From the Weather is Not Climate Department: Köppen Climate Classification Map

Way back in the Pleistocene (1976), I took a semester of Physical Geography. We learned about something called the “Köppen Climate Classification System”; a procedure that systematically categorizes climate primarily on the basis of vegetation.

If we’ve had significant climate change over the last 150 years, the Köppen Climate Classification Map should reflect those changes… Right?

Here’s the map for 1901-1925…

Here’s the map for 1951-2000…

Source: Kottek, M., J. Grieser, C. Beck, B. Rudolf, and F. Rubel, 2006: World Map of the Köppen-Geiger climate classification updated. Meteorol. Z., 15, 259-263. DOI: 10.1127/0941-2948/2006/0130.

I’m sure that if I printed these maps out at full scale and overlaid them on a light table, I could see some differences because climate is always changing… But, eyeballing it, I don’t see much difference between the early 20th century vs mid-late 20th century climates.

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One Response to “From the Weather is Not Climate Department: Köppen Climate Classification Map”

  1. David Middleton Says:

    Faraz says:
    December 8, 2011 at 1:47 pm
    Global warming is already showing its impact. In the last decade vivid climate change has happened. The whole world have witnessed the disasters in different countries which are basically the impacts of climate change. Various factors are involved for the change in climate system which are called climate forcing mechanisms. These are broadly speaking climate change causes.

    That’s so far off the mark, that it’s not even wrong…

    FEBRUARY 10, 2011
    The Weather Isn’t Getting Weirder
    The latest research belies the idea that storms are getting more extreme.

    By ANNE JOLIS
    Last week a severe storm froze Dallas under a sheet of ice, just in time to disrupt the plans of the tens of thousands of (American) football fans descending on the city for the Super Bowl. On the other side of the globe, Cyclone Yasi slammed northeastern Australia, destroying homes and crops and displacing hundreds of thousands of people.

    Some climate alarmists would have us believe that these storms are yet another baleful consequence of man-made CO2 emissions. In addition to the latest weather events, they also point to recent cyclones in Burma, last winter’s fatal chills in Nepal and Bangladesh, December’s blizzards in Britain, and every other drought, typhoon and unseasonable heat wave around the world.

    But is it true? To answer that question, you need to understand whether recent weather trends are extreme by historical standards. The Twentieth Century Reanalysis Project is the latest attempt to find out, using super-computers to generate a dataset of global atmospheric circulation from 1871 to the present.

    As it happens, the project’s initial findings, published last month, show no evidence of an intensifying weather trend. “In the climate models, the extremes get more extreme as we move into a doubled CO2 world in 100 years,” atmospheric scientist Gilbert Compo, one of the researchers on the project, tells me from his office at the University of Colorado, Boulder. “So we were surprised that none of the three major indices of climate variability that we used show a trend of increased circulation going back to 1871.”

    In other words, researchers have yet to find evidence of more-extreme weather patterns over the period, contrary to what the models predict. “There’s no data-driven answer yet to the question of how human activity has affected extreme weather,” adds Roger Pielke Jr., another University of Colorado climate researcher.

    […]

    WSJ

    Abstract
    The Twentieth Century Reanalysis (20CR) project is an international effort to produce a comprehensive global atmospheric circulation dataset spanning the twentieth century, assimilating only surface pressure reports and using observed monthly sea-surface temperature and sea-ice distributions as boundary conditions. It is chiefly motivated by a need to provide an observational dataset with quantified uncertainties for validations of climate model simulations of the twentieth century on all time-scales, with emphasis on the statistics of daily weather.

    […]

    It is anticipated that the 20CR dataset will be a valuable resource to the climate research community for both model validations and diagnostic studies. Some surprising results are already evident. For instance, the long-term trends of indices representing the North Atlantic Oscillation, the tropical Pacific Walker Circulation, and the Pacific–North American pattern are weak or non-existent over the full period of record. The long-term trends of zonally averaged precipitation minus evaporation also differ in character from those in climate model simulations of the twentieth century. Copyright © 2011 Royal Meteorological Society and Crown Copyright.

    Compo et al., 2011. The Twentieth Century Reanalysis Project. Q. J. R. Meteorol. Soc. 137: 1–28. DOI:10.1002/qj.776

    “So we were surprised that none of the three major indices of climate variability that we used show a trend of increased circulation going back to 1871.”

    Figure 16 from Compo et al., 2011.
    “The three major indices of climate variability” show no evidence that climate change is having any effect on extreme weather events…
    Which makes sense… Because there is no evidence that climate extremes are increasing either…
    NOAA Climate Extremes Index

    If we’ve had significant climate change over the last 150 years, the Köppen Climate Classification Map should reflect those changes… Right?
    1901-1925 Köppen Climate Classification Map
    1951-2000 Köppen Climate Classification Map
    I’m sure that if I printed these maps out at full scale and overlaid them on a light table, I could see some differences because climate is always changing… But, eyeballing it, I don’t see much difference between the early 20th century vs mid-late 20th century climates.

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