How to Explain Climate Change to Your Own Mother: The Science and The Scientists

by Katie Behrmann

What is climate science? Who are climate scientists? I promised an answer and I’m here to deliver, by dissecting how climate is measured and who gathers this climate data. However, to kick off this post, we will actually start with what climate is not, and that’s weather. Many misconceptions about climate science stem from the confusion between these two topics. A signature feature of climate is that it is a phenomenon that happens over the span of at least multiple decades and all over the globe. Climate is a historical average, and this simple fact can make climate a difficult concept to grasp, study, and make predictions about. Because climate is an average, scientists cannot point to a single event, say Hurricane Sandy, and blame its existence on ~climate change~. This is why the following statements are false: “It’s been a warm winter, climate change must be happening,” or, “it’s been a cold winter, climate change is not happening.” These are single events, these weather occurrences. They are points on a graph, and climate is the overall line on the graph that these points make when one zooms out from the graph. Think of it like letting the air out of a balloon. Localized random air pressure coming out of the balloon’s little tail forces the balloon every which way. Much like weather, these forces dictating the balloon’s immediate direction vary greatly and are difficult to predict. Gravity in this case acts like climate. Though the balloon zooms to and fro with delightfully farty timbre, we know that the balloon’s average trend is ultimately downward because of gravity. Similarly, climate reflects an overall trend or average regardless of minor variations. This handy video explains a lot. So does this cartoon.

So how do you study something that happens over such a gigantic temporal and spatial scale? How do researchers look into the past to find the average climate of a region? With so many aspects that make up a region’s climate—rainfall, temperature, snowmelt, season length, etc.—this seems like an impossible task. And then to predict what the climate could look like 50, 100 years down the road? What kind of black magic is this? Are climate scientists red-cheeked, bearded and bespectacled modern-day pioneers, gawking and gasping at cylindrical ice blocks somewhere in Greenland…or are they in a dark room shaking a magic 8 ball with the blessing of the United Nations and the National Science Foundation?

OK, OK I’m getting carried away. How is climate studied? Well, let’s start with the most direct type of methods. People have directly and precisely been recording weather data for about 150 years using scientific instruments. And not just data concerning daily temperature and rainfall; people have been taking high tide measurements, noting intense weather events such as snow and rain storms, and observing air quality, snowmelt, snowpack, plant blooms, timing of animal and fungal lifecycles, etc. In this way, meteorologists and other such weather recorders (such as Henry David Thoreau) contribute greatly to climate science, in that they take short-term, “snapshot” measurements. These snapshots of Earth’s weather can be put into an overall climate flip book. We can flip through this book, or plot these recorded data on a graph to get a picture of overall climate trends.

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Summer temperatures of the contiguous United States since 1895! Generate your own with the help of NOAA.

But what about the time period before humans were diligently recording observations about the weather in a common language and in real time? Well, qualitative human documentation and other anthropological or archaeological finds dating back hundreds, even thousands of years can give us some clues about the weather patterns of yore, and thus the climate of today. We know what people ate in certain regions of the world, when crop harvests began, and we have vivid and fanciful tales describing intense, almost biblical storms, unusually hot summers, and very frigid winters. Though these data are often numerically imprecise, they are still useful in piecing together an overall picture of past climates.

Talk about preparing for an El Nino kind of season--amiright?!

Talk about preparing for an El Nino kind of season–amiright?! Photo from Wikipedia.

And before curious and conscious organisms were perceiving and documenting weather? Weather and other natural forces leave their mark on many living and non-living things. Knowing what these marks look like and what causes them helps scientists speculate about and study the past. Scientists must use these proxies as a lens into the past. Certain tree rings, ice cores, corals, fossils, and sediments at the bottom of lakes and oceans date back thousands to hundreds of thousands of years and contain physical properties that reflect some aspect of climate from back then with varying precision. Ice cores from glaciers, for instance, record information on the composition of the atmosphere, as well as the average winter temperature. Glaciers are formed by falling snow that gets compacted by each subsequent year’s snowfall, creating visible layers of yearly snowfall. A warmer winter’s snow will feature different types of oxygen within the snowflakes than a colder winter. Additionally, air bubbles trapped in these ice layers give scientists a peak into the composition of the atmosphere during that time, including levels of carbon dioxide and other greenhouse gases. Though these types of data require much more analysis and calibration than simply reading a modern thermometer, they have been useful in determining climate trends over many millenia.

Layers in tree rings, sediment, and ice cores reveal information on past climate. Layers: who wore them best?

Layers in tree rings, sediment, and ice cores reveal information on past climates. Layers: who wore them best? Photos from Wikipedia.

We need information  on the Earth’s climate from hundreds of thousands of years ago because it helps to contextualize the nature of human-caused climate change today. The climate has undoubtedly undergone changes in the past, going through periods where both tropical and polar weather patterns have dominated the globe. Natural forces such as high solar output and volcanic activity have previously been the drivers of these changes, which happen over long periods of time. By examining the instrumental record and the paleontological record, we begin to see that human-caused climate change is occurring rather quickly. Past data show that glaciers, sea levels, atmospheric composition, and ocean temperatures typically transform very slowly, uncharacteristic of their grandiose changes within the past few decades. So, yes, climate has changed in the past, but through the work of meteorologists, oceanographers, geologists, biologists, anthropologists, paleontologists, chemists, mathematicians, and many others, it is clear that the Earth’s current climate trajectory is becoming more and more unpredictable.

Climate is a giant historical and spatial average, necessitating research from the past and present. Why? To make predictions about its FUTURE! The mathematical modeling that goes into making predictions is just about as painstaking as drilling for thousand year old ice cores in subzero temperatures. So make sure you and ma stay tuned for next time when we discuss this how this modeling works, and how climate change could affect you!