The document discusses the history and science of climate change, including: - 19th century scientists recognized the atmosphere plays a key role in warming the planet. - In the late 20th century, precise measurements of CO2 levels showed a rising baseline concentration in the atmosphere. - Ice core data from Antarctica demonstrated a close link between historical temperature and CO2 levels. - The risks of unabated climate change include severe impacts on water resources, ecosystems, and global food security.

3. The Greenhouse Effect Sunlight passes through the atmosphere and warms the Earth’s surface. This heat is radiated back towards space as infrared radiation. Much of the outgoing heat is absorbed by greenhouse gas molecules in the atmosphere and re-emitted in all directions, warming the lower atmosphere. ºC Global temperature rise 20 10 0 -10 -20 -30 -40

4. Radiation transmitted by the atmosphere

5. Changes in outgoing long-wave radiation CHANGES IN THE EARTH’S RESOLVED OUTGOING LONGWAVE RADIATION FIELD AS SEEN FROM THE IRIS AND IMG INSTRUMENTS H.E. Brindley*, P.J. Sagoo, R. J. Bantges and J.E. Harries Imperial College, London, UK Change in outgoing long-wave radiation 1970-1997 CO 2 CFC-11 CFC-12 O 3 CH 4

6. A short history of global warming science 1820 1900 1940 1960 1980 2000 2020 Physicists such as John Tyndall and Joseph Fourier recognise that the atmosphere plays a key role in keeping the planet warm. The physics showed that a bare, airless rock at the Earth's distance from the Sun should be far colder than the Earth actually is. Swedish scientist Svante Arrhenius calculates that a doubling of CO 2 in the atmosphere would give rise to a 4-5  C.

7. A short history of global warming science 1820 1900 1940 1960 1980 2000 2020 Physicists such as John Tyndall and Joseph Fourier recognise that the atmosphere plays a key role in keeping the planet warm. The physics showed that a bare, airless rock at the Earth's distance from the Sun should be far colder than the Earth actually is. Swedish scientist Svante Arrhenius calculates that a doubling of CO 2 in the atmosphere would give rise to a 4-5  C.

8. A short history of global warming science 1820 1900 1940 1960 1980 2000 2020 Physicists such as John Tyndall and Joseph Fourier recognise that the atmosphere plays a key role in keeping the planet warm. The physics showed that a bare, airless rock at the Earth's distance from the Sun should be far colder than the Earth actually is. Swedish scientist Svante Arrhenius calculates that a doubling of CO 2 in the atmosphere would give rise to a 4-5  C. English engineer, Guy Stewart Callendar, puts forward a number of theories related to atmospheric CO 2 , seeking a theory to explain the ice age cycles. Atmospheric physics comes of age as the world enters the “Cold War”. Computing power, direct measurement and funding for science bring new thinking and theories forward, but measurement of CO 2 in the atmosphere proves problematic With a painstaking series of measurements in the pristine air of Antarctica and high atop the Mauna Loa volcano in Hawaii, Charles David Keeling nailed down precisely a stable baseline level of CO 2 in the atmosphere. In 1960, with only two full years of Antarctic data in hand, Keeling reported that this baseline level had risen.

9. A short history of global warming science 1820 1900 1940 1960 1980 2000 2020 Physicists such as John Tyndall and Joseph Fourier recognise that the atmosphere plays a key role in keeping the planet warm. The physics showed that a bare, airless rock at the Earth's distance from the Sun should be far colder than the Earth actually is. English engineer, Guy Stewart Callendar, puts forward a number of theories related to atmospheric CO 2 , seeking a theory to explain the ice age cycles. Swedish scientist Svante Arrhenius calculates that a doubling of CO 2 in the atmosphere would give rise to a 4-5  C. Atmospheric physics comes of age as the world enters the “Cold War”. Computing power, direct measurement and funding for science bring new thinking and theories forward, but measurement of CO 2 in the atmosphere proves problematic With a painstaking series of measurements in the pristine air of Antarctica and high atop the Mauna Loa volcano in Hawaii, Charles David Keeling nailed down precisely a stable baseline level of CO 2 in the atmosphere. In 1960, with only two full years of Antarctic data in hand, Keeling reported that this baseline level had risen.

10. A short history of global warming science 1820 1900 1940 1960 1980 2000 2020 Physicists such as John Tyndall and Joseph Fourier recognise that the atmosphere plays a key role in keeping the planet warm. The physics showed that a bare, airless rock at the Earth's distance from the Sun should be far colder than the Earth actually is. English engineer, Guy Stewart Callendar, puts forward a number of theories related to atmospheric CO 2 , seeking a theory to explain the ice age cycles. Swedish scientist Svante Arrhenius calculates that a doubling of CO 2 in the atmosphere would give rise to a 4-5  C. Atmospheric physics comes of age as the world enters the “Cold War”. Computing power, direct measurement and funding for science bring new thinking and theories forward, but measurement of CO 2 in the atmosphere proves problematic With a painstaking series of measurements in the pristine air of Antarctica and high atop the Mauna Loa volcano in Hawaii, Charles David Keeling nailed down precisely a stable baseline level of CO 2 in the atmosphere. In 1960, with only two full years of Antarctic data in hand, Keeling reported that this baseline level had risen. The Vostok ice-core from Antarctica demonstrates a close link between temperature and CO 2 .

