There are a lot of uncertainties in climate science. But that does not mean it is fundamentally wrong.
20 March 2010
- People often assume that data is simple and graspable and trustworthy while theory is complex and slippery.
- The reverse is true in climate change--Constructing a set of data that tells you about the temperature of the earth over time is much harder than putting together its basic theoretical story of how temperature should be changing--given what else is known about the universe in general.
Absorb and Reflect
- Thermodynamics - for a planet at a constant temperature, the amount of energy absorbed as sunlight and the amount emitted back to space in the longer wavelengths of the infra-red must be the same.
- The discrepancy is due to greenhouse gases in the atmosphere which absorbs and re-emit infra-red radiation and thus keep the lower atmosphere, and the surface warm
- Adding to those greenhouse gases in the atmosphere makes it harder still for the energy to get out.
- Carbon Dioxide is a greenhouse gas.
- Human activity is putting more greenhouse gases into the atmosphere than natural process can remove.
- CO2 has risen from 316ppm in 1959 to 387ppm in 2009.
- Analysis of carbon isotopes shows that the CO2 from industry accounts for most of the build up in the atmosphere.
- The oceans can absorb heat and store it which means that the atmosphere warms more slowly than level of greenhouse gases expect.
- There are three records of land-surface temperature put together from thermometer readings in common use by climatologist and they all show warming and is widely accepted in academia.
- They also think the effects of urbanization have confused the data because towns, which are sources of heat have grown up near weather stations.
Simplify and Amplify
- The warming caused by an increase in CO2 can be calculated in the lab and shows that doubling CO2 leads to a 1C rate of warming which is known as climate sensitivity.
- Several types of feedback can amplify the affect such as water vapor.
- As CO2 warms the air it also moistens it, and water vapor, a greenhouse gas, will provide further warming.
- When water vapor condenses into cloud droplets, it gives up energy and warms the surrounding air.
- Where greenhouse warming is wetting the atmosphere, the lower part of the atmosphere should warm at a greater rate than the surface, most notably in the tropics. At the same time, in an effect that does not depend on water vapor, an increase in CO2 will cause the upper stratosphere to cool. This pattern of warming below and heating above is expected from greenhouse warming.
- Clouds from water vapor provide some uncertainty; they are composed of water droplets that have the greenhouse effect, but also reflect the sunlight back into space stopping from it being absorbed by the earth.
- Clouds can cool and warm.
