2 - climate changes Flashcards
what’s the climate?
- Climate is the aspect of the physical environment that most influences ecosystems, constituting the prevailing conditioning for organisms
what determines the climate?
composition of the atmosphere
What is the relationship between a body’s temperature and the wavelength of radiation it emits?
- The wavelength of radiation emitted by a body is a function of its temperature
- For example, the sun, with an average surface temperature of 5800°C, emits shortwave radiations
- while the earth, with an average surface temperature of 15°C, reradiates energy at relatively long wavelengths.
net-radiation
what does the intercepted solar radiation vary with?
- latitude
- season
variation in solar radiation causes large variations in ___ ?
temperature
- with latitude
- seasonally and daily
seasonal and daily variations in temperature caused by variations in solar radiation
- More homogenous in tropical region
- Differences in season, day and night
- differences in the intensity of solar radiation reaching the earth’s surface generate temperature differences which
- together with the effects of the earth’s rotation, originate winds and ocean currents by convection
- means: i.e. the process of heat transfer from one location to the next by the flow of fluids from a high temperature location to a low temperature location
- These, in turn, influence the distribution of precipitation, and play a crucial role in transferring heat from the equator to high latitudes
relationship between air temperature and density
- air expands when heated
- contracts when cooled
- hot air is less dense than the surrounding matter because there is more space between the molecules
- air floats upward
concept:
- Differences in height
- Fluid warm: expands
- Fluid cold: becomes more dense
what happens as air moves upward?
- temperature decreases
- due to adiabatic cooling
vertical temperature gradients due to ___?
- Greater air density near the surface (collision between molecules generates heat)
- “Warming effect” of the earth’s surface
- Adiabatic cooling (caused by gas
expansion as pressure decreases)
what is generated by changes in air temperature combined with earth’s rotation?
- the circulation of air masses
- Coriolis effect: Deflection in the pattern of air flow
- Clockwise movement in N hemisphere, counterclockwise in S. Hemisphere.
- Less dense air in warm areas –> moves up and tends to cool down –> starts moving and gets colder and colder –> ends at pole –> circulation
- 3 cells north and 3 cells: trade wind belts
- More rain where air goes up –> areas of globe naturally more and others naturally less rainy
- greater density near surface creates heat
- As we move up, pressure decrease, air expands, tends to cool down earth temp.
what does solar energy, wind and earth’s rotation generate?
- the oceans currents
- precipitation patterns
precipitation patterns
- Rain, where air cools down when moving up
Relationships between air moisture and temperature
- Certain air temp. has a certain saturation vapor pressure (roter punkt)
- Sat. vaporation pressure = max water you can have in a mass of air as vapor
- Now I am at hellblau: same amount of vapor in it –> warm air moves up, it cools down, then temperature drops, I go go orange point, amount of vapor water stays the same,
- Rain above red line
- No rain below red line
- Causes many temperature changes among different areas (climate change)
what do the arrows show?
three cells and trade wind belts
latitudinal patterns of precipitation follow ___ ?
- the circulation cells
- image: Global pattern of the three cells of trade winds
global pattern of precipitation
what are regional and local patterns of precipitation influenced by?
- topography
do irregular variations in climate also occur at a regional scale?
- yes
- e.g. El Niño Southern Oscillation (ENSO) is a periodic shift of the ocean-atmosphere system in the tropical Pacific
- it impacts weather around the world
- happens every 3-7 years (5 years on average)
- typically lasts nine months to 2 years
- associated with floods, droughts and other global disturbances
ENSO
what do “Microclimates” define?
- the local, small scale conditions in which organisms live
- includes
1. topography (aspect=direction a slope face) 2. light
3. temperature
4. air conditions
5. wind movement
6. moisture etc
what’s the IPCC?
- the Intergovernmental Panel on Climate Change (IPCC)
- the leading international body for the assessment of climate change
- to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts
observed changes in the climate
temperature increase
- human influence has warmed the climate at a rate that is unprecedented (beispiellos) in at least the last 2000 years
- the likely range of total human-caused global surface temperature increase from 1850–1900 to 2010–2019 is 0.8°C to 1.3°C
- with a best estimate of 1.07°C
- Some areas of planet (north) warm more than others
- Areas where climate change is more impacting than in other regions
has the averaged precipitation over land globally decreased? increased? stayed the same?
- has likely increased since 1950
- with a faster rate of increase since the 1980s (medium confidence)
- CNR Data
- tropicalization of rainfall regimes in Italy: on average total rainfall has only slightly decreased
- but: the number of rainy days has decreased
- and: the intensity of precipitation per day has increased
- causing both severe droughts and floods
- More intense changes when you look at a shorter amount of time (right)
- Really dramatic is the way it rains: same amount in few days
- more drought and flood is created
- dramatic alternations called “tropicalization”
ocean warming
- ocean warming dominates the increase in energy stored in the climate system
- accounting for more than 90% of the energy accumulated between 1971 and 2010 (high confidence)
- It is virtually certain that the global upper ocean (0−700 m) has warmed since 1970s
why are glaciers melting?
mountain glaciers are decreasing due to
1. increase in temperature
2. decrease in rainfall
shows decrease in both graphs
sea level rise
- the rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia (high confidence)
- Over the period 1901 to 2010, global mean sea level rose by 0.19 [0.17 to 0.21] m
Why is the sea level rising?
