10/22/ Climate Change Primer 1.The Climate System 2.The Greenhouse Effect 3.Past Climates 4.Global Warming 5.Future Predictions

10/22/ Announcements: May 2, 2011 Monday, May 2 – Finish Climate Monday, May 16 – Term paper presentations  10 to 15 minutes each paper  8 to 10 slides

10/22/ Term Paper Format The term paper must follow standard guides for research papers, and have the following sections:  Title  Abstract  Introduction & background  Body of paper - with a significant number (10-15) references to primary literature and/or review articles. This may include discussion of scientific theories, observations, and/or methods.  Conclusions  Figures (& captions) are important in the body of the paper.  Primary References (not Wikipedia) The paper must be typed, double spaced, and have ~ pages of text, not including figures, and at least 3 figures (may have more, include captions). Please number all pages.

10/22/ Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (2007) Global Average Temperature Global Average Sea Level Northern Hemisphere Snow Cover

10/22/ Intergovernmental Panel on Climate Change (IPCC) 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%.

10/22/ Intergovernmental Panel on Climate Change (IPCC) 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 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

10/22/ Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (2007)

10/22/ 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 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.

10/22/ 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).

10/22/ 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.

10/22/ Models and Decadal Averages of Observations

10/22/ Concentrations and Radiative Forcing

10/22/ 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 Error bars are 90% confidence intervals. Sea Level in Industrial Era

10/22/ ppm ~ C 550 ppm ~ 3 0 C 450 ppm ~ 2 0 C 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? 17 IPCC (2007) Forecast

10/22/ IPCC – Future Scenarios SRES: Special Report on Emissions 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.

10/22/ 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)

10/22/ 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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10/22/ SRES Scenarios (Approximately 40)

10/22/ 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.

10/22/ IPCC SRES Scenarios and Prediction Baseline Greenhouse Gas (GHG) emissions vs. Scenarios

10/22/ Model Projections and Decadal Averages of Models

10/22/ Temperatures increases from present day with different emissions scenarios 1.8 o C = 3.2 o F 2.8 o C = 5.0 o F 3.4 o C = 6.1 o F CO 2 Concentrations in Atmosphere 850 ppm 600 ppm 400 ppm 0.6 o C = 1.0 o F IPCC AR4 2007

10/22/ ppm ~ C 550 ppm ~ 3 0 C 450 ppm ~ 2 0 C 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? 17 IPCC (2007) Forecast

10/22/ Decrease in Arctic Ice Cover

10/22/ Extent of Arctic Sea Ice: 2007 showed much more severe melting than in any year on record. In September, 2007, the European 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.

10/22/ Recent Increasing Trends in Frequency of Natural Hazards WindstormsFloods Extreme Heat EventsDrought

10/22/ Great Natural Disasters 1950 – 2005 Number of events Others (Heat wave, cold wave, forest fire) Flood Storm Earthquake/tsunami, volcanic eruption © 2006 NatCatSERVICE, Geo Risks Research, Munich Re

10/22/ Center of Ocean-Land- Atmosphere studies Mean of 15 Models Surface Air Temperature Difference (Sresa1b YR ) minus (20c3m ), Global Average = 2.61

10/22/ Source: Timothy M. Lenton & Hans Joachim Schellnhuber. Nature Reports Climate Change, (2007) Risks of Temperature Increase

10/22/ 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 CO 2. 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 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. Paolino Geophys. Research Letters, 33, doi /2005GL025579, 2006 Climate Model Fidelity and Projections of Climate Change

10/22/ Center of Ocean-Land- Atmosphere studies Models with low fidelity in simulating climate statistics have low skill in predicting climate anomalies. Hypothesis DelSole, 2008 (research in progress)

10/22/ Climate Model Fidelity and Climate Prediction Interim Conclusions: If we conjecture that models that better simulate the present climate should be considered more credible in projecting the future climate change, then this relationship suggests that the actual changes in global warming will be closer to the highest projected estimates among the current generation of models used in IPCC AR4. If we conjecture that models that better simulate the present climate should be considered more credible in projecting the future climate change, then this relationship suggests that the actual changes in global warming will be closer to the highest projected estimates among the current generation of models used in IPCC AR4. Lack of understanding of causes of model differences – is source of uncertainty in predicting climate change. Lack of understanding of causes of model differences – is source of uncertainty in predicting climate change. Center of Ocean-Land- Atmosphere studies

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10/22/ 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 CO 2, deforestation,…) is certain. However, there are legitimate questions about future predictions (the detailed role of clouds, aerosols, ice sheet collapse, ocean circulation…).

10/22/ 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.

10/22/ “Computer modeling of global climate is perhaps the most complex endeavor ever undertaken by mankind.” Kerry Emanuel (2007) What We Know About Climate Change (MIT Press, Cambridge, Massachusetts) Center of Ocean-Land- Atmosphere studies

10/22/ Resources IPCC (Intergovernmental Panel on Climate Change: Summary for Policy Makers Historical Basis ObservationsPredictions US Global Change Research Program: National Oceanic and Atmospheric Administration