Its been years since I visited Mt Kenya and it feels like a lifetime ago. I am feeling a sort of longing for the land of the giant lobelia and vertical bog of Mt Kenya and also for all the good times and wonderful adventures I had throughout Kenya. I miss it.
As you can see, its an incredibly beautiful environment, and glaciers so close to the equator are a very special case. These glaciers are projected to disappear by about 2030, so
- Is climate change largely responsible for the rapid retreat of the glaciers of Kenya?
- Are there other factors that might be more responsible for the loss of ice?
Well, the summary of the research (from our research group and a lot of earlier research by Stefan Hastenrath and his colleagues) shows that climate change is impacting the glaciers and, in the case of Mt Kenya, this is likely to be due to both warming and drying of conditions at the peak of Mt Kenya, such that the glaciers are melting faster and at the same time receiving less snow.
The drying of Mt Kenya is a signal found across East Africa – at the mountains like Mt Kenya and Kilimanjaro and in the lowlands. Precipitation amounts become more variable and generally less, and wet seasons become shorter. The drying is caused by change in sea surface temperature patterns over the Indian Ocean that control the moisture transport towards East Africa. This change in sea surface pattern was found to be a consequence of global warming.
More importantly than its direct influence on ice melt, the warming signal on Mt Kenya leads to a higher proportion of rainfall instead of snowfall. This means a lack of mass input to the glacier and a decrease in albedo, which causes a higher absorption of solar radiation and thus increased melt.
Research findings suggest that the glaciers on Mt Kenya formed under climate conditions that must have differed substantially to those of recent decades, and as such the glaciers will not survive. Indeed the modern day conditions at the summit indicate temperatures only just below freezing, so in a general sense, this location is not currently very conducive to glacier formation or survival.
The especially rapid rate of recent retreat may also be partly a feedback caused by glacier shrinkage thus far leaving only very small ice bodies on Mt Kenya. Larger glaciers can form their own cooler microclimate, which reduces ice melting, and also a large glacier is also less vulnerable to ice melt due to heat emitted from the surrounding exposed rocks when they are warmed by the sun, as the glacier margin is small relative to its total volume. Small glaciers do not create a very strong microclimate and the glacier margins are large compared to their total volume so melting at the glacier edges can play an increasingly important part of glacier melt as the glacier shrinks.
The key publications from our research group on changes of Lewis glacier are:
- Prinz R., Heller A., Ladner M., Nicholson L. and Kaser G. (2018) Mapping the loss of Mt. Kenya’s glaciers: an example of the challenges of satellite monitoring of very small glaciers, Geosciences, 8(5), 174, https://doi.org/10.3390/geosciences8050174
- Prinz, R., Nicholson,L. and Kaser, G. (2012) Variations of the Lewis Glacier, Mount Kenya, 2004-2012. Erdkunde, 66 (3), 255-22.
- Prinz, R., Fischer, A., Nicholson, L., Kaser, G. (2011) Seventy-six years of mean mass balance rates derived from recent and re-evaluated ice volume measurements on tropical Lewis Glacier, Mount Kenya. Geophysical Research Letters, 38, L20502, doi:10.1029/2011GL049208.
The key publication from our research group on the climate control is:
- Prinz, R., Nicholson, L.I., Mölg, T., Gurgiser, W., and Kaser, G. (2016) Climatic controls and climate proxy potential of Lewis Glacier, Mt. Kenya, The Cryosphere, 10, 133-148.
I also have several other relevant blog posts on this topic (search for ‘Lewis Glacier’)