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Are 70% of Species Really Endangered by Climate Change?. Craig Loehle NCASI ICCC Las Vegas. THE PROBLEM. Claim: Rapid warming will cause climate zones to shift too fast Result: Risk of mass extinctions State plans for massive migration corridors (e.g., WI)
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Are 70% of Species Really Endangered by Climate Change? Craig LoehleNCASI ICCC Las Vegas
THE PROBLEM • Claim: Rapid warming will cause climate zones to shift too fast • Result: • Risk of mass extinctions • State plans for massive migration corridors(e.g., WI) • Using climate change to justify listing species as endangered
THE BASIS • Climate model projects future climate • Regional models downscale output • Bioclimate envelope models developed • Compare current and forecast species range • Change too rapid for migration • Predict 20-70% of species at risk
CLIMATE MODEL ISSUES • Climate models differ from each other • All models are running hot • The hottest models (6 deg warming) are often used for these exercises (increases impact)
Assumption underlying extinction risk claims is that species bioclimate zones will shift in the next few decades. In the cross-hatched zones, the species will perish. If there is no overlap, extinction will occur. new range dieback zone old range
BUT TREES CAN TOLERATE HEAT • Northern trees are there because of frost tolerance that trades off against growth rate • ALL Canadian species grow in botanical gardens in Australia • Lethal temperature for tropical & northern plants is the same (45 degC)
Example range of boreal species (Abiesbalsamea) compared to locations where it is found in botanical gardens. Abies in Virginia and West Virginia (small gray circles) are located at higher elevations.
Bioclimate models mischaracterize niche based on static correlation [competition narrows realized niche]. actual growth Implicit model °C
TEMPERATURE TOLERANCE • Rising CO2 increases temperature tolerance (and drought tolerance) and raises peak temperature curve NPP temperature
TEMPERATURE TOLERANCE • Greenhouse/FACE studies • Rising CO2 and temperature give rising NPP (17% to 28%) • Even 14°C rise from ambient for northern trees • Dozens of studies • Simulation Models • If include CO2 predict more growth • Lake States simulation 2X forest growth • No massive range shifts • Contradict range shift idea
NET TEMPERATURE RESPONSE • Increased primary productivity (observed in satellite data) • Increased drought tolerance (inferred from satellite data) • No dieback • No extinctions (animals also), espnot 20-75% • (New IPCC rept admits no extinctions to date) • Slow northward tree migration • Hundreds or thousands of years
IPCC and Geographic Range • AR5 admits no trailing edge die-offs • AR5 and especially NCA play up northward migrations • BUT observed range shifts are very small and NOT universal • No way to get high extinctions from these facts
True Extinction Causes • 95% bird & mammal extinctions past 200 yrs from islands • Water pollution • Habitat loss • Hunting • Listing all species as endangered & building corridors are useless activites