diff --git a/book/biogeography.qmd b/book/biogeography.qmd index 0c7696b..a92231e 100644 --- a/book/biogeography.qmd +++ b/book/biogeography.qmd @@ -201,7 +201,7 @@ Each biome is characterised by a typical assembly of *plant functional types* (P 6. C~3~ grasses 7. C~4~ grasses -Global vegetation models use PFTs as their basic unit for distinguishing plants. The exact delineation of PFTs implemented in such models may vary from the list given above. Further distinctions may be made and are relevant in a global vegetation and carbon cycle modelling context. For example, only a relatively small subset of plants are known to associate with symbiotic nitrogen (N)-fixing bacteria that live in root nodules of the host plant ("N-fixing plants", see also #sec-nutrients). This association is highly relevant for the N economy of the plant and its productivity and competitiveness under different levels of N availability. +Global vegetation models use PFTs as their basic unit for distinguishing plants. The exact delineation of PFTs implemented in such models may vary from the list given above. Further distinctions may be made and are relevant in a global vegetation and carbon cycle modelling context. For example, only a relatively small subset of plants are known to associate with symbiotic nitrogen (N)-fixing bacteria that live in root nodules of the host plant ("N-fixing plants", see also @sec-nutrients). This association is highly relevant for the N economy of the plant and its productivity and competitiveness under different levels of N availability. Plants can also be distinguished into the botanical classification of *angiosperms* (flowering plants) and *gymnnosperms* (seed-producing plants that include conifers, cycads, and Ginkgo). The distinction between angiosperms and gymnosperms largely aligns with the distinction between needle-leaved and broadleaved plants (but see Ginkgo). The two groups are not only distinguished by their phylogenetic heritage, but also by essential characteristics that relate to the efficiency by which they photosynthesise and transpire water. Angiosperm leaves typically exhibit higher photosynthesis and transpiration rates and are thinner and shorter-lived than leaves of gymnosperms. These differences relate to differences in how the water transport system (plant hydraulics) is built. A larger number and a wider diameter of water transport organs in angiosperms enable a higher water conductivity - essential for sustaining higher photosynthetic rates than in gymnosperms. @@ -460,3 +460,15 @@ Multiple vegetation reconstructions for the Last Glacial Maximum (LGM) obtained knitr::include_graphics("images/biomes-lgm.png") ``` + +::: {.callout-caution} +## Exercise + +1. Explain the difference between biomes, as defined for example by @olson01biosci, and the IGBP vegetation classes. +2. Give a good reason for why precipitation and temperature are plotted both along the y-axis in the Walter-Lieth climate diagrams. What is the meaning of the blue hashed area and the red dotted area? +3. Compare the seasonality of temperature and precipitation of the example site given for the Mediterranean forest biome (FR-Pue) and the boreal forest biome (FI-Hyy). Which site do you expect to have a stronger seasonal variation in runoff? +4. For the seven biomes for which climate diagrams are shown above, establish a ranking with respect to the growing season length. +5. Consider an ecosystem that is characterised with a fractional plant cover of trees of 10% and a fractional plant cover of grasses of 90%. What biome does it belong to? +6. In a changing climate, where do you expect vegetation composition shifts to unfold faster: in a large plain or in a mountainous landscape? + +::: diff --git a/book/feedbacks.qmd b/book/feedbacks.qmd index 897c5fe..2a6ffcc 100644 --- a/book/feedbacks.qmd +++ b/book/feedbacks.qmd @@ -3,4 +3,5 @@ Coming soon. - \ No newline at end of file + + \ No newline at end of file diff --git a/book/globenvchange.qmd b/book/globenvchange.qmd index f537df1..c524a53 100644 --- a/book/globenvchange.qmd +++ b/book/globenvchange.qmd @@ -3,4 +3,6 @@ Coming soon. - \ No newline at end of file + + + \ No newline at end of file diff --git a/book/images/IPCC_AR6_WGIII_CCBox_8_Figure_2.png b/book/images/IPCC_AR6_WGIII_CCBox_8_Figure_2.png new file mode 100644 index 0000000..c4f5767 Binary files /dev/null and b/book/images/IPCC_AR6_WGIII_CCBox_8_Figure_2.png differ diff --git a/book/images/IPCC_AR6_WGI_TS_Figure_17.png b/book/images/IPCC_AR6_WGI_TS_Figure_17.png new file mode 100644 index 0000000..7217a8a Binary files /dev/null and b/book/images/IPCC_AR6_WGI_TS_Figure_17.png differ diff --git a/book/intro.qmd b/book/intro.qmd index fb7e66c..37f4ebc 100644 --- a/book/intro.qmd +++ b/book/intro.qmd @@ -64,6 +64,13 @@ The sources of multiple land-mediated greenhouse gases will be introduced in @se Land ecosystems are a major sink for anthropogenic CO~2~. Between a quarter and a third of the C emitted by the combustion of fossil fuels and by land use change is taken up again by land ecosystems (@sec-globalcarbonbudget). This uptake flux partly buffers the anthropogenic disturbance of the Earth system. This is called a *negative feedback* (@sec-feedbacks). Without it, the rise in atmospheric CO~2~ would be about 30-50% more rapid. The terrestrial carbon cycle is steered by a multitude of processes, operating at very different scales, and it is characterised by an enormous heterogeneity in space - across ecosystem types, climate and soil conditions. There is not just a single process responsible for this apparent negative global-scale climate-land biosphere feedback and the negative feedback is partly compensated by *positive feedbacks*. +```{r echo=FALSE} +#| label: fig-feedbacks-ipcc-ts +#| fig-cap: "An overview of physical and biogeochemical feedbacks in the climate system. (a) Synthesis of physical, biogeophysical and non-carbon dioxide (CO~2~) biogeochemical feedbacks that are included in the definition of equilibrium climate sensitivity (ECS) assessed in this Technical Summary. These feedbacks have been assessed using multiple lines of evidence including observations, models and theory. The net feedback is the sum of the Planck response, water vapour and lapse rate, surface albedo, cloud, and biogeophysical and non-CO~2~ biogeochemical feedbacks. Bars denote the mean feedback values, and uncertainties representvery likely ranges; (b) Estimated values of individual biogeophysical and non-CO~2~ biogeochemical feedbacks. The atmospheric methane (CH~4~) lifetime and other non-CO~2~ biogeochemical feedbacks have been calculated using global Earth system model simulations from AerChemMIP, while the CH~4~ and nitrous oxide (N~2~O) source responses to climate have been assessed for the year 2100 using a range of modelling approaches using simplified radiative forcing equations. The estimates represent the mean and 5–95% range. The level of confidence in these estimates is lowowing to the large model spread. (c) Carbon-cycle feedbacks as simulated by models participating in the C4MIP of the Coupled Model Intercomparison Project Phase 6 (CMIP6). An independent estimate of the additional positive carbon-cycle climate feedbacks from permafrost thaw, which is not considered in most C4MIP models, is added. The estimates represent the mean and 5–95% range. Note that these feedbacks act through modifying the atmospheric concentration of CO~2~ and thus are not included in the definition of ECS, which assumes a doubling of CO~2~ , 4 but are included in the definition and assessed range of the transient climate response to cumulative CO~2~ emissions (TCRE). {5.4.7, 5.4.8, Box 5.1, Figure 5.29, 6.4.5, Table 6.9, 7.4.2, Table 7.10}. Figure and caption text from the IPCC Assessment Report 6, Technical Summary, Figure TS.17 [@IPCC_2021_WGI_TS]." +#| out-width: 100% +knitr::include_graphics("images/IPCC_AR6_WGI_TS_Figure_17.png") +``` + An