Fundamentals of climate change

True =>

Although most locations on the planet have recorded increased temperatures since 1880, changes in global ocean and atmospheric circulation patterns have created small-scale temperature decreases in a few local regions.

B. In the norther latitudes =>

Some of the fastest-warming regions on the planet include Alaska, Greenland and Siberia. These Arctic environments are highly sensitive to even small temperature increases, which can melt sea ice, ice sheets and permafrost, and lead to changes in Earth's reflectance ("albedo").

D) All of the above =>

For the past few decades, scientists have had the benefit of global satellite data. We have accurate ground-based measurements that reach back just over a century. "Proxy" methods, such as tree ring and ice core analysis, are used to reconstruct climate records before the rise of modern instruments.

True =>

Air pollution can take the form of fine particles called "aerosols," which both absorb and scatter the sun's radiation. Both natural and man-made aerosols, such as dust, sea salt, soot and sulfates, affect the climate by reflecting radiation that is transmitted through the atmosphere.

D) 28 to 32 °C cooler =>

The greenhouse effect is a naturally occurring physical process that warms the Earth's surface with energy from the atmosphere. Without the effect, Earth's average surface temperature would be well below freezing.

B. Nitrogen =>

Heat-trapping greenhouse gases absorb and emit radiation within the thermal infrared range. Water vapor, carbon dioxide and methane are Earth's most abundant greenhouse gases. Nitrogen, which makes up 80 percent of Earth's atmosphere, is not a greenhouse gas. This is because its molecules, which contain two atoms of the same element (nitrogen), are unaffected by infrared light. N2

D. 2,000 years =>

Although some think that the "Medieval Warm Period" (approx. 800 – 1200 AD) was a global phenomenon, recent studies, including one by Neukom et al. 2019, show that there is no evidence that there were uniform warm and cold periods on Earth over the last 2,000 years.

A. Average precipitation increases =>

Higher temperatures contribute to a more active water cycle, which means faster and greater evaporation and precipitation and more extreme weather events.

B. Carbon dioxide =>

Some people mistakenly believe water vapor is the main driver of Earth’s current warming. But increased water vapor doesn’t cause human-produced global warming. Instead, it’s a consequence of it. Increased water vapor in the atmosphere supercharges the warming caused by other greenhouse gases, such as carbon dioxide, followed by methane.

weather: regional scale, fluactuations, short time frame (day to day)

climate: larger scale, slow changes (inertia), long time frame (statistical construct of many years), it discribes the typical weather behavior in a region, state of a whole system

Extreme weather events always occured in history of the earth. But due to the antropogenic climate change, the propability of for different events changes. The probabilities for different weather phenomina are distributed according to the Gauß distribution. With increasing temperatures, this curve moves to the right (higher temperatures), but it also flattens. Therfore, “regular” weather events are less likely but very extreme events are even more extreme and their probability is higher. Higher probability => higher frequency

(But this is not necessarily true everywhere!)

Since the end of the 19th century

Dry will become dryer and wet will become wetter!

Mainly by the composition of its atmosphere.

The IPCC is the Intergovernmental Panel on Climate Change. Its task is to review and assess the most recent scientific, technical and socio-economical information that are relevant for the understanding of climate change (phsical changes, hazards, options). It has a scientific body with an intergovernmental panel (195 nations).

However they do not conduct research them self!

Climate is the average state of weather over a long period (30 years or more)

Climate change is a shift of that over several decades

Climate change is also caused by natural variability, but the human influence on the climate can contribute to greater levels of variability than we would expect it.

Food and Water Security might become a big problem for many people. Also tipping points occur additionally.

Maximum in April

Minimum in November

Reason for the pattern is seasonality => less photosynthesis in Winter

currently 420 ppm

We have to actively take out CO2 from the atmosphere bei the mid of the century!

180 ppm to 280 ppm ==> now we have 420 ppm !!!

