Climate Change Flashcards
What is climate change
= large-scale long term shift in global climate patterns
- climate = temperature, humidity, rainfall
Direct exposure
= a change in physical environment in which animal lives
e.g. shrinking of polar icecaps
~ rainfall - generally increased, lees in summer, high in winter
~ temperature - global surface temperature increased by 1degC since 1850, average global temperature in 2020 0.98degC warmer than 20th century average
~ sea levels - globally risen 20 cm since 1900 (3.3mm/year since early 1990s)
~ glaciers melting globally
~ arctic sea ice reducing by 4% per decade
~ ice sheets (greenland/antartica) shrinking
~ changes in air, water and food quality e.g. sudden polution (also indirect = impaired water quality leads to diseases)
~ extreme weather events (droughts, floods, heatwaves)
Indirect exposure
= a change in interspecific (between species) interactions
- usually over time
~ changes in vector ecology
~ nature: seasonal effects e.g. earlier spring, later autumn = affects species behaviour - butterflies appare earlier, change in bird migration patterns, change change in emergence of avian influenza)
~ change in ecosystems
~ change in animal populations - predation and competition
~ agriculture/industry changes to accommodate direct impacts
~ changes in settlements and landscapes
~ social and economic disruption
How does direct and indirect exposure to climate change affect animal health
- extreme temperature ~ effect physiology, reproduction and survival and food availability
- disease emergence
~ pathogens (esp those by food and water i.e. avian influenza)
~ vectors and parasites
~ water availability - disease transmission
~ host distribution and density
~ animal-human interface
~ pests, parasites and vectors colonise new areas
Disease emergance - pathogens (evolution)
- pathogens of concern = pests, parasites and vectors
Pathogens may: - colonise new teritories or host landscapes
- become more aggressive where hosts are more abundant/immunocompromised
- infect new species due to increased or new interactions
- increase their range (cove greater areas) as seen with BTV-8
- mutate genetically
Impact of pathogen evolution
- new disease patterns
- health relevant changes at landscape level, both farming and natural (change how we interact with animals) ~ climate change and general anthropogenic dynamics
- pathogen-host-environment interplay
- overall leads to disease emergence and changes in geographic range, host range or pathogen virulence
Direct of effect of increased temperatures
- heat stress
- heat stress in dairy cows
- more prevalent due to heatwaves in Uk
~ high body temp ~ reduced DMI/ cud chewing ~ increased rep rate ~ lower milk yield ~ higher SCC ~ increased risk for lameness, mastitis, acidosis-when they do eat, eat large amounts in small period of time ~ decreased conception rate ~ lower immunity ~ decreased rumen func (due to reduced DMI)
Temperature humidity index
- relative humidity % (20-100)
- air temp degC (22-40)
- low temp and humidity = no heat stress = <72
- > 72 = under some kind of heat stress
- as temp increase into 30s = severe heat stress (index in 80S and increases s humidity increases)
- 40sdegC and high 90-100% humdity = dead cows
Heat stress dairy cattle - how change in future
- Fodor et al 2018 model how temperature change in future
- 2010s-40s = 1.5 degC increase in temperature
- 2090s = 3 degC higher temperaqture than currently seeing
- recorded no. of heat stress days in a year with temp humidity index over 70
~ 10 days in 2010
~ 15 in 2040
~ rises by 2070 with 29 days
~ 37 by 2085 - temp humidity index less than 70 at coolest point of day but maximum temp humidity index greater than 70
~ 2010 = 37 days
~ 2040 = 43 days
~ 2070 = 50 days
rises consistently
Heat stress dairy cows - how impacts them in future (increasing temp)
- THI threshold of 68, 70 or 72
- as threshold lowers and years go on = more loss/cow due to more heat stress days
- expected annual milk yield loss = average 180kg/cow
- hottest grid in hottest year (2090) = 1300kg loss/cow of milk
- up to 17% loss
- south east europ most vunrable
- predicted £13.4 million loss in average years by end of 21st centrury
- £33.8 million loss in extreme years
Climate change case study - black tailed prairie dogs
- about prarie dog survival
- study aim
- methods
- results
- stephens et al 2017
- indirect exposure
- survival of canadian prairie dog in winter dependant on
~ physiology (fat accumulation, body condition)
~ enviro (temp, snow depth, snow cover, length of winter)
~ food availability in spring - study wanted to see how changes in enviro may affect survival
- drought in years 2007, 2009 and 2012 out of 8 year period
- caught dogs and counted them and separated into adults and juviniles
- density declined by 67% (2008), 70% (2010) and 54% (2013) = the years following drought
- increased numbers after drought but decreased once there was another drought
- years following drought = females lactating reduced, less offspring and animals breeding in year (e.g. 2007 = 70 lactating females, 2008 = 1)
- juviniles also reduced significantly year folowing drought (e.g. 2007 = 232 juviniles, 2008 = 3 captured) = juviniles left too young to breed, following droughts cause no.s to decrease more, unable to recover population numbers from 2014
Climate change case study - black tailed prairie dogs = reasons
Direct effects
- drought reduced forage quality and quantity
- lower nutrient reserves for survival
- lower nutrient reserves for breeding (less fertile, less lactating/poor quality milk for young)
Indirect effects
- increased predation risk (change behaviour, travel away from dens and explore new areas, interact with new predators)
- reduced immunity leading to increased disease risk (due to low nutrition and introduced to new pathogens)
