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Module 1, Lesson 1: Climate System Change

Introduction

This lesson first briefly introduces you to climate and weather concepts, which are key to understanding climate change. This is to ensure that everybody is on the same foundation at the start of this course. It involves a description of the concepts of weather and climate by clearly defining and differentiating between them and other key terms, such as variability, climate system and climate change.

Course Outcomes

Upon completion of this lesson, you will be able to:

• identify the difference between weather and climate
• describe Earth’s climatic system and its components
• distinguish the factors governing natural climate variability from human-caused climate change.
• explain why humanity should be concerned and care about climate change

Terminology

The following terms are important in understanding the science behind climate change. If you want to remember them, write their meanings in your learning journal as you encounter them in the course content.

• albedo
• atmosphere
• biosphere
• climate
• climate change
• climate system
• climate variability
• climatologist
• cryosphere
• global warming
• hydrosphere
• latitude
• lithosphere
• precipitation
• solar radiation
• weather

The difference between weather and climate

For many of you, the difference between weather and climate has already been covered in your earlier years at school. As a quick reminder, do the first learning activity.

Activity

Go outside to observe and experience the weather and climate where you live. Do you think it will remain the same throughout the day? How has the weather been in the past week? Do you expect it to remain the same throughout the year?

In your learning journal, briefly describe the weather today. Then record which part of what you see and feel is due to today’s weather and which part is due to your region’s climate. (You can also record which part you think might be due to climate change, if any.) For feedback, discuss your thoughts with your family or a friend.

What is weather?

Weather is the state of the atmosphere at a particular place and over a short period of time. It is often described in terms of elements such as temperature, precipitation, sunshine, cloud type and coverage, the speed and direction of the wind, humidity and air pressure. Weather is a complicated phenomenon because it can change at any time.

To describe the weather, we use words like hot, warm, mild, cold and freezing for temperature, and for precipitation, we use words such as rainy, hailing, snowing, drizzling or raining cats and dogs. Other important words to describe the weather are humid, windy, cloudy, clear, partly cloudy skies and sunny.

What is climate?

Climate, on the other hand, refers to the average weather conditions for a particular place over a long period of time – 30 years or longer, to be more precise. We can, therefore, say that the timescale for the climate is over a 30-year period.

Activity

Watch this short video to reinforce the difference between weather and climate.

(You can adjust the playback speed and/or turn on subtitles/captions.)

If you have trouble accessing the video, a summary is available in Annex 1.1.2.

Climate Change 101

This video explains the difference between weather and climate.

Climate Change 101 - Weather vs Climate (1:08)

There are five main climate types on Earth:

• tropical or equatorial
• dry (arid and semi-arid)
• temperate
• continental
• polar and alpine

Climate regions

Updated Koppen-Geiger Climate Map

Key to Climate Regions Map

It is important to note that different regions experience different types of climates, and these climatic regions are given names such as the Mediterranean, equatorial or tropical rainforest, hot desert, tropical monsoon, warm temperate and polar. For example, we define a Mediterranean climate as one with mild winters and hot, dry summers, because over the years, those have been the general weather conditions ruling the Mediterranean basin.

Activity

1. What type(s) of climate is (are) predominant or prevailing in your country? What is the name of the climatic zone in which you currently live? In your learning journal, describe your climate in general terms.

2. Let’s say that you are going to relocate and work in a different country for five years. When you start your planning and packing, how would you take the weather and climate of that country into consideration? Write two ways you would do so in your learning journal and explain them. Discuss your ideas with a friend or a family member for feedback.

3. With your understanding of weather and climate, do you now agree or disagree with this common saying?

“Climate is what you expect; weather is what you get.”

Explain your reasoning in your learning journal.

Optional activity

For those who are interested in agriculture, farming, food forestry, food growing and gardening, try out the interactive Köppen Climate Classification map (which is licensed CC BY-SA 4.0) Wikipedia https://en.wikipedia.org/wiki/Köppen_climate_classification

Compare it with other places you are familiar with. This classification system is used by farmers and food growers not just to understand their own climate but also to find analogue (similar) climates elsewhere. This helps them to discover what else they can grow in their climate. For example, rice is normally grown in warm, wet climates further south. But a farmer in the northeastern United States discovered that his climate matches that of northern Japan, where they grow cold-climate rice. He now successfully grows a traditionally northern Japanese rice in Vermont, a United States state known for its winters.

Scenario

Imagine receiving a call for assistance from a buddy who is interested in starting a farm in your country.

i) Describe the climate of your country by using the Köppen climate classification map.

ii) Offer suggestions for the kinds of crops that your friend can grow, and provide examples of what other nations with comparable climatic conditions can produce.

iii) Indicate whether this would increase or decrease food security in your country.

iv) You may also add any information on recent climatic challenges experienced by farmers.

After writing your response in your learning journal, discuss your information and suggestions with a family member, friend or study partner. You may check your example against the following feedback.

Feedback Example: Botswana’s climate is described as semi-arid. This means that most of the time, it is hot, with low or little rainfall Using the Köppen climate classification system, we can see that Botswana includes BWh (desert or arid climate) and BSh (semi-desert or semi-arid). Farmers and food growers in Botswana can look to see what is grown (and how) in BWh and BSh regions of Australia, other parts of Africa, the Middle East and small pockets of North and South America. This would definitely increase food security in Botswana in the face of the climate emergency. Low agricultural production in Botswana is attributed to climate impacts such as low, unreliable and inadequate rainfall.

In Geography, Science or Social Studies, you have probably learnt the different factors that affect weather and climate.

Weather

• atmospheric conditions such as
  • temperature
  • precipitation
  • humidity
  • air pressure
• wind and air masses
• mountains
• vegetation

versus

Climate

• the tilt of the Earth towards the sun
• latitude, or distance from the equator
• proximity to the ocean
• altitude, or height above sea level
• ocean currents
• prevailing winds

This shows that, like weather, the climate is a complex system influenced by a host of interacting factors. Having defined what climate is, we can now go further to understand the climate system.