- 3 mechanisms combined
- ice
- Warming of global temperature
- thermal expansion: water is a fluid, therefor the expansion is greater when it gets warmer
estimates of the relative contribution of thermal expansion, water + melting, sea level rise
ocean acidification
- change of sea-surface pH by anthropogenic CO2
Carbon in water
- it dissolves
- equilibrium of carbon-bicarbonate
what affects the pH in the ocean?
- Co2-additions
- Co2-losses
- changes in pH determine the prevailing form in which Co2 is present
how much has the Co2-concentration increased since pre-industrial times? why?
- 40%
- from fossil fuel emissions
- from net land use change emissions
- ocean has absorbed 30% of the emitted anthropogenic carbon dioxide
- causing ocean acidification
- blue: partial pressure of dissolved CO2 at the ocean surface
- green: in situ pH, a measure of acidity of ocean water
increase in drought and heat (1982-2011)
prevented plant uptake of CO2 due to
- blue: drought
- red: heat
- purple: heat and drought
- grey: other extreme events
heat waves
- Marine Heat Wave is defined as a discrete prolonged anomalously warm water event.
- “Discrete” means an identifiable event with recognizable start and end dates
- “prolonged” implies a duration of at least 5 days
- “anomalously warm” measures temperatures relative to a baseline climatology and threshold
increase in wave power
- Wave power increasing
- When wave power is changed, the bottom is not shaped any longer
- therefor wave interaction with bottom changes (refraction/diffraction)
- Change of direction has major effect on the organisms
storm hazards are rising
- likely that the global proportion of major (Category 3–5) tropical cyclone occurrence has increased over the last four decades
- very likely that the latitude where tropical cyclones in the western North Pacific reach their peak intensity has shifted northward
- these changes cannot be explained by internal variability alone
what about natural disasters and their frequency?
- Risks are all increasing
- also, costs are increasing
- Fires are increasing
summary of observed changes in extremes
- the only arrows down are the cold extremes
the greenhouse effect is a driver of the climate change
drivers of the climate change
globally averaged greenhouse gas concentrations (CO2, CH4, N2O)
Glacial-Interglacial Ice Core Data
- VERY rapid speed of change is the concerning part of this increase
- Scale and rate of change is far from nature
Global anthropogenic CO2 emissions - what are the main “sources”?
- Cement causes huge emissions of CO2
- Cementification and energy use + flaring
- or forestry + land use
overview: greenhouse-gas emissions in 2000
- energy emissions
- buildings
- transport
- power
- industry
- other - non-energy emissions
- waste
- agriculture
- land use
Climate change projections
- global surface temperature
- global warming
- predictions: even if we were in most optimictic scenario the climate will still change
- kind of resilience system
- the amount and speed of temperature change will change
different future emission scenarios
future warming - increase in this century of the global average temperature?
- by 1-5.7°C
- thats’s huge!!!!!
global warming of 2°C, relative to 1850-1900
Die globale Erwärmung von 2°C im Vergleich zu 1850-1900 würde im 21. Jahrhundert unter den Szenarien mit hohen und sehr hohen Treibhausgasemissionen überschritten werden.
–> 2°C- increase is a lot!
temperature change scenarios (relative to 1850-1900)
- All predictions go higher than they used to
warming of the Mediterranean Sea
as warm tropical water from the Red Sea flows in, its predicted to also gain salinity
projected changes to marine heat waves (MHW’s)
- We are getting to a permanent heat wave
- First real heat wave was 2003
emergence of a permanent heat wave
- First year of occurrence of permanent MHW states
- Historical and projected evolution of global mean MHW days (categorically)
increased drought risk
Discernible changes in intensity and frequency of meteorological droughts, with more regions showing increases than decreases, are seen in some regions for every
additional 0.5°C of global warming (medium confidence)
projections of precipitations
- Alternating flood and drought is becoming the trend
- Not moderate anymore
precipitation scenarios (relative to 1850-1900)
ice melting scenarios
- Expected continued ice loss
- With it: sea level rise
- Very many coastal areas that are on low sea level and therefore will be flooded
projected sea level rise scenarios
projected increase in flood risk
- Flood risk = storms as Katherina,
- Pumping and defense nowadays doesn’t work anymore because the pumps were not built for the extremes of today
future flood hazard
(good paper)
flood risk in Europe
what exacerbates the flood risk?
- coastal erosion
- We need sand for cement (sandmining)
- Rivers do not discharge sand anymore
- Massive land subsidence
sketch map of main coastal erosion causes
coastal erosion is a global problem
most common approach to coastal erosion and disaster prevention?
- Main approach to coastal erosion is hardening (hard engineering) the shore instead of going to the source
projected acidification scenarios
projected increases in anoxic events
projected increases in anoxic events
what are a few ways, that warming waters cut oxygen?
- Anoxic conditions below
- Stratification, so O2 doesn’t get from surface and then uptake due to blooms
projected increase in extreme events
proportion of CO2-emissions taken up by land and ocean carbon sinks is smaller in scenarios with higher cumulative CO2-emissions - why?
- CO2 can be partially absorbed
- In lower scenario: great capability of taking up CO2
- Certain limitation in higher amount
- They can not increase amount they can take up
- Relatively the amount decreases
