EAS 2680 1. How much anthropogenic (human-made) CO2 in is currently being emitted per year (GtC/year)? Use the projection for 2023 published in the latest Global Carbon Budget report to determine that number (Section 3.1.4 or Fig. 4a). [1 point] 2. Convert that number to GtCO2/year. Show your math with units. [1 point] • Answer 3. Using the simple climate model we introduced in class (https://climatemodels.uchicago.edu/slugulator/), determine the global temperature change resulting from a single year-2023 carbon emission pulse after 100 and 10,000 years. Attention: set methane emissions to 0 for the course of this homework. [1 point] • Answer 4. Determine today’s real-world atmospheric CO2 concentration from NOAA’s Manau Loa, HI, measurement station: https://gml.noaa.gov/ccgg/trends/. [1 point] • Answer 5. Knowing today’s CO2 concentration and assuming that the preindustrial atmospheric CO2 concentration was about 280 ppm, how large of a single pulse of carbon emissions (GtC/year) would be required to achieve that increase in CO2 concentration? Use the simple climate model to estimate this. Again, make sure you set methane emissions to 0 before running the model. [1 point] • Answer 6. Is this number equal to, lower, or higher than the cumulative amount of carbon humans have actually emitted since preindustrial times? Explain why. You can use the Summary for Policymakers of the latest IPCC Working Group 1 Assessment Report (IPCC AR6 WG1 SPM) to obtain an estimate of the true cumulative carbon emissions (for example Fig. SPM.10). [1 point] • Answer 7. Putting your answer from (5) into the simple climate model, you can see the expected warming over the next 100 years resulting from our present-day CO2 concentration. The model uses a default climate sensitivity of 3°C per doubling of CO2 concentration. Climate sensitivity is a measure of how much our planet warms in response to a doubling in CO2 concentration (for example, from 280 ppm to 560 ppm). In practice, Earth’s climate sensitivity is not known precisely, though 3°C has been a central estimate for a while. Enter the likely range (highest and lowest value) of climate sensitivity as reported in the latest IPCC report (IPCC AR6 WG1 SPM Section A.4.4) in the simple climate model to estimate the range of warming over the next 100 years. Report the upper and lower bound of that warming. Comment on whether you think we can meet the Paris Climate Agreement target of staying at or below 1.5°C of global warming just given today’s concentration and the uncertainty in climate sensitivity. [1 point] • Answer 8. Given the result of your calculations, especially from (7), the fact that CO2 concentrations are continuing to increase, and your personal perspective on the importance of the climate change issue, what do you think is the most urgent action to be taken to address climate change – if you deem action necessary. [3 pts] • Answer