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The Environmental Impacts of Climate Change; Feedbacks, Tipping Points, and Lessons from Deep Time.

Dr. Jon Conway

April 11, 2019

Cowell 126

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Questions from last time?

What is climate change?

Definition
Energy imbalance
GHGs are the driver of energy imbalance
What are GHGs/How do they work?
Sources of GHGs
GHG cycling

Sources, sinks, lifespans, relevant fluxes
Introduction to feedback loops

How do we know it’s us?

Rise in atmospheric GHGs

Spatiotemporal distribution

Changing carbon isotope ratios
Atmospheric IR band saturation limits have not been reached yet
Basic chemistry (hydrocarbons + energy = more energy + H₂O + CO₂)

Ocean acidification
Global warming (more at poles, less at equator)

Natural climate forcings are inadequate to explain current warming trend

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Radiative energy balance between the Earth and Sun. All fluxes are given in Watts per m². Source: (IPCC 2013)

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WRITING ASSIGNMENT #1 (the climate one)

Five to six pages, double spaced, due in class on Thursday, April 25^th.

Choose one of the following prompts, or have your own idea approved by the instructor:

How accurate are representations of climate change in the news and popular media, and how have they influenced public perception and policy action around climate change? What role does scientific literacy play?�
Why have climate change tipping points and/or feedback loops largely been left out of discussions on global climate action, and what, if any, impact has this had on the creation of climate change policies?�
The Intergovernmental Panel on Climate Change (IPCC) has been the global standard for climate science for decades. Discuss the strengths and weaknesses of the IPCC model of globalized, politicized scientific research in the context of the IPCC’s role in stimulating global climate change policies.�
Open prompt: Pending instructor approval, students may formulate their own writing topic relating to the intersection of climate science, public perception, and global politics.

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Overview

Current and predicted environmental impacts of climate change

Rapid increases in land, sea, and air temperatures

Geographic distribution of populations will continue shifting
Heat stress increases vulnerability to diseases and pests

Changes in climatic and seasonal patterns

Shifts in weather patterns, including more frequent and extreme weather events

Melting of the ice caps

Sea-based vs. land-based glaciers
Susceptibility to feedback loops

Sea level rise

Driven by melting of land-based glaciers and thermal expansion of water

Changes in ocean properties

pH — Direct result of increased atmospheric CO₂ levels
Temperature
Dissolved gases and nutrients
Current patterns — Case study: Running AMOC?

Feedbacks, tipping points, and lessons from deep time

What are feedback loops and tipping points?
Explore currently understood feedbacks and tipping points and their roles in previous mass extinctions
Discuss the shortcomings of the IPCC reports

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Recent Examples of Climate Change Impacts

California’s droughts, bark beetle infestations, and record-breaking wildfires

Amplification of “boom-bust” precipitation patterns means more droughts, more flooding and mudslides, and less water for human and ecosystem use

Longer hurricane seasons affecting larger regions

Hurricane Ophelia hit Ireland in October 2017, killing three and breaking the record for easternmost Atlantic hurricane
Hurricane Maria

Flooding in the Midwest

Pine Ridge Reservation

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Overview

Current and predicted environmental impacts of climate change

Rapid increases in land, sea, and air temperatures

Geographic distribution of populations will continue shifting
Heat stress increases vulnerability to diseases and pests

Changes in climatic and seasonal patterns

Shifts in weather patterns, including more frequent and extreme weather events

Melting of the ice caps

Sea-based vs. land-based glaciers
Susceptibility to feedback loops

Sea level rise

Driven by melting of land-based glaciers and thermal expansion of water

Changes in ocean properties

pH — Direct result of increased atmospheric CO₂ levels
Temperature
Dissolved gases and nutrients
Current patterns — Case study: Running AMOC?

Feedbacks, tipping points, and lessons from deep time

What are feedback loops and tipping points?
Explore currently understood feedbacks and tipping points and their roles in previous mass extinctions
Discuss the shortcomings of the IPCC reports

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How Do You Predict the Future?