18th century

Weather stations, Weather baloons, Aircrafts, Satelites, Buoys, …

We can reconstruct past climates pretty well by the use of ice cores, tree rings, shells, rocks, sedimants, … Not only temperature but also other parameters such as gas composition, precipitation, aerosoles, … This data we can also correlate and validate with different climate models

There is only a little absorption of GHG in the range of 8 to 14 mycrometers. Therfore we have a constant and significant loss of longwave solar radiation into the space. Without this window it would be much warmer. There is a peak in the middle of this window, this peak is due to ozone.

It depends! During the night clouds in general have a warming effect. During the day high clouds have a warming effect, as they are less dense and only reflect the outgoing radiation back to the earth. Low clouds are in general very dense and have a increased albedo compared to the earths surface.

The have minimum 3 atomes in the molecule; 2 atom molekules are not able to absorb solar radiation. => Vibration and Rotation => increase of cinetic energy (they transmit visible light)

The Global warmin potential is a way to classify the impact of a Greenhouse gas.

Life times are taken into account! => How much do they contribute to climate change?

Yes, the scatter radiation back into the Sky and act as condensation nukleoids => clouds

Respiration, by-product of burning processes and chemical processes, non organic CO2 from vulcanos.

No, because if we have droughts (mainly in tropical areas) like it is during a el Ninio event, the former sink turns into a source!

Wamer temperature => respiration increases

Drought => less photosynthisis and less carbon uptake

Because we meausre not only the CO2, but also the O2. We can see a reduction of O2 due to burning processes. (otherwise O2 would stay the same)

Also we can measure isotopes => normaly we would have a balance beetween 12C and 13C when the CO2 concentration rise would be caused by natural proccesses, but 13C decreases indicating that the balance changes => because plants like the C12 more for photosynthesis, they also store it and fossil organic matter has more C12 in it! => when burned C12 is released, changing the comnpostion! (isotopic signature)

El Ninio => high prodctive areas experience droughts => carbon release (higher respiration and forest fires due to hot temerpatures and no available water)

But this can also go the other way around, so if we have a strong vulcanic eruption, there are more condensation nucleiods in the air => more radiation scattering, more precipitation => less droughts and high productivity!

Agriculture, fossil fuel production, Land-use change, Natural sources

But 50 to 65 % are anthorpogenic

N2O is emitted by bacteria in soils and oceans. Agriculture is the main human source (fertalizer)

Ozon is not a GHG, because its lifetime is to short! It is needed in the upper atmosphere to filter strong UV light. On ground-level it is a pollutant! It is not emitted directly, but is formed with the help of the sun if NOX or hydrocarbons are in the air!

Because they absorb in the atmospheric window, where no other gases absorb radiation and they have a very long lifetime (100years), but they got banned by the Montreal Protocol

1t CO2 = 1kg CFC

Greenhouse gases absorb selectively in specific wavelength ranges, clouds absorb in the entire IR range.

Lifetime and absorption bands

Water vapor (as well as CO2) is a greenhouse gas, meaning, that it is capable of stopping the outgoing radiation from the earth to space by absorption. The problem is, that the watervapor content in the atmosphere is temperature dependant. Therofore, the the higher the atmospheric temperature, the more water can evaporate => more water vapor in the air => increasing tempertaures (amplifyed by increasing temperatures); also warm air can hold more humidity => additional increase

Water vapor feedback cycle! A small warming is amplifiyed to a big warming! Among with other cycles, this is what makes climate so sensitive.

The climate sensibility is the difference of average global air temperature, when we double the CO2 concentration. To this value many different effects are connected, e.g. like the rise of sea levels or how heat waves will get worse, or rainfall patterns change.

