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A new look at climate ‘tipping points,’ where familiar patterns vanish forever

This detail from the researchers’ interactive map suggests that within three to four decades, the Twin Cities region will be permanently outside its historical temperature range — that is, the region’s coldest years will be  warmer than the hottest years in a record stretching back to 1860. The red line is for temperatures modeled on a business-as-usual scenario, in which greenhouse gas emissions continue to rise without major new efforts to curb them; the yellow line is for temperatures modeled on a scenario of aggressive global reductions.

Global warming has been likened to a slow-moving train wreck, a creeping forest fire, a saucepan of water warming imperceptibly until a bullfrog — that would be human settlement as we know it — sits calm and unawares until the moment of demise.

Partly this is because the timelines for arrival of new climate regimes can be long, indistinct and in some aspects debatable, climate mechanisms being so complex. Partly it’s because scientists are circumspect in presenting research findings, especially on a topic where a claque of industry-financed contrarians waits in perpetual ambush. And partly it’s because climate shifts are global and we can’t help but think local.

Every so often, though, a piece of research comes along to show with special clarity and power the fix we’re in, how rapidly we are hurtling toward a world entirely outside our experience of this one. Such a study appeared earlier this month in Nature, a journal whose prestige may assure that the authors’ new term “climate departure” becomes as commonplace as climate change, climate disruption and climate chaos.

“Climate departure” refers to a kind of tipping point at which the up-and-down fluctuations of annual temperature averages climb into a zone completely and permanently outside a “normal” range established in a record going back to 1860.

A new Minnesota in 2042

It’s the point at which the coldest years to come are warmer than the hottest years already experienced by anyone now alive, plus a few generations of ancestors. In much of Minnesota that point is projected to arrive about 30 years from now — in 2042, give or take five years.

In places like Indonesia and Papua New Guinea, data suggest the tipping point will come around 2020 — again, give or take five years. In Jamaica, 2023. In Nigeria, 2023. In Iceland, 2066.

Around the United States, Honolulu and Phoenix will reach their tipping points in 2043. Orlando and San Diego, 2046. New York, Philadelphia and Washington, 2047. Denver, 2048. Chicago, 2052. Seattle, 2055. Anchorage, 2071.

All of these predictions are based on a business-as-usual scenario for reining in greenhouse gas emissions — that is, no concerted new international efforts to reverse the atmospheric loading of the industrial age, which increasingly appears to be the safest bet.

But even given bold new action on climate, the dates of climate departure recede by only 20 to 25 years, because it takes so long for the impacts to work their way through climate systems already so distorted by globe-warming gases.

What happens after the tipping point is reached?

[C]limates without modern precedents could cause large and potentially serious impacts on ecological and social systems. For instance, species whose persistence is shaped by the climate can respond by shifting their geographical ranges, remaining in place and adapting, or becoming extinct. Shifts in species distributions and abundances can increase the risk of extinction, alter community structure and disrupt ecological interactions and the functioning of ecosystems.

Changing climates could also affect the following: human welfare, through changes in the supply of food and water; human health, through wider spread of infectious vector-borne diseases, through heat stress and through mental illness; the economy, through changes in goods and services; and national security as a result of population shifts, heightened competition for natural resources, violent conflict and geopolitical instability.

Although most ecological and social systems have the ability to adapt to a changing climate, the magnitude of disruption in both ecosystems and societies will be strongly determined by the time frames in which the climate will reach unprecedented states (my emphasis).

Tropics hit hardest

Geography-minded readers will have noticed a latitudinal progression in the departure dates cited above, from the tropics toward the poles, and might also assume that’s good news to some degree, because it puts off till last the full impact on polar ice sheets.

But it’s really bad news. This timing reflects the fact, first, that the climate record in the polar regions shows a wider band of variability in average annual temperatures, so it takes longer for the modeled trends to climb outside it.

Moreover, the impact of temperature changes in the tropics is magnified by two factors: They have more of the world’s zones of critical biodiversity, and are home not only to a disproportionate share of the world’s population, but also of its poorest peoples, least capable of coping with a hotter new world.

