Climate Variability and Change: An Overview

Leigh Welling

Crown of the Continent Research Learning Center

Glacier National Park

What is Climate?

How does climate differ from weather?

Climate is what you expect,

weather is what you get.

OR…

Climate tells you what clothes to buy,

weather tells you what clothes to wear.

•Net transfer of heat from tropics to higher latitudes

•Is the fundamental driving force for weather and climate

Intertropical Convergence Zone (ITCZ)

GOES Satellite

Gulf Stream Temperature

• warm, tropical water travels north

• heat is released to atmosphere

• affects weather and climate on East Coast and in Europe

What is Climate Variability?

Earth’s climate varies across latitudes, seasons, and over multi-year, multi-decade and even multi-century time scales.

Equatorial Cold Tongue:

red = warm waterblue = cold water

ENSO is an example of natural climate variability

Persistent, extended Pacific Jet Stream & amplified storm track

Typical US winter patterns during El Niño and La Niña

El Niño

La Niña

Polar Jet Stream

Variable Polar Jet Stream

Variable Pacific Jet Stream

warm

dry

dry

wetcool

cold

wet

wetwarm

Pacific Decadal Oscillation (PDO)

warm phase

cool phase

PDO index

North Atlantic Oscillation (NAO) negative phasepositive phase

Carbon dioxide: up 32%

Gulf Stream Temperature

• warm, tropical water travels north

• heat transfer affects weather and climate

• surface water becomes dense and sinks

GREAT OCEAN CONVEYOR BELT

Natural Climate Influence Human Climate Influence

All Climate Influences

U.S.

186.1Total CO2

emissions since 1950 in billions of tons

EuropeanUnion

127.8Russia

68.4Ukraine

21.7Poland

14.4

China

57.6Japan

31.2

Australia

7.6

India

15.5

Kazakhstan

10.1

South Africa

8.5

Canada

14.9

Mexico

7.8Trinidad and Tobago

United Arab Emirates

Kuwait

Generalized Atmospheric Circulation