Transcript Climate Variability and Change: Introduction to Course

Climate Variability and Change: Introduction to Course
Climate Variability and Change: Introduction to Course
Observed long-term trends: manmade or natural?
Climate Variability and Change: Introduction to Course
The coupled climate system has important natural variability
Climate Variability and Change: Introduction
Temperature anomalies for July 2010
Climate Variability and Change: Introduction
Climate Variability and Change: Introduction
Climate Variability and Change: Introduction
Climate Variability and Change: Introduction
What are the causes of the observed anomalies?
Climate Variability and Change: Introduction
Can we predict these anomalies a season ahead?
Climate Variability and Change: Introduction
Was the hot July in Western Europe part of a global warming signal?
Climate Variability and Change: Introduction
Was the hot July in Western Europe part of a global warming
signal caused by us?
Climate Variability and Change: Introduction
The global average temperature for July 2013 was 0.61oC above
the 20th Century average. Is this a global warming signal?
Climate Variability and Change: Introduction
Global Highlights
The combined average temperature over global land and ocean surfaces for
July 2013 was the sixth highest on record, at 0.61°C (1.10°F) above the
20th century average of 15.8°C (60.4°F).
The global land surface temperature was 0.78°C (1.40°F) above the 20th
century average of 14.3°C (57.8°F), marking the eighth warmest July on
record. For the ocean, the July global sea surface temperature was 0.54°C
(0.97°F) above the 20th century average of 16.4°C (61.5°F), the fifth
warmest July on record.
The combined global land and ocean average surface temperature for the
January–July period (year-to-date) was 0.59°C (1.06°F) above the 20th
century average of 13.8°C (56.9°F), tying with 2003 as the sixth warmest
such period on record.
Climate Variability and Change: Introduction
Climate Variability and Change: Introduction
July 2013 was a warm one in the Northeast. Eleven of the twelve Northeast states
ranked this July among their top 20 warmest with Rhode Island and Massachusetts
having their warmest July on record. Twenty-six of the thirty-five first order sites
ranked this July among their top 20 warmest, with three sites setting monthly
temperature records.
Climate Variability and Change Affects Society
Climate impacts:
food and water
health
infrastructure and transport
demography
energy
The Sahel (15-20N)
The Sahel experienced one of the most dramatic decadal signals
last century
Climate Variability and Change Affects Society in the US
Climate impacts:
food and water
health
infrastructure and transport
demography
energy
Climate Variability and Change Affects Society in the US
Bonnie (05)
Charlie (05)
Frances (05)
Flooding in New Orleans due to Katrina
(courtesy NOAA)
Ivan (05)
courtesy A. Aiyyer
Climate Variability and Change Affects Society in the US
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).
•Multidecadal 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.
Section 4 Future Perspectives
Section 4 Future Perspectives
‘We basically have three choices: mitigation,
adaptation and suffering.
We’re going to do some of each.
The question is what the mix is going to be.
The more mitigation we do, the less adaptation will be
required and the less suffering there will be.’
John Holdren,
Former President, American Association for the Advancement of Science
now Director of the White House Office of Science and Technology Policy
(OSTP)
Other Climate-Related Courses
Spring 2015
ATM405 Water and Climate Change
ATM413 Weather, Climate Change and Societal
Impacts
ATM/ENV415 Climate Laboratory
Fall 2015
ATM404 Oceans and Climate
What is the difference between weather and climate?
"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."