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Climate Impacts Overview

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Introduction

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Topics to Be Covered

Background on Sap 4.3 Basic Concepts and Issues Another look at past and future climate Broad Conclusions Water Resources Agriculture Land Resources Biodiversity Closing Thoughts

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Topics Not Covered Today

Human Health Coastal Zones Cities and the Built Environment Adaptation Options Mitigation Intersection of Mitigation and Adaptation

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Background on SAP 4.3

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Charge Build on recent assessments in the peer-

reviewed literature and other appropriate sources. Not new scenarios or modeling.

Focus on the state of ecosystems, ecosystems services, and observation systems.

Evaluate the importance of climate and other stresses and how they are likely to change in the future.

Timeframe of interest weighted toward next 25-50 years.

Does not consider adaptive responses. Does not provide advice or

recommendations.

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Convening Authors

Peter Backlund, Director, Research Relations, National Center for Atmospheric Research

Anthony Janetos, Director, Joint Global Change Research Institute

David Schimel, Chief Executive Officer, National Ecological Observatory Network

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Chapter Lead Authors

Agriculture: Jerry Hatfield, Supervisory Plant Physiologist, USDA Agricultural Research Service

Land (Forests): Mike Ryan, Research Forest Ecologist, USDA Forest Service;

Land (Arid Lands): Steve Archer, Prof. School of Natural Resources, University of Arizona

Water: Dennis Lettenmaier, Prof. Civil & Environmental Engineering, University of Washington

Biodiversity: Anthony Janetos, Director, Joint Global Change Research Institute

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Contributing Authors R.A. Birdsey, USFS ▪ T.L. Mader, UNL K.J. Boote, U of FL ▪ L. Meyerson, U of RI C.N. Dahm, UNM ▪ J.A. Morgan, USDA ARS P.A. Fay, USDA ARS ▪ G.S. Okin, UCLA G.L. Hahn, UNL ▪ R. Oren, Duke U L. Hansen, WWF ▪ D.R. Ort, U of IL L.S. Heath, USFS ▪ W. Peterson, NOAA J.A. Hicke, U of ID ▪ L. Poff, CSU D.Y. Hollinger, USFS ▪ H.W. Polley, USDA ARS T.E. Huxman, U of AZ ▪ J.T. Randerson, UC Irvine D. Inouye, U of MD ▪ S. Running, U of MT R.C. Izaurralde, PNNL/UMD ▪ W.H. Schlesinger, Duke U B.P. Kelly, NSF/U of AK ▪ R. Shaw, TNC B.A. Kimball, USDA ARS ▪ A.M. Thomson, PNNL/UMD D. Major, Columbia U ▪ D.W. Wolfe, Cornell U

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Audience Land and resource managers, policy-makers, and

others interested in relation of climate change to agriculture, land resources, water resources, and biodiversity:– Organizations and individuals at local, state,

regional, national, and international levels who make ecosystem and resource management decisions and establish natural resource policy

– Research scientists who conduct studies of climate change impacts on systems and resources, and on their potential responses

– State and local governments– Others who depend on and use the products

and services provided by systems and resources

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Basic Concepts and Ideas

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What are climate impacts?

“The changes caused by climate change”

“Changes in physical and ecological systems, human health, and socioeconomic systems caused by climate change”

“The changes in natural resources, species, society, and ecosystems that result from changes in climate”

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Important terms

Sensitivity: the degree to which a system will respond to changes in climatic conditions

Adaptability: the degree to which adjustments are possible in practices, processes, or structures of systems to projected or actual changes in climate

Vulnerability: the extent to which climate change may damage or harm a system (vulnerability depends on both sensitivity and adaptability)

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Different ways of thinking about impacts

Change (sensitivity - adaptation) = vulnerability

Potential impacts - adaptation = realized impacts

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Difficulties in Identifying, Attributing, and Projecting Climate Impacts

Multiple stressesInadequate observationsInadequate modeling

Precise quantification of climate change impacts not yet possible in most cases

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Poll Question # 1:

Do you believe that climate change impacts are a serious problem for the United States?

