Part 3. The Future of Climate
Next up, we are going to consider what the future might look like for northwestern North America, specifically Alaska. How can we make predictions about future climate? While tree rings and other proxies tell us something about climate in the past, climate modelsa computer-based simulation of the Earth's climate systems that help us understand past and future climate are needed to predict how climate change might continue to evolve in the future. There are many different types of climate models, and together, they predict a range of potential futures depending on different scenarios in the climate system.
The IPCC is an intergovernmental organization of scientists and other experts that gather and communicate the latest information on climate change (past, present, and future) through reports, or 'assessments', which governments and policymakers can use to make informed decisions. As part of this report, the IPCC uses an array of models that predict changes in several climate variables based on different scenarios. For example, models projecting an increase of global temperature by 1.5°C, 2°C, 3°C, or 4°C by the year 2100 (relative to the 1850-1900 'baseline') can be used to evaluate relative changes in a variety of climatic and ecological variables. The degree to which any of these potential futures are realized will depend on future greenhouse gas emissions and human activities. While these increases in global temperature might seem to be minor, they can have large consequences. For example, check out this optional video from The Economist describing predicted global changes associated with a 3°C global average temperature increase.
Take a look at the following figure from the Summary for Policymakers report from the IPPC's 6th Assessment Report (AR6). Based on the four warming levels of global average temperatures, models predict regional changes in different aspects of climate. For example, take a look at northwestern North America in row (a) of the figure below. An increase in global average temperature is predicted to result in an increase in temperature of the hottest day every year (i.e., an increase in temperature extremes). In Alaska, depending on the global warming level (1.5°C, 2°C, 3°C, or 4°C by the year 2100), the hottest day of the year is predicted to increase anywhere from roughly 1-6 degrees Celsius. Such a change in extreme temperatures could have important societal and ecological implications. Review the other panels in the figure and consider the following questions.
Figure 8: Climate change projections from the IPCC AR6 Summary for Policymakers.
Stop and Think:
3.1 By the year 2100, describe the projected changes in mean total column soil moisture change (panel b in the image above), and annual wettest day precipitation change (panel c in the figure above) on average across northwestern North America.
3.2 How do the projected changes in northwestern North America described in 3.1 depend on the different scenarios of global warming levels (1.5°C - 4°C)?
We will now further explore predictions of future climate in northwestern North America using the Intergovernmental Panel on Climate Change (IPCC) Interactive Atlas. Recently, as part of the 6th Assessment Report, the IPCC developed the interactive atlas to conveniently display both observed and predicted climate across various regions of the globe. Here, we will take a look at the simple regional synthesis of projected climate change. In this regional map, several climate models are used to estimate predicted changes in different climate variables by the mid-21st century (2050s). Of the many models available for these calculations, they chose to focus on the models with climate scenarios projecting a ~2°C increase in global temperature by 2100. As you will see, this global increase in temperature results in a variety of regional climate and environmental changes. Should you wish to learn more, additional details on the atlas can be found on the About page.
- Under "Select Visualization" on the top left of the regional map, be sure that "Map" is highlighted.
- Under "Select Magnitude" on the bottom right, be sure that "Projections" is highlighted. Note that past trends can also be visualized.
- Explore climate projections by clicking on different climate variables on the left. The colors represent the direction and statistical confidence of projected changes (see the legend at the bottom).
Stop and Think:
3.3 Locate northwestern North America. Under 'Heat and Cold' on the left, what trends are expected for the four listed climate variables?
3.4 Now select one other climate variable (bullet point) from any other category and explain the projected change in northwestern North America.
3.5 Locate the region where you are currently living and view projections of three climate variables of your choosing. What climate changes might you expect to see in your own backyard, and to what degree of statistical confidence might that happen?
3.6 Based on your findings from 3.5, brainstorm two potential societal implications of these regional climate changes.
Bonus: If you are interested in exploring the more advanced version of the IPCC's interactive atlas, this comprehensive tool allows you to explore outputs from many different models, scenarios, and time periods. The "i" icon on the top right of the screen will prompt a guided tour with more information on using the tool. Be sure to take note of the sheer number of models and variables that are analyzed to better understand and predict changes in our complex climate system.
It is vital to not only consider the range of potential climate changes in the future, but also that human activities today and beyond will play a central role in the changes that we witness. The science of climate change, both in the deep past, recent years, and the future, has been (and will continue to be) critically important for understanding our climate system, and for taking action to limit human-caused changes and to prepare for its impacts.