Last time I used the example of gravity acting on a falling pen to demonstrate the inevitability of climate change. How did you know that the pen was going to hit the ground when I released it? And how did you know, approximately, how fast it would fall? You’ve probably dropped a pen before, right? So you’re taking a past occurrence and extending it to a similar situation in the future - you’re creating a conceptual model of how gravity works on Earth and playing out in your mind. If you measured the distance and time the pen fell, you could create a numerical model and use it to precisely predict what would happen the next time the pen was dropped regardless of the distance you held it at - it will take x seconds to fall y feet according to the relationship you measured. With a lot more testing and refinement, you could program that numerical model into a computer, and have create a simulation of that pen under whatever conditions you defined.

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Climate Modeling

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Climate Modeling

“All models are wrong, but some are useful.” - George E.P. Box

How to build a useful model:

Examine underlying assumptions
Verify against real world data
Adjust model when new information is found
Repeat

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Climate Modeling

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Overview

Current and predicted environmental impacts of climate change

Rapid increases in land, sea, and air temperatures

Geographic distribution of populations will continue shifting
Heat stress increases vulnerability to diseases and pests

Changes in climatic and seasonal patterns

Shifts in weather patterns, including more frequent and extreme weather events

Melting of the ice caps

Sea-based vs. land-based glaciers
Susceptibility to feedback loops

Sea level rise

Driven by melting of land-based glaciers and thermal expansion of water

Changes in ocean properties

pH — Direct result of increased atmospheric CO₂ levels
Temperature
Dissolved gases and nutrients
Current patterns — Case study: Running AMOC?

Feedbacks, tipping points, and lessons from deep time

What are feedback loops and tipping points?
Explore currently understood feedbacks and tipping points and their roles in previous mass extinctions
Discuss the shortcomings of the IPCC reports

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Overview

Current and predicted environmental impacts of climate change

Rapid increases in land, sea, and air temperatures

Geographic distribution of populations will continue shifting
Heat stress increases vulnerability to diseases and pests

Changes in climatic and seasonal patterns

Shifts in weather patterns, including more frequent and extreme weather events

Melting of the ice caps

Sea-based vs. land-based glaciers
Susceptibility to feedback loops

Sea level rise

Driven by melting of land-based glaciers and thermal expansion of water

Changes in ocean properties

pH — Direct result of increased atmospheric CO₂ levels
Temperature
Dissolved gases and nutrients
Current patterns — Case study: Running AMOC?

Feedbacks, tipping points, and lessons from deep time

What are feedback loops and tipping points?
Explore currently understood feedbacks and tipping points and their roles in previous mass extinctions
Discuss the shortcomings of the IPCC reports

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(Top left) Total global mean radiative forcing for the four RCP scenarios based on the Model for the Assessment of Greenhouse-gas Induced Climate Change

(MAGICC) energy balance model. Note that the actual forcing simulated by the CMIP5 models differs slightly between models. (Bottom left) Time series of global annual mean

surface air temperature anomalies (relative to 1986–2005) from CMIP5 concentration-driven experiments. Projections are shown for each RCP for the multi-model mean (solid

lines) and ±1.64 standard deviation (5 to 95%) across the distribution of individual models (shading), based on annual means. The 1.64 standard deviation range based on the 20

yr averages 2081–2100, relative to 1986–2005, are interpreted as likely changes for the end of the 21st century. Discontinuities at 2100 are due to different numbers of models

performing the extension runs beyond the 21st century and have no physical meaning. Numbers in the same colours as the lines indicate the number of different models contributing

to the different time periods. Maps: Multi-model ensemble average of annual mean surface air temperature change (compared to 1986–2005 base period) for 2016–2035

and 2081–2100, for RCP2.6, 4.5, 6.0 and 8.5. Hatching indicates regions where the multi-model mean signal is less than one standard deviation of internal variability. Stippling

indicates regions where the multi-model mean signal is greater than two standard deviations of internal variability and where 90% of the models agree on the sign of change. The

number of CMIP5 models used is indicated in the upper right corner of each panel. Further detail regarding the related Figures SPM.7a and SPM.8.a is given in the TS Supplementary

