In the first 6 weeks of 2014, the world spawned some of the most severe weather in hundreds of years, including record snowfall in the Midwest and Great Lakes, record cold in the US northeast, ice storms in the southeast, record drought in the southwest, record flooding and windstorms in the UK, unseasonal warming in Scandinavia and Russia, record snowfall in the southern Alps, record flooding in Italy, and record heatwaves and wildfires in Australia, Argentina, and Brazil.
Despite the record snow, ice, and freezing temperatures in some areas, the world continued its long term upward warming trend. NOAA reported that 2013 was tied with 2003 as the warmest year on record. What’s going on?
According to a paper presented this month at a meeting of the American Assn. for the Advancement of Science in Chicago, a weakening jet stream caused by Arctic warming is a possible cause. The polar jet stream is a high-altitude air current with wind speeds of 100 to 120 mph (160 to 200kph) that acts as a weather conveyor belt. When Arctic temperatures stay cold, the jet stream blows stronger and tends to stay in place, bringing normal winter weather to North America, Europe, and Asia.
In January, 2014, the air temperature over the Arctic Ocean was 2 to 4˚C (4 to 7˚ F) higher than average, and 7 to 8˚C (13 to 14˚ F) higher than average over Greenland and Alaska. As the Arctic warms, the jet stream weakens and begins sinking south of its polar route. At the same time, Arctic sea ice is melting at a record rate, exposing more ocean to the rays of the sun. The warmer ocean water in turn accelerates Arctic warming. More rapid evaporation pumps extra moisture into the atmosphere.
A sinking jet stream carries the moisture-laden high-altitude cold Arctic air south into the Midwest and southeast, and across the Atlantic to Europe. While southern Europe is experiencing record rains and snowfall, northern Europe, normally very cold in January and February, is basking in abnormally warm temperatures. With the glaciers and polar ice caps melting at a record rate, sea ice contracting, and oceans warming, it seems obvious that global warming is here, and to some extent driving the world’s current radical weather patterns. The weather will become more radical and storms more intense as the earth gets warmer.
But what is driving global warming? The UN’s International Panel for Climate Change (IPCC) has concluded from all available scientific evidence that it is 95% likely that most of the rise in global temperature since the middle of the 20th Century is due to emissions of greenhouse gases, deforestation, and other human activities.
If greenhouse emissions continue at their present rate the IPCC computer models predict our planet will warm 5˚C (9˚ F) by 2100, and by 10˚C (18˚F) during the following century. The earth is now warmer than it has been since the end of the last ice age 11,300 years ago. If we don’t drastically reduce our carbon-based emissions and start relying more on alternative fuels, are we headed for another ice age? Or another age hot enough for dinosaurs?