Warming manmade problem
I know enough about climate science to know when supposed-experts are trying to deny the seriousness of manmade global warming — exactly what one writer attempted in a July 18 letter in the Duluth News Tribune.
First he mentions that in 1936, St. Paul endured three weeks of extremely warm temperatures at a time when human carbon dioxide emissions were not nearly as high as now and therefore, disproves carbon dioxide caused warming during the last seven decades. But these changes were influenced by other natural phenomenon, including the Dust Bowl from 1931 to 1939. And, although the letter writer may be correct that St. Paul endured unusually hot temperatures in (1936) — 1934 is actually one of the hottest years on record in the U.S., but now ranks only fourth —behind 2012, 2006 and 1998. And, since global warming is a worldwide phenomenon 1934 barely qualified for the top 50 warmest years worldwide.
Scientists have long known that regional temperatures will continue varying, along with changing from year to year, but globally we are still part of a long-term trend of rising temperatures even though other natural factors can, and will, continue to affect climate.
The Medieval Warming period from 800 to 1400 A.D. should include historic global reality i.e. although temperatures may have been greater in the North Atlantic, evidence indicates that they were much cooler in the tropical Pacific, and on average, were similar to the early and mid-20th century. And the National Academy of Sciences found it plausible (in 2006) that current temperatures are actually higher today than in the Medieval period. Scientists know that between 800 and 1400 A.D., solar radiation was higher, along with less volcanic activity—both of which can cause warming.
During the Little Ice age, between the 16th and 19th centuries, the Earth is known to have had less solar activity and high volcanic activity — both of which can cause cooling. So as scientists have long said, natural variations do affect climate. However, natural influences don’t account for the rapidly increasing rate of warming we are seeing today. If one looks at the larger picture and examines the technology used to determine these facts, one will find they are all based on empirical knowledge and logical deduction. However, the letter writer’s examples have likely been chosen to deliberately deceive.