In contrast to the claims of the Mann et al "Hockey Stick", practically all proxy records around the world show large scale multi-decadal and century-scale climatic variation.
As another example, here are some of the results from a study by Tyson, Holmgren et al (2000,2001) of Lake Naivasha in Kenya and a well documented stalagmite in a cave at Makapansgat, South Africa. The principle aim was to show a "teleconnection" between the two sites which are far apart, and show almost complete climatic anti-phase between each other.
The most interesting result is the imprint of the Medieval Warm Period and Little Ice Age in Africa. During the MWP, Lake Naivasha actually dried up for more than two centuries, and during the Little Ice Age, Lake Naivasha was much deeper, with the modern depth of the lake somewhere between these two extremes.
Here’s one of the diagrams to show the teleconnection between the two sites:
The study reports:
Depleted 18O values in the Makapansgat stalagmite record are associated with drier conditions and increased occurrence of deep, intense thunderstorms and hail; enrichment occurs with wetter conditions and persistent warm rainfall from middle-level stratiform clouds (Holmgren et al., 1999). Similarly in the ´13C record, humate-induced changes in colour and growth rate correspond to changes in vegetation cover and temperature that indicate, in general, that drier periods were cooler, whereas wetter times were warmer (Holmgren et al., 1999). In the past at Naivasha, during centuries-long droughts, when rainfall, runoff and lake levels were at their lowest, conditions were warmer and wetter at Makapansgat. The climate gradient towards more mesic conditions in subtropical southern Africa reversed from time to time and was most pronounced during the medieval warm period (900 1300 AD) and during the Little Ice Age (1300 1800 AD). A clear correspondence between moist conditions and periods of solar inactivity (theWolf, Sporer and Maunder Minima) has been observed in the Lake Naivasha region (Verschuren et al., 2000), with highest lake levels in the last 1100 years having been recorded during the Maunder Minimum. In the Makapansgat record exactly the opposite occurs, with coolest and driest conditions occurring during the Maunder Minimum (Tyson et al., 2000).
Once again, the natural variation of climate is shown in proxy records and closely follows variations in the solar cycle over the past 1000 years and more.
Update, checking a tourist site on Lake Naivasha, I found this:
Lake Naivasha is a beautiful freshwater lake, fringed by thick papyrus. The lake is almost 13kms across, but its waters are shallow with an average depth of five metres. Lake area varies greatly according to rainfall, with an average range between 114 and 991 sq kms. At the beginning of the 20th Century, Naivasha completely dried up and effectively disappeared. The resulting open land was farmed, until heavy rains a few years later caused the lake to return to existence, swallowing up the newly established estates.
So Lake Naivasha does have a tendency to dry up for short periods of time. What does stand out in the reconstruction is that during warm periods Naivasha dries up and during cold periods, the lake gets deeper as the local climate gets wetter. Naivasha does not have an outlet for its water, making the depth of the lake a key function of the wetness/dryness of the Kenyan climate.