Climate Change
Because the island of New Guinea has significant areas of flat lowland and montane highlands, with steep elevation and temperature gradients, it may be relatively susceptible to the effects of climate change. According to Woinarski (2010) a sea level rise of 1m will wash away most of New Guinea’s Lowland habitat. In comparison to the Lowlands, Buytaert (2011) believes that climate change will greatly decrease New Guinea’s total range of alpine regions, due to the sharp mountainous climate gradient, resulting in species adaptation, movement or local extinction.
Figure 1. Elevation Profile. Source: Denham 2008.
One area of study that has gained significant study, is the condition of New Guinea’s coral reefs. Over the past 100ka there have been 9 cycles of coral reef perturbation caused by climate change (Pandolfi 1996). Expanding on his 1996 study, Pandolfi et al (2006) notes four events of mass coral die-off of roughly 90%, during the past 12000 years. Gagan et al (2000) believe that New Guinea’s coral die-off events correlate with ENSO variations and levels of runoff from overland rivers. This view is supported by Parker et al (2008), who write, “climate change alters river deltas and sediment processes in New Guinea.” Generally, New Guinea Highlands have higher levels of precipitation, lower rates of evaporation, and more significant water regulation capacities than lowlands (Buytaert 2011). Glaciers, which contribute to hydrological regulation, on New Guinea, frequently live a precarious existence. From 1939 to 1962, glaciers on Puncak Tikoria fully melted (Puncak Jaya 2011). In comparison, Puncack Jaya has no permanent ice on its peak, but ice persists in sheltered slope glaciers (Puncak Jaya 2011).
More direct influence of climate change on human populations in New Guinea include
Figure 2. Alpine Regions of New Guinea. Source: Buytaert 2011.
changes in Mosquito range, suitability of Highland land for agriculture and alterations to local fire regimes. In New Guinea, average temperatures higher than 14 degrees Celsius inhibit mosquito larvae from developing (Githeko 2009). As a result, malaria is non-existent above elevations of 1800m (Githeko 2009). In addition, malaria is rare in Highland elevations, as well. In 2003 there were over 1.7 Million cases of malaria in New Guinea, with the vast majority of diagnoses occurring in Lowland areas. During the same year, there were only 4986 cases of malaria in the Highlands, where over 40% of New Guinea’s population lives. In 2000, there were 638 cases of malaria in the Highlands (Githeko 2009). Githeko (2009) writes that the burden of malaria is likely to increase with climate change, as malarial events in the highlands, now rare, are likely to increase.
Figure 3. Puncak Jaya. Source: mount-kinabalu-borneo.com
In terms of agriculture, climate change may increase the total extent of highland areas, at the loss of sub-alpine regions (Buytaert 2011). Hope (1993) writes that Highland vegetation is sensitive to climate change and has frequently shifted vegetation patterns over short time periods. This may shift agricultural Highland gardens to higher elevations, if New Guinea farmers are able to migrate to higher elevations. Historically, climate perturbations have provoked natural incidents of forest fire (Haberle 2000). While Humans have occupied sub-alpine elevations for 31ka, these regions have only been occupied by low-density hunter-gatherers (Fairbairn et al 2006). When humans first began to alter Highland environments for favorable conditions, forest ecosystems collapse in the mid-Holocene with the adoption of land management practices (Haberle 2007). It is possible that climate change may push montane agriculturalists to higher elevations that have not experienced comparable levels of land management.
Take away points for climate change in New Guinea are that tropical mountain ecosystem are vulnerable to climatic warming because of steep elevation-based temperature gradients. Reef ecosystems off New Guinea’s coast are dependent on highland and alpine hydrology, due to river flow and sedimentation. As a result, hydrology changes due to climate change place reef ecosystems at risk and past mass die offs due to climate change may add support to this threat. Finally, climate change in New Guinea may threaten human living conditions, specifically relating to malarial burden.