Difference between the future and what we expect
Do you know the difference between the real future and our best estimate of it? Estimation of a future state is a process that uses knowledge of relationships among the components of a system to infer a likely future state, given certain assumptions. It is a probabilistic process that comes up with a “best guess” and, if done carefully, some reasonably precise estimate of the degree of uncertainty in that best guess. The efforts by climate scientists to project a likely future climate, given certain assumptions about how we generate energy among other things, represent one of the most sophisticated efforts at “future-casting”. But they are still probabilistic, and provide only a (very sophisticated) best guess.
Indeed, any diagram produced by IPCC over the years, and intended to show the likely future given certain assumptions about human behavior, presents a spreading fan of possibilities as one moves further into the future. When the likely futures are compared assuming different human behavior with respect to greenhouse gas emissions, level of economic activity, population growth, there are different best guesses, each with their own fan of possibilities and these fans often overlap. For example, it’s true that the most likely future under IPCC’s RCP8.5 (which carries the nickname ‘business-as-usual’ because it assumes no great change in use of fossil fuels from the present) is a world that is likely to have warmed by more than 4oC by 2100 and to keep on warming. The most likely future under RCP4.5 is one that should get us to a 2oC increase by 2050, and a maximum increase by 2100 of about 2.4oC. And it’s also true that RCP2.6, the only scenario that leads to a cessation of warming by 2100, should keep warming under 2oC. But we could have temperatures at century end under RCP8.5 that reach as high as 5.4oC warmer than at present, or temperatures that are no warmer than possible trends under RCP4.5 – the respective fans of uncertainty just overlap.
Figure SPM 7a from IPCC’s Summary for Policymakers for WG1 report within the 5th Assessment Report, 2013, shows the anticipated mean global temperature from 1950 to 2100 under four different scenarios – RCP8.5, RCP6.0, RCP4.5 and RCP2.6. The range of likely possibilities thrown up by the various global climate models used is shown as pink or blue band for RCP8.5 and RCP2.6. At 2050, these bands of possibilities still overlap. The means and ranges for all 4 scenarios over the final 20 years, shown to right of main figure, also overlap considerably even at that end of century time.
Two dark truths
Today I am going to speak some dark truths, despite the fact that the conventional wisdom holds that we do not change hearts and minds with doom and gloom. I remain optimistic that we will succeed in getting to a reasonably good future, but I do so because I cannot imagine that we will be so stupid, or so selfish, that we will not make the changes in behavior that are required to wrestle climate to that better place. My optimism is not based on a narrow focus on the best guesses in future scenarios by climate scientists; indeed, I can frighten myself by looking at some of the possible futures these scenarios show.
The two dark truths are first, that Nature does not negotiate and does not care what we do, and second, that our climate projections contain wide variances that somehow get ignored while politicians negotiate the smallest departures from the status quo that they can achieve for their jurisdictions. A few weeks ago, I commented that now was a good time to up the ante and argue for limiting average increase in global temperature to 1oC, because 2oC, the current internationally agreed target, is too high. Just this week, climate scientist James Hansen told the press about a new paper submitted to Atmospheric Chemistry and Physics, up on their website as of 23rd July, in which he and sixteen co-authors argue that we need to reduce CO2 concentration in the atmosphere to 350ppm in order to secure a safe future with an equilibrium average global temperature about 1oC above pre-industrial levels. I have not yet read Hansen’s not-yet-reviewed paper carefully, so am relying on press reports here. These are mixed. There is no doubt that Hansen’s voice has been one of the more alarmist among climate scientists over recent years, but he is also someone who clearly knows what he is talking about. His new paper (which is on open access during the review period) discusses the risk of run-away melting of Greenland and Antarctic ice sheets by pointing to data from the Eemian interglacial, a period within the Pleistocene lasting from 130,000 to 115,000 years ago, in which air temperatures were less than a degree warmer than they are today, but sea levels stood 5 to 9 meters higher due to extensive melting. The paper also includes a simulation of the effects on the oceans of the resulting melt water. This cold, fresh water would reduce the rate of sinking of surface waters in the North Atlantic and in the Southern Ocean, thereby slowing the ‘great ocean conveyor’ and radically altering climate in the process. Hansen raised this concern several years ago in his book, Storms of My Grandchildren, and I found it frightening then.
I’d suggest the anomalous heat documented by NASA in May 2015, has a lot to do with why Saskatchewan is currently dealing with hundreds of wildfires that have required 8864 people (total to July 10th) to evacuate their homes in sparsely populated northern regions of the province. Map courtesy NASA Earth Observatory, Photo from Imgur.com.
