What is Projected? Bruce A. McCarl Distinguished Professor of Agricultural Economics Texas A&M University [email protected]@tamu.edu

What is Projected?

Bruce A. McCarlDistinguished Professor of Agricultural Economics

Texas A&M University [email protected] http://agecon2.tamu.edu/people/faculty/mccarl-bruce/

Energy Climate Change Adaptation

Climate Change Mitigation Climate Change Effects

Degree of climate change - ScenariosLong-term projections require assumptions on human activities or natural effects that could alter the climate over decades and centuries.

Scenarios can be formed in many ways, from simple, idealized structures, to comprehensive scenarios with internally consistent assumptions on emissions and socioeconomic drivers (e.g., population & economic development).

Idealized Concentration Scenarios

As idealized scenario, a 1% yr–1 compound increase of atmospheric CO2 concentration until doubled or quadrupled has been widely used in the past

The Socio-Economic Driven SRES Scenarios

The SRES (Special Report on Emissions Scenarios) scenarios resulted from specific socio-economic scenarios regarding future demographic and economic development, regionalization, energy production and use, technology, agriculture, forestry and land use

The climate change projections discussed in AR4 were based primarily on the SRES A2, A1B and B1 scenarios.

Scenarios were developed for AR5 using concentrations.

Non climate scenarios

Include at least two scenarios "baseline" or "reference" scenario and

"mitigation scenario" Assumptions e.g. economic growth, technology, etc.

Source: CC 2001 mitigation p. 24 at http://www.grida.no/climate/ipcc_tar/wg3/015.htm#24

Figure TS.1: Qualitative directions of SRES scenarios for different indicators

Degree of climate change - RCPs

Representative Concentration Pathway ScenariosRepresentative Concentration Pathway (RCP) scenarios specify concentrations and corresponding emissions, but are not directly based on socio-economic storylines.

Representative Concentration Pathways (RCPs) Scenarios that include time series of emissions and concentrations of the full suite of greenhouse gases and aerosols and chemically active gases, as well as land use/land cover.

The word representative signifies that each RCP provides only one of many possible scenarios that would lead to the specific radiative forcing characteristics.

Degree of climate change - RCPsFour RCPs produced from Integrated Assessment Models were used in AR5

RCP2.6 One pathway where radiative forcing peaks at approximately 3 Watts per square meter Wm–2 before 2100 and then declines

RCP4.5 An intermediate stabilization pathway in which radiative forcing is stabilized at approximately 4.5 Wm–2 after 2100

RCP6.0 An intermediate stabilization pathway in which radiative forcing is stabilized at approximately 6.0 Wm–2 after 2100

RCP8.5 A high pathway for which radiative forcing reaches greater than 8.5 Wm–2 by 2100

From WGI AR5 Box 1.1

Degree of climate change - RCPs

From WGI AR5 Box 1.1

Degree of climate change - RCPs

From WGI AR5 Box 1.1

Figure 1: Global temperature change and uncertainty. From Robustness and uncertainties in the new CMIP5 climate model projectionsReto Knutti & Jan Sedláček, Nature Climate Change 3, 369–373 (2013) doi:10.1038/nclimate1716,

Climate models predict increasing emissions will cause a temp increase

Degree of climate change - What is projected

AR5 WGI 2013 Faq 12.1

Climate models predict increasing emissions will cause a temp increase

Degree of climate change - What is projected

IPCC AR5WG I

Degree of climate change - What is projected

Figure 12.11 | Multi-model ensemble average of surface air temperature. Hatching indicates regions where the multi-model mean change is less than one standard deviation of internal variability. Stippling indicates regions where the mean change is greater than two standard deviations.

Hotter

Degree of climate change - What is projected

Projections are for a drying region

Precipitation varies with northern gains, subtropic drying

Source IPCC 2013, WGI http://www.ipcc.ch/report/ar5/wg1/

Soil Moisture

Runoff

Precipitation

Projections are for altered river flow

What you see is nonstationarity: the future is not like the past Less water in sub tropical regions

Milly P.C.D., Betancourt J., Falkenmark M., Hirsch R.M., Kudzewicz Z.W., Lettenmaier D.P., and Stouffer R.J. Climate Change: Stationarity is Dead: Whither Water Management? Science 2008;319:573-74

Projections are for sea level rise

WGI AR5 2013 Figure 13.11 | Projections of (a) global mean sea level (GMSL) rise relative to 1986–2005. The likely range is shown as a shaded band.

Only the collapse of the marine-based Antarctic ice sheet could cause GMSL to rise substantially above the likely range during the 21st century. medium confidence that addition would not exceed several tenths of a metre

• Very likely that heat waves will be more intense, more frequent and longer lasting

• Precipitation generally increases but with general decreases in the subtropics

• Precipitation intensity is projected to increase but there would be longer periods between rainfall events.

