"Media and scientists blame human activity, but a 120-year-old natural climate shift is the cause."

At issue is whether these apparent climate shifts are driven by internal or external forces.

First, they establish the exact age and duration of these climate shifts.

The global climate shifts have started to wreak havoc across the world.

Volcanism plays a large role in climate shifts, both locally and globally.

Civilization on the Earth was destroyed by a permanent abnormal climate shift.

So when we see changes in plant life from one of these middens to the next, it doesn't always indicate a climate shift.

The climate shift could make western areas such as Puget Sound more ideal for wine production.

Any substantial climate shift is likely to pose enormous, though probably surmountable, challenges.

Scientists don't know what causes climate shifts; we only understand governing physical principles.