The Fallout of Global Warming

Today, we return to the commentary about climate that we started last December. There (archives, Dec. 2010) we noted unusual precipitation in the continental US just before Christmas. To complete the picture globally, we have only to reflect upon the news and weather reported from all over the world during the past year. Beginning with lowland flooding in the British Isles and across Europe during the fall and winter of 2009, torrential rains in the Spring of 2010 in China, followed by intensification of monsoons in Pakistan and southern Asia, an Austral summer of record-setting rains and flooding in Northeastern Australia, and massive floods in Brazil, we have witnessed an entirely unprecedented increase in severity and frequency of precipitation events world-wide.


Mountain regions, too, are subject to flooding, especially where runoff is accelerated by clear-cutting of forests. Overall, rivers and streams world-wide should be expected to carry heavier silt loads as a consequence of increased precipitation throughout both hemispheres. Some have even speculated that this year's Australian runoff sediments might even endanger marine life on the Great Barrier Reef!

Not only do we have to contend with increased flood events, but, at the other end of the spectrum, we are experiencing regional droughts and heat waves that are crowding the extremes recorded in the historical past. The links above, and internet sites linking to them, are rife with accusations as to who, or what, is responsible for what we are seeing.

All politics and finger-pointing aside, let's look at some basic physics and statistics to see if we can understand what is happening.

Water leaving the sink, tub, or moving downriver will self-organize the fluid flow to provide maximum relief from the gradient of stress imposed by the viscosity of the water and the pull of gravity. Eddies result. In marine environments, differences of salinity or temperature may drive the flow, a Gulf Stream or gyre will transport huge volumes of water into the global circulation, the great oceanic conveyors.

In the atmosphere, temperature and pressure provide the gradients. Cyclonic rotation of the air mass is the visible outcome, tornados over land, waterspouts or hurricanes over water. The vigor of the emergent circulation will be in direct proportion to the magnitude of the gradients.

What can statistics reveal about the consequences of increases in temperatures, even small ones? If we increase the upper limit of observed temperatures, the lower limit has not changed, so the range has increased, and with it, the variation in storm expression.

Trout and salmon fishermen, the world over, are going to have to expect that anadromous runs of fish will be impacted by these changes in climate. Do we have to rely on politicians, industrialists or climatologists to explain this to us? We can count the events and see the devastation for ourselves. The fish have spoken volumes already.