GLOBAL WARMING 1. What is the greenhouse effect? 2. Are human activities leading to the warming of the global climate?3. What will be the consequences of global for Jamaica?4. What can you do to help?
Evidence of Global Warming? • Earth's average surface temperature has fluctuated over geologic time. During the past 800,000 years, several ice ages have covered the planet with thick ice. Each lasted for about 100,000 years and was followed by a warmer Interglacial period of between 10,000 - 12,500 years. • Last Ice Age occurred over 20,000 years ago and in the past 10,000 years, the earth has enjoyed the relative warmth of the latest Interglacial period called the Holocene.
Evidence of Global Warming • Studies show that over the past 160,000 years, water vapor level in the troposphere has fluctuated between 190 and 290 parts per million. • C02 concentrations correlated with estimated variations in the earth's mean surface temperature
Time series analysis of seasonally averaged temperature anomalies; land & sea: 1880–1999
Time series analysis of seasonally averaged global surface temperature land & sea combined 1879–1999
Global surface temperature trends (°C/decade) for the 20-year period 1979– 98Global surface temperature trends (°C/decade) for the 20-year period 1979– 98
Projected Carbon Dioxide Emissions Projected anthropogenic CO2 emissions from fossil fuel use, deforestation and cement production are shown for some of the IPCC emission scenarios. The highest emission scenario - IS92e - assumes moderate population growth, high economic growth, high fossil fuel availability, and a phase out of nuclear power; and the lowest emission scenario - IS92c - assumes low population growth, low economic growth, and severe constraints on fossil fuel supplies.
Over a 40 year period, scientist Charles Keeling has measured the amount of CO2 in the atmosphere at 4,000 meters high on the peak of Mauna Loa mountain in Hawaii since 1958. The "Keeling Curve" below shows increases in the total concentrations of CO2 (316-369ppmv) in the atmosphere between 1958-1998.
A graph showing 1oF rise in the temperature record of the entire earth's surface during the 20th century.
Arguments for Global Warming ..1 • Increases in Greenhouse gases has matched the warming trend in global temperature • For the past Century, Scientists have observed a warming trend in Global temperature and a rise in sea level. • The 10 hottest years on record have all occurred since 1980 and since the 1990, global temperatures has risen every year except 1992-3 due to volcanic dust from Mt Pinatubo. • The rise in Global Temperatures over the past century has been too steep to consider as normal or natural. • The size of observed warming has been consistent with the predictions of current scientific models
Arguments for Global Warming ..2 • The retreat of glaciers and the warming of the Tundra permafrost is clear evidence of a warming climate. • A startling 2.5oC warming has been reported in Antarctica and other places. • Evidence from air trapped in 250,000 year old ice cores reveal that the level of greenhouse gases in the atmosphere has varied in the past, but those variations have occurred concurrently with changes in global temperatures • Greenhouse gases have been increasing since pre-Industrial times and concentrations are almost 30% more today. Such a high concentration is likely to impact global temperatures.
Global Warming Skeptics • Global Climate Coalition http://www.globalclimate.org/index.htm Founded in 1989 by 46 corporations and trade associations representing all major elements of US industry, the GCC presents itself as a "voice for business in the global warming debate." • George Marshall Institutehttp://www.marshall.org This conservative think tank shifted its focus from Star Wars to climate change in the late 1980s. In 1989, the Marshall Institute released a report claiming that "cyclical variations in the intensity of the sun would offset any climate change associated with elevated greenhouse gases. • Oregon Institute of Science and MedicineThe Marshall Institute co-sponsored with the OISM a deceptive campaign -- known as the Petition Project -- to undermine and discredit the scientific authority of the IPCC and to oppose the Kyoto Protocol. • Science and Environmental Policy Project (SEPP) [ http://www.sepp.org. Founded in 1990 by widely publicized climate skeptic S. Fred Singer, SEPP s stated purpose is to "document the relationship between scientific data and the development of federal environmental policy. Funding: Conservative foundations including Bradley, Smith Richardson, and Forbes • Greening Earth Society [ http://greeningearthsociety.org The Greening Earth Society (GES) was founded on Earth Day 1998 by the Western Fuels Association to promote the view that increasing levels of atmospheric CO2 are good for humanity. Funding: The Greening Earth Society receives its funding from the Western Fuels Association, which in turn receives its funding from its coal and utility company members • Center for the Study of Carbon Dioxide & Global Changehttp://www.CO2science.org The Center claims to "disseminate factual reports and sound commentary on new developments in the world-wide scientific quest to determine the climactic and biological consequences of the ongoing rise in the air's CO2 content." The Center is led by two brothers, Craig and Keith Idso. Their father, Sherwood Idso, is affiliated with the Greening Earth Society
Arguments against Global Warming ..1 • The consequences of the greenhouse effect is not well understood. Increases in carbon can be absorbed by oceans or can lead to more forest growth • Scientists still disagree as to whether there is going to be significant temperature rise in the near future since climate has varied greatly in the past too. • Global temperature data is available for only a few years (since 1846) • There is no temperature data collection for several locations on the earth (especially before 1900 and in developing countries today)
Arguments against Global Warming ..2 • Some local temperature changes are different from the global temperature warming. In some parts of the United States temperature has actually cooled in the past 5 years • Aside greenhouse gases, global climate is affected by several other factors • Climate has never been stable but has naturally fluctuated in the past. For example, during the Ice Age, temperature rose and fell leading to warm and cold phases.
CO2 concentration Temperature changes Past changes in Global Temperature Over the last 400,000 years the earth's climate has been unstable, with very significant temperature changes going from a warm climate to an ice age in as rapidly as a few decades. The changes in climate have matched changes in CO2
20th century Data from ice layers, corals & trees rings show 1000 years of temperature in the N. hemisphere. The 20th century's 1oF warming stands out.
450,000 year record of carbon dioxide (CO2) levels in the earth's atmosphere compiled from analyzing bubbles of fossilized air trapped in ice cores. The last 100-150 years of the 20th Century show a significant rise in CO2
Scenarios of Sea Level Rise Using the IS92 emission scenarios, projected global mean sea level increases relative to 1990 were calculated up to 2100. Taking into account the ranges in the estimate of climate sensitivity and ice melt parameters, and the full set of IS92 emission scenarios, the models project an increase in global mean sea level of between 13 and 94 cms between 2000-2100.
Washington New York The East Coast – after 5 meter rise in sea level
Washington Philadelphia New York N.E USA coast – after 50 meter rise in sea level
New Orleans Bahamas Florida, covered after 50 meter rise in sea level Miami