+2,5 W/m^2

about + 7%

Natural: dust from mineral soils, vulcanic eruptions, sea spray, ocean, desert storms

Anthropogenic: Indursty and traffic, forest fires, combustion, open fire,

Direct influence due to absoption or scattering of solar radiation (colour dependant)

Indirect influence due to cloud formation (condensation nucleoids)

(water washes aerosoles out of the atmosphere)

Africa => Sahara, desert dust

Brazil => Forest Fires

China and Asia => burning fossil fuels and industry

Cooling if we only consider the radiation interaction! It not only depends on the particles them self, but also on the surface below. Dark aerosoles over dark ground have less influence then dark aerosoles over bright ground (double absorption).

Also with more aerosoles in the atmosphere, clouds will have smaller droplets => higher reflectivity

RF expresses the change in energy in the atmosphere due to GHG emissions. The RF of a gas /aerosol is defined as the difference between incoming solar radiation and outgoing IR caused by the increased concentration of substances. So it is a energy imbalance imposed on the climate system either externally or by human activities.

Radiative forcing is what happens when the amount of energy that enters the Earth’s atmosphere is different from the amount of energy that leaves it. Energy travels in the form of radiation: solar radiation entering the atmosphere from the sun, and infrared radiation exiting as heat. If more radiation is entering Earth than leaving—as is happening today—then the atmosphere will warm up. This is called radiative forcing because the difference in energy can force changes in the Earth’s climate.

positive: twaing Permafrost - CH4, ice-albedo, water-vapor

negative: ice-albedo, water-vapor,

Without feedback loops => 2x Co2 => +4 W/m^2 => +1,1 °C

With feedbacks => +3°C (1,5 to 4,5 °C)

positive = amplifying effect

negative = reduction effect

Clouds for weather and climate (albedo and absorption)

Particles for absorption and scattering

Scattering of solar radiation into the sky

more condensation nucleoids => more clouds with smaller dropslets and higher albedo

(longer lasting clouds)

High clouds => warming (GHG)

Low clouds => cooling (albedo)

Night clouds => warming

2016 because of a very strong el Ninio event, but 2023 cracked it

Because water has a higher heat capacity than solids and we have mixing processes!

2040 if the current trend continous

It is warming almost everywhere

Its warming rapidly

Its been a long time since it has been this warm

Many people life there => produce energy (industry, households, heating)

traffic

sealed areas => reduced evaporation and reduced sensible heat flux

Higher surface because of high buildings => can absorb more

also reflection to other buildings needs to be considered

many albedos are very low => much absorption due to dark coulours

In general 2- 3 °C but can be upto 10 °C in hot nights

• Stronger over land-mass compared to the ocean, because water has a higher heat capacity and mixing processes

• Stronger in the arctic regions => Ice-Albeo-Feedback is stronger

• In some regions even cooling due to meltwater inflow in the ocean (Greenland and Antarctica)

• Also in areas with high evaporation rates the warming is less intense, but even the already hot tropics are still heating up

• Global air circulation and ocean currents change (pressure fields and jet stream position) cause regional differneces

• Antarctica Ice-Albeo-Feedback has not started yet

Correlate different measurement techniques and models to each other.

use Long measurement series and use Paleoclimatologie

to calibrate Numerical models

Compare all; do they come to the same conclusion? Consider model uncertanties and provide confidence intervall.

In the arctic, because of the Ice-Albedo-Feedback

• less evaporation

• higher surface

• more thermal storrage mass

• higher excess heat (heating, traffic, industry)

• Less air circulation

• darker surfaces => higher absorption and higher IR emissivity

2 to 3 °C warmer compared to the rural areas (max. 10°C during some nights), poor ventilation, high aerosol content, low latent cooling

Surface water gets colder and sinks down. After that it is replace by warmer, more boyent water. So it is al long process, until the top water reaches the freezing point of about -1,8°C.

How fast this process is going, depends on the heat that is storred during summer!

climate change => formation of sea ice takes longer

When water freezes, salinity of the not forzen water increases => water becomes more dense and sinks down => drives the global ocean currents

But also natural effects have an influence on the sea ice formation => much snow accumulating on thin ice slows down the porcess (blanket keeps the heat in)

Yes, without large-scale reduction in greenhouse gas emissions, globalwarming is projected to cause substantial changes in the water cycle at both global and regional scales

Atmospheric water vapor increases by about 6 to 7% in response to each 1 °C of warming.