Material. {Box 12.1; Figures 12.4, 12.5, 12.11; Annex I}

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Temperature Changes 2000-2015

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Warm days up, cold days down - important for growing seasons

Global projections of the occurrence of (a) warm days (TX90p), (b) cold days (TX10p) and (c) precipitation amount from very wet days (R95p). Results are shown

from CMIP5 for the RCP2.6, RCP4.5 and RCP8.5 scenarios. Solid lines indicate the ensemble median and shading indicates the interquartile spread between individual projections

(25th and 75th percentiles). The specific definitions of the indices shown are (a) percentage of days annually with daily maximum surface air temperature (Tmax) exceeding the 90th

percentile of Tmax for 1961–1990, (b) percentage of days with Tmax below the 10th percentile and (c) percentage change relative to 1986–2005 of the annual precipitation amount

from daily events above the 95th percentile. (From Sillmann et al., 2013.)

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https://phys.org/news/2013-09-movement-marine-life-climate.html

researchers found a "complex mosaic" of climate velocity and species movement in nine areas central to North American fishing industries (above from left to right): the Aleutian Islands (light blue); the eastern Bering Sea (blue); the Gulf of Alaska (light green); the West Coast (purple); the Gulf Coast (orange); the Northeast (peach); Nova Scotia (pink); the southern Gulf of St. Lawrence (red); and Newfoundland (green). The insets (image A) show shifts in the maximum (blue), average (black) and minimum (red) latitude during the period studied for Pacific cod in the Gulf of Alaska, big skate on the West Coast and American lobster in the Northeast. The close-ups of the Eastern Bering Sea (B), the Gulf Coast (C) and Newfoundland (D) show the nuances of regional animal movements that global-scale models often miss. Credit: Image by Science/AAAS

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Overview

Current and predicted environmental impacts of climate change

Rapid increases in land, sea, and air temperatures

Geographic distribution of populations will continue shifting
Heat stress increases vulnerability to diseases and pests

Changes in climatic and seasonal patterns

Shifts in weather patterns, including more frequent and extreme weather events

Melting of the ice caps

Sea-based vs. land-based glaciers
Susceptibility to feedback loops

Sea level rise

Driven by melting of land-based glaciers and thermal expansion of water

Changes in ocean properties

pH — Direct result of increased atmospheric CO₂ levels
Temperature
Dissolved gases and nutrients
Current patterns — Case study: Running AMOC?

Feedbacks, tipping points, and lessons from deep time

What are feedback loops and tipping points?
Explore currently understood feedbacks and tipping points and their roles in previous mass extinctions
Discuss the shortcomings of the IPCC reports

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Overview

Current and predicted environmental impacts of climate change

Rapid increases in land, sea, and air temperatures

Geographic distribution of populations will continue shifting
Heat stress increases vulnerability to diseases and pests

Changes in climatic and seasonal patterns

Shifts in weather patterns, including more frequent and extreme weather events

Melting of the ice caps

Sea-based vs. land-based glaciers
Susceptibility to feedback loops

Sea level rise

Driven by melting of land-based glaciers and thermal expansion of water

Changes in ocean properties

pH — Direct result of increased atmospheric CO₂ levels
Temperature
Dissolved gases and nutrients
Current patterns — Case study: Running AMOC?

Feedbacks, tipping points, and lessons from deep time

What are feedback loops and tipping points?
Explore currently understood feedbacks and tipping points and their roles in previous mass extinctions
Discuss the shortcomings of the IPCC reports

