last bullet point is especially interesting for the insurance sector involved in providing property catastrophe protection. Graphically I have reproduced two interesting projections below (Note: no volcano activity is assumed).

click to enlargeIPCC temperature near term projections

Under the longer term projections in Chapter 12, the IPCC makes the definite statement that opened this post. It also states that it is virtually certain that, in most places, there will be more hot and fewer cold temperature extremes as global mean temper­atures increase and that, in the long term, global precipitation will increase with increased global mean surface temperature.

I don’t know about you but it seems to me a sensible course of action that we should be taking scenarios that the IPCC is predicting with virtual certainty and applying a risk management approach to how we can prepare for or counteract extremes as recommended by experts such as Pindyck and Stern.

The quote “it’s better to do something imperfectly than to do nothing perfectly” comes to mind. In this regard, for the sake of our children at the very least, we should embrace the imperfect art of climate change modelling and figure out how best to use them in getting things done.

A quick look over the latest IPCC climate change assessment

After the debacle of the last report, the spotlight is back on climate change with the release of the new (fifth) assessment by the Intergovernmental Panel on Climate Change (IPCC). The financial crisis, combined with credibility issues over the last report as a result of errors found after publication, has meant that the issue has taken a back seat in recent years. This assessment is drawn from the work of 209 authors with 50 review editors from 39 countries and more than another 600 contributors from across the global scientific community. It will hopefully dispel the nut job climate change deniers and allow for a renewed focus on concrete actions that can be taken to address climate change issues.

The latest publication from IPCC yesterday is actually a summary of headline statements and a “summary for policymakers” from the IPCC Working Group I which makes an assessment of the physical scientific aspects of the climate change. A full draft report will be published in a few days and is expected to be finalised by late 2013 or early 2014. The two other working groups, creatively named IPCC Working Group II and III, are due to publish their reports in 2014 and are charged with assessments of vulnerability to climate change and options for mitigating the effects respectively.

The language used by IPCC is important. For some reason they use a number terms for uncertainty, as follows:IPCC uncertainty

The strongest (and most obvious) statement is:

“Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased.”

It does sound silly that it has taken us this many years for a statement like that to be made unequivocally but that’s the world we live in. A graph from the summary from WG I is below.

IPCC findings

A number of the headline statements that are being reported in the press are included below.

Very high confidence is assigned to the ability of climate models “to reproduce observed continental-scale surface temperature patterns and trends over many decades, including the more rapid warming since the mid-20th century and the cooling immediately following volcanic eruptions“.

High confidence is assigned to each of the following:

  • Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010.
  • Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent.
  • The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia.

Medium confidence is assigned to the assertion that in “the Northern Hemisphere, 1983–2012 was likely the warmest 30-year period of the last 1400 years.

Other strong statements include the following section (by the way, I think extremely likely is yet another new term meaning over 95% probability!):

“It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.”

The summary documents also refer to the scenarios used, including four new scenarios, to assess impacts on items including CO2, temperature, sea levels and temperatures. The full draft assessment and next year’s WG II and III reports will likely give more detail.

There is a few intriguing assertions in the report although they are subject to final copyedit.

Medium confidence is used to describe the assessment of whether human actions have resulted in an increase in the frequency, intensity, and/or amount of heavy precipitation. For the early 21st century and the late 21st century it is assessed that increased precipitation is likely over many land areas and very likely over most of the mid-latitude land masses and over wet tropical regions respectively.

Low confidence is used to describe the assessment of whether human actions have resulted in an increase in intense tropical cyclone activity and is also used to describe the likelihood of a change in intense tropical cyclone activity in the early 21st century.

The more detailed draft report from WG I will be interesting reading.