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PROSPERIDAD J. ABONETE JULY 3, 2003 Understanding Climate Change.

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Presentation on theme: "PROSPERIDAD J. ABONETE JULY 3, 2003 Understanding Climate Change."— Presentation transcript:

1 PROSPERIDAD J. ABONETE JULY 3, 2003 Understanding Climate Change

2 Outline Climate Change and Global Warming  Definition  Causes The Greenhouse Effect Evidence of Climate Change Effects of Global Warming

3 Climate change Long-term change in the average weather patterns over a specific period, over a significant period of time The Earth's climate has always varied, so the term climate change is now generally used to describe the changes caused by human activity - specifically, greenhouse emissions which build up in the atmosphere and trap heat. Global Warming, increase in the average temperature of the atmosphere, oceans, and landmasses of Earth

4 Causes of Climate Change Solar variation Orbital variation Plate tectonics Volcanic action Thermohaline circulation Human influences  Measurements at the Earth's surface show that average temperatures have risen by some 0.4C since the 1970s. Scientists are confident this change can be blamed on human emissions because the increase is too big to be explained by natural causes.

5 Although natural factors such as changes in the sun and large volcanic eruptions are known to have warmed and cooled the planet in the past, these effects are not powerful enough to explain the rapid warming seen recently. Only an increased greenhouse effect caused by higher amounts of heat-trapping gases in the atmosphere can explain it.

6 The Greenhouse Effect

7 Greenhouse Gases Occur naturally Concentrations determined by natural factors Naturally-occurring GHGs:  Water vapor  Methane (CH4)  Nitrous oxide (N20)  Carbon dioxide (CO2) Not naturally occurring:  Halocarbons – e.g CFCs  Artificial/human-made; products from chemical industry

8 Enhanced Greenhouse Effect Today, concentrations of naturally occurring GHGs, e.g. CO2, are enhanced by human action


10 Summary of Principal Greenhouse Gases GHGCO2CH4CFC-11CFC-12N2O Atmospheric concentration Late 18 th century 280 ppm0.7 ppm00288 ppb 2001371 ppm1.75 ppm252 ppt480 ppt315 ppb Atmospheric lifetime (yrs) 50-2001245130114

11 Carbon Cycle

12 The current concentrations of greenhouse gases IPCC WG1 SPM, 2007

13 13 Source: Jones, 2002


15 Global Surface Temperature (IPCC, 2007)

16 Intergovernmental Panel on Climate Change (IPCC) International scientific guidance Established in 1988 by WMO & UNEP Tasks:  Assess the scientific information related to the various components of the CC issue, such as…, as well as the science needed to assess environmental and socio-economic consequences  Formulate realistic response strategies for the management of CC issues

17 IPCC 2007 Report The understanding of anthropogenic warming and cooling influences on climate has improved …, leading to very high confidence that the globally averaged net effect of human activities since 1750 has been one of warming….

18 Warming of the climate system is unequivocal….  Increases in global average air and ocean temperatures  Widespread melting of snow and ice  Rising global mean sea level Anthropogenic warming and sea level rise would continue for centuries due to timescales associated with climate processes and feedbacks, even if GHG concentrations were to be stabilized.

19 Effects of Global Warming Weather Sea levels Agriculture Animals & Plants Human Health

20 Forests Climate interrelated with biology/ecology Rising CO2 levels – increased global temperature Carbon sequestration by forests forest vegetation accounts for 80% of above- ground C; forest soils capture 40% C of soil C forests both C source and sink even 1oC change in air T sustained over time is likely to affect growth and regeneration patterns of many forest species 1/3 of global forests will experience major changes

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