The Nature  paper’s chief author, Camilo Mora, is not himself a climatologist. His scholarship and labs at the University of Hawaii’s Manoa campus are devoted to studying the interactions of geography and biodiversity, and to bringing enormous masses of data to bear on certain questions about ecological health and conservation.

In this case, they aimed the data at a simple question said to have been raised by Abby Frazier, a doctoral candidate in Mora’s department: Rather than look at overall warming trends across the entire globe, or over smaller but still vast areas like the polar regions, couldn’t it be possible to predict the pace of change on a much finer scale — like a selection of the world’s largest cities?

The answer turned out to be yes, given enough graduate students and computing power, and the method was elegantly simple.

Plenty of data, and praise

Plenty of data was already publicly available in the form of forecasts generated from widely accepted climate models, some 39 in all.

Choosing mean annual near-surface air temperature as the variable to be mapped, the team overlaid the earth with a grid whose cells measured 100 kilometers on a side. It then computed a baseline band of temperature variability for each by plotting recorded temperatures from 1860 to 2005 (the hottest year on record, globally, so far).

Finally, it plotted for each cell the average of future temperatures predicted by the 39 climate models. A lot of math, but a clear — and conservative — comparison was now possible, pinpointing the year in which future temperatures at each location climb completely outside the pattern of past variability, never to return.

Although this paper has received little attention in Minnesota media, it attracted considerable coverage elsewhere and drew high praise from climate scientists and others who had no involvement with the work. A sampling:

“This paper is unusually important,” Jane Lubchenco, former head of the National Oceanic and Atmospheric Administration and now professor at Oregon State University, said in a statement quoted in USA Today, because it “connects the dots between climate models and impacts to biodiversity in a stunningly fresh way.”

“One can think of this year as a kind of threshold into a hot new world from which one never goes back,” Christopher Field, director of the Department of Global Ecology at the Carnegie Institution for Science, told the Associated Press. “This is really dramatic.”

The pace of change predicted for the tropics “immediately raises all sorts of alarms bells,” said Stuart Pimm, a conservation ecologist at Duke University, told the Los Angeles Times. “The greatest variety of life and biodiversity and the poorest people in world live in tropics, and the new climate shifts will be outside their parents’ and grandparents’ experience.”

Judith Curry, an earth scientist at Georgia Tech who has been publicly skeptical of climate models’ ability to make accurate predictions, told the Washington Post that she found the paper “compelling.”

And Michael Mann of Penn State observed, in comments to the AP, that the research “may be actually presenting an overly rosy scenario when it comes to how close we are to passing the threshold for dangerous climate impacts. By some measures, we are already there.”

* * *

The Nature paper is available here, but you’ll have to buy or rent access beyond the abstract and charts (which are rather stunning). The team’s interactive map of tipping points across the globe, and other information about the research, is available from Camilo Mora’s lab.

Comments (15)

  1. Submitted by Neal Rovick on 10/24/2013 - 11:30 am.

    After reading the current results of in-progress studies, I would guess that we have already passed the “tipping point” for the climate.

    The summer temperatures in places like the north Siberian coasts have reached a point where large and unprecedented releases of methane from the permafrost are occurring. 90 degrees on the Siberian Arctic shore? It happened this summer. There are hundreds of billions of tons of methane up there, formerly locked in permafrost. And methane is 20 times as potent as carbon dioxide as a greenhouse gas.

    The US has experienced several major weather systems that have moved in an unprecedented manner from east TO west, counter to normal flow due to a much weakened jet stream. The weakened jet stream is also identified as the culprit behind major flood events (like in Colorado), where the systems get “stuck” for days or weeks. Some areas stuck in drought, others in flood. Coastal China experienced weeks of temperatures of 100 to 110 degrees, with the ocean temperature at 90+ degrees.. Torrential rains in Siberia flooded over 100 Million square kilometers after a month or so of record-breaking heat, drought and forest fires. All due to weather that doesn’t move on because of the decreasing temperature differential between the arctic and temperate latitudes that formerly dove the jet stream.

    My guess is that it will be entirely obvious to all in 5 to 10 years that the tipping point was passed a while ago. And the new normal will not be normal. Even the most hard-core denier.

    • Submitted by Lance Groth on 10/24/2013 - 02:03 pm.


