The Earth is in a period of rapid warming. 2016 was the warmest on record. According to NASA, 2017 was the second warmest.

The planet’s average surface temperature has risen about 2 degrees Fahrenheit (slightly more than 1 degree Celsius) since the late 19th century according to NASA and NOAA.

The warming of the planet is confirmed by international organizations such as the Met Office of England, the Potsdam Institute of Germany, and the Japanese Meteorological Society.

Further evidence of a warming planet is confirmed by several changes in the Earth’s climate. For example, glaciers are melting, sea levels are rising, the oceans are warming, arctic sea ice is disappearing, the land and sea surface is warming, snow cover is declining, wildlife and plant life are moving north. Each of these indicators are supported by multiple data sets.

The warming is not even across the planet. The Arctic is warming twice as fast as the rest of the planet. The air over land is warming faster than air over the oceans. Nights are warming faster than days. Winters are warming faster than summers. Scientists have cause-effect evidence of why this is happening. In fact all of these effects now being observed were predicted by the cause-effect climate model published in the early 1980s.

This amount the planet is warming may not seem like a lot considering the variations in temperature we experience from day to day and season to season. But the average temperature of the Earth has been surprisingly constant over the last 10,000 years. This constancy has allowed for the emergence of human civilization.

A small change in average temperature can cause significant changes in climate. For example, the Earth’s average temperature during the last ice age, when huge ice sheets covered much of North America, was only about 10 to 15 degrees Fahrenheit colder than it is now.

With strong economic growth and no efforts to curb greenhouse gas emissions, the rate of warming will remain strong or even increase. Under these conditions the temperature increase is estimated to be 8.5 degrees Fahrenheit by the year 2100, according to the Interagency Panel on Climate Change and the Environmental Protection Agency.

In addition to the amount of warming, the speed of warming is also a concern. Rapid warming makes it difficult for life on Earth to adapt. It took thousands of years for the Earth to move out of the ice age. By comparison, the projected 8.5 degree Fahrenheit increase by the year 2100 described above will have occurred in only 200 years.

Don Hofstrand is a retired agricultural economist from Iowa State University Extension. During the last few years of his work life, he focused on renewable energy and climate change. He and his wife live in Mason City.

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