The New Normal Is No Normal

Temperature new normal hydrology corner blog

I was stunned when I looked at NASA’s plot of monthly temperature anomalies showing that not only was July the hottest July ever recorded, it was the hottest month ever recorded, and the most recent (maybe not the last!) in an streak of new monthly records going back 10 months.

There is shock value in seeing the whitespace on this graph separating the recent sequence of consecutive anomalies from the 136 years previous period of record.

We aren’t flipping coins with an improbable run of turning up heads. The law of large numbers and regression toward the mean are not going to help.

There is now ample physical evidence that the science of climate change may have got it right.

There was always the possibility that climate dynamics are more complex in reality than what we account for with our simplistic modeling assumptions. With greater complexity comes greater resilience. There are bound to be many atmosphere/hydrosphere/lithosphere/biosphere/cryosphere interactions that we don’t understand and that we will only be able to discover with the benefit of hindsight. While some of those dynamics could accelerate change, some must impart stability. Perhaps we have been focusing on the ‘bad’ dynamics and not looking hard enough for the ‘good’ dynamics.

This plot of monthly anomalies is not what you would expect to see from a resilient system.

What does this mean for water resources? You could do a calculation to find out. The Clausius-Clapeyron relation relates vapor pressure to temperature, which could be used to estimate the increase in water holding capacity of the entire atmosphere due to this change in temperature. I haven’t done that but would speculate that the increase in temperature is enough to swell the size of some atmospheric rivers to an Amazonian scale. It also means that in water supply limited landscapes every last drop of water will be sucked up to satisfy this water vapor deficit.

Does this mean that dry places will get dryer and wet places will get wetter? Maybe, but maybe not.

The high Arctic is warming disproportionately to the rest of the world. Arctic sea ice is disappearing and the ice-free season is getting longer. The jet stream is sensitive to the temperature differential between the tropics and the Arctic and hence, can’t be counted on to continue to deliver weather following historic patterns. Some dry places may get wetter and some wet places may get dryer.

If you are in California or Africa you may welcome a new atmospheric river hosing down an abundance of fresh water. But too much of a good thing can be a bad thing. Wet landscapes, such as the Amazon have had millennia to develop sufficient conveyance capacity for their water abundance. In contrast, dry landscapes are maladapted to handle massive volumes of water.

I like to be optimistic about our future. After all, if we found a nearby planet that was identical to earth in every respect except it was two degrees warmer we would be building massive rocket ships to get as many people there as quickly as possible.

We can adapt. I just wasn’t expecting that we would need to adapt quite as quickly as this graph indicates.


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6 responses to “The New Normal Is No Normal”

  1. Jaime Saldarriaga August 23, 2016 at 5:55 am

    Fortunately monthly air temperature is a seasonal variable.

    • Hi Jaime,
      I have wondered about the apparent seasonality in the global anomalies. Naively, I would have expected seasonality would cancel out at a global scale. I think it might have something to do with the proportion of ice-free land mass in the northern hemisphere relative to the southern hemisphere. However, I don’t see how seasonality helps with the persistence of this trend.

  2. The time series that has been strung together for this data set consists of apples, oranges, bananas, kumquates, lemons and then some. Granted, NASA has done their best to adjust it all to be comparable, but we should never lose sight of the fact that we are not comparing 1880 apples to 2015 apples. Not even 1980 apples to 2015 apples. This is also using the MERRA-2 (Modern-Era Retrospective analysis for Research and Applications, Version 2 ) which is only a few years old. As I look at that white space, my first concern is that MEERA-2, or one of its components, is the anomaly rather than the actual global temperatures. Time will tell. Maybe I’m just biased because July where I live was very pleasant and not anomalously hot.
    Global climate change is real, but science is not well served by rushing to dramatic headlines. Better to carefully, and deliberately analyze the inputs to MEERA-2 to understand better what is behind those data points. A less than one month turn around doesn’t allow for much deliberation. Actually, it doesn’t allow for any at all. That should concern all parties involved.

    • Hi Matthew
      The strength of conclusions should be tied to strength of the data and you are right, the strength of the data for assimilating global monthly temperatures for the past 136 years is weak. The lines in the plot are colour-coded by year and I was looking for the mid-twentieth century cooling that is very evident in many long time-series and cannot see it even though it should show up as an anomalously cool period (nearly as cool as the start of the period of record). This shows monotonic warming. However, having said that, the strength of global climate data in recent decades is fairly robust so even if you throw out the previous 100 years as being ‘suspicious’ it still leaves the last 10 months sticking out like a sore thumb relative to the last 30 or so years.

      I am not as concerned as you are about the quick turn-around for the monthly statistics. Data assimilation to resolve the state of the entire atmosphere is done several times a day to initialize numerical weather prediction models. It must be reasonably accurate or we would not be successful at forecasting the present, never mind next weekend. If the data exist there are some algorithms and some pretty powerful computers that can crunch the numbers pretty quickly.

  3. Edward M. Dexter, P.G. September 1, 2016 at 7:09 am

    I like your mention of the effects that Arctic warming will have. I’m just a dumb geologist, not a climatologist, but after 36 years as a practicing hydrogeologist, I do know one thing: your drink gets warm a lot faster after all the ice has melted. It will be an exciting next 50 years.

    • Hi Ed,
      Every kg of ice melt is consuming 333.55 kJ of available energy. What will all that energy be doing when there is less ice to melt? It is hard to imagine.

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