Climate Change: How Much Time Do We Have?
The other day, I found myself sitting in a Sunday school room talking about climate change. Mostly, I’m pretty comfortable doing that—despite a rather informal background in science, I’ve spent a good chunk of the last decade educating myself on the topic. But this question surprised me.
“How much time do we have?”
It wasn’t really the question itself, which was logical enough. It was my own emotional reaction. The folks awaiting an answer were my friends, and there was something in their eyes that both spoke of hope and of fear. They cared deeply about the answer. They were ready to work on the issue of climate change, and they wanted a reasonable number to work with. I so wished that I could have said twenty years, or even ten.
I suppose technically, I could have; no-one specified what exactly the time was needed to accomplish, so I could have picked some goal attainable within twenty years, or ten, and spoken from there. But I’d have been lying, or at least equivocating. So I said, “None, really. We are late, and we just need to work not to get any later.” And my heart broke, just a little.
Why do I believe that to be the least misleading thing I could possibly said to such a very open question?
Because it’s already too late for the victims of climate change to date.
It’s too late for the 2,000 or so who died in Katrina—and they may have been victims of climate change, as well as victims of mismanagement of the levees and the Louisiana wetlands and FEMA. It’s too late for the 70,000 who died in the 2003 European heatwave—and climate change almost certainly contributed to that disaster. It’s too late for the 56,000 who died during the Russian heatwave and wildfire event of 2010.
It’s impossible to say with any certainty that all of these victims died as a result of climate change. What’s called “attribution” of single events to climate change is difficult. But we do know that these sorts of events are much more likely in a warming world. And we do know that we live in a warming world.
My guess is that, allowing for many other events (up to and including the deadly Asian heatwave hurting Japan, Korea and China as of this writing) as well as the three examples already mentioned, it is very possible that as many as 100,000 people have so far died prematurely due to climate change. Many others have been impoverished or displaced, and economic losses—again, my best guess, not scientific estimate—are probably well in excess of $100 billion US.
Again—that is not a scientific estimate. It’s a personal and very rough one. But scientific analysis has specifically shown that the odds of the 2003 and 2010 events are much higher due to climate change than they would have been. It’s hard to say just how many deaths and how much damage are due to climate change. But it’s quite likely a significant number of each.
Update 1/11/14: Inuit Mental Health Impact
- Climate change rattles mental health of Inuit in Labrador - Technology & Science - CBC News
It's not 'too late' for these people, as people--but this study shows it is too late to avoid causing them distress and harm. And since climate change can't currently be reversed, the distress will not soon cease.
Because climate change is insidious.
Like lung cancer, or heart disease, the damage being done by climate change is not obvious at first, and may already be mortal by the time it really becomes evident.
Consider this scenario: it is dinner time, and you decide have some soup. You put your pan of soup on the stove and turn on the heating element. But then phone rings and the conversation quickly engrosses you. You don't hear the sound of the pan boiling over, but you do soon smell burning soup...
After duly considering the possibility, science now tells us that there is little or no chance that a runaway greenhouse effect can cause our oceans to boil. But just as the heat from the stove takes time to warm the soup to the boiling point, the greenhouse effect takes time to warm the oceans—decades, in fact.
Because of that delay, it is difficult for us to appreciate the damage we have already done. We see a small change without understanding that we have already made a considerably larger change unavoidable. In that sense, it is always ‘later than we think.’
A dramatic example comes from the work of Benjamin Strauss. According to his commentary article in the Proceedings of the National Academy of Science, evidence suggests that “we have already committed to an additional 1.3 m[eters] [about 4 feet, 3 inches] of rise above the current sea level.” If one uses a standard of 25% of municipal area below the high tide line, then approximately “500 American towns and cities are already committed, now home to 6.0 million...” Miami is expected to join that list within 10 years or so, unless extremely drastic reductions occur.
So if Strauss is correct, it is too late to save several hundred American towns from eventual inundation, and nearly too late to save Miami—even though that inundation will take much longer to actually happen. Those towns will be ‘walking dead.’
Strauss PNAS commentary on sea level rise commitments.
Because global emissions still seem to be increasing.
Consider the following graph of global carbon dioxide emissions:
Despite irregularities, the overall slope of the curve is increasing. It’s not surprising that this should be so. Political and economic factors have favored such an outcome. The very rapid economic growth in developing nations during the last couple of decades has been notable—and built on the exploitation of cheap fossil fuel.