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Projected changes in tropical cyclone statistics. All values represent expected percent change in the average over period 2081–2100 relative to 2000–2019, under

an A1B-like scenario, based on expert judgement after subjective normalization of the model projections. Four metrics were considered: the percent change in I) the total annual

frequency of tropical storms, II) the annual frequency of Category 4 and 5 storms, III) the mean Lifetime Maximum Intensity (LMI; the maximum intensity achieved during a storm’s

lifetime) and IV) the precipitation rate within 200 km of storm center at the time of LMI. For each metric plotted, the solid blue line is the best guess of the expected percent change,

and the coloured bar provides the 67% (likely) confidence interval for this value (note that this interval ranges across –100% to +200% for the annual frequency of Category 4

and 5 storms in the North Atlantic). Where a metric is not plotted, there are insufficient data (denoted X) available to complete an assessment. A randomly drawn (and coloured)

selection of historical storm tracks are underlaid to identify regions of tropical cyclone activity. See Section 14.6.1 for details. {14.6.1}

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Phenology

Seasonal shifts offset plant/pollinator timings
Mismatch between birthing seasons and food availability

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Overview

Current and predicted environmental impacts of climate change

Rapid increases in land, sea, and air temperatures

Geographic distribution of populations will continue shifting
Heat stress increases vulnerability to diseases and pests

Changes in climatic and seasonal patterns

Shifts in weather patterns, including more frequent and extreme weather events

Melting of the ice caps

Sea-based vs. land-based glaciers
Susceptibility to feedback loops

Sea level rise

Driven by melting of land-based glaciers and thermal expansion of water

Changes in ocean properties

pH — Direct result of increased atmospheric CO₂ levels
Temperature
Dissolved gases and nutrients
Current patterns — Case study: Running AMOC?

Feedbacks, tipping points, and lessons from deep time

What are feedback loops and tipping points?
Explore currently understood feedbacks and tipping points and their roles in previous mass extinctions
Discuss the shortcomings of the IPCC reports

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Overview

Current and predicted environmental impacts of climate change

Rapid increases in land, sea, and air temperatures

Geographic distribution of populations will continue shifting
Heat stress increases vulnerability to diseases and pests

Changes in climatic and seasonal patterns

Shifts in weather patterns, including more frequent and extreme weather events

Melting of the ice caps

Sea-based vs. land-based glaciers
Susceptibility to feedback loops

Sea level rise

Driven by melting of land-based glaciers and thermal expansion of water

Changes in ocean properties

pH — Direct result of increased atmospheric CO₂ levels
Temperature
Dissolved gases and nutrients
Current patterns — Case study: Running AMOC?

Feedbacks, tipping points, and lessons from deep time

What are feedback loops and tipping points?
Explore currently understood feedbacks and tipping points and their roles in previous mass extinctions
Discuss the shortcomings of the IPCC reports

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Northern Hemisphere (NH) sea ice extent in September over the late 20th century and the whole 21st century for the scenarios RCP2.6, RCP4.5, RCP6.0 and RCP8.5

in the CMIP5 models, and corresponding maps of multi-model results in 2081–2100 of NH September sea ice extent. In the time series, the number of CMIP5 models to calculate

the multi-model mean is indicated (subset in brackets). Time series are given as 5-year running means. The projected mean sea ice extent of a subset of models that most closely

reproduce the climatological mean state and 1979–2012 trend of the Arctic sea ice is given (solid lines), with the minimum to maximum range of the subset indicated with shading.

Black (grey shading) is the modelled historical evolution using historical reconstructed forcings. The CMIP5 multi-model mean is indicated with dashed lines. In the maps, the CMIP5

multi-model mean is given in white and the results for the subset in grey. Filled areas mark the averages over the 2081–2100 period, lines mark the sea ice extent averaged over

the 1986–2005 period. The observed sea ice extent is given in pink as a time series and averaged over 1986–2005 as a pink line in the map. Further detail regarding the related

Figures SPM.7b and SPM.8c is given in the TS Supplementary Material. {Figures 12.18, 12.29, 12.31}

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Overview

Current and predicted environmental impacts of climate change

Rapid increases in land, sea, and air temperatures

Geographic distribution of populations will continue shifting
Heat stress increases vulnerability to diseases and pests

Changes in climatic and seasonal patterns

Shifts in weather patterns, including more frequent and extreme weather events

Melting of the ice caps

Sea-based vs. land-based glaciers
Susceptibility to feedback loops

Sea level rise

Driven by melting of land-based glaciers and thermal expansion of water

Changes in ocean properties

pH — Direct result of increased atmospheric CO₂ levels
Temperature
Dissolved gases and nutrients
Current patterns — Case study: Running AMOC?

