Future of the Cryosphere
In Lab 4, you explored the history of the cryosphere and looked at indicators of past climate, including ice cores. Now, you will consider the future of the cryosphere in a changing climate and how scientists use models to make predictions.
To complete a climate model, the physical equations, which represent how the spheres interact, are coupled with scenarios (described below) of how Earth's human population, land use, and economy could evolve. Once a climate model is run, the model output data is compared with the observed data from the past. This process allows scientists to check the accuracy of the models.
Watch this brief video from the Australian science agency CSIRO for an explanation of climate models:
Worldwide, various teams of scientists have modeled climate change and the subsequent impacts to the year 2100 and beyond. While the models show that rising global temperatures generally characterize the future world, human behavior will determine how dramatic the changes may be.
What is a scenario?
A scenario is an image of a potential future that is based on historical knowledge and expectations of future change. The IPCC scenarios are based on a data-driven pathway (or narrative) of what events have occurred in the past and how the future may unfold.
The scenarios describe the relationships between the forces driving greenhouse gas and aerosol emissions and their potential future change during the 21st century for the globe. The most recent models also include pathways representing different projections of a set of influential socioeconomic factors, including population growth, technological development, economic development, and their associated energy, land use, and emission implications.
Shared Socioeconomic Pathways (SSPs) look at projected global socioeconomic changes until 2100. These scenarios consider possibilities for countries globally and how each may choose to approach their future socioeconomic development. There are five narratives that consider a range of possibilities.
Representative Concentration Pathways (RCPs) looks at possible future greenhouse gas emissions. The numbers in the RCPs stand for the amount of radiative forcing a difference to Earth's energy balance, which results in either warming or cooling (measured in watts per meter squared or W/m2) that the atmosphere will reach before leveling off. As the radiative forcing is caused primarily through the rise in greenhouse gases, the number will, therefore, also correspond to a concentration of GHGs in the atmosphere. In order to simplify calculations, all of the GHGs have been given a CO2 equivalency (CO2e) for modeling.
SSPs + RCPs = SSP Scenarios
By combining the SSPs and RCPs, a number of combined scenarios are possible. However, because the SSPs have assumed certain future socioeconomic trajectories, there are RCPs they cannot easily match withfor example, SSP1, which is focused on sustainability, will not match with RCP8.5's high emissions pathway; similarly, RCP1.9, which has very low emissions and would require consensus building, can't match with SSP3, which models a socioeconomic pathway of rivalry between countries that don't work together. These assumptions helped scientists to narrow their focus to models using five different combined scenarios.
According to the IPCC, the five combined scenarios (in white text in image at right) have been designed to span a wide range of possible future conditions, including a no-additional-climate-policy scenario of SSP3-7.0, and a strong mitigation scenario with SSP1-1.9. The scenarios don't try to forecast how events will happen in the future or account for the impact of climate change on the SSPs, nor do they try to prove which, if any, is more likely than another.
Get a sense how much the temperature may increase
1. To begin, go the the WGI Interactive Atlas website.
2. Find the box below left, labeled Regional Information. Click the lower right corner of this box to access the Advanced version of the climate models the temperature data is based on.
3. On the toolbar above the map, hover over or click Dataset. Make sure that in the Model Projections column, the CMIP6 radio button is selected.
4. Next, hover over or click Variable in the toolbar. Beneath Atmosphere select Mean Temperature (T).
5. Hover over or click Quantity & Scenario in the toolbar. Confirm that beside Quantity, Change is selected. Then select Period: Medium-term (2041-2080) and Scenario: SSP3-7.0. Confirm that the Baseline remains 1850-1900 to be consistent with the other data you've looked at.
6. Click the shapes covering the contiguous US to bring up a time series graph of temperature for the selected area from 1950 to 2100 with the period displayed on the map highlighted with a gray square. Moving the cursor over the map will show the change in average temperature for that area on the temperature scale to the left of the map.
7. Once you have observed the changes in the time period 2041-2080, change the time period to Long-term (2081-2100).
Consider projected changes where you live
On the map, click the area containing your home state or region to bring up a graph and see the predicted future changes in temperature.
Put climate change in perspective by considering the following:
- How old will you be in 2050, 2080?
- How much will the temperature in most of the United States have changed by 2080?
- Give several examples of how the increase in average temperature could impact your daily life.
Try the climate change questionnaire and learn more about scenarios
How would you change the world?
Read the article to the 9-question interactive, and answer the interactive's questions. Keep in mind that each choice you make will have costs for both the climate and for the pocketbooks of people under the policies. After you have completed the questionnaire, you will see a projection of climate and energy costs (from 2019 to 2100) based on your choices. Repeat the questionnaire several times and compare your results.
How did your choices affect the outcome?
Note: The black line in the results incorrectly labeled "Business as usual" depicts the high-emissions RCP8.5.
How do individual lifestyle choices influence global climate change? Can one person really make a difference? Brainstorm and share ideas for changes in your lifestyle that you and your classmates and families can make.