Is global warming just a natural cycle?


The question posed in the headline above goes to one of the more common claims made by global-warming skeptics.

Those claims are addressed HERE.

An excerpt:

A common misunderstanding of the climate system characterizes it like a pendulum. The planet will warm up to “cancel out” a previous period of cooling, spurred by some internal equilibrium. This view of the climate is incorrect. Internal variability will move energy between the ocean and the atmosphere, causing short-term warming and cooling of the surface in events such as El Nino and La Nina, and longer-term changes when similar cycles operate on decadal scales. However, internal forces do not cause climate change. Appreciable changes in climate are the result of changes in the energy balance of the Earth, which requires “external” forcings, such as changes in solar output, albedo, and atmospheric greenhouse gases. These forcings can be cyclical, as they are in the ice ages, but they can come in different shapes entirely.

For this reason, “it’s just a natural cycle” is a bit of a cop-out argument. The Earth doesn’t warm up because it feels like it. It warms up because something forces it to. Scientists keep track of natural forcings, but the observed warming of the planet over the second half of the 20th century can only be explained by adding in anthropogenic radiative forcings, namely increases in greenhouse gases such as carbon dioxide. 

Of course, it’s always possible that some natural cycle exists, unknown to scientists and their instruments, that is currently causing the planet to warm. There’s always a chance that we could be totally wrong. This omnipresent fact of science is called irreducible uncertainty, because it can never be entirely eliminated. However, it’s very unlikely that such a cycle exists.

UPDATE: The National Climatic Data Center SAYS the year just ended tied 2005 as the warmest on record.

The center also says that nine of the 10 warmest years on record have occurred since 2000. The exception was 1998, which is the third warmest year on record going back to 1880.

Ah, but the global-warming deniers want you to think that the Earth has been cooling of late.



  1. john.wilson

    Peanut the new Lafayette Ronald Hubbard

  2. john.wilson

    Pat, you still trying to figure out Ip’s? Lot of ways to spoof an ip address.

  3. john: Butt out! If I need your assistance, I’ll ask for it.

  4. john.wilson


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