This is a continuing series of posts on the “Representative Concentration Pathways” (RCPs), presented by the Intergovernmental Panel on Climate Change as possible trajectories of atmospheric concentrations of green house gases (GHGs) over the next century. The RCPs start with a target GHG concentration, on the basis of which they estimate global temperature over various time periods. The scariest is RCP8.5, which projects a mean global temperature rise of 3.7°C by 2100. The story line of RCP8.5 has been described as  a “conservative business as usual” scenario that assumes “a 10 fold increase in the use of coal as a power source and a move away from natural gas as an energy source”.

“Business as usual” usually means the way things are expected to be if current trends continue. So, is the global use of coal on the upswing? Here is what the  International Energy Agency has to say:

“Coal is the slowest-growing energy source in the IEO2016 Reference case, with 0.6%/year average increases in total world coal consumption from 2012 to 2040, considerably slower than the 2.2%/year average over the past 30 years. The EIA forecasts declines from 40% of total generation in 2012 to 29% in 2040.”

Here’s what a recent Goldman Sacks analysis concludes:

“Unlike most other commodities, thermal coal is unlikely to experience another period of tightness ever again because investment in new coal-fired generation is becoming less common and the implied decline in long-term demand appears to be irreversible.”

And here is what David Rutledge, Professor of Engineering and Applied Science at the California Institute of Technology, predicts:

“If the current trends continue, 90% of the coal would be produced by 2067.”

Once again, in the case of coal, there is no way RCP8.5 represents a plausible “business as usual” trajectory.

That completes this series on RCP8.5. I suspect that many people would say the plausibility of climate change scenarios is beside the point, and that the point is: unless you scare people shitless, they won’t take sufficient action, and if they don’t act now, and act decisively, the future of the biosphere – including humanity –  is going to be very, very bleak.

Next up: really?

This post is part of a continuing series on the “Representative Concentration Pathways” (RCPs), presented by the Intergovernmental Panel on Climate Change as possible trajectories of atmospheric concentrations of green house gases (GHGs) over the next century. The RCPs start with a target GHG concentration, on the basis of which they estimate global temperature over various time periods. The scariest is RCP8.5, which projects a mean global temperature rise of 3.7°C by 2100.

Each RCP is associated with development paths that could plausibly lead to the projected GHG concentrations. For instance, RCP8.5 assumes fairly robust human population growth rate this century, culminating in a global population of 12 billion by 2100.  The current UN estimate for 2100 is a global population of 11.2 billion.

That extra 800 million matters, because other projected developments are based in part on assumptions about population trends. For instance, according to RCP8.5, cultivated land is expected to expand 16% above 2000 levels by 2080, largely in response to global population pressures. If the population estimate is off-base, so is the projected global increase in cultivated land (a net contributor to emissions). But, then the global expansion in cultivated land envisioned by RCP8.5 makes little sense anyway, given that global land use for agriculture peaked in 1998 and has slowly declined since – despite continued population growth of almost 1.5 billion people since then.

In terms of predicting climate change and its effects, it’s essential to get population projections right.  And in terms of climate change mitigation, the fewer humans the better. Per O’Neill et al, every 1% decrease in global population would mean a 1% decrease in emissions. And the best way to reduce our numbers is continued development throughout the world. Unfortunately, some climate activists see development as the problem and not part of the solution. As Dean Spears puts it:

“…many of the present-day high-emissions populations have comparatively lower fertility. Human development—such as improving health, education, and women’s social status—could encourage parents to freely choose to reduce population size while improving average well-being, and could therefore be an exception to the standard claim that development is in conflict with climate policy.”

References:

Spears, D. (2015) Smaller human population in 2100 could importantly reduce the risk of climate catastrophe. PNAS vol. 112 no. 18 E2270, doi: 10.1073/pnas.1501763112

O’Neill BC, et al. (2012) Demographic change and carbon dioxide emissions. Lancet 380(9837):157–164

The Intergovernmental Panel on Climate Change (IPCC) has presented various “Representative Concentration Pathways” (RCPs) to represent possible trajectories of atmospheric concentrations of green house gases (GHGs) over the next century. The scariest one is RCP8.5, which projects a mean temperature rise of 3.7°C, with a likely increase range of 2.6 to 4.8°C by 2100. RCP8.5 has been called the “business as usual” RCP, which means it’s considered a likely development path if current trends continue. According to the scientists who proposed RCP8.5 in 2011, its trajectory is plausible based on assumptions of “….low income, high population and high energy demand due to only modest improvements in energy intensity.”   Are these assumptions reasonable based on current trends – that is, do they represent a plausible  “business-as-usual” scenario?

Let’s look at income first.  Per RCP8.5, global GDP will reach around $250 trillion in 2100.  That does reflect a fairly low rate of economic growth, given a current (2014) global GDP of  about $78 trillion. How does that figure jive with current predictions of global economic growth?

