Homework Questions Unit 3 and 4 PDF

During a typical El Nino event (select one for each): 1. Sea surface temperature in the western tropical Pacific becomes COOLER than normal (less warm) 2. Sea surface temperature in the eastern tropical Pacific becomes WARMER than normal (less cold...

During a typical El Nino event (select one for each): 1. Sea surface temperature in the western tropical Pacific becomes COOLER than normal (less warm) 2. Sea surface temperature in the eastern tropical Pacific becomes WARMER than normal (less cold) 3. Easterly trades winds are WEAKER in the months prior to El Nino onset 4. Rainfall DECREASES in the western tropical Pacific Give two examples how ENSO impacts are felt beyond the tropical Pacific. 1. ENSO impacts the atmospheric circulation across the globe, which impacts the global weather patterns. For example in North America El Niño can cause increased rainfall and floods, but in Australia and Southeast Asia it can cause there to be droughts 2. ENSO can also cause conditions such as increased rainfall and temperature that facilitate the increased spread of mosquito borne diseases such as dengue (a lot of this in SE Asia, I’ve experienced this, a few of my friends got dengue due to increased amounts of mosquitoes from ENSO impacts even though they spray for mosquitos like crazy in Singapore) and malaria. How many El Nino events (following the NOAA classification) have occurred in the last 20 years? According to the NOAA classification and my interpretation of the char it seems like 7 in the past 20 years. What ENSO phase (El Nino, La Nina, neutral) is the NOAA Climate Prediction Center calling for this year? This year it looks like we are in a La Niña Year. 1. Give one way in which the PDO can be considered similar to ENSO and one way in which it is different. The PDO is similar to ENSO because it has to do with oscillations in Pacific Sea Surface Temperatures. They are different in their time scales, where the PDO shifts on a 10 to 20 year time scale, while ENSO occurs on a time scale typically of around every 2 to 5 years. 2. What is the main way that PDO influences surface temperatures over North America? The main way PDO influences surface temperatures in North America is by making a ridge over western North America during its positive phase and a trough over Eastern North America, which leads to warmer conditions in the West and cooler conditions in the East. In the negative phase, this is reversed, although the ridge and trough aren’t as pronounced. SST deflect PNA pattern (-1) 3. What are two impacts from a positive NAO? One impact from a positive NAO is that it makes storms take a more northerly path which results in wet and mild winters over Northwestern Europe. Another is that there is a lack of storms further south that results in droughts over the Mediterranean. 4. Give two other examples of natural variability that occurs on long time-scales besides ENSO, PDO, and NAO. Two other examples of natural variability that occur over long time scales are Arctic Oscillation and Southern Annual Mode. if you are looking for Even longer time scales of natural variability, when looking at the time (years) vs. variance increasing graph there are Milankovitch cycles and Tectonic cycles Give two different theories for the layout/orientation of land masses as we know them today. The Contracting Earth Theory suggested that Earth cooled and shrank over time, causing the crust to fold and create the landmasses we see today, similar to how some fruits wrinkle as they dry. Continental Drift, proposed by Alfred Wegener, explained that the continents were once joined in a supercontinent. He argued that the continents fit together like a jigsaw and that fossil records from now-distant continents provided evidence they were once connected, and then gradually drifted apart. We learned about the current mean atmospheric and oceanic circulation patterns earlier (Module 1). Over what time period (e.g., past X thousand/million years) do you think the current picture is valid (i.e., what would be considered "modern world")? I think that the current picture is starting with the beginning of the Cenozoic era because that is when the continents were moving in to positions that most closely resembled where they are today. The specific location of the continents contribute greatly to the formation of the specific ocean and atmospheric circulation patters, such as the mid-ocean gyres. So starting roughly around 65 million years ago (about 2% of earths history) the continents would have been shifting closer to where they are today currently and allow for the formation of these patters. What two critical factors allow for plate tectonics to occur on Earth? The first factor is that we need Oceanic crust and continental crust that is of different densities, and there must be stratification in the minerals to have there be different kinds of crust. The second factor is that there must be a molten layer under the crust so that the crust is capable of moving around. About how fast is North America moving with respect to Europe and in what direction (closer together or farther apart)? North America is moving further apart from Europe and not very fast at all. In the lecture it was put as much much slower than Wegener’s initial hypothesis on continental drift, where North America and Europe are moving away from each other at an estimated rate of 250 cm/year, which was way too fast and an incorrect estimate. We know how fast NA is moving, about 2.5 cm/year Ice ages are estimated to have occurred in two different eras since the Precambrian. What are these eras? The Paleozoic Era and Cenozoic Era. How many inter-glacial periods have there been in the past 500,000 years? There have been five inter-glacial periods. Give two examples of feedbacks in the climate system, one positive and one negative (and indicate as such). Positive feedback: Ice-Albedo Feedback Negative feedback: Changes in Terrestrial Biomass Is present time considered to be a glacial or inter-glacial period? Present time is considered to be an inter-glacial period. 