Arguments
Are we heading into a new Ice Age?
What the science says...
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Worry about global warming impacts in the next 100 years, not an ice age in over 10,000 years. |
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Climate Myth...
We're heading into an ice age
"One day you'll wake up - or you won't wake up, rather - buried beneath nine stories of snow. It's all part of a dependable, predictable cycle, a natural cycle that returns like clockwork every 11,500 years. And since the last ice age ended almost exactly 11,500 years ago…" (Ice Age Now)
According to ice cores from Antarctica, the past 400,000 years have been dominated by glacials, also known as ice ages, that last about 100,000. These glacials have been punctuated by interglacials, short warm periods which typically last 11,500 years. Figure 1 below shows how temperatures in Antarctica changed over this period. Because our current interglacial (the Holocene) has already lasted approximately 12,000 years, it has led some to claim that a new ice age is imminent. Is this a valid claim?
Figure 1: Temperature change at Vostok, Antarctica (Petit 2000). The timing of warmer interglacials is highlighted in green; our current interglacial, the Holocene, is the one on the far right of the graph.
To answer this question, it is necessary to understand what has caused the shifts between ice ages and interglacials during this period. The cycle appears to be a response to changes in the Earth’s orbit and tilt, which affect the amount of summer sunlight reaching the northern hemisphere. When this amount declines, the rate of summer melt declines and the ice sheets begin to grow. In turn, this increases the amount of sunlight reflected back into space, increasing (or amplifying) the cooling trend. Eventually a new ice age emerges and lasts for about 100,000 years.
So what are today’s conditions like? Changes in both the orbit and tilt of the Earth do indeed indicate that the Earth should be cooling. However, two reasons explain why an ice age is unlikely:
- These two factors, orbit and tilt, are weak and are not acting within the same timescale – they are out of phase by about 10,000 years. This means that their combined effect would probably be too weak to trigger an ice age. You have to go back 430,000 years to find an interglacial with similar conditions, and this interglacial lasted about 30,000 years.
- The warming effect from CO2 and other greenhouse gases is greater than the cooling effect expected from natural factors. Without human interference, the Earth’s orbit and tilt, a slight decline in solar output since the 1950s and volcanic activity would have led to global cooling. Yet global temperatures are definitely on the rise.
It can therefore be concluded that with CO2 concentrations set to continue to rise, a return to ice age conditions seems very unlikely. Instead, temperatures are increasing and this increase may come at a considerable cost with few or no benefits.
Basic rebuttal written by Anne-Marie Blackburn
Update August 2015:
Here is a related lecture-video from Denial101x - Making Sense of Climate Science Denial
Last updated on 7 August 2015 by MichaelK. View Archives
Argentina is colder than Antarctica. 8/3
Huge fish & other wildlife die-off from cold in Bolivia. 8/3
State of emergency due to cold for 2/3 of Peru. 7/27
6 country S. America cold snap kills 175+. 7/20
I'm just getting started. Give me some more time and I'll stretch that back some more where, if I recall correctly, you see widespread record cold happening in all of the places I mentioned. Amazing that colony of endangered penguins was hurt hard by a widespread cold snap in South Africa recently. Penguins, hurt by cold? Wow. Australia is the sketchy part of my claim however we'll see as I go through my archive. I do seem to recall some widespread record cold on its West and North coasts. Hmmm, come to think of it, on their northeast coasts as well. Hope to give that some substance shortly but, I do have a life you know. :~)
Strong winds, heavy snow and record cold across Tasmania. 9/17
South pole has record cold. 7/31
Much of New Zealand experiencing record cold. 6/2
Queensland, Australia towns get record cold. 5/22
Cold snap hits Argentina, Paragua, Uruguay & Bolivia. 7/18
Record low temperature in Brazil. 7/15
At least this one is a record for 82 year old Juana Benitez: Cold snap hits several South America countries. 7/10
Well, how about coldest SE Australia in some 60 years?: Unusual widespread cold in Australia. 6/30
Here's the story about S. Africa penguins though it doesn't mention any records being broken. Maybe it is a record that over half of the penguin chicks died from the cold this time. One island hardly qualifies as wide spread though: Cold rain kills %50+ endangered S. Africa penguin chicks. 6/15
There was some widespread crop damage from cold in S. Africa but it doesn't mention any records being broken: Severe cold & frost damages S. Africa crops. 7/15
Oh, don't get me going on the widespread cold in the northern hemisphere over the last couple of years. Notices of those far out weigh those for the southern hemisphere. Two years ago, my mom died due to complications in what I understand was Washington state's first ever state of emergency due to record cold and snow. I truly expect the cold and snow to be worse this year across the northern hemisphere and there are some long range predictions suggesting that too.