My Turn — Gran: Cold winter doesn’t contradict science of climate change

  • GRAN

Friday, May 04, 2018

The winter of 2017/2018 set new cold weather records across the U.S.’s Midwest and East. The cold winter weather gives climate change deniers the opportunity to falsely contradict and ridicule the reality of global warming. President Trump, in December tweeted “In the East, it could be the COLDEST New Year’s Eve on record. Perhaps we could use a little bit of that good old Global Warming that our Country, but not other countries, was going to pay TRILLIONS OF DOLLARS to protect against. Bundle up!”

But these smug comments reveal profound ignorance of what is actually going on. The cold blasts of Arctic air Trump was suggesting as proof that Earth is not warming, is actually the result of rapid warming of the Arctic Ocean. This warming disrupts the polar jet stream, allowing cold Arctic air to plunge deep into the Midwest, Northeast and Southeast. As the Arctic continues to warm these excursions of cold air will diminish.

The last (2014) National Climate Assessment section for the Northeast includes the following key messages:

“Heat waves, coastal flooding, and river flooding will pose a growing challenge to the region’s environmental, social, and economic systems. This will increase the vulnerability of the region’s residents, especially its most disadvantaged populations.”

“Infrastructure will be increasingly compromised by climate-related hazards, including sea level rise, coastal flooding, and intense precipitation events.”

“Agriculture, fisheries, and ecosystems will be increasingly compromised over the next century by climate change impacts. Farmers can explore new crop options, but these adaptations are not cost — or risk-free. Moreover, adaptive capacity, which varies throughout the region, could be overwhelmed by a changing climate.”

While a majority of states and a rapidly growing number of municipalities have begun to incorporate the risk of climate change into their planning activities, implementation of adaptation measures is still at early stages.

Over the next two or three decades the average summer temperature in the Northeast could increase 3 degrees Fahrenheit, and by the last decades of the century to over 13 degrees. This may not sound like much, but it is more than the temperature difference between the last glacial period, with a mile of ice overhead, and today.

According to the Union of Concerned Scientists (UCS), by later this century Massachusetts could have a climate equivalent to that of South Carolina today. Summer heat waves and longer periods of drought will become more frequent. Heavier downpours, when it does rain, will produce more flooding. The number of days per year over 90 degrees in Boston will go from averaging under 10, for the period 1961 to 1990, to over 60 toward the end of the century.

According to UCS, winters will be shorter with warmer temperatures bringing earlier snow melt. Records from the mid-20th century through 2000 show that the number of snow-covered days across the Northeast has already decreased significantly. Less precipitation has fallen as snow and warmer temperatures have melted the snow more quickly. At the same time, the snow on the ground has become wetter and heavier on average. Winter precipitation in the future is likely to increase, however this is unlikely to mean more white winters but rather more winter rain.

The amount of possible precipitation depends on atmospheric temperature, with 4 percent more moisture in the atmosphere for every 1 degree Fahrenheit increase in temperature. The type of precipitation, however, depends on the surface temperature at the time. The heaviest snowfalls occur with surface temperatures between 28 and 32 degrees, with the amount of snowfall at 32 degrees at least double that at 14 degrees. With increasing temperatures by late this century Massachusetts could see little if any winter snow at all.

This decrease or total lack of snow will of course impact skiing, snowmobiling and other traditional winter sports in the Northeast. But many other industries will be impacted as well. Forests will transition from maple, beech and birch to oak and hickory, eventually ending the maple syrup industry. Heat stress on dairy cows and other livestock will reduce production and birth rates. Hotter, dryer summers will affect agricultural production.

According to the EPA, warmer temperatures are also increasing outbreaks of forests pests and pathogens. Growing deer populations have been degrading forest understories, while invasive plants like kudzu have been expanding their range and contributing to a loss of biodiversity in some ecosystems. Temperature changes also influence the timing of important ecological events, causing birds to migrate sooner and plants to bloom and leaf earlier.

We all know by now that these changes are primarily caused by our high carbon emissions, and due to carbon’s long-term atmospheric persistence, even rapid emissions reduction now will not prevent major climate change to come, but the sooner we act the better our chances of avoiding the worst outcomes.

William Gran, now retired, was an adjunct instructor at Greenfield Community College on global warming and climate change. He can be reached at whgran@gmail.com