The fact is that in planning the steps that should be taken in order to secure a safe future, we should be erring on the side of caution rather than gambling that all will be well. Maybe it won’t. And if 16 respected and capable climate and environmental scientists says 2oC is too much, we should at least look carefully at what they are saying. Hansen and colleagues are looking at the long-term behavior of ice under the temperature regimes we have already created; such long-term processes were not included in the calculations that led to the suggestion that a CO2 concentration of 450ppm would lead to a 2oC rise in average global temperature. Risk management requires that one plans for the unexpected extreme case, not for the expected best guess, and certainly not the best guess that leaves out consideration of some important processes (such as melting of ice sheets). But this is precisely what the world has not been doing until now. As I said in March, the 2oC target was a result of typical political compromise. Draft copies of the agreement being negotiated at Copenhagen talked of 1.5oC, but those references were all removed by the time negotiations ceased. It’s the same sort of process that led to the recent G7 commitment to eliminate use of fossil fuels by 2100, instead of 2050 as originally intended. Negotiation towards a compromise is a normal and respectable political process, but Nature does not negotiate, and while political leaders may be satisfied that they reached a ‘good’ agreement in Copenhagen, it is distinctly possible that they set the bar too low (low in level of effort needed, high in terms of CO2 allowed). Many scientists said so at the time. Now, when Hansen and colleagues speak up, there is a great tendency to caution that they are being alarmist. If the freight train is coming down the tracks, and seems unlikely to stop in time, it’s OK to be alarmist.
Most climate negotiators seem to be proceeding on the assumption that the science is precise enough that something like a 2oC or a 1.5oC target can be hit accurately, by reducing emissions by a specific amount. They also seem to be operating on the assumption that reaching a good decision on climate action is much like negotiating any other kind of treaty – each country gives a little bit, nobody wins completely, but all go away happy. Only problem is, the targets are fluffy, and Nature does not negotiate.
There will be a future with a warmer climate than at present, and it could be frighteningly warmer unless our political leaders start acting more risk-averse than they have been. Listening to the up-side risks that many climate scientists talk about (it’s not just James Hansen) should be an important part of understanding the climate problem.
While the best guesses, shown as solid lines in Figure SPM7a, are distinguishable before 2050, it is clear that adopting the policies underlying any one of these scenarios does not guarantee a clearly different future to adopting one of the others. The ability of climate scientists to project decades into the future is simply not that precise, and political leaders should think about the value of what ecologists refer to as the precautionary principle – acting aggressively to guard against the unlikely but dangerous outcome, rather than acting complacently, content that a best guess will prove to be correct.
In its 5th Assessment Report, the IPCC tackled the issue of a warming target directly. IPCC stated clearly that, because CO2 remains in the atmosphere for so long, the extent of warming that will occur due to emissions depends very directly on the cumulative amount of CO2 we will emit since the start of the industrial revolution. By 2011, human activity had released a total of 515 Gt Carbon (that is Giga Tonnes carbon = 1890 Gt CO2), and if we wish to have a 50% chance of keeping warming below 2oC, we should not emit more than 820 Gt Carbon total (= 3010 Gt CO2). In other words, we have available 1120 Gt CO2 to emit, and we could still (a 50% chance) find the world warmer than we expect.
There are variances around all these cumulative amounts as well. Emissions to 2011 might have been as high as 2150 or as low as 1630 Gt CO2, meaning that we may have as little as 860 Gt CO2 available to emit in the future. (IEA has reported we emitted 32.3 Gt CO2 in 2014 – we need very substantial cuts to keep within the 860 – 1120 Gt CO2 total budget available).
Talking glibly about a 2oC target, and how to reach it conveniently ignores the necessary uncertainty in the estimates of the amount of warming that will occur, and focusing on the average projection from a scenario ignores the risk that reality will be substantially warmer than that best guess. And yet, our politicians continually look for ways of fudging to minimize the extent of changes needed, and proceed very much as if striking a deal they can all live with is a good outcome, regardless of what Nature might have to say in a few more years’ time. Nature does not negotiate and does not compromise.
Trend since 2000 in the amount of energy needed to produce $1M of GDP, termed the carbon intensity of the economy. The two lines demonstrate the huge gap between the path we are on, and the one we need to be on to stay within the target. Figure © Price Waterhouse Cooper.