• A warmer climate increases moisture transport into weather systems, which, on average, makes wet seasons and eventswetter

• Increased evapotranspiration will decrease soil moisture in many regions (e.g. over the Mediterranean, south-western North America, southern Africa, south-western South America, and south-western Australia) Warming over land drives an increase in evapo(transpi)ration and the severity of droughts

• Extremes will increase faster than the average

Yes, because warmer air can hold more water vapor => more snowfall => high glaciers can grow

(low glaciers are to much vulnerable to the hotter temperatures, so they will disappear)

But most of all glaciers decline!!!!!

Arctic and boreal permafrost contain almost twice the carbon in the atmosphere (1460–1600 Gt organic carbon). Scientific discussion is going on whether northern permafrost regions are currently releasing additional net methane and CO2 due to thaw.

Climate change impacts various parts of the water cycle in significant ways. Here are the key components affected:

1. Evaporation: As global temperatures rise, the rate of evaporation increases. Warmer air can hold more moisture, leading to more water vapor in the atmosphere.

2. Condensation and Cloud Formation: Increased evaporation leads to more water vapor, which can result in more cloud formation. However, the type and distribution of clouds may change, affecting the Earth's radiative balance and, consequently, climate patterns.

3. Precipitation: Changes in temperature and atmospheric moisture content affect precipitation patterns. Some regions may experience increased rainfall, while others may suffer from droughts. The intensity and frequency of extreme weather events, such as heavy downpours and storms, are also likely to increase.

4. Runoff and Streamflow: Altered precipitation patterns influence runoff and streamflow. Increased precipitation in some areas can lead to more runoff and potential flooding, while reduced precipitation in other areas can decrease streamflow, impacting water availability for ecosystems and human use.

5. Snow and Ice Melt: Warmer temperatures lead to the melting of glaciers and ice caps, contributing to sea level rise. Changes in snowfall and snowmelt timing also affect water availability, especially in regions dependent on seasonal snowpack for water supply.

6. Soil Moisture: Higher temperatures and altered precipitation patterns impact soil moisture levels. Increased evaporation and changes in precipitation can lead to drier soils in some areas, affecting agriculture and natural vegetation.

7. Groundwater: Changes in precipitation and runoff patterns can affect groundwater recharge rates. Reduced recharge can lead to lower groundwater levels, impacting water supply for drinking, irrigation, and industrial use.

8. Transpiration: Changes in temperature and atmospheric CO2 levels can affect plant growth and transpiration rates. Increased temperatures may enhance transpiration, while higher CO2 levels can reduce transpiration by causing stomata (plant pores) to partially close.

These changes in the water cycle components are interconnected and can have cascading effects on ecosystems, agriculture, water resources, and human societies.

Because the probability curve flattens and shifts towards higher temperatures => extreme events are more likely => in allready dry regions, the higher evaporation rate leads to droughts & in wet areas the higher evaporation leads to heavy precipitaion events because here is alot of water available

1. Albedo Effect: Sea ice has a high albedo, meaning it reflects a significant portion of incoming solar radiation back into space. This reflection helps to cool the Earth by reducing the amount of heat absorbed by the ocean and the atmosphere. As sea ice diminishes, darker ocean water, which has a much lower albedo, absorbs more solar energy, leading to further warming and a feedback loop known as the ice-albedo feedback.

2. Insulation: Sea ice acts as an insulating layer between the relatively warm ocean and the much colder atmosphere. This insulation reduces the amount of heat and moisture transferred from the ocean to the atmosphere. Without sea ice, heat and moisture fluxes would increase, leading to changes in atmospheric circulation patterns and weather systems, potentially disrupting global climate patterns.