11. A short history of global warming science 1820 1900 1940 1960 1980 2000 2020 Physicists such as John Tyndall and Joseph Fourier recognise that the atmosphere plays a key role in keeping the planet warm. The physics showed that a bare, airless rock at the Earth's distance from the Sun should be far colder than the Earth actually is. English engineer, Guy Stewart Callendar, puts forward a number of theories related to atmospheric CO 2 , seeking a theory to explain the ice age cycles. Swedish scientist Svante Arrhenius calculates that a doubling of CO 2 in the atmosphere would give rise to a 4-5  C. Atmospheric physics comes of age as the world enters the “Cold War”. Computing power, direct measurement and funding for science bring new thinking and theories forward, but measurement of CO 2 in the atmosphere proves problematic With a painstaking series of measurements in the pristine air of Antarctica and high atop the Mauna Loa volcano in Hawaii, Charles David Keeling nailed down precisely a stable baseline level of CO 2 in the atmosphere. In 1960, with only two full years of Antarctic data in hand, Keeling reported that this baseline level had risen. The Vostok ice-core from Antarctica demonstrates a close link between temperature and CO 2 .

12. A short history of global warming science 1820 1900 1940 1960 1980 2000 2020 Physicists such as John Tyndall and Joseph Fourier recognise that the atmosphere plays a key role in keeping the planet warm. The physics showed that a bare, airless rock at the Earth's distance from the Sun should be far colder than the Earth actually is. English engineer, Guy Stewart Callendar, puts forward a number of theories related to atmospheric CO 2 , seeking a theory to explain the ice age cycles. Swedish scientist Svante Arrhenius calculates that a doubling of CO 2 in the atmosphere would give rise to a 4-5  C. Atmospheric physics comes of age as the world enters the “Cold War”. Computing power, direct measurement and funding for science bring new thinking and theories forward, but measurement of CO 2 in the atmosphere proves problematic With a painstaking series of measurements in the pristine air of Antarctica and high atop the Mauna Loa volcano in Hawaii, Charles David Keeling nailed down precisely a stable baseline level of CO 2 in the atmosphere. In 1960, with only two full years of Antarctic data in hand, Keeling reported that this baseline level had risen. The Vostok ice-core from Antarctica demonstrates a close link between temperature and CO 2 .

13. A short history of global warming science 1820 1900 1940 1960 1980 2000 2020 Physicists such as John Tyndall and Joseph Fourier recognise that the atmosphere plays a key role in keeping the planet warm. The physics showed that a bare, airless rock at the Earth's distance from the Sun should be far colder than the Earth actually is. English engineer, Guy Stewart Callendar, puts forward a number of theories related to atmospheric CO 2 , seeking a theory to explain the ice age cycles. Swedish scientist Svante Arrhenius calculates that a doubling of CO 2 in the atmosphere would give rise to a 4-5  C. Atmospheric physics comes of age as the world enters the “Cold War”. Computing power, direct measurement and funding for science bring new thinking and theories forward, but measurement of CO 2 in the atmosphere proves problematic With a painstaking series of measurements in the pristine air of Antarctica and high atop the Mauna Loa volcano in Hawaii, Charles David Keeling nailed down precisely a stable baseline level of CO 2 in the atmosphere. In 1960, with only two full years of Antarctic data in hand, Keeling reported that this baseline level had risen. The Vostok ice-core from Antarctica demonstrates a close link between temperature and CO 2 . The Intergovernmental Panel on Climate Change (IPCC) brings the global scientific community together.

14. IPCC 4 th Assessment Report - 2007 Warming of the climate system is unequivocal , as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level. Observational evidence from all continents and most oceans shows that many natural systems are being affected by regional climate changes, particularly temperature increases. Global GHG emissions due to human activities have grown since pre-industrial times, with an increase of 70% between 1970 and 2004. Global atmospheric concentrations of CO 2 , methane (CH 4 ) and nitrous oxide (N 2 O) have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values determined from ice cores spanning many thousands of years. Most of the observed increase in global average temperatures since the mid-20 th century is very likely due to the observed increase in anthropogenic GHG concentrations. Anthropogenic warming over the last three decades has likely had a discernible influence at the global scale on observed changes in many physical and biological systems. Continued GHG emissions at or above current rates would cause further warming and induce many changes in the global climate system during the 21 st century that would very likely be larger than those observed during the 20 th century.