Yet another way of looking at the task in front of us is to consider the rate at which we are reducing the carbon intensity of the global economy. Carbon intensity is a measure of the amount of carbon emissions per unit of GDP, and increases in energy efficiency and the shift away from fossil fuels both lower carbon intensity. The global economy has got to reduce its carbon intensity by an average of 6.2% per year every year until 2100 to stay under a 2oC target. And these curves also have variance not shown in this figure taken from Two Degrees of Separation. Our present progress is clearly insufficient, however; insufficient even for a 2oC target that seems very likely to be too high.
The Trials of Jason Box
Climate scientists are very aware of the complacent negotiations that have characterized the political negotiations over climate. Image from Lumes channel.
Esquire currently has an article at its website that gives a detailed and quite personal glimpse into what climate scientists are dealing with at the present time. Through interviews with several prominent climate scientists, the article explores how their research, and the political maelstrom that swirls about the climate change topic, impact their own lives and the lives of their families. These are the people who perhaps best understand how atypical this period in Earth’s history has become, and how close to catastrophe we may be getting. They understand the limits of the science, and the risks that it is revealing, and they watch with concern as their concerns are ignored, or attacked (sometimes viciously and personally) by climate deniers. The climate scientists are well aware that we are engaged in an immense political struggle, and they are frequently conflicted not knowing if they should remain dispassionate, available on the sideline with information, but otherwise outside the game, or whether they should get into the thick of it and try to ensure that the science is properly understood. As Jason Box, an American glaciologist now based in Denmark, is quoted as saying, “We need the deniers to get out of the way. They are risking everyone’s future…. The Koch Brothers are criminals…. They should be charged with criminal activity because they’re putting the profits of their business ahead of the livelihoods of millions of people, and even life on earth.”
Other types of environmental scientists also struggle with what their responsibility should be as they see the results of their own research revealing the massive rates of change on this planet. Do you just buckle down and get on with your work, or do you try to inform and educate, correct the inaccuracies that are out there either because the science is complicated and not always easily understood by laypeople, or because of the massive effort by deniers of various types to distort what the scientists are finding out. As Box remarks in the Esquire article (which is well worth reading), “But let’s get real, fossil fuels are the dominant industry on earth, and you can’t expect meaningful political change with them in control. There’s a growing consensus that there must be a shock to the system.” Maybe Naomi Klein is correct in calling for revolutionary change?
Complacency everywhere while the climate worsens
At the end of June, Bloomberg New Energy Finance put out a glitzy web-based report called the New Energy Outlook 2015. Its focus was on the global electricity system. It had lots of words and some colorful, animated graphs showing how many trillions of dollars were being invested in solar and other non-fossil sources of energy, how much of a share of the total energy mix renewables were commanding, and how trends appeared to be up to 2040. Lots of rosy predictions; lots of positive news; lots of ways for investors to make money. The fifth of five bullets in the accompanying press release was “Despite investment of $8 trillion in renewables, there will be enough legacy fossil-fuel plants and enough investment in new coal-fired capacity in developing countries to ensure global CO2 emissions rise all the way to 2029, and will still be 13% above 2014 levels in 2040”. They headed that bullet, Climate Peril.
So, how much peril are they talking about, not that they spend much time at all discussing it? Their projection refers only to CO2 emissions from the electricity sector, or approximately 40% of emissions from the entire global economy. Think back to that allowable budget that the world can emit after 2011 and still keep within a 2oC target, somewhere between 860 and 1120 Gt CO2. If the electricity sector decarbonizes at the same rate as other sectors (it will probably be faster), then their statement that emissions will still be 13% above 2014 levels in 2040, leads to an estimate of total annual emissions that year of about 36.8 Gt CO2 (total emissions in 2014 = 32.3 Gt CO2). Keeping things simple and assuming a linear increase from 2014 to 2040, that represents 26 years at an average of 34.55 Gt CO2, or 898.3 Gt CO2, which must be added to the measured emissions for 2011, 2012, and 2013 – 31.3 + 31.7 + 32.3 – for a total emissions to 2040 of 993.6 Gt CO2. Great, we remain more or less within the allowable budget of 860 to 1120 Gt CO2. Right? No, very wrong, because as Bloomberg says, fossil fuels will still represent 44% of electricity generation in 2040. What do we do then? Suddenly cut our use of electricity by 44%? No, we massively overshoot the 2oC target. The way Bloomberg states this observation in their press release is, “The CO2 content of the atmosphere is on course to exceed 450 parts per million by 2035 even if emissions stay constant, so the trend we show of rising emissions to 2029 makes it very unlikely that the world will be able to limit temperature increases to less than two degrees Centigrade”. Measured, calm, no cause for alarm because lots of money is being made.