3. Thermohaline Circulation: The formation and melting of sea ice influence the thermohaline circulation, also known as the global ocean conveyor belt. When sea ice forms, it expels salt, increasing the salinity and density of the surrounding water. This denser water sinks, driving deep ocean currents that are part of the global circulation system. This process is essential for distributing heat and nutrients around the globe. Disruptions in sea ice formation can alter these circulation patterns, impacting global climate and marine ecosystems.

Differences in Reactions

1. Geography:

   • Arctic: Ocean surrounded by land; confined, rapid warming.

   • Antarctica: Continent surrounded by ocean; buffered by ocean currents, variable warming.

2. Climate Trends:

   • Arctic: Significant warming, rapid sea ice decline.

   • Antarctica: Variable temperature changes, complex sea ice patterns.

3. Ice Dynamics:

   • Arctic: Seasonal, thinner, and younger ice.

   • Antarctica: Influenced by wind and currents, can be thicker and older.

Significant Risks

1. Arctic:

   • Climate Feedbacks: Accelerates global warming.

   • Ecosystem Disruption: Threatens species like polar bears.

   • Human Impacts: Affects Indigenous communities, opens new shipping routes.

2. Antarctica:

   • Ice Sheet Stability: Contributes to sea level rise.

   • Ecosystem Changes: Affects species dependent on sea ice, like krill.

   • Global Climate Impacts: Disrupts global ocean circulation.

A mountain glacier that disappears under global warming will not reappear under subsequent global cooling at the same global mean temperature because:

1. Loss of Ice Mass: Once the glacier melts, the ice mass is gone and cannot easily reaccumulate.

2. Altered Landscape: The landscape changes (e.g., loss of ice-smoothing, exposure of rocky surfaces) inhibit new ice formation.

3. Delayed Recovery: Ice accumulation processes are slower than melting, needing colder temperatures for longer periods to rebuild the glacier.

30 %

Ocean acidification => pH decrease => shell and skeleton formation becomes difficult for animals

Wind

Tide / Moon

Heat and Salinity => Thermohaline

Temperature

Partial pressure

waves, ice cover (surface)

Wind and currents (only temporal)

Glaciers, snow and ice on the land (second)

Steric expansion (temperature expansion) (most)

Tide / Moon (only temporal)

The Great Ocean Conveyor Belt => thermohaline current might weaken or even stop due to less ice and additional freshwater outflow

Upper ocean currrents are also influenced, but can partly accelerate (Antarctic ocean)

AMOC waekend already

Ocean acidification => pH drops => shell and skeleton building becomes more difficult

Biological pump might speed up (higher productivity) => deep ocean carbon sink might not work anymore because all algees are eaten by phytoplankton (nothing left)

Ocean warms up, currents change => warming might speed up (feedbacks ice-albeo; biological pump), becomes more acidic quickly => nature has no time to adapt, extinction of animals

And of course => sea level rise => submerching habitats

Thermohaline circulation / Geart Ocean Conveyor Belt

Salinity decreases, temperature increases

Short Term (Less than a Year)

1. Heat Absorption: Oceans absorb excess heat from the atmosphere, moderating temperature fluctuations.

2. Weather Patterns: Influence weather events such as hurricanes, monsoons, and El Niño/La Niña phenomena.

Long Term (A Few Hundred Years)

1. Carbon Sink: Oceans absorb large amounts of CO2, helping to mitigate climate change but leading to ocean acidification.

2. Thermohaline Circulation: Drives long-term climate regulation by distributing heat and nutrients globally, impacting global climate patterns and sea level.

Changes in surface salinity can indicate climate change impacts for several reasons:

1. Evaporation and Precipitation: Climate change can alter evaporation and precipitation patterns. Increased evaporation in warmer regions raises salinity, while higher precipitation or ice melt in other areas reduces it.

2. Ice Melt: Melting polar ice and glaciers due to warming add fresh water to the ocean, decreasing salinity in those regions.

3. Ocean Circulation: Changes in salinity can affect ocean density and circulation patterns. Shifts in these patterns can indicate broader climate changes.

