Climate Change What Do Climate Scientists Say?

1. Climate ChangeWhat Do Climate Scientists Say?

2. Is Climate Change Fact or Fiction? • The overwhelming majority of climate change scientists say that the globe is warming and that they are 90% certain that people are responsible. • So why has the media often portrayed climate change as a controversial theory? -- Failure to distinguish science from politics (portraying the issue as political requires a “balanced treatment of both sides of the issue”) • Climate change deniers have primarily come from 3 groups: • 1. energy companies • 2. political conservatives who do not like government regulation • 3. a very small minority of scientists

3. But Didn’t We Have Climate Changes Before Industrialization? • Yes: preindustrial climate change was caused by periodic changes in sunlight due to slight changes in the earth’s orbit and the tilt of the earth’s axis, which bring fluctuations in the amount of sunlight earth receives. • During periods of more sunlight, the oceans release CO2 into the air (like a Pepsi bubbling when warmed), which traps more warm air in the atmosphere (which is why it is called a “greenhouse gas”) causing further warming and more bubbling. • These normal fluctuations over very long periods of time account for changes in CO2 concentrations of 180 ppm-300 ppm (parts per million) in our atmosphere.

4. So How Is Post-Industrial Climate Change Different? • Since the Industrial Revolution (which began around 200 years ago), people started burning fossil fuels, such as coal, and later, petroleum, which created a new source of carbon dioxide being released into the air. • During this period, the concentration of CO2 in the air rose from 280 ppm to 384 ppm – much higher than during previous fluctuations. • Scientists can date carbon, and have determined that this large increase in CO2 has occurred primarily in the past 50 years (with our vast increase in use of fossil fuels). They have concluded with 90% certainty that we are causing global warming through greenhouse gas emissions.

5. So Why Does That Matter? Unprecedented levels of CO2 in the atmosphere will lead to unprecedented global warming. The International Panel on Climate Change (IPCC), which includes some 2000 climate scientists from around the world, has concluded that if we continue on our current path, CO2 concentrations will reach 550 ppm by mid-century, which will in turn raise average global temperatures 3 degrees centigrade. They also concluded that a 2-2.5 degrees centigrade increase could lead to intolerable impacts, such as a significant rise in sea level, flooding, more violent weather patterns, widespread drought, spread of disease, and massive loss of species.

6. Examples of How a Few Degrees Warming Could Create Serious Problems? • Melting ice at the poles would raise the sea level worldwide, causing coastal flooding. • Evaporation of moisture from soil would increase, creating drought in drier areas and putting more moisture into the air, which would create more torrential rains in areas that already get a lot of rain, causing more flooding. • Insects that cannot survive low temperatures at higher elevations would encroach upon high elevation forests, killing trees and making them vulnerable to lighting strikes, causing more widespread forest fires. • Changes in the ocean temperatures would change the path of ocean currents and create more severe hurricanes (which increase with intensity over warmer water). • More CO2 in the atmosphere creates higher concentrations of carbonic acid in our oceans, which dissolves corals, and higher water temperatures also kill corals.

7. How Much More CO2 Is Tolerable? We don’t know for sure because scientists are uncertain about how particular impacts of global warming will affect others. The interaction among effects may accelerate warming. Example 1: The tundra in the Arctic and Siberia contains large amounts of carbon, which, if released through thawing, will form methane gas, which is a much more powerful source of atmospheric warming than CO2. This release of methane could significantly accelerate global warming. Example 2: As the snow pack in Montana shrinks, less water flows down major rivers, such as the Missouri and Columbia, in the summertime. Farmers are forced to run pumps more to irrigate fields, and we lose some of our hydroelectric power from our dams (a clean source of electricity). This forces us to burn more fossil fuel (coal) to make more electricity, releasing more CO2 into the air.

8. These Changes Seem to be Happening More Rapidly than Expected A decade ago, scientists were predicting that the polar ice cap could melt sometime between 2040-2070 because of climate change. Now, they are predicting that this could occur in a few short years. In the summer of 2007, ships were able to pass through parts of this frozen ice cap for the first time.

9. Metaphors to Remember We don’t really know whether CO2 levels of 450 ppm or 550 ppm will be disastrous. Perhaps the tiny minority of climate scientists who think we have little to be concerned about will turn out to be right. However, taking the advice of the climate-change deniers is like doing the following: • You hear from 98 doctors that your child must take medicine or die. Two doctors disagree, so you decide not to give the child medicine. • You are driving fast in a car with bad brakes through a dense fog. You know there is a cliff up ahead somewhere, but you aren’t sure exactly where it is, so you decide to just keep driving fast.