      All excellent points. I saw no mention in the article of whether methane release is factored into the models, but release of large amounts of methane can spike the temperature abruptly. The long term gradual trend is bad enough, but it is the existence of feedback loops that present an even greater danger that things can spiral out of control (as if they were ever in control) much more quickly than the models indicate.

      As the arctic warms and the jet stream weakens further, one can imagine summers in the Midwest in which there are very long heatwaves – weeks or even months – in which stagnant hot air stays in place with no cool fronts to break up the pattern. Imagine what this, combined with depletion of aquifers which will eventually mean the end of irrigation, will do to agriculture.

      Access to water is going to become a huge problem too. I just recently heard discussion of how the Saudis depleted an ancient aquifer by using it to irrigate wheat fields. They got 20 years of wheat production in exchange for using up a millions-year old aquifer that is not being replenished. This will happen more and more.

      The range of problems confronting the world now are just staggeringly daunting.

  2. Submitted by Jeff Michaels on 10/24/2013 - 05:15 pm.

    Dire predictions

    As a fellow with gray hair and a good memory, I continue to chuckle over those predicting the next disaster that will befall humankind. I easily recall the alarmists of the early 1970s who were certain most of us would be dead (or really, really skinny) by the year 2000 since we were going to run out of food because there would be too many people.

    I think of that dire prediction every time I hear our brilliant and beloved First Lady say her major worry is the country simply has too many really, really fat kids.

    Despite the tipping concerns expressed above, I will still be sleeping very well this evening. Disasters are always predicted to happen just far enough into the future so that no one will ever remember — except those of us with gray hair and good memories.

    • Submitted by Todd Adler on 10/25/2013 - 07:35 am.


      I too have grey hair. Unfortunately though the predictions have already become reality as we go through record storms, heat waves, flooding, and droughts. This isn’t a matter of some religious nut predicting the world ends in the year 2000 or when the Mayan calendar ends. These are real scientists with real data following the points as they progress from A to B to Z. If you think their models are bunk you’re free to fund an effort to take the data, build your own climate model, and see where it leads.

      Some people will chuckle as Jeff has above and try to say the earth is too big for man to affect. All the while they ignore the man mad disasters around them. The Minnesota River is an open sewer, directly leading to a vast dead zone in the Gulf of Mexico. The Aral Sea in Russia is only a fraction of its original size due to irrigation. And let’s not forget the hole in the ozone layer, brought to you by chlorofluorocarbons.

      Food production was indeed a very real problem due to population growth outstripping the food supply. It got solved, at least temporarily, because people took it seriously and scientists figured out ways to boost crop yields.

      Personally, I prefer to identify and tackle problems using a fact-based system rather than a patronizing pat on the head that is promptly stuck in the sand.

    • Submitted by Neal Rovick on 10/25/2013 - 08:06 am.


      It’s worth a chuckle to know that the problems we are facing are exactly the result of overcoming other survival and quality of life issues.

      Those issues, solved over the past 150 years or so, were solved largely by liberating millions of years of trapped carbon.

      It is definitely worth a bucket of chuckles to know that this problem cannot be solved by the same solution– liberating another couple million years of carbon.

      But save a chuckle for the day when it becomes clear to you we have passed around a corner and that the flywheel of liberated carbon is still speeding up and cannot be slowed for many, many years.

  3. Submitted by Dennis Tester on 10/24/2013 - 10:00 pm.

    Oh well

    By the way, if this turns out not to be true, can the taxpayers get our grant money back?

  4. Submitted by Rolf Westgard on 10/25/2013 - 06:30 pm.

    Ignores negative feedback

    This paper makes the same mistake as all the IPCC Assessments. They both ignore negative feedbacks, stressing only the positive. One example is the reflectivity of clouds which increase with rising temperatures. This negates the trivial warming contribution of CO2, one part in 2500 in the atmosphere.
    The IPCC temperature forecasts are way off compared to reality as earth and ocean atmosphere temps have been stable for 12-15 years. Severe storms and droughts have not increased in recent years. The 2013 Atlantic hurricane season is the quietest in 100 years.
    The earth has been warming since the Wisconsin Glaciation melted 12,000 years ago, but the rate has slowed to a crawl.