4. River Discharge: Altered precipitation and increased glacial melt affect river flows into the ocean, influencing coastal salinity.

Monitoring these salinity changes helps scientists understand and track the impacts of climate change on oceanic and atmospheric systems.

it functions like a land sea circulation pattern (because land heats up and cools down faster than water) => pressure differences => windflow

When the sun stands high in the summer, the sub-tropical jet stream (west to east) weakens and moves northern => a new jet stream foms => equatorial esterly jet. This jet strengthen the high pressure field over the Indian Ocean. Over the land a massive low pressure filed forms due to hot temperatures. Air moves form land to sea and is blocked by the Himalaya => air rises => condensation and rain. Due to the corrilois force, the air spends more time in over the ocean => stronger rain.

The warm phase of ENSO can lead to a drier southwest monsun => droughts

The cold phase, La Ninia can cause the opposite => flooding

In the winter the pressure fields switch => The tropical easterly jet disappers and the suptropical jet moves southwards again => south-east winds bring the dry season

More solar radiation at the equator => temperature difference between poles and equator

But distribution of ocean land masses is uneven and the earth spins => circulation patterns are more difficult

=> 3 cells

• Headley Cell is the biggest cell

• Ferrel Cell spins the other way around => like a gear

• Polar cell is the smallest

=> those cells lead to semi-permanent areas of high and low pressure => climatic zones (e.g. descending air => deserts (not all are necessary hot)

El Ninio Southern Oscilation is the reverse of the Walker Circulation between South-America and South-East-Asia. It is initiated by the shift of the Inner Tropical Convergationzone (ITC) to the south which hinders the Passt Winds from reaching the equator => Humbold Current at the cost of South-America weakens and the the water starts to heat up (less cool water with high oxygen content => less plankton => lesss fish) => When the water temperatures are almost similar between South America and South East Asia, the Walker Circulation reverses.

Effects are Strong precipitation events in South America and droughts in South East Asia and Australia

It is a very intense normal Walker Circulation, often after El Ninio. In this event the temperature differences between South East Asia and South America are even stronger, because the ITC shifts further north than normal and the Passat winds are stronger => strenghtening the current towards South East Asia (makes the ocean warmer). Also the Humbold current reaches further north (makes the ocean cooler) => The Walker Circulation becomes stronger => Heavier rainfall in Asia and droughts in South America, but more fish!

North Altlantik Oscilation => High pressure next to Afrika and Low pressure northwest of GB => thats why we often have west winds in Europe. But how strong those pressures are varries => can reduce the weest wind and make east winds more likely => they bring dry cold air in the other then the westwinds that bring warm humid air

In its positive phase => warmer Atlantik => More hurricanes, wetter summers in Europe, droughts in Brazil, heavy rainfall in Sahel, reduce of Arctic Sea Ice, wetter Monsun in India

In its negative phase => cooler Atlantik => opposite

70 years

It is important that we understand, how natural variability functions; in what frequency and dimensions. Only if we understand that, we can differantiate between natural (internal) variability and anthropogenic climate change.

Fluctuations in the climate about a mean state that occur with preferred patterns and intervalls.

They would also occur in absence of humans. => large-scale phenomena such as ENSO, Asian Monsoon, NAO, PDO, ….

They are not exactly periodic, they are oscillating!

In tropical countries the people. often clear the forest by burning. This can get out of control when there is no rainfall. On the other side in e.g. Austrailian deserts the high amount of precipitation leads to flooding!

The Monsoon will be less predictable in the future. We will have more aerosoles and moisture in the air, but the temperature gradient between Ocean and Land will be less. => weaker circulation due to lower temperatuer difference.

The Headley cell will become wider => dry regions expand. Also the ITC will become toghter => more precipitation, higher clouds => less outgoing solar radiation

Yes, during El Ninio the CO2 concentration in the atmosphere is higher due to less productivity in tropical regions!

