Spring Cooling: Hamburg’s Forsythia Blossoming Whopping 17 Days Later Than 30 Years Ago!

Forsythia are an indicator plant used by the German DWD Weather Service for marking the beginning of spring in March. The trend of spring blossoming show that springs in Hamburg have been cooling over the past 30 years.

The north German port city of Hamburg happens to have a long data series on the the date the plant blossoms and so it has some use as a spring climate tracker for that perticular region.

An ever increasingly earlier blossoming of the plant is claimed to be evidence by alarmists of climatic warming, which would be again exclusively CO2’s doing.

It is often suggested that the forsythia only blossomed in May 40 years ago and now the date has since moved forward.

But Josef Kowatsch at the European Institute (EIKE) has looked into the matter and asked: Do the forsythia really bloom earlier? The answer is no.

Phenologist Iska Holtz recently reported that this year the reference forsythia bush located at the Hamburg Lombardsbrücke began to blossom on March 12th, which is 71 days after the beginning of the year.

The following chart shows the date of blossoming since 1987. The vertical axis shows the number of days after the beginning of the year that the shrub first blossomed. The greater the number, the later the shrub blossomed, and thus the colder the spring was:

Figure 1: The left vertical y-axis shows the calendar days since the beginning of the year. The more calendar days, the later the start of forsythia flowering. Back in 1988/89/90 the start of the flowering of the forsythia was in February! Chart: Josef Kowatsch.

Surprise! the linear trend shows that the forsythia are blossoming 17 days later than 30 years ago. This would indicate cooling, and not warming.

Hamburg’s springs have cooled considerably

The temperatures of February and March essentially determine the start of flowering of the Forsythia shrub in the city centre of Hamburg. Note also February/March 1996 was very cold and thus the late flowering.

First the chart which shows February mean temperature since 1987, the last 33 years:

Figure 2: Even without a drawn trend line, you would see it right away: February in Hamburg has gotten colder. February 2019 was mild in Hamburg, in contrast to last year (2018) when the beginning of flowering was delayed to April 4th. Chart: Josef Kowatsch

March has cooled as well

Even more than the month of February, March temperatures influence the forsythia flowering date at the Lombardsbrücke in Hamburg. And the first 12 days of March 2019 in Hamburg were very mild with an average of 6 to 7 degrees. This favored the relatively early start of flowering in 2019.

Overall, however, the month of March also has become somewhat colder in Hamburg.

Figure 3: March has also been getting somewhat colder in Hamburg for over 30 years. (2019 data not yet available). Chart: Josef Kowatsch

The temperatures of February and March essentially determine the beginning of the flowering season of the forsythia shrub in downtown Hamburg. Note also the very cold February/March of 1996 and the late flowering.

Next we look at the the blossom date going back to 1971:

Figure 4: Since 1971, the flowering date of forsythia in Hamburg has been steady. The mean is about 80 days after New Year. Despite an increase in CO2 – a fertilizer from the air and despite an increase in fertilizers in groundwater, all growth-promoting and flower-driving factors, spring in Hamburg has not been earlier over the past 47 years, and has even been delayed in the last 33 years. Chart: Josef Kowatsch

There’s been no trend over the past 5 decades. And if one accounts for the urban heat island effect, then we can only conclude some underlying cooling has taken place.

18 responses to “Spring Cooling: Hamburg’s Forsythia Blossoming Whopping 17 Days Later Than 30 Years Ago!”

  1. SebastianH

    I missed the Kowatch posts. Thank you for adding to that category again, Pierre.

    I’d like to add the complete Forsythe blooming record:

    Note how the blooming correlates with the mean temperature in the 90 days prior and surprise, it is getting warmer in Hamburg as well.

    Let’s also look at the complete temperature record for the area for February:

    and March:

    There’s been no trend over the past 5 decades. And if one accounts for the urban heat island effect, then we can only conclude some underlying cooling has taken place.