example for an important positive feedback arising from land biosphere processes is that of permafrost melting. As the climate warms, previously frozen soil that is very rich in organic matter content melts and the C becomes exposed to decomposers (heterotrophic soil bacteria and fungi). CO~2~ is produced. This climate warming-induced CO~2~ from melting permafrost amplifies the warming, which triggered it in the first place, due to its greenhouse effect - a positive feedback. Melting permafrost soil often becomes water-logged. The anaerobic conditions promote the production of methane (CH~4~) - an even stronger greenhouse gas than CO~2~. The positive feedback gets further amplified. The land biosphere is connected with the Earth system through a multitude of positive and negative feedbacks, leading to complex interactions. While Earth System Models resolve many of these feedbacks and aid our understanding of the systems response to the anthropogenic forcing, translating these concepts into verbal and mental models of how climate change unfolds is challenging. A positive feedback is often described as a "vicious cycle" and sometimes vaguely conflated with a *tipping point*. A solid understanding of terrestrial biosphere processes, clear definitions, and a concise formalism, grounded on known physical relationships, helps to clarify concepts and the contextualization and communication of the risks of climate change. @sec-feedbacks will serve this purpose. @@ -75,7 +82,7 @@ Tipping points in the Earth system are points at which of a part of the Earth sy ```{r echo=FALSE} #| label: fig-tippingpoints #| fig-cap: "The location of climate tipping elements in the cryosphere (blue), biosphere (green), and ocean/atmosphere (orange), and global warming levels at which their tipping points will likely be triggered. Figure and caption text from @mckay22sci." -#| out-width: 80% +#| out-width: 100% knitr::include_graphics("images/tippingpoints.png") ``` @@ -86,10 +93,11 @@ For the climate to be stabilized at 1.5°C or 2.0°C, rapid and large CO~2~ emis Afforestation and reforestation have been estimated to be a potent solution for climate change mitigation [@walker22pnas; @mo23nat] and tree planting has moved to centre stage in the public perception and in policy efforts to avert dangerous climate change. ```{r echo=FALSE} -#| label: fig-cdr_ar_potential -#| fig-cap: "Unrealised potential for C storage in biomass and soil per country. This corresponds to a *technical potential* which does not take into account socio-economic constraints. Categories include: Restore/High suitability for forestry-based NCS (R/H; red), Maintain and manage/High suitability for forestry-based NCS (MM/ H; dark green), Maintain/High suitability for forestry-based NCS (M/H; dark blue), Restore/Low suitability for forestry-based NCS (R/L; orange), Maintain and manage/Low suitability for forestry-based NCS (MM/L; light green), Maintain/Low suitability for forestry-based NCS (M/L; light blue), and Nonwoody (yellow). Figure taken from @walker22pnas. " -#| out-width: 80% -knitr::include_graphics("images/cdr_ar_potential.png") +#| label: fig-cdr_scenario +#| fig-cap: "Roles of CDR in global or national mitigation strategies. Stylised pathway showing multiple functions of CDR in different phases of ambitious mitigation: (1) further reducing net CO2 or GHG emissions levels in near-term; (2) counterbalancing residual emissions to help reach net zero CO2 or GHG emissions in the mid-term; (3) achieving and sustaining net-negative CO2 or GHG emissions in the long-term. Figure and caption text from IPCC Assessment Report 6, Working Group III, Cross-Chapter Box 8 [@IPCC_2022_WGIII]." +#| out-width: 100% +# Figure from https://www.ipcc.ch/report/ar6/wg3/figures/chapter-12/ccbox-8-figure-2 +knitr::include_graphics("images/IPCC_AR6_WGIII_CCBox_8_Figure_2.png") ``` However, ecological principles and multiple aspects of the role of land