Global Warming 2007

1. Global Warming 2007 With secondary data taken mostly from the IPCC report February 2007 ADPA March 2007

2. Contents The Greenhouse Effect The Enhanced Greenhouse Empirical Evidence Deduction Summary of Temperature Records Greenhouse Gases Models and Feedbacks Predictions ADPA March 2007

3. The Greenhouse Effect The concept of the global greenhouse effect was proposed in 1824 by Joseph Fourier. It is a natural phenomenon associated with the various green house gases (GHGs) in the atmosphere, that trap heat radiation emitted from the planet. Carbon Dioxide, Methane and Water Vapour are all naturally occuring GHGs that help to keep the planet around 17 degrees warmer than without. ADPA March 2007

4. Enhanced Greenhouse Effect Human activities release additional greenhouse gases into the atmosphere – anthropogenic source. It seems likely that this will increase the power of the greenhouse – in other words cause an “Enhanced Greenhouse Effect”. This idea is not particularly new either first proposed by British physicist John Tyndall in 1859. In the 1880’s Swedish physicist Svante Arrhenius predicted that a doubling of Carbon Dioxide would lead to a global temperature rise of 5 degrees Celsius. ADPA March 2007

5. Empirical Evidence • There is plenty of good empirical evidence for all of the following. • Anthropogenic GHG emissions have increased and continue to increase. • Due to the warming GHG emissions are increasing from a number of sources • Temperatures are rising rapidly. ADPA March 2007

6. Deduction and Debate • It is a matter of scientific deduction as to whether anthropogenic emissions are causing global warming, and consequently it is an area of debate amongst scientists and politicians. • The IPCC report stated: “Most of the observed increase in globally averaged temperatures since the mid-20th century is verylikely due to the observed increase in anthropogenic greenhouse gas concentrations.” ADPA March 2007

7. Is the word getting hotter? Evidence from historical records back over the last 100 years and from ice cores that record temperature over the last 650,000 years (four glacial/interglacial cycles) show that we are currently experiencing a hotter average temperature. Eleven of the last twelve years (1995 -2006) rank among the 12 warmest years in the instrumental record ofglobal surface temperature(since 1850). ADPA March 2007

8. Historical Records Line – Decade Average Circles – Yearly Shaded Area – Margins of Uncertainty ADPA March 2007

9. Ice Core Data ADPA March 2007

10. Foramiferan Indicator Species Data This figure shows the climate record of Lisiecki and Raymo (2005) [1] constructed by combining measurements from 57 globally distributed deep sea sediment cores. The measured quantity is oxygen isotope fractionation in benthicforaminifera, which serves as a proxy for the total global mass of glacial ice sheets. ADPA March 2007

11. Models Climate Scientists use complex computer models to generate predictions on warming. One complication are the large number of both positive and negative feedbacks in that influence climate. ADPA March 2007

12. Negative Feedbacks Feedbacks in the global ecosystem can be negative, leading to a controling effect and an amelioration of warming. For example the warming is predicted to increase precipitation in polar areas as snow, increasing albedo (reflectivity of surface) leading to a cooling effect. ADPA March 2007

13. Positive Feebacks There are many positive feedbacks that may increase warming, possibly resulting in a runaway greenhouse. For example the solubility of Carbon Dioxide in sea water decreases with increasing temperature leading more to be released and further increasing the temperatures. ADPA March 2007

14. Feedbacks – are these positive or negative? • Thawing of permafrost leads to a release of methane from waterlogged soils. • Rate of photosynthesis in plants increases more carbon dioxide is therefore removed from the atmosphere. • Ice cover melts, exposing soil or water and albedo decreases • Increased evaporation produces more clouds increase tropospheric albedo, reflecting more light away from Earth • As Earth warms, organic matter in soil is decomposed faster more carbon dioxide is released ADPA March 2007

15. Runaway Greenhouse Effect This has been a suggestion since the earlier work of the IPCC. Scientists such as Steven Schneider hypothesised that we may pass a tipping point when positive feedbacks in the greenhouse effect become more powerful than the negative. This would lead to an accelerating warming and could give the Earth a Venusian climate system on a short time scale. ADPA March 2007

16. Summary of GHG Changes • Global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increasedmarkedly as a result of human activities since 1750 and now far exceed pre-industrial valuesdetermined from ice cores spanning many thousands of years. • Direct measurements of carbon dioxide since the 1960’s at Mauna Loa in Hawaii show a steady increase to the present day. • The globalincreases in carbon dioxide concentration are due primarily to fossil fuel use and land-use change,while those of methane and nitrous oxide are primarily due to agriculture. ADPA March 2007