A. YesB. Not sureC. No

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Another Look at Past and Future Climate

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US Temperature Change, 1901-2006

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US Precipitation Change, 1901-2006

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Climate will continue to change

Even if mitigation is successful

21U.S. Temperature and Precipitation Changes by 2030.

Multi Model Results for 2030

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Multi-Model Results for 2030

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Multi-Model Results for 2030

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Poll Question # 2:

Are adaptation and emissions reductions both needed to address climate change?

A. YesB. Not sureC. No

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Overarching Conclusions of SAP 4.3

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Climate changes – temperature increases, increasing CO2 levels, and altered patterns of precipitation – are already affecting U.S. water resources, agriculture, land resources, and biodiversity.

Climate change will continue to have significant effects on these resources over the next few decades and beyond.

Many other stresses and disturbances are also affecting these resources.

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Climate change impacts on ecosystems will affect the services that ecosystems provide, such as cleaning water and removing carbon from the atmosphere, but we do not yet possess sufficient understanding to project the timing, magnitude, and consequences of many of these effects

Existing monitoring systems, while useful for many purposes, are not optimized for detecting the impacts of climate change on ecosystems.

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Water Resources

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Findings: Water Resources

Most of the United States experienced increases in precipitation and streamflow during the second half of the 20th century. It is likely that these trends are due to a combination of decadal-scale variability and long-term change.

Consistent with streamflow and precipitation observations, most of the continental United States experienced reductions in drought severity and duration over the 20th century. However, there is some indication of increased drought severity and duration in the western and southwestern United States.

Mountain snowpack is declining, and earlier spring snowmelt runoff peaks occurring across much of the western United States. This trend is very likely attributable to long-term warming, although some part may have been played by decadal scale variability..

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Findings: Water Resources Where earlier snowmelt peaks and reduced summer and

fall low flows have already been detected, they are very likely to continue and may have substantial impacts on the performance of reservoir systems.

Trends toward increased water use efficiency are likely to continue in the coming decades. Pressures for reallocation of water will be greatest in areas of highest population growth, such as the Southwest.

Declining per capita (and, for some cases, total) water consumption will help mitigate the impacts of climate change on water resources.

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Findings: Water Resources

A suite of conducted for the IPCC show that the United States may experience increased runoff in eastern regions, climate simulations gradually transitioning to little change in the Missouri and lower Mississippi, to substantial decreases in annual runoff in the interior of the west (Colorado and Great Basin).

Uncertainties in Regional ChangeSub-Saharan Rainfall

Model #2

Model #1

Winter Precipitation

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Agriculture

Background and Context

• Diversity of climate across the US • Diversity of climate change across the

US• Diversity of agriculture across the US

– (food, feed, fiber, fuel, and flowers)• Implications

– Not all responses will be the same nor will all sectors of agriculture be impacted equally

– Agriculture will be impacted by the increasing variability in temperature and precipitation and the trends in temperature, precipitation, and CO2

Key Findings:

With increased CO2 and temperature, the life cycle of grain and oilseed crops will likely progress more rapidly.

As temperature rises, these crops will increasingly begin to experience failure, especially if climate variability increases and precipitation lessens or becomes more variable.

The marketable yield of many horticultural crops – e.g. tomatoes, onions, fruits – is very likely to be more sensitive to climate change than grain and oilseed crops.

Key Findings:

Climate change is likely to lead to a northern migration of weeds. Many weeds respond more positively to increasing CO2 than most cash crops, particularly C3 “invasive” weeds.

Disease pressure on crops and domestic animals will likely increase with earlier springs and warmer winters, which will allow proliferation and higher survival rates of pathogens and parasites.

