2.4 Back to the Arctic

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En provenance du cours de University of Alberta

Introduction to the Arctic: Climate

195 notes

University of Alberta

Introduction to the Arctic: Climate

195 notes

The University of Alberta, the University of Tromso and the University of the Arctic invite you to explore this four week course that examines the environment and climate of the circumpolar North. This course is the result of an international collaboration and provides you with an insight into our planet's North. Following an overview of regional geography, we will focus on the cryosphere (ice), as well as the atmosphere and ocean of the region. We will learn why the Arctic is cold and ice covered, and how that impacts its climate and ecosystems. We will also consider how the Arctic is connected to the rest of the world. Finally, we will examine present day climate change, the processes driving it, and evidence for it in the Arctic, before looking at the implications in the rapidly evolving North. Watch a preview of the course here: https://uofa.ualberta.ca/courses/arctic-climate

À partir de la leçon

Climate Systems

In this lesson we’ll learn about the climate of the Arctic, and the way the climate interacts with the rest of the Earth system. In Lesson 1, we saw how the Earth receives energy from the sun and how heat is trapped on our planet through the natural greenhouse effect. We will now discuss how this energy is distributed throughout the globe and how it is transferred from the tropics to the poles via the large-scale circulation systems of the atmosphere and the ocean. We’ll learn the difference between the natural and the human-induced greenhouse effect - driven by the input of greenhouse gases created by burning fossil fuels, such as carbon dioxide and methane - and discuss what the future holds for the Arctic’s climate. As you will see, the global climate system is tightly linked and climate change in the Arctic also strongly affects temperate latitudes.

2.1A Climate and Atmosphere18:21

2.1B Climate and Atmosphere19:17

2.2A Ocean Circulation and the Arctic Ocean13:21

2.2B Ocean Circulation and the Arctic Ocean18:18

2.3 Carbon Cycle and Greenhouse Gasses28:03

2.4 Back to the Arctic5:40

Rencontrer les enseignants

Paul Myers, Ph.D
Professor
Department of Earth and Atmospheric Sciences

Conservative estimates from peer reviewed models now suggest there is a greater than

65% probability that global temperatures will exceed 1.5 degrees Celsius

above preindustrial levels by the year 2100.

Other models predict more than a two degree Celsius increase

during the same time period.

Throughout the 21st century, global temperatures higher than today

are a virtual certainty and are expected to continue to rise beyond the year 2100.

While these impacts are global, their influence on the Arctic

is particularly concerning, and there is already evidence of their impact.

The impacts of climate warming on the Arctic's cryosphere will be substantial.

The extent of Northern Hemisphere sea ice

has decreased continuously since 1950, or even earlier.

The area covered by seasonal snow in the Northern Hemisphere is also decreased,

as is the area covered by glaciers.

Snow, sea ice, and glacier ice all have high albedo and

reflect as much as 90% of solar radiation back to space.

Where sea ice is absent, the ocean absorbs up to 90% of this energy.

Likewise, the land surface absorbs more radiation when snow or

glacier ice is absent, further enhancing warming.

Microscopic black carbon soot

from fossil fuel burning is also a very important warming agent for the Arctic.

Globally, atmospheric black carbon absorbs solar radiation,

adding about 0.6 watts per square meter of energy.

But is all off set by reflective dust and aerosols.

But when black carbon is deposited on snow, glacier ice, or

sea ice, it decreases the albedo and enhances melting.

On a global scale, black carbon on snow and

ice adds only 0.04 watts per square meter of energy.

But locally, as in the arctic, even this small increase

can greatly speed up melting and substantially shorten the winter season.

The IPCC findings show that Northern Hemisphere sea ice

extent has decreased continuously since 1950.

Select the statement or statements that best describe the Arctic sea ice melting.

Select all the answers you think are correct.

A, the melted ice will increase snowfall and lead to glacier growth.

B, ocean water will absorb more heat than ice, causing increased ice melt.

C, black carbon soot increases the albedo but is insignificant to ice melt.

D, black carbon soot decreases the albedo and enhances snow and ice melt.

Both B and D are correct.

Global temperature increases that melts ice and snow lead to decreased albedo and

the absorption of additional energy that enhances melting.

This positive feedback causes enhanced local temperature increases.

The 2005 Arctic Climate Impact Assessment, using IPCC data and

methodology, estimates that average temperatures in the Arctic

will increase by as much as seven degrees Celsius by the year 2100.

The impact of this is likely to be severe.

With warmer temperatures there will be less snow and

ice, as well as longer seasons.

Permafrost landscapes will begin to melt, leading to changing ecosystems and

species migration, as well as infrastructure damage.

CO2 and methane, that have been stored in permafrost for tens of thousands of years,

will be released, further enhancing global warming.

Arctic coastal communities will become subject to erosion

as a result of decreased sea ice.

Melting glaciers and ice sheets will return water that has been stored on land

to the ocean, contributing to rising sea levels around the world.

Arctic residents who practice traditional ways of life will need to rapidly adapt

to this changing environment that may affect their food sources.

Although changes may be dramatic, there's reason to be optimistic about

the ability of indigenous communities to adapt, as we'll see in lesson four.

We've come to the end of lesson two, but come back soon for lesson three,

where we'll learn all about the snow, ice, and glaciers of the Arctic.

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