(UN) Chapter 2_Updated on Thursday, May 9, 2024

It's no secret that our planet is in for some major changes- from higher temperatures to more frequent extreme weather events and rising sea levels. But have you ever wondered how we actually know?

It’s all thanks to climate models. So what do you think scientists mean when they say the words ‘climate model’?

• A new eco-friendly model of a famous car brand

• A mathematical model designed to simulate how the climate will change in the future

• A cardboard sculpture of the Earth for a school project

People have been recording different types of climate data as far back as the 1850s. This means we have a pretty good idea of what the climate was like back then, but how do we know what aspects of our climate system (temperatures, sea levels, CO₂ concentrations) were like before then? Select all that apply.

• Looking at the size of rings in tree trunks

• Analysing the bubbles of ancient air and thickness of layers of snow in ice cores from glaciers and ice sheets.

• Running climate models over the past

• Finding fossils and minerals deep under the seabed

Why is estimating pre-1850 climate important?

• To determine the exact temperature of the past

• To compare changes in climate over time

• To predict future climate patterns

• To study the effects of solar energy

How do scientists test climate models using historical data?

• By comparing model results with observed conditions

• By measuring air temperatures millions of years ago

• By using thermometers to estimate past climates

• By running models forward in time

Climate models have been used to make accurate projections for the past 50 years and have advanced significantly during this time.

Nowadays models can make projections based on a huge range of aspects of the climate system. Do you think it will ever be possible to make a perfect model?

• Yes

• No

Current climate change is happening at a much faster rate than any past increases in temperature. By 2100, Earth’s average temperature is projected to increase by roughly 3.2°C above the pre-industrial levels

Take a look at the graph. When was the last time Earth was this warm?

• 150 thousand years ago

• 5 million years ago

• 42 million years ago

What state was the Earth's climate heading towards before 1850 ?

• A warming phase due to increased solar energy

• A natural equilibrium in temperature

• A new ice age in about 1.5 thousand years

What do you think are the major factors that will affect temperature change over the next century? Select all that apply.

• How much greenhouse gas is released

• How the climate system reacts to increasing temperatures

• Changes in the tilt of the Earth and the shape of its orbit

Many land areas are experiencing greater warming than the global average. For example, when global warming above pre-industrial levels has an average value of 1.5°C across the Earth, the average value across some land regions could be 3°C.

Which region do you think will experience the most warming in comparison to the global average?

• North Africa

• Asia

• The Arctic

Answer explanation

The Arctic is warming 2-3 times faster than the global average, resulting in knock-on climate effects in other areas of the world. This increased warming is because when ice melts, it exposes a darker surface beneath (e.g. rocks), which absorbs more sunlight.

Where do you think most of the water that evaporates into the atmosphere comes from?

• Tropical countries with warm temperatures

• The ocean

• Far to the North and South during warm summers, like in Russia and Argentina

Answer explanation

In fact, 86% of all evaporated water comes from the ocean. This means that the oceans are responsible for 430,000 cubic kilometres of evaporated water every year - roughly equivalent to the top 1.2m of the ocean's surface!

Much of this water then moves around the planet under the influence of general circulation - or the three-dimensional movement of air within the atmosphere