First, the world climate as the best scientists see it:
1. The climate has varied from warm periods called interglacials to cold periods know as glacials for at least three million years. Data shows this well.
2. These natural periodic variations, called the Milankovitch cycle, are related to variation in the tilt of the earth’s axis and have a period of about 60,000-100,000 years. That is, 30,000-50,000 years of warmth followed by the same period of cold. Data like 800,000 year old ice cores show this. We’re about 30,000 years into the current interglacial.
Then, the world climate as the best scientists foresee it:
3. Key questions that are difficult to identify due to sparse data are: how rapid is the changeover from cold to warm and vice versa? And why are there significant variations during an interglacial? There are some observations:
4. Interglacials prior to about 400,000 years ago, which were generally cooler as compared to those occurring later, were characterized by lower atmospheric carbon dioxide levels.
5. The maximum sea level during the previous interglacial was several meters higher than that today, and has been linked to melting of the Greenland and Antarctic ice sheets.
6. This scenario is similar to that predicted to occur during the coming centuries, as atmospheric CO2 concentrations peak. A better handle on what controlled variations in past interglacials may hold the key to predicting how the interglacial that we are living in will respond to the impact of humans.
Nature Geoscience, 2009, 2:751-755.
So maybe we should invest a few million in finding this out? Just a small fraction of a wall street CEO or Big Oil exec’s salary; or a few hours of a middle east war.
The Obama administration has supported this a bit, but the absense of money for research of the past eight years leaves a big hole.