If the Climate is Warming – Why is it So Cold?

by Mary Campbell, Extension Director and Urban Sustainability Agent

Ice Hanging from LeavesA question that is often asked – “Why do we have record setting cold weather in the middle of global warming? “ The term “global warming” is often confusing and that is why the term “climate change” is beginning to be used more frequently. The term global warming refers to the specific increase in global temperatures caused by the increase in greenhouse gas emissions from human activities. Globally, surface air temperatures increased by approximately 1oF during the 20th century. Some regions of the world have experienced much greater warming; Alaska and the Antarctic Peninsula, for example, have warmed by approximately 4oF over the same time period. Other regions of the world, such as the oceans of the Southern Hemisphere and the interior of Antarctica, have not experienced warming. Very small changes in temperature can have big impacts on sensitive ecosystems.

Climate Change refers to changes in the climate over decades – not just seasonal changes or local weather patterns. So the local conditions at any particular time are really weather patterns and should not be confused with climate change or global warming. There may be a wetter spring or a warmer or cooler winter one year, but climate change refers to sustained changes taking place over very long periods. Some of the sustained changes to the environment that scientists are seeing are: greater frequency of droughts and flood; melting of polar ice caps and sea level rise due to warmer ocean temperatures; changes in plants and wildlife migration patterns; and pest and disease spread.

The frequency of more severe weather patterns supports what scientists predicted as one of the impacts of climate change. Due to warmer air temperatures holding larger amounts of water vapor – it can create droughts in some areas and then floods in other areas – or more snow and sleet. Some of the records for severe weather – hottest days on record, major floods, sustained droughts – have been observed in the past decade. The observed warming over the 20th century was accompanied by a 10% increase in precipitation in the Northern Hemisphere and an increase in global sea-level of 4-8 inches.

So the next time the weatherman reports unusually cold weather – we may want to think about that. On the short term it is simply local weather conditions, but added to the long-term data that scientists study to understand overall climate, it will be another piece in the puzzle.

Please join me for a Webinar on the Basics of Climate Change to hear about why scientists are concerned and some of the common myths

References:

Extreme Events – US Environmental Protection Agency
Science FAQs – Pew Center on Global Climate Change