Then too, although the Kyoto accord to control emission has had some successes—a number of nations, mostly European ones, will meet their Kyoto emissions reductions targets—Kyoto was never adequate to the scale of the climate challenge humanity faces. Developing nations were excluded, the US—then the world’s largest emitter—never ratified it, and several nations, including Canada and Russia, have now withdrawn from it, either formally or in practice. Worse, it will soon expire, and progress toward a successor agreement has been desperately slow—no such agreement is anticipated to be in place before 2020.
In the meantime, advances in the technology for extracting oil and gas (including the now-famous “fracking” techniques) expand the practical reserves of fossil fuels and lower prices. This, of course, provides economic incentive to burn yet more oil and gas. Ironically, climate change itself threatens to open up new reserves in the Arctic Ocean—reserves already subject to greedy anticipation. This, too, would drive the emissions curve higher still.
But I didn’t mention the straight lines in the graph, and they are worth considering as well. They represent different ‘emissions scenarios’ used by the International Panel on Climate Change. Warming will depend in large part on us—how much carbon humans allow to enter the atmosphere. Different social choices mean different warming. Each emissions scenario assumes a certain type of social development generating a characteristic ‘trajectory’ of carbon emissions.
We needn’t go into all of them here. But note the green line on the graph, labeled “B2.” It’s the most ‘ecologically friendly’ scenario—but by 2010, the world was already emitting two billion tonnes more than that. In fact, we are not very far below the emissions projected for A1F1—essentially, the ‘worst-case’ scenario.
In terms of reducing our emissions, it is very late indeed.
Because we are running out of time to avoid what is generally considered ‘dangerous’ warming.
The international community has set an ‘aspirational target’—which seems to mean something like ‘the target we’d like to adopt, but can’t because it is too expensive economically or politically’—to limit warming to less than 2 degrees Celsius. It’s not truly a ‘threshold.’ As we’ve seen, it’s quite possible that significant damage has already occurred, and it’s nearly certain that we are committed to more. And it’s very likely that damage wrought by warming will increase as we approach the so-called ‘buffer.’
But one might consider 2 C as ‘sort of safe.’ Under that amount of warming, we will still expect to see some benefits to climate change: some areas will have more favorable weather for agriculture and recreation or tourism, and so one. Past that, the more climate ‘losers’ there will be, and the more critical will be the limits that are approached—limits to the heat tolerance of food crops like wheat, rice and corn, and to the heat tolerance of wildlife—and humans.
But the practical measures so far undertaken, or committed to, are not even close to adequate to meet the ‘aspirational target’ of 2 C. And the more we delay, the more daunting the necessary steps become.
Distinguished Professor Emeritus Dr. Richard Somerville (of Scripps Institute) writes:
To have a reasonable chance of meeting this 2 degree Celsius goal, the science shows that global emissions of heat-trapping gases and particles must peak soon and then start to decline rapidly, not in 50 or 100 years, but within the next 5 to 10 years, reaching near zero well within this century. Given the 2 degree Celsius goal already agreed to by many governments, the case for great urgency in taking meaningful actions to reduce emissions is a consequence of science. It is based on facts and evidence. It is not an ideological or political choice. We have a window of time within which we simply must act if we are serious about meeting the 2 degree Celsius goal. The window is still open, but it will soon close and will then remain closed.
If the world continues to procrastinate throughout the current decade, so that global emissions of heat-trapping gases and particles continue unabated for another ten years, then we will almost certainly have lost the opportunity to limit warming to 2 degrees Celsius.
One could perhaps call this ‘encouraging’ with less of an ironic edge, if one were speaking, not about our own lives, but of those of the next generations. For there is still time to have very large impacts upon their lives.
While the warming to be experienced by 2050 is largely ‘locked in’ as a result of emissions to date, that is not the case for the warming seen by 2100. Several studies demonstrate this.
For example, the IEA—International Energy Agency—has developed its own emissions scenarios, and used them to investigate the chances of exceeding the 2 C ‘buffer’ value. The scenarios all show from 1.5 to 2.5 degrees C warming in 2050—a difference that is significant, but less than dramatic. The story is quite different for 2100, however: the most harmful scenario shows roughly 5C, while the most benign has not shown significant warming from the 2050 value, near 1.5 C. This is graphed below:
The US Global Change Research Program had already reached a broadly similar conclusion in an earlier study:
USGCRP 2009 report summary, including emissions graph above.