Feedbacks, tipping points, and lessons from deep time

What are feedback loops and tipping points?
Explore currently understood feedbacks and tipping points and their roles in previous mass extinctions
Discuss the shortcomings of the IPCC reports

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Overview

Current and predicted environmental impacts of climate change

Rapid increases in land, sea, and air temperatures

Geographic distribution of populations will continue shifting
Heat stress increases vulnerability to diseases and pests

Changes in climatic and seasonal patterns

Shifts in weather patterns, including more frequent and extreme weather events

Melting of the ice caps

Sea-based vs. land-based glaciers
Susceptibility to feedback loops

Sea level rise

Driven by melting of land-based glaciers and thermal expansion of water

Changes in ocean properties

pH — Direct result of increased atmospheric CO₂ levels
Temperature
Dissolved gases and nutrients
Current patterns — Case study: Running AMOC?

Feedbacks, tipping points, and lessons from deep time

What are feedback loops and tipping points?
Explore currently understood feedbacks and tipping points and their roles in previous mass extinctions
Discuss the shortcomings of the IPCC reports

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Projections from process-based models of (a) global mean sea level (GMSL) rise relative to 1986–2005 and (b) the rate of GMSL rise and its contributions as a

function of time for the four RCP scenarios and scenario SRES A1B. The lines show the median projections. For GMSL rise and the thermal expansion contribution, the likely range

is shown as a shaded band. The contributions from ice sheets include the contributions from ice-sheet rapid dynamical change, which are also shown separately. The time series

for GMSL rise plotted in (a) are tabulated in Annex II (Table AII.7.7), and the time series of GMSL rise and all of its contributions are available in the Supplementary Material. The

rates in (b) are calculated as linear trends in overlapping 5-year periods. Only the collapse of the marine-based sectors of the Antarctic ice sheet, if initiated, could cause GMSL to

rise substantially above the likely range during the 21st century. This potential additional contribution cannot be precisely quantified but there is medium confidence that it would

not exceed several tenths of a metre of sea level rise.

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Sea Level Rise

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Overview

Current and predicted environmental impacts of climate change

Rapid increases in land, sea, and air temperatures

Geographic distribution of populations will continue shifting
Heat stress increases vulnerability to diseases and pests

Changes in climatic and seasonal patterns

Shifts in weather patterns, including more frequent and extreme weather events

Melting of the ice caps

Sea-based vs. land-based glaciers
Susceptibility to feedback loops

Sea level rise

Driven by melting of land-based glaciers and thermal expansion of water

Changes in ocean properties

pH — Direct result of increased atmospheric CO₂ levels
Temperature
Dissolved gases and nutrients
Current patterns — Case study: Running AMOC?

Feedbacks, tipping points, and lessons from deep time

What are feedback loops and tipping points?
Explore currently understood feedbacks and tipping points and their roles in previous mass extinctions
Discuss the shortcomings of the IPCC reports

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Overview

Current and predicted environmental impacts of climate change

Rapid increases in land, sea, and air temperatures

Geographic distribution of populations will continue shifting
Heat stress increases vulnerability to diseases and pests

Changes in climatic and seasonal patterns

Shifts in weather patterns, including more frequent and extreme weather events

Melting of the ice caps

Sea-based vs. land-based glaciers
Susceptibility to feedback loops

Sea level rise

Driven by melting of land-based glaciers and thermal expansion of water

Changes in ocean properties

pH — Direct result of increased atmospheric CO₂ levels
Temperature
Dissolved gases and nutrients
Current patterns — Case study: Running AMOC?