The IMF expects a global GDP growth rate of 3.6% in 2017. A comparable growth rate (around 3.6 give or take) is predicted to continue for the next several decades for the G20 economies*, which represent about 84% of global GDP. Since the G20 economies are such a large part of the global GDP pie, I’m going to use projections about the G20 to anchor the discussion of whether the RCP8.5 projection of global GDP in 2100 is a reasonable approximation of “business as usual”.

The PWC World in 2050 report expects GDP for the G20 economies to double by 2037 and triple by 2050. The Carnegie International Economics Program estimates that GDP for the G20 economies will reach $161.5 trillion by 2050. Taking the Carnegie projection, if the G20 still represented 84% of the global economy in 2050, that means the global GDP in 2050 would be about $192 trillion in 2050 (161/.84) – an admittedly very rough estimate; for one thing, it is more likely that the G20 would represent a smaller percentage of the world economy by then, because smaller, less developed countries tend to grow at a faster rate than large developed countries. But I’m trying to be very modest in my projections here.

If we accept $192 trillion as a low-ball proxy for global GDP in 2050, what growth rate would be necessary for global GDP to reach $250 trillion by 2100, as per RCP8.5? Less than 1%. Given that current and expected annual global GDP growth is roughly 3.6%, RCP8.5 hardly represents a “business as usual” scenario.

Next, population growth.

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*The G20 consists of: Argentina, Australia, Brazil, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Mexico, Russia, Saudi Arabia, South Africa, South Korea, Turkey, the United Kingdom, the United States and the European Union.

The last post introduced the concept of Representative Concentration Pathways (RCPs), which are used by the Intergovernmental Panel on Climate Change (IPCC) to represent possible trajectories of atmospheric concentrations of green house gases (GHGs) over the next century. These Pathways were designed to model a set of conditions that would lead to various upper limits of climate forcing by 2100 – climate forcing being the heating effect caused by GHGs in the atmosphere. Heating effects are calculated in watts per square meter. The RCPs are named after their targeted heating effects. For instance, RCP8.5 represents a trajectory that could result in atmospheric heating of 8.5 watts per meter squared by 2100.

RCP8.5 is the most extreme of the four RCPs considered by the IPCC.  It projects a mean temperature rise of 3.7°C and a likely increase range of 2.6 to 4.8°C by 2100, wreaking all sorts of havoc along the way.

Starting with a target heating effect by 2100, the RCPs work backwards to create a plausible  “story line” that would result in the target effect. The story line of RCP8.5 has been described as “conservative business as usual”.  Here are some its key plot points:

• Delayed development of renewable energy technologies
• Rebound of human population to 15 billion by 2100
• Wide and increasing international disparities in productivity, energy efficiency, and GDP
• Delayed improvements in agricultural land use
• 10-fold increase in the use of coal as a power source
• Move away from natural gas as an energy source
• Little change in environmental and economic policies across the world

In brief, RCP8.5 paints a picture of “… low income, high population and high energy demand due to only modest improvements in energy intensity” throughout the 21^st century. Is this truly a “business as usual” scenario?

The Intergovernmental Panel on Climate Change (IPCC) has laid out a range of scenarios for what might happen to the planet, atmosphere, biosphere, and human society over the course of the next century. These scenarios are based on different “Representative Concentration Pathways” (RCPs), each with its own story line about population growth, economic activity, land use patterns, energy use, lifestyle, climate policy, and mitigation efforts.  RCPs provide time-dependent projections of atmospheric greenhouse gas (GHG) concentrations. Their purpose is to contribute to a better understanding of the uncertainties, interactions and dynamics involved in climate change and provide guidance to policy makers.

In the IPCC Synthesis Report: Summary for Policymakers (2014), the authors compare four RCPs: RCP2.6, RCP4.5, RCP6.0, and RCP8.5.  These four RCPs don’t exhaust all plausible trajectories but do cover a reasonable range of severity, from the pretty manageable to the horrific.  At the pretty manageable end is RCP2.6, which  projects that by 2100 the mean global temperature rise will be 1°C, with a likely increase range of 0.3 to 1.7°C. At the other end, RCP8.5 projects  a mean temperature rise of 3.7°C and a likely increase range of 2.6 to 4.8°C.

The RCPs are only as good as their story lines – that is, what they choose to assume about humanity’s  near-future  in order for their projections to be plausible. So, what are the assumptions  that inform these Pathways?

Stay tuned…..

Just 10% of Americans currently say that human-caused climate change is not happening or is not about to happen. Climate change “dismissives” are a vanishing species. Disagreement is mostly about how fast, how much, possible effects and what the best course of action is. We’re wasting our time bemoaning the unbelievers, or trying to convert them.  It’s time to move on to the hard part: considering plausible scenarios and weighing the ol’ pros and cons of different approaches to mitigation and adaptation.