Effects od deforestation depend on regional conditions => first ccarbon is released, less evaporation, albedo increases => the sum of these effects lead to …

• warming in the tropics (CO2 emissions and reduced evapotranspiration)

• cooling in higher latitudes (albeod effect dominates)

Strong Vegeatation has a lower albedo => more absorption

Strong vegetation => higher evaporation => release of latent heat

Strong vegeatation => higher roughness => lower wind speed

70%

Biochemical is regarding => GHG, Aerosoles, Pollutants, other gases

Biophysical => Heatflux, Waterflux, Wind

Brazil, Indonesia, DR Congo

China 11 Gt CO2 in 2022

USA 14 tons per person

9 tons per person in germany

We need them to project and understand future climate change impacts. For example changes in precipitation patterns, which are critical to agriculture and the human living conditions. Or for understanding the changes of the biochemistry of the oceans are critical for fishery and ocean acidificatio => coral reefs

Weather models:

• Initial state is critical

• Dont care about entire distribution, just most likely event

• need no conservation of mass and energy

Climate models:

• Independant of initial state

• need to get distribution of weather right

• Critical to conserve mass and energy

The goal of a climate model is to incoporate all aspects of climate into a computer model for the purpose of predicting futur climate states (mathematical eqations based on the law of physics)

ca. 100km raster, but it can also be smaller (some important processes happen on scales below the discretization like rain wind, …)

Detection of significant observed climate change and attribution of this observed change to one or more causes is a signal-in noise problem: identifying possible signals in the noise of natural internal climate change variations in the chaotic climate system.

=> Detection is the process of demonstrating that an observed change is significantly different than it can be explained by natural internal variability (statistical proof)

=> attribution is the process of establishing a causal relationship between a forcing and the detected changes (Plausibilty Argument)

=> unlikely to be natural variability, consitent with estimated responses of natural and anthropogenic influences and inconsistent with other plausible alternatives!

If you create a climate model you first need to validate it with past observations. When it fits quite well, you can then run this model with different scenarios, where different forces (both natural and anthropogenic) are the main drivers. Its then easy to show that only with the CO2 concentration as the dominant driver the model fits the reality! (seperate signals bewteen different forcings)

Anthropogenic climate change can be detected through long-term observations and data analysis showing trends such as rising global temperatures, increased frequency of extreme weather events, melting glaciers and ice caps, and shifting climate patterns. Climate models that simulate natural versus human influences demonstrate that observed changes align closely with human activities like greenhouse gas emissions, deforestation, and industrial processes, rather than natural variability alone. Of course there is a high noise around the different variables, but a clear signal can still be detected.

Attribution of climate change refers to the process of determining the causes of observed climate changes, specifically distinguishing the extent to which human activities (like greenhouse gas emissions, deforestation, and industrial processes) versus natural factors (such as volcanic eruptions and solar variability) contribute to observed changes in the climate. This involves using climate models and observational data to assess the relative impact of these different factors. It is a statistical approach!

Yes, a single event can be attributed to climate change using a scientific method known as "event attribution." This approach involves comparing the likelihood and intensity of an event occurring in a world influenced by human-induced climate change to a world without such influences. Advanced climate models and statistical analysis are used to determine how much more likely or severe the event has become due to anthropogenic factors. This helps quantify the extent to which climate change has influenced specific extreme weather events like heatwaves, floods, or hurricanes.

Climate change can be attributed to changes in the environment through several lines of evidence:

1. Temperature Records: Long-term global temperature data show a clear warming trend that correlates with increased greenhouse gas emissions from human activities.

2. Ice Melt: Observations of shrinking glaciers, ice caps, and reduced Arctic sea ice indicate warming temperatures.

3. Sea Level Rise: Rising sea levels, measured by tide gauges and satellites, are consistent with melting ice and thermal expansion of seawater due to warming.

4. Extreme Weather Events: Increased frequency and intensity of extreme weather events like heatwaves, heavy rainfall, and hurricanes align with climate model predictions of a warming world.