Feedbacks, tipping points, and lessons from deep time

What are feedback loops and tipping points?
Explore currently understood feedbacks and tipping points and their roles in previous mass extinctions
Discuss the shortcomings of the IPCC reports

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Climate Chemistry 102

Carbon Dioxide

Water

Carbonic Acid

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B) Marine mollusk and

crustacean fisheries (present-day estimated annual catch rates ≥0.005 tonnes km-2) and known locations of cold- and warm-water corals, depicted on a global map showing the

projected distribution of ocean acidification under RCP8.5 (pH change from 1986–2005 to 2081–2100). [WGI AR5 Figure SPM.8] The bottom panel compares sensitivity to

ocean acidification across mollusks, crustaceans, and corals, vulnerable animal phyla with socioeconomic relevance (e.g., for coastal protection and fisheries). The number of

species analyzed across studies is given for each category of elevated CO2. For 2100, RCP scenarios falling within each CO2 partial pressure (pCO2) category are as follows:

RCP4.5 for 500–650 μatm (approximately equivalent to ppm in the atmosphere), RCP6.0 for 651–850 μatm, and RCP8.5 for 851–1370 μatm. By 2150, RCP8.5 falls within the

1371–2900 μatm category. The control category corresponds to 380 μatm. [6.1, 6.3, 30.5, Figures 6-10 and 6-14; WGI AR5 Box SPM.1]

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Phytoplankton Photosynthesis

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Atlantic Meridional Overturning Circulation (AMOC)

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Atlantic Meridional Overturning Circulation (AMOC)

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Overview

Current and predicted environmental impacts of climate change

Rapid increases in land, sea, and air temperatures

Geographic distribution of populations will continue shifting
Heat stress increases vulnerability to diseases and pests

Changes in climatic and seasonal patterns

Shifts in weather patterns, including more frequent and extreme weather events

Melting of the ice caps

Sea-based vs. land-based glaciers
Susceptibility to feedback loops

Sea level rise

Driven by melting of land-based glaciers and thermal expansion of water

Changes in ocean properties

pH — Direct result of increased atmospheric CO₂ levels
Temperature
Dissolved gases and nutrients
Current patterns — Case study: Running AMOC?

Feedbacks, tipping points, and lessons from deep time

What are feedback loops and tipping points?
Explore currently understood feedbacks and tipping points and their roles in previous mass extinctions
Discuss the shortcomings of the IPCC reports

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Overview

Current and predicted environmental impacts of climate change

Rapid increases in land, sea, and air temperatures

Geographic distribution of populations will continue shifting
Heat stress increases vulnerability to diseases and pests

Changes in climatic and seasonal patterns

Shifts in weather patterns, including more frequent and extreme weather events

Melting of the ice caps

Sea-based vs. land-based glaciers
Susceptibility to feedback loops

Sea level rise

Driven by melting of land-based glaciers and thermal expansion of water

Changes in ocean properties

pH — Direct result of increased atmospheric CO₂ levels
Temperature
Dissolved gases and nutrients
Current patterns — Case study: Running AMOC?

Feedbacks, tipping points, and lessons from deep time

What are feedback loops and tipping points?
Explore currently understood feedbacks and tipping points and their roles in previous mass extinctions
Discuss the shortcomings of the IPCC reports

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Carbon Sinks and Feedback Loops

Fossil fuels
The Ocean
Dirt
Methane clathrates
Peat bogs, marshes, wetlands
Rainforests
Permafrost

Fossil fuels
The Ocean
Dirt
Methane clathrates
Peat bogs, marshes, wetlands
Rainforests
Permafrost

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Mass Extinctions

End Ordovician, 444 million years ago, 86% of species lost

Appalachians?
Rapid cooling due to weathering of rocks

Late Devonian, 375 million years ago, 75% of species lost

Algal blooms causing anoxia?

End Permian, 251 million years ago, 96% of species lost

Volcanic activity caused rapid climate change

End Triassic, 200 million years ago, 80% of species lost

???

End Cretaceous, 66 million years ago, 76% of all species lost

Volcanic activity, climate change, asteroid impact

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IPCC Shortcomings

Frequency
Reliance on existing literature
Bias
Politicization

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Questions?