© NASA’s Earth Observatory
Physical Sciences

We’re Going to Need a Bigger Thermometer

Measuring Global Warming

You’ve probably said it more than once, we all have. You step out of your house and into a wind-whipped snow storm or a crushingly humid heatwave. “Thanks, global warming,” you say half jokingly as you ready yourself to face the weather. But is that weather really from global warming? What does living in a warming world really mean?

This isn’t about a cure so much as it is about a better diagnosis.

Global warming and climate change are all but inescapable facts at this point. Even so, we are still working to understand what exactly our greenhouse gas-spewing ways are doing to the planet. Much like doctors seeking to learn more about a condition using advanced medical scanners, scientists are using a huge network of advanced sensors complemented by good, old fashioned scientific observation to track our home planet’s vital signs ever more closely. This isn’t about a cure so much as it is about a better diagnosis.

PAST, PRESENT, FUTURE

One aspect of that better diagnosis is piecing together a picture of what Earth’s climate has looked like in the past. Understanding how Earth’s weather used to work is an incredibly important step in understanding how our activities have changed it. But how do we resurrect weather that happened hundreds or even thousands of years ago? It’s actually easier (and in some cases much more bizarre) than you might think.

For hundreds of years, ships’ crews have kept meticulous notes aboutlrecordsogbooks full of sea, weather, and ice conditions. Taken en masse, these daily records provide a bird's eye view of weather from across the seven seas and across the centuries. Many countries have begun to digitize their handwritten logbooks and post them online for citizen scientists to transcribe. That’s the mission of OldWeather.org, which posts images of logbook pages from the National Archives in D.C. Once transcribed, the information from the pages can be analyzed by computers and incorporated into models of past climates.

Built in 1874 in Scotland as a whaling and sealing ship, after which it was bought by the US Navy for the Greely Arctic rescue msission.© DANFS and USCG Historian's site

Another powerful source of information about the past can be found in slightly more obscure places. Both tree rings from old growth trees and ice core samples taken from deep inside glaciers can unlock troves of data about our world as it was before human-caused global warming. Because tree rings correspond to one season of growth, their thickness and overall health can tell scientists about the temperatures, rain or snowfall levels, and even general cloudiness of the region where the tree grew.

Lonnie Thompson and team taking an ice core sample © NSTMF

Likewise, ice core samples contain a pristine record of past worlds. Samples can be analyzed to learn about rain and snowfall amounts and even sea level changes. Tiny particles and air bubbles trapped in the ice provide clues about everything from atmospheric CO2 levels to major disruptive events like volcanic eruptions and meteor impacts.

SCIENCE IN THE SKY

While studying the past provides us with a helpful baseline from which to measure the modern changes we’ve wrought, the age of flight has opened up new ways in which to measure and understand our current predicament. An army of satellites and planes equipped with special sensors now regularly comb our planet sending us back information about changes in sea ice, snowfall amounts, groundwater changes, sea level rise, atmospheric CO2, ocean acidification, and deforestation.

the age of flight has opened up new ways in which to measure and understand our current predicament. 

NASA in particular has a fleet of satellites providing some of the most critical and up-to-the minute information about our changing planet. The OSTM satellite, for example, is capable of measuring changes in the sea surface level as small as a centimeter. These tiny changes reveal the speed and direction of ocean currents as well as the heat stored in the ocean—all important factors that influence weather around the world and will continue to change as the planet warms. The satellite’s sensitive instruments can also measure sea level rise as small as a millimeter. That helps scientists forecast the speed with which seas are rising as well as make better predictions about our future coastlines.

A 10-day average of sea surface height anomaly data from the OSTM/Jason-2 satellite, centered on July 21, 2015. © NASA

Water, both in abundance and absence, is a key player in climate and the global carbon cycle—studied in depth by Charles Keeling and Roger Revelle. Many satellites exist to track the global water supply in the air, in the ocean, as well as in the ground. In January of 2015, NASA launched a new satellite known as SMAP for Soil Moisture Active Passive. SMAP measures soil moisture in topsoil around the world, which is a key component of understanding how water and heat energy move between the surface and the atmosphere, with huge impacts on weather and climate. The data can be used to help predict floods, mudslides, drought potential, or conditions that may lead to extreme weather. Other space observatories are measuring snowpack, the depletion of freshwater aquifers, and the health of forests—important sources of carbon storage.

BOOTS ON THE GROUND

While the ability to send high-tech equipment barreling through our atmosphere has literally provided us with a new perspective on our planet, there is still something to be said about some good old fashioned, boots on the ground science. All across the globe, scientists are feverishly working to record a huge variety of measurements.

 the key to surviving the challenges we’ve heaped upon ourselves is understanding them

Long-established weather observatories keep temperature and atmospheric CO2 records, a network of ocean buoys (designed to travel between the darker, cooler depths and the warmer surface) records temperature and levels of acidity, and tide gauges stationed on piers and docks record daily water movements. Citizens in remote places are doing their part as well, using specialized sensors on the blades of their dog sleds to record and transmit information about sea ice thickness—something satellites still cannot do.

DATA, DATA EVERYWHERE

Satellites circling the skies, scientists circling the globe, citizens poring over old records… all of this has given us more data than ever before about the health and dangers of the present moment. But what exactly are we doing with the data? Why is it so important to have? The answer seems pretty clear: the key to surviving the challenges we’ve heaped upon ourselves is understanding them. Without good, solid data we won’t be able to predict, much less prepare for a changing future.

Simply put, more data means the ability to create ever more refined models that can help us see the past (and the disruptions we’ve already caused) as well as the future (with all the disruptions we may yet have time to forestall or prevent). This kind of data trove is something that climate model pioneer Warren Washington could have only dreamed of; now it’s time to put it to work.

Better models and deeper data also mean that we can better predict extreme weather events. Though it’s tempting to lump all freak weather events into the ‘caused by climate change’ category, scientists are slowly learning to tease apart those events that are caused or made more likely by global warming and those that are a part of natural cycles in Earth’s climate. If climate change means droughts are more common in one area, but floods are more common elsewhere, the preparations for those two different realities stand a much better chance of being not only effective, but also lifesaving.

Humanity arrived at this critical juncture because of our endless capacity for innovation and toolmaking, now those very same features seem to be what we need most.

Understanding the exact consequences of global warming in any one location also has implications for how wildlife is managed and species are protected. As the world warms, vegetation is changing from region to region, leaving many plant eaters and seasonal migrators without the necessary food sources for survival. Many species are being forced to move further north than their traditional ranges as temperatures climb, just as many sea creatures are being forced to move to deeper, somewhat cooler water as the oceans heat up. Growing acidity in the oceans is also wreaking havoc on the ability of shelled critters to grow their protective covering. Polar bears are well known example of animals facing extreme danger from climate change; but many if not all plants and animals will need to make drastic changes to survive in the world we’re creating.

Though it must be said that much of the data we’re compiling about global warming tells a pretty dire story, there is no reason to think that we are incapable of taking meaningful action to alleviate some of the problems we’ve caused. Humanity arrived at this critical juncture because of our endless capacity for innovation and toolmaking, now those very same features seem to be what we need most.