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Climate Change PrimerClimate Change Primer

1. The Climate System2. The Greenhouse Effect3. Past Climates4. Global Warming5. Future Predictions

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Announcements: May 2, 2011Announcements: May 2, 2011

Monday, May 2 – Finish Climate

Monday, May 16 – Term paper presentations 10 to 15 minutes each paper 8 to 10 slides

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Term Paper FormatTerm Paper Format

The term paper must follow standard guides for research papers, The term paper must follow standard guides for research papers, and have the following sections:and have the following sections:

TitleTitle AbstractAbstract Introduction & backgroundIntroduction & background Body of paperBody of paper - with a significant number (10-15) references - with a significant number (10-15) references

to primary literature and/or review articles. This may include to primary literature and/or review articles. This may include discussion of scientific theories, observations, and/or methods.discussion of scientific theories, observations, and/or methods.

ConclusionsConclusions Figures (& captions) Figures (& captions) are important in the body of the paper.are important in the body of the paper. Primary References (not Wikipedia)Primary References (not Wikipedia)

The paper must be typed, double spaced, and have ~ 15-25 The paper must be typed, double spaced, and have ~ 15-25 pages of text, not including figures, and at least 3 figures (may pages of text, not including figures, and at least 3 figures (may have more, include captions). Please number all pages.have more, include captions). Please number all pages.

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Intergovernmental Panel Intergovernmental Panel on Climate Change (IPCC)on Climate Change (IPCC)

Fourth Assessment Fourth Assessment Report (2007)Report (2007)

Global Average Temperature

Global Average Sea Level

Northern Hemisphere Snow Cover

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Intergovernmental Panel on Climate Change (IPCC)Intergovernmental Panel on Climate Change (IPCC)Fourth Assessment Report (2007)Fourth Assessment Report (2007)

Warming of the climate system is unequivocal.

Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic (human) greenhouse gas concentrations.

Anthropogenic warming and sea level rise would continue for centuries due to the timescales associated with climate processes and feedbacks, even if greenhouse gas concentrations were to be stabilized, although the likely amount of temperature and sea level rise varies greatly depending on the fossil use intensity of human activity during the next century.

The probability that this is caused by natural climatic processes alone is less than 5%.

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Intergovernmental Panel on Climate Change (IPCC)Intergovernmental Panel on Climate Change (IPCC)Fourth Assessment Report (2007)Fourth Assessment Report (2007)

World temperatures could rise by between 1.1 and 6.4 °C (2.0 and 11.5 °F) during the 21st century and that:

Sea levels will probably rise by 18 to 59 cm (7.08 to 23.22 in).

There is a confidence level >90% that there will be more frequent warm spells, heat waves and heavy rainfall.

There is a confidence level >66% that there will be an increase in droughts, tropical cyclones and extreme high tides.

Both past and future anthropogenic carbon dioxide emissions will continue to contribute to warming and sea level rise for more than a millennium.

Global atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values over the past 650,000 years

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Intergovernmental Panel on Climate Change (IPCC)Intergovernmental Panel on Climate Change (IPCC)Fourth Assessment Report (2007)Fourth Assessment Report (2007)

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Figure TS.3

Figure TS.3. Annual changes in global mean CO2 concentration (grey bars) and their five‑year means from two different measurement networks (red and lower black stepped lines). The five-year means smooth out short-term perturbations associated with strong ENSO events in 1972, 1982, 1987 and 1997. Uncertainties in the five-year means are indicated by the difference between the red and lower black lines and are of order 0.15 ppm. The upper stepped line shows the annual increases that would occur if all fossil fuel emissions stayed in the atmosphere and there were no other emissions.

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Figure TS.6

Figure TS.6. (Top) Patterns of linear global temperature trends over the period 1979 to 2005 estimated at the surface (left), and for the troposphere from satellite records (right).

04/20/23 10Figure TS.23

Figure TS.23. (a) Global mean surface temperature anomalies relative to the period 1901 to 1950, as observed (black line) and as obtained from simulations with both anthropogenic and natural forcings.

04/20/23 11Figure TS.22

Models and Decadal Averages of Observations

04/20/23 12Figure TS.2

Concentrations and Radiative Forcing

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Figure TS.18

Figure TS.18. Annual averages of the global mean sea level based on reconstructed sea level fields since 1870 (red), tide gauge measurements since 1950 (blue) and satellite altimetry since 1992 (black). Units are in mm relative to the average for 1961 to 1990. Error bars are 90% confidence intervals.

