Natural processes are rarely linear because the steering factors are both plentyful and complex. Physics professor and mathematician Ernest Zebrowski Jr. has expressed our dilemma in a scientific way in his book "Perils of a restless planet. Scientific perspectives on natural disasters":
The time factor is crucial when making forecasts. When it comes to natural processes there are so many factors involved, many of them unexperienced by living things today. Extraterrestrial factors such as the movement of planets are not everyday events, like night and day, ebb and flood. Like the mechanisms that cause water to boil at a specific temperature, some factors have implications. Springtide and spring flood are both possible to forecast — under certain circumstances they can trigger earthquakes and volcanic eruptions which can influence climate forecasts. The sun has 11-year cycles of dark spots that affect climate but we cannot say how many dark spots that will show up, nor where on the sun they will appear. This has a relation to solar mass ejections, causing auroras on Earth and telecom disturbances, because of high energy transfer/radiation. We cannot forecast when the the most disastrous volcanic eruptions will take place even within decades and centuries. But we can say that statisticaly it is possible, even probable, that we will get a volcanic VEI:7 eruption that could lower the global annual mean temperature for a decade and give poor harvests for years in a row, causing famine and historically migrations and civil wars.
In general it is impossible to make correct forecasts also when you have a thermometer. The thermometer was not invented until the mid-17th century, and had no precision until the time of Fahrenheit and Celsius in the early 1720s-40s. Without using thermometers, geochronologists, geochemists and palaeontologists have many other possibilities to find out, for instance, if winter was warm and spring early. For example squids living in the Cretaceous seas record the water temperature to a tenth of a degree Centigrade in the annual growth rings in their inner calcium carbonate skeleton. So we know the temperature variation of ocean water during the lifetime of squids tens of millions of years back in time.
Corals are also useful as proxies for the temperature of the sea water for more than 300 million years back in time. By entirely different methods, astronomers and palaeontologists have been able to calculate and find agreement on the number of days per year backwards in time. The earth had 419-421 days during the Silurian period but has slowed its speed of rotation since then to 365 days per year today. The number of days will continue to decrease, but slowly — you will not experience a year with 364 days.
Global change is the rule in Nature and it is the driving force behind evolution. Geology is the science of global change.
A key to an understanding of climate change in our time is an analysis of long unbroken records in as many climate zones and geographic areas as possible. My database includes an analysis of the river Nile's annual water balance recorded without any gaps during the 563 years 622-1284. This record shows all floods and droughts. The Nilometer was built for this purpose because the pharao in office taxed the Egyptian farmers fairly — high taxes in a flood year because the harvests were good, lower tax rates for dry years with poor harvests. We have less intelligent tax systems today.
It is already well known that epidemics in Egypt are correlated with this water balance and that there is a correlation with the El Niño-Southern Oscillation (ENSO) in the Pacific Ocean and with the North Atlantic Oscillation (NAO). Now it is possible to correlate the Nile events with the Balkans, Near-Middle East and even the South and East parts of Asia. Time has come to try dating all natural events more precisely than our practice until now.