1. What are two limitations to proxy climate data? in order to collect certain data you need to have access to particular resources which can be a limiting factor. One of those would be having trees and another would be having ice (to get tree rings and ice cores) 1. How could fossils of animals be used as a climate proxy record? Fossils of animals can give us clues about what the climate was like in the past based on the species that lived there and their adaptations.  2. Approximately what percent of the Earth's temperature during the Holocene can be determined by direct measurement? Direct evidence is comprised of observations and historical docuumehts. So the percent of earths temperature durring the Holocene that can be determine by direct meansurement will be correlated with the time period in which humans had created and had acess to tools such as gauges, thermometers, and satilights and could marke those measurements and record them in historical documents. I would estimate less than a percent based on how long the Holocene has been and how long we have had acess to the technology to take these measurements. 3. What are two different ways to relate a "proxy measurement" to a specific variable? Calibration in time and Calibration in space 1. Numerical models are limited in the sense that they are run on a finite lat/lon grid, and so some smaller processes are not directly resolved. This leads to parameterization of these processes. What is a typical resolution of an atmospheric forecast model (in square kilometers)? a typical atmospheric forecast model has a resolution of around 50 km for global. A high resolution model would be 25 km. for regional model it is 1 km. (nothing in lecture mentions km^2) 2. Following the first question, name two processes that you think may be important for atmospheric modeling but that are two small to be directly resolved (give the process and spatial scale). Two processes that are too small to be directly resolved in atmospheric models are cloud drops and microphysics, which seem to occur on micrometer scales, and turbulence, which operates on scales from 1 meters to 100 meters. 3. The National Weather Service produces global weather forecasts a few times a day. How far into the future do you think these models are reliable? Looking at the models discussed in the lecture slides, it appears that weather predictions are likely reliable up to one week. The model from Anthes et al. suggests that forecasts can be made with reasonable accuracy over this time period. After one week, the uncertainty around weather events increases, making it difficult to maintain the same level of confidence in predictions beyond this point. How would you respond to the statement "scientists can't even predict the weather tomorrow, how can they possible predict the weather 100 years from now?" (just a sentence or two is needed here) I would respond to that statement by saying: While short-term weather predictions are based on current conditions and can have uncertainties, climate predictions rely on long-term patterns and averages, which tend to be more stable over time. So, while predicting daily weather can be challenging, scientists can still predict long-term climate trends with more confidence because they focus on long term patterns and processes like milankovitch cycles rather than specific events. what are the two methods of providing climate projects at the regional level? Statistical Downscaling is the first method. You take output from climate models and relate the known physics to global dynamics. Dynamical Downscaling is the second method. This is when you run a "nested" model where a larger model provides boundary conditions for a smaller domain. What forcing is required for an ocean general circulation model? For the Ocean General Circulation Models required forcing is at the surface (this is stress at the surface) as wind, fresh water flux, and heat. Give two examples of how coupled models have improved from the first IPCC set of experiments (FAR) and now. The models we use today (CGCM’s and ESM’s) show many more responses to factors such as ocean warming. The old models did not account for how heat in the ocean affected plankton, for example, but these do. They account for ocean ecology and biogeochemistry. They also include land physics, land hydrology, and land use, further increasing the ability of the models to provide more well rounded data since the first set, which didn’t account these factors. A specific new capability in this area is the emerging capability for land use change and dynamic fire modeling. Can you think of one additional component that could be included in future CGCMs? One additional component that could be included in future Coupled General Circulation Models (CGCMs) is the modeling of sea level rise and the subsequent loss of land. By modeling sea level rise, future CGCMs can enhance our understanding of coastal impacts, not only ecosystems but also human settlements and infrastructure, and inform adaptation strategies to mitigate risks associated with climate change. The "greenhouse effect" applies to which specific heat flux term? The green house effect applies to radiative heat flux in the form of Infrared emissions. The green house effect describes the relationship between surface infrared emission and infrared emissions from earth. Greenhouse effect = Surface infrared emission - Earth infrared emission If climate sensitivity due to some process was 0.5, and climate forcing from this process were to double, what would be the anticipated change in global mean temperatures? The anticipated change in global mean temperature would be 1.0 degree celsius because change in temperature = climate sensitivity * change in forcing. Name one atmospheric gas that could act both as positive radiative forcing and negative. An atmospheric gas that could act as both a positive radiative forcing and negative is water vapor. Using the radiative terms discussed in class, why do some people claim that a wide-spread switch to a more vegetarian diet would be good for the climate? Some people claim that a wide-spread switch to a more vegitarian diet would be good for the climate because it would reduce the