Transcript Climate Variability and Change: Introduction

Climate Variability and Change: Introduction
Temperature anomalies for July 2010
Image from NASA’s Terra satellite
Climate Variability and Change: Introduction
Temperature anomalies for July 2010
Eastern Europe: 5C warmer
than climatology – severe
wildfires and smoke
Image from NASA’s Terra satellite
Climate Variability and Change: Introduction
Temperature anomalies for July 2010
Eastern US: unusual heat
Eastern Europe: 5C warmer
than climatology – severe
wildfires and smoke
Image from NASA’s Terra satellite
Climate Variability and Change: Introduction
Temperature anomalies for July 2010
Eastern US: unusual heat
Parts of S. America: subfreezing temperatures and
heavy snow – hundreds of
cold-related deaths
Image from NASA’s Terra satellite
Eastern Europe: 5C warmer
than climatology – severe
wildfires and smoke
Climate Variability and Change: Introduction
What are the causes of the observed anomalies?
Image from NASA’s Terra satellite
Climate Variability and Change: Introduction
Can we predict these anomalies a season ahead?
Image from NASA’s Terra satellite
Climate Variability and Change: Introduction
Is the hot summer in Eastern Europe part of a global
warming signal?
Image from NASA’s Terra satellite
Climate Variability and Change: Introduction
Is the hot summer in Eastern Europe part of a global
warming signal caused by us?
Image from NASA’s Terra satellite
Climate Variability and Change: Introduction
The global average temperature for July 2010 was
0.55C warmer than climatology (51-80). Is this a
global warming signal?
Image from NASA’s Terra satellite
Climate Variability and Change: Introduction
Floods in Pakistan
Floods caused by torrential monsoon rains
More than 1,600 people have died and about 6Million are
homeless - about 17 million people have been affected
Climate Variability and Change: Introduction
Floods in Niger, West Africa
Heavy rains in August and resulting floods have left more
than 100,000 people homeless (UN).
The Sahel (15-20N)
Climate and its variability impacts society (e.g. food and water
resources, health, energy and demography)
Climate Variability Matters!
Climate Variability matters!
Bonnie (05)
Charlie (05)
Frances (05)
Flooding in New Orleans due to Katrina
(courtesy NOAA)
Ivan (05)
courtesy A. Aiyyer
Science and Society Interact
Society demands useful predictions of climate so that it can
respond to climate variability.
One key question to ask is: What do the users of these forecasts
need?
In recent years most seasonal predictions have been concerned
with providing the mean seasonal rainfall anomaly – not always
useful. Users tend to want more than this – when will the rainy
season start? How will the rainfall be distributed within the
season (weather?)? These are much harder to predict.
Limits of predictability
weather – theoretically 1-2 weeks – TOPS!; currently much less
than this, probably around 5 days or so – limitations include
poor models and poor observations of the atmosphere especially
climate – forecasts are made at seasonal-to-interannual and
multi-decadal timescales (including climate change) –
limitations include poor models, poor observations of “climate
system” – includes land and ocean , less important for weather.
•Seasonal-to-Interannual variability
We will discuss the basis for these forecasts in this course.
Need to understand causes of seaonal-to-interannual
variability.
At these timescales it is crucial to
provide information on the status of
ENSO and to be able to predict the
impacts of ENSO locally and
around the globe (teleconnections).
•Interdecadal Fluctuations and Trends
Efforts are also made to make predictions on longer timescales
Introduction to the course
Section 1: Introduction to the Climate System
Provides background to the mean climate system, combines
observations of key variables of the climate system and a
physical understanding of key processes. These sections are
required for a basic understanding of the climate system and
processes before we can attempt to consider its variability. Many
textbooks exist that cover these areas.
Section 2 Natural Climate Variability
We will consider the nature of observed seasonal-to-interannual
variability – (things we wish to predict) - Most importantly in this
section is ENSO (observations, mechanisms and impacts
(teleconnections).
In addition we will discuss decadal variability – important to be
aware of this when attempting to attribute anomalies to a “global
warming” trend.
We will discuss how climate predictions are made
Finally we will consider how climate variability is manifested in
changes in high impact weather.
Section 3 Climate Change
We will consider the theory of climate change
We will look at the observational evidence as well as how climate
predictions are consistent (or not) with this.
The IPCC process will be discussed
Section 4 Future Perspectives
We will finish with some discussion on how science and society
are interacting with regards to climate variability and change.
ANY REQUESTS?
"climate is what you expect and weather is what you get."
"climate tells you what clothes to buy, but weather tells you
what clothes to wear."