dr stephen holness & prof guy midgley springbok march 2012

Dr Stephen Holnesssholness@nmmu.ac.za

Expected Impacts of Climate Change on Biome

Stability in the Namakwa District:new biome envelope predictions & identification of areas supporting resilience

Dr Stephen Holness & Prof Guy Midgley

Springbok

March 2012

Components

• “Areas of biome stability”– Particular parts of the Namakwa District are at

higher risk from climate change induced impacts

• “Areas important for supporting ecosystem resilience to climate change impacts”– Intact ecosystems have the potential to reduce

climate change impacts through supporting ecosystem based adaptation

– Particular parts of the district are of particularly high value for supporting cc resilience

Technical process (1)

• Revised climate data from 15 GCMs were used to calculate anomalies between now and mid century

• Does not focus on a single model• Used the range of predicted outcomes from these

models to define three scenarios: – High risk scenarios with low rainfall and high

temperatures– a medium risk scenario– and low risk scenario with high rainfall and smallest

temperature

• Anomaly calculated and combined with current agro hydrology data

Technical Process (2)• MAXENT - widely used ecological modelling

and forecasting program (we will now extend this to other methods)

• Model of current biomes & test prediction ability• Develop biome maps for future high, medium

and low risk scenarios• Identify areas with high risk of biome envelope

change and areas which are likely to remain stable.

Can we predict biomes?

“Actual current” “Modelled current”

•MAXENT models of each biome

•Biome determined by strongest model outputs at each site

•86% accurate prediction – most missed blocks have a mixture or are on boundaries

Changes

Current BiomesCurrent Biomes

Low risk scenario

Medium Risk Scenario

High risk scenario

Consistently predicted areas in all scenarios

Areas of biome stability

But...need to use new data