Key Findings

Higher temperatures will very likely reduce livestock production during the summer season. For ruminants, current management systems generally do not provide shelter to buffer the adverse effects of changing climate; such protection is more frequently available for non-ruminants (e.g., swine and poultry).

Key Findings

Carbon dioxide– Increases in CO2 increase plant

growth and decrease the water use by plants

– Increases in CO2 will decrease forage quality

– Weeds are showing a positive response to increases in CO2 which reduces the efficacy of weed management practices

Key Findings

• Temperature– Warmer temperature will cause

plants to grow more quickly– High temperature events during

pollination decreases pollen survival– Warmer nighttime temperatures

increases the respiration rate and reduces grain size

– Warmer temperatures increase the likelihood of overwinter survival of insects and diseases

U.S. Temperature and Precipitation Changes by 2030.

Multi Model Results for 2030

Multi-Model Results for 2030

Key Findings

• Precipitation– Increased variability in precipitation

will impact plant growth– Impacts from both deficit and

excessive precipitation– Increased intensity of precipitation

events may increase erosion and efficacy of conservation practices

– Increased variability in precipitation will affect irrigation water supplies

Availability of irrigation water

Scholze et al. (2006) Blue tendency to increase

Red tendency to decrease

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Projection of Future U.S. Runoff

A suite of conducted for the IPCC show that the United States may experience increased runoff in eastern regions, climate simulations gradually transitioning to little change in the Missouri and lower Mississippi, to substantial decreases in annual runoff in the interior of the west (Colorado and Great Basin).

Additional Factors

Increases in temperature will increase the growing season and extend forage production into early spring and late fall, reducing the need for winter season reserves, variability in precipitation will affect forage availability

Climate changes are affecting the species composition of rangelands and will impact rangeland productivity

Conclusions Climate impacts on agriculture are not a

simple relationship to one variable but the interaction among temperature, precipitation, and CO2 changes

In the U.S., overall yields are likely to decrease slightly over next 30-50 years, but there will be much variation across crops ands regions

Agriculture is a sector where adaptation is very important

Observational networks and integration with models are critical to quantifying the response of agricultural systems to climate

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Land Resources: Forests and Arid Lands

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Focus

Changing climate (temperature and precipitation means and extremes, CO2, N, O3) and ecosystem productivity, composition and services.

Effects of changing climate and disturbance: fire, insect outbreaks, storms –and the ecological impact.

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Forests

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Forests: Background

Disturbance resets forests. Processes vary with forest age.

Climate defines an envelope for tree species.

Kashian et al. (BioScience 2006)

Chuine and Beaubien (Ecol. Letters. 2001)

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Findings - Forests Climate change has very likely increased the size and

number of forest fires, insect outbreaks, and tree mortality in the interior west, the Southwest, and Alaska, and will continue to do so.

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Findings - Forests

Rising CO2 will very likely increase photosynthesis for forests, but the increased photosynthesis will likely only increase wood production in young forests on fertile soils.

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Findings - Forests

Nitrogen deposition and warmer temperatures have very likely increased forest growth where water is not limiting and will continue to do so in the near future.

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Arid Lands

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KEY POINTS

Projected climate changes will:

- Increase sensitivity to grazing, fire, off road vehicle use - limit the ability to recover from disturbances

- promote desertification

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KEY POINTSHigher temperatures, increased drought and more intense thunderstorms will:

- promote invasion of exotic grasses - create physical conditions conducive to wildfire- increase risk loosing iconic, charismatic mega flora (e.g., Saguaro cacti, Joshua trees)

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Springs, river and riparian ecosystems: stream flow, water removal, competition from exotics (Russian olive, salt cedar)

Springs and streams will likely contract; more susceptible to stress

KEY POINTS

Likely do not offer a large capacity to serve as C sink; will likely lose C as climate-induced disturbances increase

vegetation cover & erosion will reduce N availability and hence NPP

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KEY POINTS

Loss of vegetation cover accelerated wind and water erosion increase sediment loads in streams & frequency of dust storms.

