Earth's Warming Climate: Are We Responsible?

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Models of future climate change rely on lots of data. Scientists use computer climate models to help them understand how temperature in different regions of the world may change as carbon dioxide increases. Through the use of mathematical equations and various modeling techniques, scientists use existing data to estimate what may occur in the future with regards to climate change and to communicate the success or failure of specific mitigations and adaptations. View “Dr. Gavin Schmidt” discussing and showing how computer climate models provide scientists with a useful method for estimating how the climate system may change in the future.

In this section, you will have the ability to view changing atmospheric CO2 levels through time, from short to long time scales, and to evaluate the role this particular greenhouse gas plays in global climate change.

Data Activity: Plotting Atmospheric CO2 Levels through Time

These data activities guide you through data sets that document carbon dioxide (CO2) concentrations in the Earth’s atmosphere. Atmospheric CO2 concentrations are examined from far back in Earth’s past and up to the recent record using data downloaded from a variety of data archives. Remember, data provides the backbone support of a STEM lesson and as you complete the following activities, you should think about how you may implement these data activities with your students.

Data Story

The NASA AIRS (Atmospheric Infrared Sounder) instrument is an advanced infrared sensor with 2378 spectral channels designed to measure the key atmospheric gases affecting climate. AIRS can create 3-D maps of a range of atmospheric properties: water vapor, cloud properties, ozone, carbon monoxide, carbon dioxide, and methane.

The AIRS instrument flies aboard the NASA Aqua Spacecraft with a variety of other advanced tools designed to further our understanding of Earth's water cycle and our environment.

In addition to monitoring atmospheric gas concentrations such as CO2, the AIRS instrument provides 3-D scans of atmospheric moisture and temperature that are used to track and understand major storm activity such as Hurricane Katrina in 2005.

Before starting these two activities, explore the raw data for mole fraction CO2 measured by the AIRS Instrument in the vicinity of the Hawaiian Islands. Data downloaded from MY NASA DATA is represented in the yellow/orange columns while data for future years is shown in blue columns. MY NASA DATA makes NASA Earth science data easily accessible to K-12 students and teachers through pre-packaged, easy-to-use data sets that contain appropriate content for classroom instruction. These micro sets are accompanied by corresponding lesson plans and computer tools. Carefully study this raw data and notice the patterns and trends. What are some observations you can make about this data?

What factors might cause the rate of increase of carbon dioxide to become greater or lesser in the future? The ocean absorbs almost half of all carbon dioxide released through the burning of fossil fuels, a role that keeps our Earth a hospitable place. However, what happens to the ability of the ocean to keep up this role as a huge carbon sink as the Earth warms? Read “Is the Planet's Carbon Sink Getting Too Full?” and consider why the warming of the oceans is of such concern and what this warming means for marine life.

Currently, the oceans absorb large quantities of atmospheric CO2 thus slowing the rate of increase. As the oceans become more acidic and warmer they will absorb less atmospheric CO2 and thus the rate of increase should become greater. If human contributions to atmospheric CO2 continue to increase then the rate of increase will also steepen. Primary human contributions to atmospheric carbon dioxide include the burning of fossil fuels for energy, the production of cement, and deforestation. Without dramatic changes in energy, construction, and global farming practices these human sources of atmospheric carbon dioxide are unlikely to decrease in the future.

There is a growing body of evidence that the chemistry of the ocean ecosystem is being affected by global climate change. This could have catastrophic effects on the way we live. Take a firsthand look at the changes that have been documented by watching the “Ocean Tipping Point?” video from NOW on PBS. Pay close attention to the simple, but clear demonstration of how important polar ice is to the health of the oceans.

Data Story

The longest continuous record of atmospheric carbon dioxide levels (1958-present) comes from the Mauna Loa Observatory in Hawaii. In many ways the mountain is the ideal location for studying the atmosphere. Isolated in the Pacific, it is far from major sources of pollution. Its 11,000 foot, high-altitude, lava-coated flanks are free of plants and trees, whose cycles of photosynthesis and respiration affect carbon dioxide concentrations.

Activity 1: Examining Instrumental Data for Atmospheric CO2 from Mauna Loa Observatory, Hawaii

Explore the data on atmospheric CO2 gathered from the Mauna Loa Observatory from 1958 to 2010. Data downloaded from the NOAA website is represented in the white columns. The Year and Month columns have been combined into the Decimal Date column to make the data easier to plot.

Next, examine the 2000-2010 Record of the Mauna Loa Observatory CO2 Record and the Mauna Loa Dry Mole Fraction Atmospheric CO2 chart. The raw data (black dots) are connected by a blue line and have a linear trend line running through the data. The R2 value and line equation is provided in the chart. As you explore these diagrams, examine the short and long term variability in the record.

