Chapter 7: How Do We Know That Happened? Reconstructing The Past To Understand The Present

IF WE WANT STUDENTS TO UNDERSTAND WHAT THE FUTURE HOLDS, THEY WILL HAVE TO GRASP WHAT’S HAPPENING WITH EARTH SYSTEMS IN THE PRESENT. However, the present becomes meaningful and predictive only if we can find out how past climate conditions such as temperature, CO2 levels, and precipitation influenced one another. Because natural planetary changes unfold on immense time scales, scientists have to rely on evidence that was generated centuries or many millennia ago to make sense of the past and to offer conjectures about the future. The past, present, and future can be understood only in relation to one another.

Now famous visualizations of climate

The graph below is from Ed Hawkins, Climate scientist, NCAS/University of Reading. I mentioned in the book chapter than a seventh grade teacher projected something like this to her class. While most of her students were gasping at humanity’s precarious perch on the right, one student exclaimed that we have no way of knowing the temperatures that long ago (about 800,000 years). This started a rich conversation about how nature always leaves behind clues about temperatures, humidity, precipitation and other conditions.

You have probably seen the famous “stripes” representation, also created by Hawkins. Each stripe represents the global temperature averaged over one year, from 1850 to 2022. Red stripes are years that were hotter than the 1971-2000 average; blue stripes are years that were cooler. The representation has been recognized as one that influences people’s perceptions most about the reality of climate change. If we think about all the graphs and charts that are out there, there must be something magical about the stripes that have made adults and children take climate change more seriously. The picture below is the projection of the stripes on the white cliffs of Dover in the UK—the written message above is part of the “Britain Talks Climate” campaign. Here you can find temperature stripes for your own region and read the history of their application.

Past, resent, future are all entangled

The image below is one that I wanted to put into the book, but could not make it work for readers. My point was that we should be helping students understand how data from the past (in the form of proxies) and present (instrumental records) work together to reveal what has happened historically, puts today’s climate in context, and allows us to model the future. These are important messages, and even young students can grasp the basics of this idea.

The beauty of the historical climate record

The modern historical record includes data represented by Native Americans. Since as early as the seventeenth century, many Plains Indian groups kept pictographic calendrical records called waniyetu wówapi or “winter counts” that record how events memorably affected individual bands of Plains Indians. Here is an overview by Matthew Therrell and Makayla Trotter. The National Museum of the American Indian provides a lesson in which students learn about the oral culture and history-keeping of the Nakota people, who made the Lone Dog Winter Count.

Other resources

In this middle school activity, students assume the role of paleoclimatologists to figure out an answer to the driving question, “What was the climate like in the Anacostia watershed over the past 12,500 years?” The “Looking Backward, Looking Forward” activity expands students’ understanding of climate and climate change through exploration of the geologic record.

Here are some reliable and rich resources to learn more about how climate data is used from the past and represented in the present. On the CarbonBrief site you can find Mapped: How ‘proxy’ data reveals the climate of the Earth’s distant past by Robert McSweeney and Zeke Hausfather. it provides a wealth of information including how paleoclimatic data is being collected in your state. A site from NOAA asks: How Do We Study Past Climates? and gives authoritative information about the diverse methods of collecting paleoclimatological data.

And then there is the paleoclimate haiku page–enjoy!

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