Office of the VP for Communications – Keeping alumni and friends connected to U-M

Time to act

Hot in Paris

The Eiffel Tower

On July 25, 2019, the high temperature in Paris was 108.7 degrees Fahrenheit. (Image: Pixabay.)

On July 25, 2019, the high temperature in Paris was 108.7 degrees Fahrenheit. I don’t usually get spun up about record-high temperatures, because on a warming planet, we expect record highs. It has been more than three decades since we have experienced a month with the global average surface temperature registering cooler than the 20th-century average. Record new highs dwarf the number of record new lows.

The July record in France astounded me because it broke the all-time record in Paris by four degrees. In the realm of weather and climate, that is a huge number.

July of 2019 was, in the National Oceanographic and Atmospheric Administration’s observations, the warmest month since the late 1800s. Climate scientists limit their reporting of monthly records to the last 140 years, because that is a span of time when temperature measurements are complete enough to render the uncertainty of monthly, global averages to be quite small.

Flooding in Michigan

Eroding coastline, Michigan

Flooding is increasingly common along the coast of Lake Michigan.

In Michigan last month, the temperature was not as exceptional as in Paris (or Greenland or Alaska), but an extreme environmental event continues to plague us just the same. In May, Lakes Erie and Superior set record-high water levels. Record and near-record lake levels persisted in June and July. There has been flooding along the Lake Michigan shoreline and in Detroit. Lake Ontario also has been in flood.

Professor Drew Gronewold and I have maintained that these record-high water levels are related to climate change. However, as recently as 2013, scientists also attributed record-low water levels to climate change. Climate-change skeptics point to these seemingly conflicting conclusions as proof that climate scientists blame everything on climate change

The Echo Effect

In 2013 and 2014, advocates — including scientists and the broader public — embraced the message that climate change was causing lake level decline. This statement had natural appeal: If the future is getting warmer and more water evaporates from the lakes, then lower lake levels make sense. Plus, the record followed several years of observed lake level decline, which made for easy, casual attribution.

The message spread widely, especially in the Great Lakes region. However, in the scientific literature, it was well known that such an explanation of systematic lake level decline was too simple. Some of us suggested that many other factors might influence lake levels, i.e., rain, snow, and runoff from the land. But that message never resonated in the public forum the way the “evaporation message” did.

In fact, the spread of the simplistic message about lake level decline was so pervasive, it exemplified the “echo effect.” That is, the appeal of the message was so strong it was echoed, whether or not it was the full story – or even correct.

It is about variability

Flooding in Detroit

Recent flooding in Detroit. (Image: Pixabay.)

The Earth responds to increased heat in the environment in many ways. Climate change does not, necessarily, lead to one outcome or another. Outcomes that in isolation appear contradictory might, in reality, be correct.

For the problem of lake levels, if weather patterns are in a drought condition and evaporation dominates the surface water balance, the increasing temperatures drive the downward influence on water levels. Hence, lower lows.

To the contrary, in a flood condition, the increased heat in the environment means more water is available for precipitation. Thus, the upward influence of weather on water levels is stronger.

Drought and flood conditions existed in the past, and they will exist in the future. New extremes, both highs and lows, are expected.

In many instances, climate change leads to increased variability.

Roller coaster ride

We are at the beginning of decades of rapid change. The heat in Paris and the floods of the Great Lakes are offering us the opportunity to learn what we need to do.

As already observed, we see many more new record-high temperatures than low temperatures. Record-low temperatures will become more and more rare. How lake levels will change is more complicated because lake levels rely on many more environmental factors than temperature and precipitation. If heat continues to accumulate without mitigation, we expect the influence of that heat to overwhelm the historical record of variability, and new modes of variability will emerge.

How can we plan for increased variability? Rather than one outcome or another, a more usable and more honest way to think about climate change in the future is a set of plausible scenarios that describe the variability. If we use the emerging behavior in our changing climate to develop these scenarios, then planners and managers can work through how to respond to those scenarios.



  1. Brad Wright - 1974 Michigan Engineering

    Let us look at the basics. All scientists are skeptics. The word “believe” is spiritual and does not exist in science. Progressive logic is vital. One must first be curious, then want to think (work) to gain knowledge, then develop understanding, arrive at conclusions, and finally develop paradigms. I have seen no certification or definition of “climate scientist”. Weather and climate have no connection. Climate has constantly changed for 4.5 billion years. Humans have adapted to changes in climate (ice ages) for 300,000 years. All complex computer models can be gamed, especially those with thousands of interdependent variables. Raw data must go through a validation processes, which may vary. Valid data must be interpreted, which invites bias, as has been demonstrated in many scientific journals……… Now let us look at carbon. Since humans emit 3% of all carbon, what is happening to the other 97%? Carbon is 9% to 15% of the greenhouse effect. Multiply .03 by .15 and you get .005. So one half of one percent of the greenhouse effect comes from humans. If one looks at what is in that .005, one will notice that it will only rise. In any event, carbon will always be insignificant. Do we have any idea of how carbon sinks vary over time? Is carbon in the atmosphere a leading or following indicator?….Now look at other significant variables, including the albedo effect. The reflectivity is constantly changing….. Books, such as “The Structure of Scientific Revolutions” (Kuhn), “The Believing Brain” (Shermer), and “Curious” (Leslie) help to explain the power of the human subconscience. Brain washing, now demonstrated by constant videos of melting glaciers at airports (and the levels in the Great Lakes), remind me of what I heard about China when I was young. These videos appears to create a sense of fear, regardless of whether anything can be done…. Still, the University of Michigan sends students out in the field to study carbon emissions without a foundation of curiosity, knowledge, and understanding.


    • Richard Rood

      Interesting set of statements. Some of which, I believe, are verifiably incorrect.

      I do believe that the word “believe” has some role in science. The dictionary definition is “To accept (something) as true or real.” But we have decided to associate “belief” with things spiritual, and to “accept” the results of scientific investigation as a source of verifiable knowledge. However, I am not sure why you chose to make your statements about “believing.”

      The progression of scientific investigation is often observations, hypotheses based on correlated behavior of the observations, and theories from related hypotheses. The nature of scientific investigation is that hypotheses and theories are testable through measured parameters. They are reproducible by independent investigators. The outcome is knowledge and an uncertainty description of that knowledge. The process is iterative, with new observations being brought to bear on the body of knowledge. The process is not linear. Climate science adheres to this philosophy of science.

      Our department at the University of Michigan, Climate and Space Sciences and Engineering, offers credentials as a “climate scientist.” Indeed, 100s of institutions offer this credential.

      Though I consider it an inadequate definition, climate was traditionally defined as a 30-year average of weather. They are, hence, related by definition.

      Indeed, climate varies. “Constantly changed” is probably not a correct characterization. We can use the methods of scientific investigation to understand climate variability. As curious, sentient beings, we do.

      Indeed, humans have adapted. We continue to adapt, and we will need to adapt. My goal is to provide students with improved skills of adaptation.

      The changes we are, presently, experiencing are strongly influenced by human activities. We are part of the cause of variability. The change is fast. It is disruptive. We will have to adapt quickly. We will be best served by limiting the extent of the change.

      I don’t understand your carbon budget and the numbers. Then, well, I don’t know what to with the progressive logic at the point of “melting glaciers at airports.”

      I am constantly impressed by the curiosity, knowledge, and understanding on the students I meet.

      Thank you, for your comment.


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