Sometimes when I sound a note of hope about climate change, others seem irritated or even angry. As if hope negates strong measures, and unless we take strong measures, the situation is truly hopeless.  As if hope engenders complacency. But hope can spur action, especially hope tempered by a sense of urgency and an understanding that sacrifice is also part of the equation.

Since much of my hope has to do with economic development, advances in technology, and cultural trends, resistance to my specific message of hope may also reflect the anti-technology, anti-business, and anti-modernity bias that’s pretty common within the environmentalist movement.  Within their dystopian imaginations, some environmentalists maintain a utopian vision of small farmers living modestly and in harmony with nature: a pre-capitalist world of plain living and simple virtues.  Not exactly compatible with a vision of big cities and big farms.

My last post ended on a note of optimism: continued economic growth, cultural change and technological development can go a long way in ameliorating climate change, and the effects thereof. In short: with economic development, empowerment of women, intensification of sustainable agriculture, and urbanization, human populations plummet and wild habitat expands.  Technological advances and changing consumption patterns in developed countries will reduce the environmental impact of human activity. Examples would be improved seed stock, the de-materialization of production processes, increased supply chain efficiencies, and a shift away from having fancy things as markers of status to having fancy experiences. Kelp noodles, anyone?

Not to imply the ride will be smooth. Some countries will increase their carbon footprint as their economies pick up. The newly affluent in less developed countries will be enamored of fancy things. But these countries don’t have to repeat the US pattern in the 20^th century, with all the decades of excess, waste, and environmental degradation that implies. They will be able to take advantage of the already developed technologies and efficiencies that reduce carbon emissions. And with the increase in urbanization and agricultural productivity, less land will be shared and more spared for the resurgence of the biosphere.

Ignoring possible human suffering and death caused by climate change adaptation and mitigation efforts is no different than  drone pilots disassociating from the effects of their bombing runs. Of course, sometimes drastic – and lethal – measures are justified. But trade-offs are involved – and if you care about human life, trade-offs must be seriously considered.

We know people will die because of climate change. We know people will die if global economic growth stalls. How many of us have a good idea of the numbers? What might increase or reduce those numbers?

It’s a cop-out to say that “in the long run” more human lives will be saved, or that all forms of life matter, not just humans. Is a die-off of humans necessary for other forms of life to prosper? Are there ways to help other species thrive without requiring that a bunch of people suffer and die?

In a previous post, I simplified climate change action priorities as follows: reduce green house gases, protect habitats, protect wildlife and protect humans. With the empowerment of women and economic development throughout the world, human population will plummet. Sorry guys – when women have options, they don’t want a dozen kids – one or two will do. With technological advances, humans can grow food on less and less land. Without dependency on the land, more and more will flock to the cities. All these developments will reduce greenhouse gases, increase wild habitat, protect wildlife and save human lives.

We already know that a lot of people will die because of the havoc wreaked  by climate change. The  World Health Organization (WHO) estimates that between 2030 and 2050, climate change will cause roughly 250 000 additional deaths per year, from malnutrition, malaria, diarrhea and heat stress. Most of these “excess deaths” will be due to the effects of extreme heat, variable rainfall, and the spread of infectious diseases.  Developing countries and poor farmers will be especially hard hit.

Compare the above to current excess deaths due to air pollution: WHO reports that in 2012 around 7 million people died as a result of air pollution exposure. The sources of air pollution mostly overlap with the sources of carbon emissions. Coal is by far the biggest cause of deaths caused by air pollution. In 2013, for instance, outdoor air pollution from coal  caused an estimated 366,000 deaths in China.  

Coal also gives you more death per unit of energy. This from Nexbigfuture:

Energy Source                                                     Death Rate (world average deaths per TWh)

Coal (26% of world energy)                           100 (from 15 in US to 170 in China)

Oil (36% of world energy)                               36

Natural Gas (21% of world energy)              4

Nuclear (5.9% of world energy)                     0.04

(TWh = terawatt-hours)

Coal is not only the most deadly source of energy;  it’s also  the biggest emitter of CO2 per unit of energy output – almost twice that of natural gas. No one’s saying natural gas is clean or safe – only that it’s a whole lot cleaner and safer than coal. Then there’s nuclear: even counting the Fukushimas and Chernobyls, nuclear is the cleanest and safest around. Wind, solar and biofuels aren’t yet at a scale that bears comparison in this club. Maybe someday but not yet.

Of course we want to keep developing alternative, non-emitting, energy sources so that eventually they become sufficiently cheap and scalable to compete with the Big Four – Coal, Oil, Natural Gas, and Nuclear.  But if we care about saving lives, we’d get a lot more bang for our buck by encouraging natural gas and nuclear for now while continuing to work on their eventual replacements.