Climate change is very real and it has been going on in cycles since the planet formed.

Three Orbital cycles that affect climate:

• Orbital Eccentricity: 100,000 year Cycle
  
• Orbital Tilt: 42,000 year cycle
  
• Orbital Wobble: 25,800 year cycle
  

Orbital Eccentricity: the earth's orbit around the sun forms an ellipse. Every 100,000 years or so the ellipse "flops" into a pattern that changes solar exposure. This trend is working is way to a peak this century.

Orbital Tilt: The tilt of the equator varies between 21.6 to 24.5 degrees. This cycle is right in the middle.

Orbital Wobble: The earths axis of rotation "wobbles" in a circular pattern over the period of the cycle which is approaching maximum.

Catastrophic climate change

Over the course of the planets geological record, it is apparent that there have been a number of catastrophic events that have caused either short or long term variations in the climate. These events are:

• Comet Impacts
  
• Asteroid Impacts
  
• Super-Volcanic Eruption/Out-gassing
  

Comet Impacts: have taken place with regularity over geological time. One theory of the origin of our atmosphere is that water and gases locked up in comets seeded our atmosphere. Other theories are that comets delived the seeds of life to our planet in the very distant past. While they have had beneficial side effects in the past, comets are unbelievably destructive. Comets are gas and ice and have a nasty tendency to explode when heated by the atmosphere creating a huge fireball airburst of thousands of megatons of energy: enough energy to completely destroy a continent and wreak the climate for decades in a condition not unlike nuclear winter. Are you ready for the good part? This has happened several times in our planets history: most recently the Tunguska comet impact of 1908.

Asteroid Impacts: the bad news of comet impacts is even worse for asteroids: they are solid and survive the atmosphere. They strike the surface and vaporize rock/soil and hurl molten material for hundreds of miles in all directions. The fireball itself is very much like a huge nuclear explosion which puts tremendous amounts of super-heated ash and dust into the upper atmosphere. This causes a decades long "nuclear winter" which changes the entire ecosystems. It is believed that this is what caused the mass extinctions that ended the Permian and Cretacous eras (AKA KT extinction).

Super-Volcanic Eruption/Out-gassing: from time to time there have been extremely massive volcanic eruptions and periods of volcanic hyper-activity that have been so violent and have released so much CO₂ and SO₄ that they have simply poisioned massive land areas. I'm not describing the eruption of a Mount St. Helens or even a Krakatau, which both influenced the global climate, but entire regions erupting at once. One of the great extinction events of the past was thought to have been caused when hundreds of volcanoes, rifts and magma flows formed Siberia.