• Tendency for drying of mid-continent during summer, indicating a greater risk of droughts in those regions.

• Sea level projected to rise 1999 and 2099 by 0.18 to 0.59 m.• Likely increase in hurricane peak wind intensities - an

increase in the numbers of the most intense.• Fewer mid-latitude storms- poleward shift of storm tracks• Atlantic Ocean Meridional Overturning Circulation (MOC)

– Gulf Stream will slow down

Degree of climate change - What is projected

So What?

Climate Change can be disruptive

Source : National Assessment

Burning Embers – Reasons for Concern

Source : IPCC

Climate Change can be disruptive

Source : National Assessment

http://environment.newscientist.com/channel/earth/mg19526141.600-huge-sea-level-rises-are-coming--unless-we-act-now.html

http://maps.grida.no/go/graphic/potential_impact_of_sea_level_rise_on_bangladesh

What is Projected - sea level

Example 1 Sea Level and hurricanesAdapt

Structural protectionAbandonment

http://yosemite.epa.gov/oar/globalwarming.nsf/content/ResourceCenterPublicationsSLRMapsIndex.html

http://www.glo.state.tx.us/coastal/erosion/reimbursement/pdf/Surfside_Beach_historic_shorelines.pdf

What is Projected - sea level

Types of Effects - National Assessment1. Increased warming

Assuming continued growth in world greenhouse gas emissions, the primary climate models used in this Assessment project that temperatures in the US will rise 5-9ºF (3-5ºC) on average in the next 100 years. A wider range of outcomes is possible.

2. Differing regional impactsClimate change will vary widely across the US. Temperature increases will vary somewhat from one region to the next. Heavy and extreme precipitation events are likely to become more frequent, yet some regions will get drier. The potential impacts of climate change will also vary widely across the nation.

3. Vulnerable ecosystemsMany ecosystems are highly vulnerable to the projected rate and magnitude of climate change. A few, such as alpine meadows in the Rocky Mountains and some barrier islands, are likely to disappear entirely in some areas. Others, such as forests of the Southeast, are likely to experience major species shifts or break up into a mosaic of grasslands, woodlands, and forests. The goods and services lost through the disappearance or fragmentation of certain ecosystems are likely to be costly or impossible to replace.

4. Widespread water concernsWater is an issue in every region, but the nature of the vulnerabilities varies. Drought is an important concern in every region. Floods and water quality are concerns in many regions. Snowpack changes are especially important in the West, Pacific Northwest, and Alaska.

5. Secure food supplyAt the national level, the agriculture sector is likely to be able to adapt to climate change. Overall, US crop productivity is very likely to increase over the next few decades, but the gains will not be uniform across the nation. Falling prices and competitive pressures are very likely to stress some farmers, while benefiting consumers.

6. Near-term increase in forest growthForest productivity is likely to increase over the next several decades in some areas as trees respond to higher carbon dioxide levels. Over the longer term, changes in larger-scale processes such as fire, insects, droughts, and disease will possibly decrease forest productivity. In addition, climate change is likely to cause long-term shifts in forest species, such as sugar maples moving north out of the US.

7. Increased damage in coastal and permafrost areasClimate change and the resulting rise in sea level are likely to exacerbate threats to buildings, roads, powerlines, and other infrastructure in climatically sensitive places. For example, infrastructure damage is related to permafrost melting in Alaska, and to sea-level rise and storm surge in low-lying coastal areas.

8. Adaptation determines health outcomesA range of negative health impacts is possible from climate change, but adaptation is likely to help protect much of the US population. Maintaining our nation's public health and community infrastructure, from water treatment systems to emergency shelters, will be important for minimizing the impacts of water-borne diseases, heat stress, air pollution, extreme weather events, and diseases transmitted by insects, ticks, and rodents.

9. Other stresses magnified by climate changeClimate change will very likely magnify the cumulative impacts of other stresses, such as air and water pollution and habitat destruction due to human development patterns. For some systems, such as coral reefs, the combined effects of climate change and other stresses are very likely to exceed a critical threshold, bringing large, possibly irreversible impacts.

10. Uncertainties remain and surprises are expectedSignificant uncertainties remain in the science underlying regional climate changes and their impacts. Further research would improve understanding and our ability to project societal and ecosystem impacts, and provide the public with additional useful information about options for adaptation. However, it is likely that some aspects and impacts of climate change will be totally unanticipated as complex systems respond to ongoing climate change in unforeseeable ways

Types of Effects - National Assessment