5. Ocean Changes: Warming ocean temperatures, ocean acidification, and altered marine ecosystems reflect increased CO2 absorption and warming.

6. Phenological Shifts: Changes in the timing of natural events, such as earlier blooming of plants and shifting migration patterns of animals, are linked to rising temperatures.

By analyzing these and other indicators through climate models and statistical methods, scientists can attribute specific environmental changes to anthropogenic climate change.

• all important nutrients are taken out of the cycle (phosphor)

• forest destruction

• competition with food production

• long time business as usual

Stores CO2

Fertalizer

Environmental damages due to mining

Water and energy consumption for crushing and mining

Good for the environment

Latent heat flux

Takes time

Monoculture

Forestfires

land use competition

high latitudes => warming

algee production increases, when they die they sink to the bottom

Co2 might be released again with the food chain

possible toxic algee blooms => lower oxygen => fish die

No there is no geoengineering technique that can bring us to the 1,5 °C target alone. We still need to reduce our emissions, otherwise this is not possible. But if we want to reach the target, we definitly need to acitively take CO2 out of the atmosphere!

Even if it is not considered as a true geoengineering technique, I am a big fan of afforestation because it also has many ecologigal benefits. But there are also some risks like droughts, wildfires and it also takes alot of time. Another very nice solution would be the enhanced weathering, as it also acts as a fertalizer when used on agricultural land. Also carbon capture utilisation and storrage would be a nice way to decarbonize heavy industry in the futrue.

It can be critical, because such large-scale modifications of the environment may have unpredictable consequences. For example it might influence the water cycle => this can lead to droughts or heavy precipitation events and former rainfall patterns might become less predictable. This influences agriculture, food- and water-secutity and the lifelyhood of people. The main question is: Are there winners and loosers of such a modification?

19 cm +3mm/year

Flooding and saltwater intrusion

natures resilience is weakend due to human influence (removal of magro (ves for example)

• floating houses and gardens in costal regions

• dams and deichs

• improve built structures

• mangroves and coral reef restoration (also boosts fish poppulation and makes it more attracktive for tourists)

Due to alot of agriculture and urbanisation, species might not find a suitable habitat anymore

Change in precipitation patterns => extreme events become more likely => droughts or heavy rain => soil degradation

Habitat loss => warming temperatures make habitats unsuitable for some species => Polar bear => changes in species distribution diue to migration

Extinction of species that might not be able to adapt to the fast changes

=> all are very very concerning, but especially for humanity more extreme events and soil degradation is a very severe problem as it also affects agriculture, water and food security and peoples livelyhood.

Pests => pestizides

Droughts => irrigation

Vulnerability is dependant on the exposure, the sensitivity and the adaptive capacity. If we compare Bangladesh to the Netherlands, both have almost the same exposure to sea level rise. But, due to a lower GDP and many poor people Bangladesh relies stronger local agriculture. The rich Netherlands could also import food from somewhere else. Therfore Bangladesh has a higher sensitivity then the Netherlands. Finaly due to a lack of financial recoures and a lack of education of the very poor part of society, Bangladesh does not have the necessary adaptive capacity, making this country much more vulnerable to climate change.

Flooding due to rising sealevels and Stormsurges

a) Active large scale flood management with dams and deichs pumps ….

b) Houses on stilts and structures that are able to float when a flood occurs (can be made of bamboo and barrels => cheap)

• Axial tilt (40 k years)

• Eccentricity (100 k years)

• Precession (20 k years)

Global warming is not due to urbanization alone because:

1. Global Temperature Trends: Warming is observed globally, including rural and remote areas, not just urban regions.

2. Atmospheric Composition: The rise in greenhouse gases like CO2, documented worldwide, correlates with industrial activities, not just urbanization.

3. Climate Models: Models show that observed warming matches greenhouse gas increases, not natural factors alone, and includes global impacts beyond urban areas.

4,2 Gt Co2 per year

1,9 Gt Co2 per year