ecosystems and their interaction with climate and the carbon cycle have to be considered - apart from conflicts with biodiversity and sustainability goals and social, economic, and cultural aspects of land use [@deprez24sci]. For example, the carbon stored in a tree is susceptible to a range of threats, including wildfires, deforestation, and tree mortality by aggravating climatic stress [@anderegg22sci]. Moreover, surface properties, relevant for land-climate interactions, and their differences between forests and grasslands imply that forests may heat the local climate more than a grassland would - despite the additional C stored in a forest [@bala07pnas]. diff --git a/book/references.bib b/book/references.bib index 0b55895..dc26624 100644 --- a/book/references.bib +++ b/book/references.bib @@ -1185,3 +1185,29 @@ @article{walker22pnas file = {Full Text PDF:/Users/benjaminstocker/Zotero/storage/ZM7RWX7A/Walker et al. - 2022 - The global potential for increased storage of carb.pdf:application/pdf}, } +# from https://github.com/openclimatedata/ipcc-bibtex/blob/main/ar6-wg-i.bib +@incollection{IPCC_2021_WGI_TS, + address = {Cambridge, UK and New York, NY, USA}, + author = {Arias, P. A. and Bellouin, N. and Coppola, E. and Jones, R. G. and Krinner, G. and Marotzke, J. and Naik, V. and Palmer, M. D. and Plattner, G-K. and Rogelj, J. and Rojas, M. and Sillmann, J. and Storelvmo, T. and Thorne, P. W. and Trewin, B. and Achuta Rao, K. and Adhikary, B. and Allan, R. P. and Armour, K. and Bala, G. and Barimalala, R. and Berger, S. and Canadell, J. G. and Cassou, C. and Cherchi, A. and Collins, W. and Collins, W. D. and Connors, S. L. and Corti, S. and Cruz, F. and Dentener, F. J. and Dereczynski, C. and Di Luca, A. and Diongue Niang, A. and Doblas-Reyes, F. J. and Dosio, A. and Douville, H. and Engelbrecht, F. and Eyring, V. and Fischer, E. and Forster, P. and Fox-Kemper, B. and Fuglestvedt, J. S. and Fyfe, J. C. and Gillett, N. P. and Goldfarb, L. and Gorodetskaya, I. and Gutierrez, J. M. and Hamdi, R. and Hawkins, E. and Hewitt, H. T. and Hope, P. and Islam, A. S. and Jones, C. and Kaufman, D. S. and Kopp, R. E. and Kosaka, Y. and Kossin, J. and Krakovska, S. and Lee, J-Y. and Li, J. and Mauritsen, T. and Maycock, T. K. and Meinshausen, M. and Min, S-K. and Monteiro, P. M. S. and Ngo-Duc, T. and Otto, F. and Pinto, I. and Pirani, A. and Raghavan, K. and Ranasinghe, R. and Ruane, A. C. and Ruiz, L. and Sallée, J-B. and Samset, B. H. and Sathyendranath, S. and Seneviratne, S. I. and Sörensson, A. A. and Szopa, S. and Takayabu, I. and Treguier, A-M. and van den Hurk, B. and Vautard, R. and von Schuckmann, K. and Zaehle, S. and Zhang, X. and Zickfeld, K.}, + booktitle = {Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change}, + doi = {10.1017/9781009157896.002}, + editor = {Masson-Delmotte, V. and Zhai, P. and Pirani, A. and Connors, S. L. and Péan, C. and Berger, S. and Caud, N. and Chen, Y. and Goldfarb, L. and Gomis, M. I. and Huang, M. and Leitzell, K. and Lonnoy, E. and Matthews, J. B. R. and Maycock, T. K. and Waterfield, T. and Yelekçi, O. and Yu, R. and Zhou, B.}, + publisher = {Cambridge University Press}, + title = {Technical Summary}, + type = {Book Section}, + url = {https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_TS.pdf}, + year = {2021} +} + +# Full report +@book{IPCC_2022_WGIII, + address = {Cambridge, UK and New York, NY, USA}, + author = {IPCC}, + doi = {10.1017/9781009157926}, + editor = {Shukla, P.R. and Skea, J. and Slade, R. and Khourdajie, A. Al and van Diemen, R. and McCollum, D. and Pathak, M. and Some, S. and Vyas, P. and Fradera, R. and Belkacemi, M. and Hasija, A. and Lisboa, G. and Luz, S. and Malley, J.}, + publisher = {Cambridge University Press}, + title = {Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change}, + type = {Book}, + url = {https://www.ipcc.ch/report/ar6/wg3/downloads/report/IPCC_AR6_WGIII_FullReport.pdf}, + year = {2022} +} \ No newline at end of file