Transcript Lectures 1 and 2

Earth System Science
Dan Lunt,
Prof. Paul Valdes, Prof. Tony Payne
Big Picture
How do these systems work?
What are the key drivers?
How do the different parts
interact?
How do we measure and
predict climate?
What will happen in the near
future?
What has happened in the
past?
Course aims and
objectives
• Introduce the study of the “Earth
System”
• Understand the processes important
in influencing the Earth System
• Understand the inter-connectivity of
the major components of the Earth
system
• Develop an appreciation of the
methods used for studying climate
• Understand how and why we use
climate models to inform our
understanding of the climate system
Lecture series
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Lecture 1: Introduction.
Lecture 2: Future modelling and the IPCC.
Lecture 3: Past Climate Changes
Lecture 4: Geoengineering
Lecture 5: Atmospheres
Lecture 6: Energy balance modelling
Lecture 7: Basics of General Circulation Modelling
Lecture 8: Oceans
Lecture 9: Ice sheet dynamics (1)
Lecture 10: Ice sheet dynamics (2)
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+ practical sessions
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Assessment
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Based on practicals
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Write a brief report (in the style of a
Nature paper) on your investigations
with the climate model (e.g. a past or
future simulation).
Text books
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To help see the “overall” picture, you may wish to look
at:
 IPCC Working Group 1: Summary for Policymakers
IPCC Working Group 1: Technical Summary
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IPCC Working Group 1: Individual chapters
(All available at http://ipcc-wg1.ucar.edu/wg1/wg1-report.html)
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Plus:
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McGuffie K. and Henderson-Sellers A., 2005. A Climate Modelling Primer. 3rd Ed.
Wiley.
Barry R.G. and Chorley R.J , 2003. Atmosphere, weather and climate. 8th Ed.
Routledge.
Bigg G.R. , 1996.The oceans and climate. 2nd Ed. Cambridge University Press.
Benn D.I. and Evans D.J.A., 1998. Glaciers and glaciation. Hodder Arnold.
Kump L.R., Kasting J.F., Crane R.G., 2004. The Earth system: an introduction to Earth
systems science. 2nd Ed.Prentice Hall.
Ruddiman W.F., 2001. Earth’s climate : past and future. W.H. Freeman and Company.
Holton, J.R.: An Introduction to Dynamic Meteorology. Academic Press. 4th Ed.
Peixoto & Oort “Physics of Climate”
Media
Government
“Urgent action is needed to combat climate change”
“Above all, climate change is the greatest challenge facing
this generation.”
“Internationally, we will work for an ambitious, fair and
legally binding climate change agreement”
Atmospheric CO2
CO2 emissions
Oceans absorb approx. 25% of
emissions, and land (plants) absorb
a further 25%
Leaving 50% of emissions to
increase atmosphere concentration
The Greenhouse Effect
The Earth System
Oldfield, p4
General Circulation Models (GCMs)
History of GCMs
1990
1990
1995
1995
2001
2007
2001
2007
Surface Temperature: observations
Surface Temperature: HadCM3
How good are GCMs?
(1) temperature
Precipitation: observations
Seaice: observations vs models
Precipitation: HadCM3
How good are GCMs?
(2) Precip and seaice
How good are GCMs?
(3) El Nino
Radiative Forcing – anthropogenic component
Historical Forcing and response (century)
Historical Forcing and response (millenium)
Attribution (global)
Attribution (regional)
The future – climate sensitivity
Predicting the Future
"Prediction is very difficult, especially if it's about the
future." --Nils Bohr, Nobel laureate in Physics
"Those who have knowledge, don't predict. Those who
predict, don't have knowledge. " --Lao Tzu, 6th Century
BC Chinese Poet
"This is the first age that's ever paid much attention to the
future, which is a little ironic since we may not have one. "
--Arthur C. Clarke
http://www.met.rdg.ac.uk/cag/forecasting/quotes.html
SRES (special report on emissions scenarios) storylines
SRES storylines
Economic growth rapid
Economic development
regional - disparity
Population peak 2050
Population continues rising
Technological growth rapid
Technological growth - slow,
fragmented
Capacity building
A1F1: fossil intensive
Self reliance, heterogeneity
A1T: non-fossil energy
A1B: Balance
Economic shift services/information
Economic development
intermediate
Population peak 2050
Population continues rising
slowly
Technology -clean/efficient
Technological growth diverse
Global solutions to
sustainability/equity
Local and regional solutions
to environment/equity
No Additional climate initiatives
SRES storylines summary
A1F1 BAD
B1 GOOD
From Jo House
SRES storylines summary
Radiance calibrated lights
obtained from night satellite
imagery. Situation in 1995/1996
(bottom panel) and illustrative
simulation for the SRES A1
scenario's implied GDP growth
for 2070 (top panel).
IPCC SRES
SRES storylines in more detail
IPCC TAR
SRES: Emissions
Also include
emissions scenarios
for other greenhouse
gases and aerosols.
IPCC TAR synthesis report 2001
How to go from emissions to concentrations?
Need to
consider the
components of
the carbon
cycle important
on these
timescales –
ocean, land,
and human
pertubations.
IPCC TAR
How to go from emissions to concentrations?
However, we still don’t
fully understand the
Vostok CO2 curve!!
Petit et al, Nature, 399, 429-436, 1999.
From Andy Ridgwell
CO2 concentration projections
IPCC use relatively simple
models to give CO2
concentration scenarios…..
IPCC TAR
The IPCC Process - summary
Future Climate
Predictions - global
Future Climate Predictions – regional
(1) temperature
Future Climate Predictions –
regional
(2) Precipitation and cloud cover
[stippling – at least 80% agree on sign of
change]
Future Climate Predictions – regional
(3) Ocean circulation
Summary
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The atmospheric composition has changed over the last
century.
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The climatic consequences of these variations can be
represented using numerical models.
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These models do a relatively good job of the last century
(millenium) compared to observations.
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Climatic change over the last century is predominantly
anthropogenic.
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Future scenarios of atmospheric composition have been
developed.
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Some modelled consequences of these future changes are
robust, others less so.