Sea Level in Industrial Era

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750 ppm ~ 4.3 0C

550 ppm ~ 3 0C

450 ppm ~ 2 0C

There is the potential that the climate is likely, as projected

by the IPCC, to take humankind where it

has never been

The question is: At what temperature will we stabilize?

IPCC (2007) Forecast

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IPCC – Future ScenariosIPCC – Future ScenariosSRES: Special Report on SRES: Special Report on

Emissions ScenariosEmissions Scenarios

Figure 2-11: Schematic illustration of SRES scenarios. The four scenario “families” are shown, very simplistically, for illustrative purposes, as branches of a two-dimensional tree. The two dimensions shown indicate global and regional scenario orientation, and development and environmental orientation, respectively. In reality, the four scenarios share a space of a much higher dimensionality given the numerous driving forces and other assumptions needed to define any given scenario in a particular modelling approach. The schematic diagram illustrates that the scenarios build on the main driving forces of GHG emissions. Each scenario family is based on a common specification of some of the main driving forces.

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A1: The A1 storyline and scenario family describes a future world of very rapid economic growth, global population that peaks in mid-century and declines thereafter, and the rapid introduction of new and more efficient technologies. Major underlying themes are convergence among regions, capacity building, and increased cultural and social interactions, with a substantial reduction in regional differences in per capita income. The A1 scenario family develops into three groups that describe alternative directions of technological change in the energy system. The three A1 groups are distinguished by their technological emphasis: fossil intensive (A1FI), non-fossil energy sources (A1T), or a balance across all sources (A1B).

A2: The A2 storyline and scenario family describes a very heterogeneous world. The underlying theme is self-reliance and preservation of local identities. Fertility patterns across regions converge very slowly, which results in continuously increasing global population. Economic development is primarily regionally oriented and per capita economic growth and technological change are more fragmented and slower than in other storylines.

SRES Scenarios A1 and A2 (Strong Economic Growth)

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B1: The B1 storyline and scenario family describes a convergent world with the same global population that peaks in mid-century and declines thereafter, as in the A1 storyline, but with rapid changes in economic structures towards a service and information economy, with reductions in material intensity, and the introduction of clean and resource-efficient technologies. The emphasis is on global solutions to economic, social, and environmental sustainability, including improved equity, but without additional climate initiatives.

B2: The B2 storyline and scenario family describes a world in which the emphasis is on local solutions to economic, social, and environmental sustainability. It is a world with a continuously increasing global population at a rate lower than in A2, intermediate levels of economic development, and less rapid and more diverse technological change than in the B1 and A1 storylines. While the scenario is also oriented towards environmental protection and social equity, it focuses on local and regional levels

SRES Scenarios B1 and B2 (Environmental Protection and Sustainability)

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SRES Scenarios (Approximately 40)

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Figure TS.26

Figure TS.26. Model projections of global mean warming compared to observed warming. Observed temperature anomalies, as in Figure TS.6, are shown as annual (black dots) and decadal average values (black line). Projected trends and their ranges from the IPCC First (FAR) and Second (SAR) Assessment Reports are shown as green and magenta solid lines and shaded areas, and the projected range from the TAR is shown by vertical blue bars.

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IPCC SRES Scenarios and Prediction

Baseline Greenhouse Gas (GHG) emissions vs. Scenarios

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Model Projections and Decadal Averages of Models

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Temperatures increases from present Temperatures increases from present day with different emissions scenariosday with different emissions scenarios

1.8oC = 3.2oF

2.8oC = 5.0oF

3.4oC = 6.1oF

CO2

Concentrations in

Atmosphere

850 ppm

600 ppm

400 ppm0.6oC = 1.0oF

IPCC AR4 2007

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750 ppm ~ 4.3 0C

550 ppm ~ 3 0C

450 ppm ~ 2 0C

There is the potential that the climate is likely, as projected

by the IPCC, to take humankind where it

has never been

The question is: At what temperature will we stabilize?

IPCC (2007) Forecast

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Decrease in Arctic Ice CoverDecrease in Arctic Ice Cover

04/20/23 26http://www.metafilter.com/65512/September-2007-polar-sea-ice-anomaly

Extent of Arctic Sea Ice:

2007 showed much more severemelting than in any year on record.