    Well, this assertion completely collapses when you look further back. There were a few “warm” winters in Hamburg in the 70s and in the 90s. Starting with those in a timeline will always result in distortion, just like if you were to start a global temperature timeline at the top of an El Nino like the 1998 one. Same happens when you look at the Arctic sea ice extent, but limit your data to just the summer extent and starting from 2007 (2012 works as well). You’ll see that sea ice is actually growing. Weird, huh? But that’s how cherry picking works and Kowatsch is a master in the discipline.

  2. tom0mason

    Yep this fits with the 30 years of global warming hiatus, and in some places temperatures have been on a slow 30 year decline.

    I wonder where on this planet is the evidence for 30 years of rapid warming? Those climate models say it exists so where is it? Or maybe the models, the programmers and their pseudo-scientific advisers just got it all wrong.

  3. Yonason

    Look what’s “blossoming” in the UK!

    How sweet to see some sanity in bloom.

    1. SebastianH

      Steel is used to produce many things, not least wind-turbine blades […]

      Oh boy … I guess you learn something new every day 🙂

    2. Yonason

      “Steel is used to produce many things, not least wind-turbine blades which cannot be produced cost effectively by renewable energy.”

      I just thought that part about blades was a typo, and that he meant the wind turbines themselves, since they do require steel, and the erratic and highly expensive and inefficient energy provided by “renewables” isn’t going to do the trick. The last is the important part, which is why the troll ignores it.

      Leave it to the troll to try to distract from the important part of the message.

      1. SebastianH

        The question is, what value does “the important part” have when the author can’t get the simple parts right?

        Besides, steel is made with the help of electric arc furnaces. Why should renewables not be able to power those cost effectively? You do know that many countries exist which have a very high percentage of renewable energy in their grids, right?

    3. tom0mason

      More CO2 to be generated.
      As there is no downside to CO2 generation, only fools and their advocates ‘believe’ it is a problem but they have NO evidence that it is.
      Keep it UK, it’s what the vegetable world requires.

      Hopefully we’ll be up to 600ppm soon, then onward to the 800ppm or more.

  4. sasquatch

    In 1987 the lilacs were in full bloom on May 11th.

    Every year since then, the lilacs have blossomed on later dates.

    I can’t forget that date and the lilacs in blossom that day, never will. My wife and I had our first child on that day.

    Have made the observation ever since then and every year after, the blossoming of lilacs has always been later than May 11th of 1987.

    Not that it is of any significance, just something I have observed over the years. There a a lot of lilac bushes and groves out there in the hinterlands near my location.

  5. John F. Hultquist

    In Washington D.C., the Cherry Trees are watched.
    When there, the right side link goes to general info, the left side link is to the latest update and daily photos.
    A few years ago they blossomed early and it was proof of global warming.
    Last year they “reached full bloom” on the long term average. This year the forecast is for an “average” date also.

    The link above has lots of pretty photos. The text is intended for tourists, not science-interest types.

    1. John F. Hultquist

      The National Park folks use the phrase “peak bloom” and this is in a page titled:
      “What Peak Bloom Means and Why It (sort of) Matters”

      Full bloom and peak bloom are not exactly the same thing.

      1. Yonason

        Back in the spring of 1977 I was looking forward to strolling among the cherry blossoms when I was in the area. They were off to a good start, but the day of my trip an arctic blast came down and froze them. I wonder, when they say how early blossoms begin, do they totally ignore the fact that if it had been a cash crop, that year would have been a catastrophic loss due to late cold?

  6. Kevin Lohse

    I’ve planted my garden in tropical east Kent, UK, for year-round colour. This year, the flowering currants and a magnolia shrub are about 3 weeks earlier coming into bloom than expected. Given that Gaia is not combusting, any ideas why this should be so?

  7. Phil Salmon

    Yes the “earlier spring” story has indeed gone quiet in recent years.
    Reality didn’t get the memo.

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