W7 Flashcards
What are the two main processes that govern the climate
Thermodynamic
Dynamic
What is the thermodynamic system?
As the atmosphere warms by 1oc the moisture holding capacity increases by 7%
What is the dynamic system?
Idea that there are different climate systems and weather patterns
different circulatory patterns around the globe- ie. hadley cells etc.
with warming there will be changes - exacerbate the expectations in the thermodynamic systems
What is the impact of cc on the chances and strength and type of extreme events?
Normal distribution curve is shifting - more extreme events tail end events are happening with increasing probability
it is hotter it will be hotter
What is the key attribution question when we look at the distribution of events?
has the likelihood and strength of events altered due to climate change
has it shifted to such an extent that X event would have been impossible without climate change
What are the two methodolgoical approaches to understanding the influence of climate change on the two systems?
Storyline approach
probability-based approach
What is the storyline approach?
Thermodynamic and dynamic processes that led to event
useful in understanding if we are prepared for the impacts of the future
look at the patterns in the variable that you are interested in and compare that pattern to several modelled scenarios
How does the probability-based approach work to understand the influence of climate change?
Change in probability of event at leasts as extreme as the event
what are the chances that the same pattern will happen in the atmosphere and the same amount of extreme weather
How does probabilistic attribution work?
look into the change in likelihood of an event occurring in an anthropogenically modified climate as compared to a naturally evolving climate
What is the probability ratio?
PR= P1/P0
P1 = prob of occurrence in the actual world
P0= prob of occurrence in the world that would have been
if less than 0 - the probability of event in a world without cc was higher - cc made it less likely
If greater than 1- the probability of the event in a world without cc was lower - cc made it more likely
How does observed data modeling work?
- take observed data and model simulations - historical long data
- Statistical distribution fitting ex.gev
- fit parameters are dependent on global mean temperature
> scaled/shifted to past/future
> scaled/shifted to the current year - obtain the probability in each scenario
- calculate the probability ratio
How does fixed model runs work?
Coupled or atmosphere only model runs
- factual or counterfactual
fit distribution to variable of interest
obtain the probability in each scenario - P1 or P0
calculate the probability ratio
see if the probability is the same in different counterfactual climate
Can you explain what the probability of exceedance is?
Talking about the upper tail extremes - what is the probability of seeing an event as strong or stronger than X
What is the probability of non-exceedence?
This would be any event in the middle of the distribution - like not exceeding x strength
Why is calibrated language important?
Using words like very high confidende or virtually certain have the same understanding to everyone when it is used
= calibrates the amount of evidence supporting each claim or the probability of the same event happening multiple times (i.e. experimentally does it happen every time)
How many regions of the globe are there that the IPCC uses to synthesis its assessment?
45 regions
What is the expected pattern for warming?
medium to high temperature risks - hot events will become hotter and more frwuent
consistency across all regions
What is the expectation for heavy preceitpitation?
high precipitation events are to become increasingly likely as the climate warms
dry areas are simultaneously going to get drier
there are hardly any regions with high evidence but all evidence points to a change
What are the three key elements required in an attribution study?
- event definition
- hazard attribution
- vulnerability and exposure
What is an example of an attribution assessment
2022 heatwave study in wheat cultivation in India and Pakistan
looked into the one day max temperature
look into the probability ratio of the likelihood and strength happening in a counterfactual climate –> XX amount of cc is made more or less likely due to cc
qualitative assessment to understand what was missing and what would need to be addressed should the event happen again in the future
What are the three main droughts?
Meteorological
- reduced rainfall
Hydrological
- impact on stream flow and soil moisture
Agricultural and Ecological
- rainfall not percolating from the soil, roots draw the rainfall from the soil - not infiltrate itself
- important requirements for rain at certain points of the agricultural growing period vs requirements for it to be dry
Why are droughts more interesting than heatwaves?
droughts are a creeping phenomena - dont necessarily see the impacts of droughts in the immediate future
irrigated resions and crop yields delayed response - doesn’t necessarily impact this season but would have an impact in future seasons
Droughts are often exacerbated by accompanying temperatures - impacts due to heat, water and concurrent impacts - combined effects due to temperature and droughts
How do you quantify droughts?
Look at a hydrological variable - rainfall, runoff, groundwater level or soil moisture
standardised indicators like SPI
rainfall deficit - below expected threshold consistently then will have a long drought
Why is it important to consider regional warming?
There were anomolously high rainfall deficits accompanied by high temperature - issues of evapotranspiration
the impact of low rainfall are exacerbated by high temperatures
What are some of the direct and indirect impacts of drought on the environment
Direct
- soil moisture
- groundwater level
- runoff
-spring yields
-surface runoff
- water level in lakes
- available exploitable amounts of drinking water
Indirect
- water quality
-biomass development
-biodiveristy
- dust storms
-desertification
- forest fires
What are the direct and indirect impacts of drought on the economy?
Direct
- exploitation of surface water
- exploitation of groundwater
- diminishing of drinking water sources
Indirect
- irrigation water
-water for farming
-failure of irrigation
- loss of animals on farms
- reduction of navigable rivers
- reduce of hydroelectric power production
- food price increasing
-reduction of economic growth
What are the direct and indirect impacts of droughts on social
Direct
- drinking water
Indirect
- conflicts and conflicts of interest
What is the patter of literature around droughts?
Increasingly prominent - more frameowkrs being developed
Concentration of studies in certain parts of world
Can you speak to the study done for the spring heatwave in India and Pakistan in 2022
the heatwave was made 30x more likely and 1o hotter by cc
expected to become 2-20 x more likely and 0.5-1/5oc hotter at +2o warming
blocking of the rainfall patterns that usually bring moisture in from the himilayas - short spell of rain but system failed therefore soil was already dry when the heatwave happened
Wheat yields suffered the most but region was irrigated which mediated the loss - ukraine what - export ban
high temperatures due to cc caused the crops to reduce and as a result the vulnerabilities cascaded into agricultural vulnerabilities
What was the impact of cc on the droghts in the northern-hemisphere 2022
made at least 20x more likely and 2% drier due to cc
looked at soil moisture content as the variable - available for most the region
What were some of the imapcts of the northern-hemosphere drought?
- power generation due to heat and drought coincided with energy price increases ukraine conflict
- impacted agricultural yeilds in Europe coincided with reduced exports from Russia and Ukraine
- low reservoir levels impacted agri
- Po basin drying up affected rice in Italy
What are the three methods of disaggregating sensitivity of crop yields to climate variables?
Regression model - understand the relationships –> but need long records or could use a crop model
probabilisitic model - understand the dependency - can provide probabilistic estimates
process-based model
How do you disentangle climate and socioeconomic factors for agriculture?
India - high agricultural region - 90% live there rely on agriculture for their livelihood but also drought prone region
impacts mediated due to human based errors rather than cc but there can be a signal loss due to cc
look at crop databases to understand crops sensitivity/resiilence to rainfall, nutritional content, and profitability - see what the patterns and benefits are of these crops
Why is it important to loook at vulnerabilities?
V is mediated by cc in how the hazards can increase vulnerability to cc agriculture but also compounded by cc
conflicts due to land use change and how emissions are being managed
important to also consider our current practices to ensure that we can mitigate any future impacts