Warming Speed Up
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Hi, I'm Dave Thurlow for the Mount Washington Observatory and on today's Weather Notebook, it's full steam ahead for global warming. Correspondent Robin White explains:

RW: Most scientists agree the world is warming and the cause is gases like carbon dioxide and water vapor - greenhouse gases - which are given off during fossil fuel burning. But even though fossil fuels have been used widely since the 1920's the globe didn't warm at all from the 1940's to the 1970's. The reason, says Phil Jones of the Climatic Research Unit of Norwich University, was sulphate aerosols.

PJ: These are sulfate particles that enter the atmsophere as a result of fossil fuel burning and they cause what you might think of as acid rain..and they have an inverse effect on the global temperatures.

RW: Sulfate aerosols were actually cooling the globe and masking the effect of greenhouse gases which make the world hotter. In the 1970s, regulations to stop acid rain reduced the amount of sulphate aerosols and temperatures began to rise. Jones says global temperatures have risen and fallen before, usually over long periods of time. When earth experiences rapid fluctuations of temperature ñ that causes problems for us humans:

PJ: In the past when climate has changed it's often the dramatic rise in temperatures that have had the biggest influence on humans - it's the rate of rise .We're able to cope by making advances - new crops - we can change the way we use water but we can do it relatively slowly we can't do it quickly...

RW: Farmers can adapt within a few seasons, but building reservoirs takes long term planning. Jones says, we need to slow down the speed of climate change to give ourselves time to adapt.

Robin White is an independent producer from San Fransico. The Weather Notebook is underwritten by Subaru, the beauty of all wheel drive.