17. GHG Sources, Warming Potential and Significance ADPA March 2007

18. Carbon Dioxide - The Last 10,000 years Measurements are shown from ice cores(symbols with different colours for different studies) and atmospheric samples (red lines). ADPA March 2007

19. Mauna Loa Carbon Dioxide Measurements ADPA March 2007

20. Methane the Last 10,000 years Measurements are shown from ice cores(symbols with different colours for different studies) and atmospheric samples (red lines). ADPA March 2007

21. Nitrous Oxide the Last 10,000 years Measurements are shown from ice cores(symbols with different colours for different studies) and atmospheric samples (red lines). ADPA March 2007

22. Carbon Dioxide • Carbon dioxide is the most important anthropogenic greenhouse gas. The globalatmospheric concentration of carbon dioxide has increased from a pre-industrial value of about 280 ppm to379 ppm in 2005. The atmospheric concentration of carbon dioxide in 2005 exceeds by far the naturalrange over the last 650,000 years (180 to 300 ppm) as determined from ice cores. The annual carbondioxide concentration growth-rate was larger during the last 10 years (1995 – 2005 average: 1.9 ppm peryear), than it has been since the beginning of continuous direct atmospheric measurements (1960–2005) average: 1.4 ppm per year) although there is year-to-year variability in growth rates. ADPA March 2007

23. Predictions The following slides show a series of graphs and maps that predict climate change against a number of scenarios described in the slides at the end of the presentation. ADPA March 2007

24. IPCC Scenarios A1 A1B A2 B1 ADPA March 2007

25. Predicted Warming against the IPCC ScenariosB1A1T B2A1BA2A1F1 ADPA March 2007

26. Isotherm Maps of Predicted Warming ADPA March 2007

27. ADPA March 2007

28. The Emission Scenarios of the IPCC Special Report on Emission Scenarios An illustrative scenario was chosen for each of the six scenario groups A1B, A1FI, A1T, A2, B1 and B2. All shouldbe considered equally sound. The SRES scenarios do not include additional climate initiatives, which means that noscenarios are included thatexplicitly assume implementation of the United Nations Framework Convention on Climate Change or the emissionstargets of the Kyoto Protocol. ADPA March 2007

29. A1 Family of Scenarios The A1 scenario family develops into three groups that describe alternative directions of technological change in the energy system. Thethree A1 groups are distinguished by their technological emphasis: fossil intensive (A1FI), non-fossil energy sources(A1T), or a balance across all sources (A1B) (where balanced is defined as not relying too heavily on one particularenergy source, on the assumption that similar improvement rates apply to all energy supply and end usetechnologies). Back to First Graph ADPA March 2007

30. A1 • A1a 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 socialinteractions, with a substantial reduction in regional differences in per capita income. Back to First Graph ADPA March 2007

31. A2. • The A2 storyline and scenario family describes a very heterogeneous world. The underlying theme is selfreliance and preservation of local identities. Fertility patterns across regions converge very slowly, which results incontinuously increasing population. Economic development is primarily regionally oriented and per capita economicgrowth and technological change more fragmented and slower than other storylines. Back to First Graph ADPA March 2007

32. B1 • The B1 storyline and scenario family describes a convergent world with the same global population, that peaksin mid-century and declines thereafter, as in the A1 storyline, but with rapid change in economic structures toward aservice and information economy, with reductions in material intensity and the introduction of clean and resourceefficient technologies. The emphasis is on global solutions to economic, social and environmental sustainability,including improved equity, but without additional climate initiatives. Back to First Graph ADPA March 2007

33. 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 continuously increasing global population, at a rate lowerthan A2, intermediate levels of economic development, and less rapid and more diverse technological change than inthe B1 and A1 storylines. While the scenario is also oriented towards environmental protection and social equity, itfocuses on local and regional levels. Back to First Graph ADPA March 2007

34. The Consequences of Global Warming • Cause biomes to shift their distribution patterns(How could this occur with fragmented, isolated habitats moving across urban areas, agricultural systems, transport networks? Could it happen at the speeds of temperature change given?) • Change the location of crop growing areas (what would be the geopolitical consequences of this?) • Change Weather Patterns (Cyclones increase in frequency and intensity) • Cause Coastal Flooding ( Predicted sea level rise would swamp low-lying areas) • Cause a change in the distribution of diseases limited by temperature (Such as Malaria) ADPA March 2007

35. Further Reading http://www.ipcc.ch/ http://www.unep.org/ http://www.climatecrisis.net/ www.funnyweather.org ADPA March 2007