Look at how the data overlap in this combined diagram. Notice how there is good agreement between the two records for the period of time for which the two records overlap.

  1. What does the Mauna Loa data suggest for the future of global climate change?

    Answer

    The longer Mauna Loa record shows an increasing accumulation of atmospheric CO2 and that the rate of increase is becoming steeper over time. This suggests that the Earth’s climate will continue to warm into the future – the exact amount being dependent upon a variety of feedbacks, which are not completely understood.

Note: You may wish to explore CO2Now.orgdata for the most recent concentrations of atmospheric CO2. This site uses NOAA’s data from Mauna Loa and includes other relevant resources.

Data Story

Lake Vostok is a large lake buried under 4 km of ice in Antarctica. An ice core was recovered from the ice above the lake, which yielded a paleoclimate record of 400,000 years. Reconstructing atmospheric carbon dioxide levels from ice cores involves removing gas samples in air bubbles trapped in the ice from glaciers. Prior to transitioning from snow to glacial ice, the gases are free to mix and migrate within the snow so that measurements of atmospheric gases are an average of the composition during that period of time. The depth of the transition can be 100+m representing several thousand years.

Read more about the ice core record.

Activity 2: Examining CO2 Concentrations Trapped in Ice Cores Recovered From Vostok, Antarctica

How can ice cores help us understand atmospheric changes in carbon dioxide concentrations over time? Explore the “Greenland Ice Sheet Project 2: A Record of Change” interactive from PBS LearningMedia to see scientists' efforts to study Earth's climatic history for the last 250,000 years by drilling into the Greenland Ice Sheet and examining ice cores. What specifically can scientists determine by analyzing these ice cores?

Now, explore the data produced from the Vostok (Antarctica) ice core downloaded from the NOAA World Data Center for Paleoclimatology. The first column shows the age of the gas sample in years and the second column is the CO2 content of the trapped gases in parts per million by volume (ppmv). This data provides a record of past atmospheric composition, evidencing that CO2 and methane levels today are higher than at any other time in the past 400,000 years.

Now look at the plotted data from the Vostok ice core from about 414,000 years ago until about 2,300 years ago. There is a great deal of variability in atmospheric CO2 exhibited by this record (between 300 ppm during Interglacial times and as low as 180 ppm during glacial periods) due to the formation and melting of continental ice sheets in the Northern Hemisphere. What is clear from these ice core analyses is that Earth's climate has varied significantly over time. Over the course of the past 800,000 years, our planet has seen eight 90,000-year ice ages interspersed with 10,000-year warm periods. In addition, scientists have found a direct correlation between global temperatures and greenhouse gas concentrations, lending support to the observations made in the last century. What's more, in 2004, scientists studying an ice core taken from Antarctica concluded that current CO2 concentrations are higher than they have been in 440,000 years—an observation with significant implications for understanding future climate change.

Finally, review the combined record, which overlays AIRS satellite CO2 data, the instrumental data for atmospheric CO2 from the Mauna Loa Observatory, and concentrations trapped in ice cores recovered from Vostok, Antarctica. This chart gives a perspective of atmospheric CO2 variation from 414,000 years ago to the present. These cores provide CO2 data that allow us to reconstruct a continuous CO2 record from approximately 420,000 years ago to the present.

The CO2 values at Mauna Loa for the period of time from 1960 to 2010 are well outside the range of values for the Vostok ice core data. The Vostok ice core data show that the CO2 values range from about 180-280 ppm, but modern values—as shown in the Mauna Loa graphs—are approaching 400 ppm.

There are some factors that may account for the differences in the CO2 values. The one factor that makes the more recent record stand out from previous interglacial periods is the exponential increase in atmospheric CO2 that we see since the Industrial Revolution (the time in the graph depicted in green and red). This was the time when fossil fuels began to be used in great quantities and the spike in CO2 is the result of fossil fuel combustion, releasing CO2 into the atmosphere. Importantly, the levels of CO2 since the time when people began to harness fossil fuels for industrial purposes are much greater than values we have seen, including the “natural cycles” observed in the Vostok core, for almost a half million years.

Think about what you have learned so far and then explore “The current and future consequences of global change” and “The greenhouse effect” web pages from NASA. What are some of the regional impacts of global change that are forecast by the Intergovernmental Panel on Climate Change (IPCC)?

What barriers do you currently experience with global climate change instruction in the classroom, and how might you use data to overcome those barriers?

Global Climate Change Modules

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