Climate Crisis Comments (Part 7)

Written by admin on 09 September 2011

Climate Change Myth #012:
“Global temperatures change quite a bit as the planet goes into and out of ice ages, what we are currently seeing is normal.”

Temperature increase rates exceed normal post ice age warming

True enough there have been 7 ice age cycles in the last 650,000 years, with the last one ending a mere 7000 years ago, so the planet is perhaps due to be in a warming phase. However, the IPCC says the rate at which the planet is currently warming is faster than in the last 1300 years. The cause behind the rate increase is thought to be greenhouse gases and CO2, which is trapping heat in the atmosphere, and not due to natural causes such as variations in the earth’s orbit.

In fact greenhouse gases should have caused even more warming than has been observed, but was countered by global dimming and the cooling effects of volcanic and human-caused aerosols. In addition though the 2000s the planet also experienced a resulting in an unusually deep solar minimum in 2007-2009.

As far as global temperature rises associated with previous ice age cycles, what has been observed is that the average Northern Hemisphere temperatures during the second half of the 20th century were very likely higher than during any other 50-year period in the last 500 years and likely the highest in at least the past 1300 years (including both the Medieval Warm Period and the Little Ice Age).

The primary variable that’s changed is the increase in human population and their activities which add 30 billion tons of CO2 to atmosphere each year. In addition to other greenhouse gases such as methane, which is 25 times more potent than C02, have doubled since the start of the Industrial Revolution in the 1800s, with half of that amount coming from agriculture, landfills and coal mining.