Very unlikely? No! Impossible! If we have only managed to reduce use of fossil fuels from 67% to 44% of electricity production over the next 26 years, we will be well on our way to a climate change of 5 or 6oC by the end of the century. But the politicians negotiating in Paris are likely to listen to Bloomberg rather than to scientists like me, and Bloomberg says wonderful things are happening although we do need to try a tiny bit harder to keep within our target. What utter misrepresentation of the problem the world faces.
But calm and measured is the rule within the economy. Royal Dutch Shell has announced in internal documents that it is planning for a future of 4oC increase, rising to 6oC after 2100; they have decided that the political process is not going to succeed in capping increases at 2oC, and have apparently assumed that their business can proceed in this new, exciting world.
The recent G7 agreement to eliminate use of fossil fuels by 2100 is similarly calm and measured, and we will have a disastrous outcome if we do not do a lot better than that.
Meanwhile, all around the world, reports keep showing just how rapidly climate is changing, and how severe the impacts are becoming. The American Meteorological Society published a 288 page report, State of the Climate in 2014. Its Abstract begins as follows:
“Most of the dozens of essential climate variables monitored each year in this report continued to follow their long-term trends in 2014, with several setting new records. Carbon dioxide, methane, and nitrous oxide—the major greenhouse gases released into Earth’s atmosphere—once again all reached record high average atmospheric concentrations for the year.
“Carbon dioxide increased by 1.9 ppm to reach a globally averaged value of 397.2 ppm for 2014. Altogether, 5 major and 15 minor greenhouse gases contributed 2.94 W m–2 of direct radiative forcing, which is 36% greater than their contributions just a quarter century ago.
“Accompanying the record-high greenhouse gas concentrations was nominally the highest annual global surface temperature in at least 135 years of modern record keeping, according to four independent observational analyses. The warmth was distributed widely around the globe’s land areas, Europe observed its warmest year on record by a large margin, with close to two dozen countries breaking their previous national temperature records; many countries in Asia had annual temperatures among their 10 warmest on record; Africa reported above-average temperatures across most of the continent throughout 2014; Australia saw its third warmest year on record, following record heat there in 2013; Mexico had its warmest year on record; and Argentina and Uruguay each had their second warmest year on record. Eastern North America was the only major region to observe a below-average annual temperature.
“But it was the oceans that drove the record global surface temperature in 2014. Although 2014 was largely ENSO-neutral, the globally averaged sea surface temperature (SST) was the highest on record. The warmth was particularly notable in the North Pacific Ocean where SST anomalies signaled a transition from a negative to positive phase of the Pacific decadal oscillation. In the winter of 2013/14, unusually warm water in the northeast Pacific was associated with elevated ocean heat content anomalies and elevated sea level in the region. Globally, upper ocean heat content was record high for the year, reflecting the continued increase of thermal energy in the oceans, which absorb over 90% of Earth’s excess heat from greenhouse gas forcing. Owing to both ocean warming and land ice melt contributions, global mean sea level in 2014 was also record high and 67 mm greater than the 1993 annual mean, when satellite altimetry measurements began”. I could quote more, but this is sufficient to show that the world is really changing.
NOAA has reported that 12% of reefs have suffered bleaching in the last year. Half of these corals (12000 km2) may never recover. Caused by a weak el Nino. Photo © O Hoegh-Guldberg.
I think my point is clear. We do not yet have policies in place that come close to limiting warming to 2oC, yet seem to be proceeding as if this is a clear, easily hit target which we will get to in due course. It is not. We really could be heading towards 5 or 6oC, and even 2oC may turn out to be too high. Is not Hansen correct to warn about run-away climate change? And shouldn’t responsible economic powerhouses like Bloomberg pay more attention to the risks we face by continuing to be complacent about the seriously inadequate extent of steps taken so far? The economic consequences, never mind the hardships millions of poor people will face, if climate risks continue to escalate would suggest that economic leaders should speak out more forcefully than they do. As for Royal Dutch Shell…
Nature does not negotiate and does not care. We will get the climate we create by our pollution of the atmosphere. If it gets dangerously warm, Nature will not step in to save us. If all life on earth goes extinct, Nature will not care. We have the power to decide the near-term future of this planet, and while we can use that power to get a good result, we can also use that power to really mess up. The political class does not yet seem to understand that this is not just a game. It is certainly far more existential than is the need to take care of our economy.