Dust deposition on alpine snow pack: accelerate spring snowmelt earlier seasonal drought conditions in lower stream reaches.

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Biodiversity

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Findings: BiodiversityCorals in many tropical regions are experiencing substantial mortality from increasing water temperatures, increasing storm intensity, and a reduction in pH, on top of a host of other ongoing challenges from development and tourism, fishing, and pollution.

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Findings: Biodiversity The rapid rates of warming in the Arctic observed in recent

decades, and projected for at least the next century, are dramatically reducing the snow and ice covers that provide denning and foraging habitat for polar bears.

2006

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Findings: Biodiversity

There has been a significant lengthening of the growing season and increase in net primary productivity (NPP) in the higher latitudes of North America. Over the last 19 years, global satellite data indicate an earlier onset of spring across the temperate latitudes by 10 to 14 days.

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Findings: Biodiversity

There are other possible, and even probable, impacts and changes in biodiversity (e.g. disruption of the relationships between pollinators, such as bees, and flowering plants), for which we do not yet have a substantial observations.

Marine Ecosystem Response to Ocean AcidificationHigh Uncertainty – High Risk

Widespread elimination of organisms Major extinction event (e.g. Permian)

Widespread response of organisms Major ecosystem disruption

Selected Species Response Significant ecosystem response

Selected Species Response Low ecosystem effects

No effect Selective extinction of some scientists!Good

Worst

Bad

IMBER Science Plan 2005

Effects of Increasing Acidity

Physiology:Respiration rateBlood chemistryGrowth rate

Reproduction Eggs or Larvae

Food Supply

Fine & Tchernov, Science 315, 1811 (2007)

Dissolution of coral skeletons under low pH conditions

Normal pH:• Coral skeleton is normal

Low pH:• Coral skeleton has dissolved

away• Coral polyps are “anemone-like”

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Poll Question # 3:

Which set of climate impacts seems worst?

A. Water resource impactsB. Agricultural impactsC. Land resource impactsD. Biodiversity impacts

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Closing Thoughts

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Climate impacts are and will be widespread, but many of the most severe impacts of climate change in the U.S. are occurring – and will continue to occur – in Western regions

Climate impacts are one of many different stresses on ecosystems; the relationships and feedbacks among stresses is not yet well understood

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There are numerous adaptation options for intensively managed systems – water, cities, agriculture – but many issues around costs, policies, trade-offs, etc.

There are not so many options for lightly managed systems, such as wildland areas

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Precipitation change matters as much, if not more, than temperature change

Competition for water (between agriculture, industry, cities) will be a major factor in adapting to climate change

Many traditional management and planning activities that have relied on history as a proxy for the future will need to change

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The big picture is increasingly clear, but…

There is still considerable uncertainty regarding fine scale changes in many regions of the US and other nations – we can gain insight through improved observations, experimentation, and modeling

Successful adaptation will depend on improved partnerships among scientists and local, regional, state, and federal decision-makers

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Existing monitoring systems, while useful for many purposes, are not optimized for detecting the impacts of climate change on ecosystems.

*Current observations cannot separate the effects of climate change from consequences of other stresses unambiguously.

*Current systems monitor either drivers of change (climate) or ecological responses but not the two together to allow unambiguous attribution.

*There is no integrated analysis and forecast of climate change impacts using existing and planned future investments in observing systems.

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Poll Question #4:

Do you believe that climate change impacts are a serious problem for the United States?

A. YesB. Not sureC. No

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Sources

The Effects of Climate Change on Agriculture, Land Resources, Water Resources, and Biodiversity in the United States (CCSP Synthesis and Assessment Product 4.3)

IPCC Fourth Assessment Report, Working Group II Report "Impacts, Adaptation and Vulnerability“

Other CCSP SAP reports, including Analyses of the effects of global change on human health and welfare and human systems (CCSP Synthesis and Assessment Product 4.6)