Going back to 2002, a British team, Johns et al, also came up with a very similar result. This uses older emissions scenarios, and an earlier generation climate model to do the necessary calculations, but still shows a range of about a degree for 2050, but a range of over 3.5 degrees for 2100. (Note that the flat trajectory at the bottom (shown in blue) represents a control run, with greenhouse forcings held to 19th century levels.)
- Warming trajectories & emissions
Johns et al warming travectories by emission scenario
What's 8 C?
Consider the following mean maximum temperatures:
- Miami mean annual high: 28.7 C; Toronto mean annual high: 11.9 C
- Miami mean August high: 32 C; Toronto mean August high: 25 C
- Miami mean January high: 24 C; Toronto mean January high: -1 C
So, 8 C is:
- greater than the variance among Miami’s monthly mean highs;
- greater than the difference between Miami and Toronto August mean highs;
- greater than half the difference between Miami and Toronto annual mean highs;
- nearly a third of the difference between Miami and Toronto January mean highs.
(An 8 C difference in Toronto’s January mean high would make Toronto warmer during that month than Lexington, KY, which currently experiences a January mean of 5 C.)
Considering these results together, it will be difficult to be sure of avoiding 2 C by century’s end. That's the bad news.
But it would be very possible to limit warming to amounts not much greater than that. There would be an enormous difference between 2 C and—to take a worst-case number for a moment—8 C. And that is definitely good news.
(To consider some illustrations of what 8 C might mean in a North American context, see the sidebar to the right.)
The bottom line is that climatic fate is of today’s adults is more or less sealed. Whether we continue down our present course or make a rapid change to a more sustainable energy economy, the full effects won’t be felt for another few decades. But by 2050 most of us will be at, approaching, or even past, what we would today consider to be our expected lifespans. So we will see climatic conditions that I would characterize as ranging from 'moderately bad' to 'significantly worse.'
But our kids and grandkids may well be living in 2080, or 2100. For them, our choices will make the difference between the 'challenging' conditions that we may experience if we survive to 2050, and the horrific conditions of a 2100 world that is 8 C warmer.
For that purpose, we have time. It remains to be seen whether we have the wisdom, and the will.
- UN report: Don't delay on climate change - CNN.com
CNN report on the Working Group II draft.
- Log In - The New York Times
NY Times report on the Working Group II draft.
- The Two Degree World
Summary table for expected impacts of global warming of 2 degrees Celsius, after Mark Lynas's "Six Degrees."
Just as the Working Group I portion of the International Panel on Climate Change Fifth Assessment Report was leaked prior to release of its finalized draft, so, too, has that of Working Group II. (WG I was concerned with 'the physical basis'--the core science at the heart of human-induced climate change. WG II is tasked with summarizing for us the the associated "impacts, vulnerabilities and adaptation"--the more practical questions of climate change harms and the ways of lessening them.)
The leaked WG II draft provides another answer to the question of how much time we have:
Delaying mitigation through 2030 will increase the challenges of, and reduce the options for, bringing atmospheric concentration levels to 530 ppm or lower by the end of the century...
530 parts per million would certainly take the planet well past the two Celsius degrees of warming that are (somewhat optimistically) considered relatively safe. Further warming would be increasingly likely to 'take on a life of its own' by triggering climate 'feedbacks' such as releases of carbon from sources such as warmer seawater, melting permafrost, or dying vegetation. On the other hand,
If in 2100 the atmospheric carbon dioxide levels are between 430 and 480 parts per million, the global temperature change, as compared to the mid-1800s, will be likely to stay below 2 degrees Celsius, according to a chart in the report.
For context, as of writing the most recent observations released from the Scripps CO2 Observatory in Hawaii reported CO2 readings of 398 parts per million. (January 29, 2014.)
But a New York Times story reporting the leak puts matters in still clearer terms than CNN:
Nations have so dragged their feet in battling climate change that the situation has grown critical and the risk of severe economic disruption is rising, according to a draft United Nations report. Another 15 years of failure to limit carbon emissions could make the problem virtually impossible to solve with current technologies, experts found.
A delay would most likely force future generations to develop the ability to suck greenhouse gases out of the atmosphere and store them underground to preserve the livability of the planet, the report found. But it is not clear whether such technologies will ever exist at the necessary scale, and even if they do, the approach would probably be wildly expensive compared with taking steps now to slow emissions.
The report said that governments of the world were still spending far more money to subsidize fossil fuels than to accelerate the shift to cleaner energy, thus encouraging continued investment in projects like coal-burning power plants that pose a long-term climate risk.
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