    • Submitted by Todd Adler on 10/26/2013 - 08:38 am.


      Actually the temperatures have not stabilized in the past 12 – 15 years. They only look that way if you selectively pick a high starting point 15 years ago and an artificially low ending point today. If you use the full range of data you’ll see that temperatures do indeed continue to rise.

      The lack of major hurricanes this year has no bearing on whether or not global warming is a fact. As every scientist knows, one data point does not a trend make. If you come back with ten or twenty years of reduced activity, then you’ll have something to talk about.

      For droughts, you can’t point to any one drought and say it is or isn’t caused by global warming as they have multiple causes. The 2012 drought though is one of the worst in the past 100 years, so it would be silly to claim they have not increased in any way.

      The IPCC reports do indeed take into effect the cooling nature of clouds. It took about 30 nanoseconds with a Google search to find it thoroughly addressed in their 2007 report.

      Do you have additional mistakes you would like to discuss?

      • Submitted by Rolf Westgard on 10/28/2013 - 08:05 am.

        IPCC forecasts

        Yes. Their warming forecasts are all way off. And it doesn’t matter which year you start with, there is no warming in the 21st Century. And not likely to be any for another 15 years or so as the Pacific Decadal Oscillation is in a negative phase.
        And it has been 8 years since a Force 3 or stronger hurricane has arrived in the US. Force 1 Sandy did major damage because we have built so much stuff in flood plains. There is no increase in unusual weather events.
        Relax and let the plants, forests, and food crops have the CO2.

        • Submitted by Todd Adler on 11/03/2013 - 10:02 am.


          If you look at just the past 16 years global warming has been about .141 degrees. Add in one more year though and it jumps to about .350. That’s hardly flat–that’s cherry picking data.

          Not to mention that those 16 years also cover 15 of the hottest years on record. Even if you claim the years are flat they’re still a pretty darn high flat.

          Head, meet sand. Sand, meet head. I’m sure you two are already very well acquainted.

  5. Submitted by Neal Rovick on 10/26/2013 - 10:19 am.

    Even more chuckles….

    Adults of the modern world, conducting their live with technology that would have been considered witchcraft a century ago—technology borne on the liberation of hundreds of millions of years of accumulated carbon—technology that has provided for billions more people than this ol world ever supported—technology that has marked virtually every square mile of arable or usable land—all clinging to the belief that it all has no effect on the global climate.

    150 years of incredible change–it all adds up to no effect.


  6. Submitted by Rolf Westgard on 10/30/2013 - 05:58 pm.

    Effect of technology, especially fossil fuels

    Thanks to the energy from fossil fuels, life on earth overall has never been better. There is still a lot to do, but the air and water are cleaner than ever, and life spans are much longer than in the past.

  7. Submitted by Todd Adler on 11/01/2013 - 02:22 pm.

    Clean Air & Water

    Let me go grab a glass of water from the Minnesota River and have you take a chug. Then you can tell me the water is cleaner than ever.

    Seriously. Where do people get these notions?

    Actually, life spans in the U.S. are on their way down. Life expectancy peaked for people born in the 1960s and have started down from there due to obesity and environmental factors.

  8. Submitted by R. M. Ramsay on 11/02/2013 - 04:44 pm.

    So many facts…..

    So many facts and a new way of viewing Climate Science with seemingly little time to learn how to interpret it. That seems to be where the ‘naysayers/doubters, etc.’ find a home for their counter-arguments.
    It’s the nature of humans to intellectualize the obvious, to argue for self-supporting concepts that provide justification for lifestyle, profit motives, etc.
    But, with fear and facts, well, it usually takes science to calmly review field findings by various metthods of analysis to keep the fears at bay, and let what filters through do the talking. Too, there is little ‘profit’ to be gained, and most importantly, a strong sense of responsibility, which governs the scientific community that is most important. SOME type of climate change IS happening, what the outcome will be is, and will be an unknown until it progresses, obviously.
    I believe the studies, and one thing that is important and yet probably not yet really understood; what the studies cannot provide is the FEELING we will have when things get worse. Humankind is in for a great sadness, a kind that we will wish was nothing more than a bad dream. I for one, hope I’m wrong.

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