In September, 2007, theEuropean space agency (ESA) reported that the shrinking of Arctic ice had opened the fabled Northwest Passage, clearing a long-sought, but until recently impassable, route between Europe and Asia.

http://news.bbc.co.uk/2/hi/americas/6999078.stm

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Recent Increasing Trends in Frequency of Recent Increasing Trends in Frequency of Natural HazardsNatural Hazards

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Great Natural Disasters Great Natural Disasters 1950 – 20051950 – 2005

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© 2006 NatCatSERVICE, Geo Risks Research, Munich Re

04/20/23 29Center of Ocean-Land-Center of Ocean-Land-

Atmosphere studiesAtmosphere studies

Mean of 15 Models Surface Air Temperature Mean of 15 Models Surface Air Temperature DifferenceDifference(Sresa1b YR 71-100) minus (20c3m 1969-98), Global Average = (Sresa1b YR 71-100) minus (20c3m 1969-98), Global Average =

2.612.61

04/20/23 30Source: Timothy M. Lenton & Hans Joachim Schellnhuber. Nature Reports Climate Change, 97 - 98 (2007)

Risks of Temperature Risks of Temperature IncreaseIncrease

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Model sensitivity versus model relative entropy for 13 IPCC AR4 models. Sensitivity is defined as the surface air temperature Model sensitivity versus model relative entropy for 13 IPCC AR4 models. Sensitivity is defined as the surface air temperature change over land at the time of doubling of COchange over land at the time of doubling of CO22. Relative entropy is proportional to the model error in simulating current climate. . Relative entropy is proportional to the model error in simulating current climate.

Estimates of the uncertainty in the sensitivity (based on the average standard deviation among ensemble members for those Estimates of the uncertainty in the sensitivity (based on the average standard deviation among ensemble members for those models for which multiple realizations are available) are shown as vertical error bars. The line is a least-squares fit to the values.models for which multiple realizations are available) are shown as vertical error bars. The line is a least-squares fit to the values.

J. Shukla, T. DelSole, M. Fennessy, J. Kinter and D. PaolinoJ. Shukla, T. DelSole, M. Fennessy, J. Kinter and D. PaolinoGeophys. Research Letters, 33, doi10.1029/2005GL025579, 2006Geophys. Research Letters, 33, doi10.1029/2005GL025579, 2006

Climate Model Fidelity and Projections of Climate ChangeClimate Model Fidelity and Projections of Climate Change

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Atmosphere studies

Models with low fidelity in simulatingclimate statistics have low skill in

predicting climate anomalies.

HypothesisHypothesis

DelSole, 2008 (research in progress)

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Climate Model Fidelity and Climate PredictionClimate Model Fidelity and Climate Prediction

Interim ConclusionsInterim Conclusions: : • If we conjecture that models that better simulate the If we conjecture that models that better simulate the present climate should be considered more credible in present climate should be considered more credible in projecting the future climate change, then this relationship projecting the future climate change, then this relationship suggests that the actual changes in global warming will be suggests that the actual changes in global warming will be closer to the highest projected estimates among the current closer to the highest projected estimates among the current generation of models used in IPCC AR4.generation of models used in IPCC AR4.

• Lack of understanding of causes of model differences – is Lack of understanding of causes of model differences – is source of uncertainty in predicting climate change. source of uncertainty in predicting climate change.

Center of Ocean-Land-Atmosphere studies

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Why are there Skeptics?Why are there Skeptics?Questioning and responsible skepticism is healthy (and most would argue essential) for scientific progress.

The greenhouse effect is a demonstrated physical process. Global warming is an observational fact. Human influence (e.g., increasing CO2, deforestation,…) is certain.

However, there are legitimate questions about future predictions (the detailed role of clouds, aerosols, ice sheet collapse, ocean circulation…).

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Why are there Skeptics?Why are there Skeptics?

In reality, there are very, very few skeptics. Most, but not all, skeptics have little scientific credibility. Many skeptics have a conflict of interest (books, speaking, attention…) Pathological science and “skeptics”

The press has vastly overplayed the significance of global warming skeptics.

The politics of global warming has been largely counterproductive.

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““Computer modeling of global climate is Computer modeling of global climate is perhaps the most complex endeavor ever perhaps the most complex endeavor ever

undertaken by mankind.undertaken by mankind.””

Kerry Emanuel (2007)Kerry Emanuel (2007)

What We Know About Climate ChangeWhat We Know About Climate Change

(MIT Press, Cambridge, Massachusetts)(MIT Press, Cambridge, Massachusetts)

Center of Ocean-Land-Atmosphere studies

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ResourcesResourcesIPCC (Intergovernmental Panel on Climate Change:IPCC (Intergovernmental Panel on Climate Change:

www.ipcc.ch

Summary for Policy MakersSummary for Policy Makers

Historical BasisHistorical Basis

ObservationsObservations

PredictionsPredictions

US Global Change Research Program:US Global Change Research Program:

www.usgcrp.gov/usgcrp/default.php

National Oceanic and Atmospheric National Oceanic and Atmospheric AdministrationAdministration

www.noaa.gov