15. CO 2 levels in perspective

16. Global Temperature Anomaly

17. Models using only natural forcings Models using both natural and anthropogenic forcings Observations

18. A new direction is needed The way we use our planet today is not sustainable

19. The risk we are currently running . . . ºC 6 - 5 - 4 - 3 - 2 - 1 - 0 - 1990 Global temperature rise Large- s cale h igh- i mpact e vents Higher Very Low

20. . . . . . . has some bad outcomes

21. . . . . . . or like this

22. We can shift the outcome . . . . . . ºC 1990 Global temperature rise Large- s cale h igh- i mpact e vents Higher Very Low 6 - 5 - 4 - 3 - 2 - 1 - 0 -

23. High and low carbon pathways 0 2 4 6 8 10 12 14 16 2000 2010 2020 2040 2050 Global Carbon Emissions, GT 2030 2002 IEA reported fossil emissions plus correction for unsustainable biomass & deforestation. WRE 450 (IPCC) WRE 550 (IPCC) WRE 1000 (IPCC) Theoretical carbon emissions profiles published in IPCC 3 rd Assessment Report

24. High and low carbon pathways 0 2 4 6 8 10 12 14 16 2000 2010 2020 2040 2050 Global Carbon Emissions, GT 2030 WRE 450 (IPCC) WRE 550 (IPCC) WRE 1000 (IPCC) Theoretical carbon emissions profiles published in IPCC 3 rd Assessment Report 2002 IEA reported fossil emissions plus correction for unsustainable biomass & deforestation. >> 550 ppm Trajectory Current “business as usual” trend, even with more renewable power, biofuels and energy efficiency improvements. << 550 ppm Trajectory An alternative trajectory will require concerted action at national and inter-national level. It must start now.

25. . . . but the debate is shifting rapidly IPCC 3 rd AR Hadley G8 Report IPCC 4 th AR Jim Hansen <550 ppm 450 ppm 400 ppm 350 ppm ?? 2001 2005 2007 2008 Avoiding Dangerous Climate Change

27. A world of energy nationalism A world of emerging coalitions Accelerated structural & regulatory change Reactive structural & regulatory change

28. Consequences for energy CO 2 emissions Late reactions Early actions Europe North America Asia & Oceania - Developed Asia & Oceania - Developing Latin America Middle East & North Africa Sub-Saharan Africa

29. Blueprints is stabilising at 550 ppm CO 2 ; Scramble reaches 683 ppm CO 2 in 2100, . . . . . . but still rising at 3 ppm each year Source: MIT

30. Blueprints is stabilising at 630 ppm CO 2 e; Scramble passes 1000 ppm CO 2 e in 2100 Source: MIT

31. Expected temperature rises start to diverge after 2030 IPCC: mean temperature in 2005 is around 0.5°C warmer than pre-industrial (1750), and 0.74°C warmer than 100 years ago (1906).

32. Key Impacts - Water Global mean annual temperature change relative to 1980-1999 (  C) 0 1 2 3 4 5  C Increased water availability in moist tropics and high latitudes Decreasing water availability and increasing drought in mid-latitudes and semi-arid low latitudes Hundreds of millions of people exposed to increased water stress

33. Key Impacts - Ecosystems Global mean annual temperature change relative to 1980-1999 (  C) 0 1 2 3 4 5  C Up to 30% of species at Significant extinctions increasing risk of extinction around the globe Increased coral bleaching Most corals bleached Widespread coral mortality Terrestrial biosphere tends toward a net carbon source Increasing species range shifts and wildfire risk Ecosystem changes due to weakening of the meridional overturning circulation

34. Key Impacts - Food Global mean annual temperature change relative to 1980-1999 (  C) 0 1 2 3 4 5  C Complex, localised negative impacts on small holders, subsistence farmers and fishers Tendencies for cereal productivity Productivity of all cereals to decrease in low latitudes decreases in low latitudes Tendencies for some cereal productivity Cereal productivity to to increase at mid-to-high latitudes decrease in some regions

35. Key Impacts - Coasts Global mean annual temperature change relative to 1980-1999 (  C) 0 1 2 3 4 5  C Increased damage from floods and storms About 30% of global coastal wetlands lost Millions more people could experience coastal flooding each year

36. Key Impacts - Health Global mean annual temperature change relative to 1980-1999 (  C) 0 1 2 3 4 5  C Increasing burden from malnutrition, diarrhoeal, cardio-respiratory, and infectious diseases Increased morbidity and mortality from heat waves, floods, and droughts Changed distribution of some disease vectors Substantial burden on health services

37. Arctic Impacts The annual ice mass lost from glaciers in the Gulf of Alaska has been 84 gigatons annually, about five times the average annual flow of the Colorado River through the Grand Canyon.

38. Arctic ice trends

39. Antarctic ice trends

40. Antarctic temperature trends

41. Glaciers in decline Muir Glacier taken on August 13, 1941; on the right, a photograph taken from the same vantage on August 31, 2004 Qori Kalis Glacier taken in July 1978, and on the right, a photograph taken from the same vantage in July 2004. Glacier photograph collection. Boulder, Colorado USA: National Snow and Ice Data Center/World Data Center for Glaciology. Digital media.

42. The other big problem Change in sea surface pH caused by anthropogenic CO 2 between the 1700s and the 1990s While the full ecological consequences of these changes in calcification are still uncertain, it appears likely that many calcifying species will be adversely affected.

43. What do we think of all this ??