Lab 6: Climate Extremes and Impacts on People

This lab is designed as a supplement to Lab 5.

Download a Student Activity Worksheet. (Microsoft Word 2007 (.docx) 17kB May13 24)

Introduction

In the previous lab (Lab 5), we learned that paleoclimate records, such as those derived from tree rings, are valuable for learning about recent climate change relative to the last several centuries. We also explored how trees from borealof the north or northern regions forest sites can record historical and important cold events, such as those caused by volcanic eruptions. In this lab, we will continue our exploration of climate extremesunusual or rare climate events in the Arctic region of northwestern North America, including Alaska (USA) and northwestern Canada (CA); see the map below. We will (1) consider what tree rings tell us about past and recent climate extremes in space and time, (2) what models can tell us about the future of climate, and (3) the impacts of regional climate extremes and trends on people.

Figure 1: Map of northwestern North America, including Alaska (USA) and western provinces of Canada (CA).

Climate in northwestern North America has varied significantly across different time scales. Due to the annual nature of tree growth, tree-ring reconstructions capture year-to-year ('interannual') variability in climate, as well as decades or longer slow oscillationsa repetitive and/or periodic variation over a given time period or trendschanges in a particular direction in climate. This climate variability can be related to both natural processes and human activities. Climate variability is sometimes associated with external climate processes (e.g., volcanism, solar activity, or changes in the concentration of greenhouse gases in the atmosphere due to human activities), or it can be linked with atmosphere and ocean dynamics. The complexity of these systems and their interactions contribute to the variability in weather and climate over time and space that we experience in various regions of the globe. Regional climate conditions and extreme climate events (e.g., severely cold/hot temperatures, or droughts/floods) can have tremendous impacts on people and communities, so it's important to understand how they change over space and time.

When do climate extremesunusual or rare climate events occur? In Lab 5, we studied a northern hemisphere temperature reconstruction which is based on a large network of 54 tree-ring datasets that record variability in summer temperatures (shown again below; Wilson et al., 2016). Climate scientists will often refer to three notable periods of prolonged cold/warm temperatures that occurred during the last millennium: the relatively warm Medieval Climate Anomaly (MCA; ~950-1250 CE), the colder Little Ice Agea period of time characterized by cool conditions (~1450-1850 CE), particularly in the North Atlantic region (LIA; ~1450-1850 CE), and the Modern Warm Period (MWP; ~1850 CE - present).Can you identify these long periods of relatively warm and cold temperatures below? You might notice that many of the single-year warm extremes happened during the Medieval Climate Anomaly or the Modern Warm Period, and that many of the cold extremes occurred during the Little Ice Age. Here, we will focus on some of these climate extremes and what the future might hold.

Figure 2: A Northern Hemisphere temperature reconstruction based on tree-ring data (Wilson et al. (2016).

What will I learn?

In this lab, you will examine the timing, magnitude, and spatial characteristics of past climate extremesunusual or rare climate events in northwestern North America, a region that often experiences extreme conditions. We will investigate select extreme events from boreal tree-ring records and think about what drove those climate extremes and how they might have impacted communities. Lastly, we will shift our focus to the current state (and future) of climate extremes in the Arctic region of North America by evaluating instrumental and climate modela computer-based simulation of the Earth's climate systems that help us understand past and future climate data, and we will consider implications of warming temperatures for Indigenousthe original Peoples of a region, and their descendants, that share distinct cultural traits  communities in the Arctic.