amount of methane emissions, a greenhouse gas. It is less radiative forcive than CO2, so the idea is that if we can reduce our consumption of meat, which the production of is the major source of methane in the atmosphere, we can then significantly decrease the radiative forcing by methane emissions. This would could be more efficient in the short term then focusing on reducing the CO2 emissions because the world is hyper dependent of fossil fuels that make up most of these emissions, and a immediate shift away from that is a lot more difficult than just reducing meat consumption. In the older terminology of the IPCC, which SRES scenario would be considered the "best case" for reducing climate warming and which would be "worst case?" The best vase would be A1T and the worst case would be A1Fl Which of the RCP's would basically ensure that global mean temperatures will remain below 2.5 C? A1B, B1, 20th Stabilization (according to the Temperature (output) Graph) How are RCP's related to "climate sensitivity?" RCPs describe different future greenhouse gas concentration scenarios and their corresponding radiative forcing levels, which can be used to explore the potential temperature changes (climate sensitivity). Why do you think the IPCC assessment reports are important? I think the IPCC assessment reports are important because they provide relatively clear and objective evaluations of scientific, technical, and socio-economic information on human induced climate change and its impacts. These reports guide informed decision-making and support global efforts to address climate change effectively. 1.Give two definitive statements from the IPCC Summary for Policy Makers regarding climate change The first definitive statement from the IPCC Summary for Policy Makers regarding climate change is SPM-1.1: “ Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen.” A summary/interpretation of this statement is: The climate system's warming is undeniable, with recent decades showing unprecedented warming, ice loss, and sea level rise. The second definitive statement from he IPCC Summary for Policy Makers regarding climate change is SPM-1.3: “In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans. Impacts are due to observed climate change, irrespective of its cause, indicating the sensitivity of natural and human systems to changing climate.” A summary of this statement is: In recent decades, climate changes have affected natural and human systems worldwide, highlighting their sensitivity to a shifting climate. 2.How can climate models be used to demonstrate the likelihood that human impacts are responsible for recent, observed temperature changes? They can be used to demonstrate the likelihood that human impacts are responsible for recent, observed temperature changes by comparing climate models that include only natural factors with those that also account for greenhouse gas emissions from human activities. Only the models incorporating these emissions match the observed warming, indicating that greenhouse gas emissions are the primary driver of recent temperature changes. 3.What is the current, approximate mean pH of the oceans, and what is it expected to be in 2100 given the extreme RCP-8.5 scenario? Currently the approximate mean pH of the oceans is 8.1 and it is expected to be below 7.8 in 2100 given the extreme RPC-8.5 scenario. 4.Again using the extreme RCP-8.5 scenario, given one place anticipated to receive more rainfall in the future and one area that will receive less. Areas that are wetter are seeming to get wetter and places that are dry are seeming to get drier. Australia is considered dry and it will get dryer. The tropics are considered wet, and they are giong to get wetter. 1.Some claim that the "climate has always changed," and that what we see now is nothing unusual. Which of the ten main points in the IPCC AR-6 report address this, and how? The first main point addresses this, as it highlights that climate change is unprecedented. Through models we can see that at no time in the past 2000 years have we seen warming like there is today (1850 to 2020). If we look at the global mean temperature we are in the warmest multi-century period in more than 100,000 years. In order to get the rates and amount of warming that the earth is currently experiences in models, the IPPC has concluded that you need to include anthropogenic forcing in the system. The simulated human and natural trends of warming that are currently being observed are statistically different from the simulated natural only (solar and volcanic) model. The current warming that we are seeing is 1.1 C since preindustrial times is not being caused by natural factors, the climate is warming because of human activity. 2.One of the IPCC summary points shows anticipated regional changes. Pick one region and list three potential impacts. One region is Northern Europe (NEU): 1. There is high confidence in human contribution to the observed increase in hot extreme in this region. A specific projection is that there will be an increase in the mean surface temperature - impact = increase heat extremes  2. There is high confidence in human contribution to the observed increase in heavy precipitation in this region - impact = increased rainfall 3. There is high confidence in human contribution to the observed increase in coastal flooding (this is given by the IPPC website interactive map) 3.Some claim that natural events like volcanic eruptions can contribute to climate change. What is the expected impact of such eruptions with respect to climate? When you look at the expected impact of such eruptions with respect to climate, you simply cannot match the increase in temperature that we are currently observing. Models that only simulate natural events such as volcanic eruptions do not come near the current trends being observed. It is only when you add back in anthropogenic forces can you observe the unprecedented warming and change in climate that we see today. 4.If climate warms by 2-degrees, what is the likelihood of a "50year event" If the climate warms by 2-degrees a “50 year event” will likely occur 13.9 times over the next 50 years.