Transcript Lesson 6 Climate modellingx

How do scientists predict future
climate?
Models
•Scientists use models to predict future climate:
including temperature, CO2 levels in the atmosphere,
precipitation and more
•Scientists must create these models using
information and science they know
•Scientists also test or calibrate the models to make
sure they are accurate
What is a model?
In this case, an equation or lines of programming that has inputs and
outputs
fortran code from Dennis Shea
Very simple climate model
T = T0 + S log2 (C / C0)
Climate Modeling
• Using computers to do
the most impossible
math homework known
to man
What do we know about CO2?
Over the past 425,000 years, cool periods have coincided with times when the CO2
concentration in the atmosphere was lower. When there is less CO2 in the atmosphere, the
greenhouse effect is reduced and the world cools.
The blue and red line indicates the variation in average global temperature compared with the 1961–1990
average. The green line shows the concentration of CO2 in the atmosphere. (Pay close attention to the righthand edge of the graph.)
This graph shows four eras when the world was cooler than it is today. These are separated by brief warm
periods, like the one we are now in.
What do we know?
Simplified carbon cycle
Atmosphere
Oceans
Fossil Fuels
Land & Plants
Calibrating a model
Scientists need to make sure the model works
They check the model by comparing the model’s
prediction with measured data
Resolution
Graph that includes temperature
predictions from 20 different models
Several Models Show the Same Trend
http://climate.nasa.gov/warmingworld/gl
obalTemp.cfm
Climate Modeling
You be the climate scientist!
• What might cause carbon emissions to change in
the future? (brainstorm)
What does the future hold?
What will happen if we keep emitting
CO2?
Scenario
CO2 Emissions
(Gt/year)
What this means
Current
9
Same fossil fuel usage
High
18
High economic growth,
increased fossil fuel usage
Medium
11
Steady economic growth,
slightly increased fossil fuel
usage
Low
4
Decreased fossil fuel usage
1 gigaton = 1 billion tons
What is IPCC?
• Intergovernmental Panel on Climate Change (IPCC) is an
international organization that includes scientists and
representatives of governments around the world.
• It reviews the most recent scientific, technical and
socio-economic information relevant to climate change
HOWEVER
It does not conduct any research
• It provides policy makers (congress or governments) with
an objective report of the scientific evidence of climate
change, its impacts and possible responses.
How Does it Work?
• Thousands of scientists from all over the world
contribute to the work of the IPCC
▫ None of them are paid by the IPCC
• IPCC aims to reflect a range of views and
expertise
• Review is an essential part of the IPCC process
▫ Ensures an objective and complete assessment of
current information
Oslo, 10 December 2007
The Intergovernmental
Panel on Climate Change
and Al Gore were awarded
of the Nobel Peace Prize
"for their efforts to build
up and disseminate
greater knowledge about
man-made climate
change, and to lay the
foundations for the
measures that are needed
to counteract such
change".
Many Different Scenarios for the Future
Many different Scenarios for the Future
Chapter 5 - Emission Scenarios: Figure 5-1
IPCC predicts…
• short video of IPCC projections
NEXT TIME…
What do models predict for the future
climate of Colorado?
Future projections
Observed and Projected Temperature Rise for the
Southwest
The average temperature in the Southwest has already increased roughly 1.5°F compared
to a 1960-1979 baseline period. By the end of the century, average annual temperature is
projected to rise approximately 4°F to 10°F above the historical baseline, averaged over
the Southwest region. The brackets on the thermometers represent the likely range of
model projections, though lower or higher outcomes are possible.
Future projections
Projected Change in Spring Precipitation, 2080-2099
Percentage change in March-April-May precipitation for 2080-2099 compared to
1961-1979 for a lower emissions scenario (left) and a higher emissions scenario
(right). Confidence in the projected changes is highest in the hatched areas.
Future Drought Projections
(Courtesy Wiley Interdisciplinary Reviews, redrawn by UCAR.