Cayenne Engel, UNLV Public Lands Institute

Global climate change and implications for ecological restoration

Outline

• Global climate change: how it works (the science behind it)

• How it is projected to affect Earth’s ecosystems and what changes do we observe?

• How should these changes influence decisions about ecological restoration?

Vocabulary• Global change

• Environmental and ecological changes, climate change, extinction, changes in land use, etc.

• Climatic and atmospheric change

• Climate: “average weather” (>30 yrs), most often variables such as temperature, precipitation, and wind.

• Atmosphere: Changes in chemical composition

• Global warming

• Response to the above

• ‘Provide world with clear, balanced view of present state of understanding of climate change’.

• Does not conduct research.

• Reviews and assesses information relevant to the understanding of climate change.

• High scientific and technical standards, and aim to reflect a range of views, expertise and wide geographical coverage

• Shared Nobel Prize in 2007 with Al Gore.

Mr. Rajendra K. Pachauri Chairman, IPCC

IPCC

Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level.

R.K. Pachauri, IPCC ChairBubu Jallow, Working Group 1 Vice ChairNairobi, 6 February 2007

C OO

Infrared heat

C

Molecule absorbs infrared energy

C OO

Then distributes it in any direction

Radiative Forcing

• An externally imposed perturbation in the radiative energy budget of the Earth’s climate system, which may lead to changes in climate parameters

• Responsible parties: Particulates, gasses, etc. in the atmosphere

• Segregate the human impact by estimating natural levels of radiative forcing from increased solar energy and particulates from volcanic events

Gas Name Chemical Formula Percent Volume

Nitrogen N2 78.08%

Oxygen O2 20.95%

Water H2O 0 to 4%

Argon Ar 0.93%

Carbon Dioxide CO2 0.0380%

Neon Ne 0.0018%

Helium He 0.0005%

Methane CH4 0.00017%

Hydrogen H2 0.00005%

Nitrous Oxide N2O 0.00003%

*Ozone O3 0.000004%

GHG are a small proportion of the atmosphere

These gases have a large global warming potential

Level of scientific understanding

Human driven and natural drivers of climate change

Time (before 2005)10000 5000 0

Long-term records indicate CO2 is higher than in the past 600,000 years.

http://www.epa.gov/climatechange/science/pastcc_fig1.html

Radiative forcing

Observed changes are consistent with expected responses to forcings and inconsistent with alternative explanations

Solar & volcanic

All forcing variables

IPCC 2007

Observations of recent climate change

Global average air temperature (IPCC 2007)

• 100-year linear trend of 0.74oC for 1906-2005

• Larger than the predicted trend of 0.6oC for 1901-2000 given in 2001 IPCC report

Ocean temperature

• Average ocean temperature increased to depths of at least 3000 m – ocean has absorbed 80% of heat added

• Direct results: seawater expansion and sea level rise

Period Rate

100 0.0740.018

50 0.1280.026

Global mean temperatures are rising faster

“Paleoclimate information supports the interpretation that the warmth of the last half century is unusual in at least the previous 1300 years. The last time the polar regions were significantly warmer than present for an extended period (about 125,000 years ago), reductions in polar ice volume led to 4 to 6 meters of sea level rise.”

A paleoclimatic perspective

R.K. Pachauri, IPCC ChairBubu Jallow, Working Group 1 Vice ChairNairobi, 6 February 2007

IPCC 2007

Uneven distribution of heat

Warming predictions

• For the next two decades a warming of about 0.2°C per decade is projected for a range of emission scenarios.

• Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1°C per decade would be expected.

• Earlier IPCC projections of 0.15 to 0.3 oC per decade can now be compared with observed values of 0.2 oC

As GHGs are released, surface of planet expected to warm at least 2°C

Environmental impacts of rising temperatures

• Higher low temperatures

• Less frequent cold days, cold nights and frost

• More frequent hot days, hot nights, and heat waves

• Changes in snow cover

• Rising sea levels (due to formerly landbound ice)

• Drier or wetter (geographically dependant)

• More “extreme” weather events

• There is observational evidence for an increase of intense tropical cyclone activity in the North Atlantic since about 1970, correlated with increases of tropical sea surface temperatures

Precipitation increases very likely in high latitudes

Decreases likely in most subtropical land regions

Dec - Feb Jun - Aug

Increased precipitation intensity expected

IPCC, 2007

And drought intensity…

IPCC, 2007

Biological impacts of rising temperatures

• Shifts in species range due to temperature tolerances

• Changes in phenology (biological timing)

• Birds

• Insects

• Leaf-out

• Flowering

• Genetic shifts (adaptation, evolution, selection)

May be most influential

Genetic shifts due to phenology shown

Examples of North Sea fish distributions that have shifted north with climatic warming. Relationships between mean latitude and 5-year running mean winter bottom temperature for (A) cod, (B) anglerfish, and (C) snake blenny are shown. In (D), ranges of shifts in mean latitude are shown within the North Sea.

Climate Change and Distribution Shifts in Marine Fishes: Perry, Allison L.; Science, 2005, vol. 308, p 1912-1915

Predicted shifts in dominant forest types in Eastern US

Cotton, PNAS 2003

Bird Phenology

Root T.L., et al, Fingerprints of global warming on wild animals and plants, Nature, 2003

Changes observed over the last 100 years

Harris et al. 2006, Ecological Restoration

Impacts of climatic shifts – some populations left behind, new niches open up

Impact of normal climatic shifts

“locked” assemblages unable to change in response to

changing climate

Change in niche in response to climate change

Invasion meets climate change

Belote, et al, New Phytologist, 2004

(invasive grass)

(invasive honeysuckle)

An

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al b

iom

ass

gro

wth

Addressing climate change impacts in restoration:

• Consider likely changes in species ranges that may occur due to climate change

• Reintroduced species may not be adapted to new climate

• Build resilience to future change into restoration

• Species with wide ranges?

• Incorporate genetic diversity

Reference conditions and restoration targets

• “Because of climate change, historic conditions are likely to be very different from present and are poor models for restoration.” (Millar and Brubaker)

• Should we manage for continuance of threatened species now, or for what communities we predict would be the “natural progression” with such rapid climate change?

Climate Change and Paleoecology:New Contexts for Restoration EcologyConstance I. Millar and Linda B. Brubaker

Should we forget about reference conditions?

• Restoration should focus on sustaining future options for flexibility and adaptation to changing conditions, rather than attempting to recreate stable conditions that resist change.

• Sustainability might instead embrace landscape macrodynamics

• Ability to shift locations significantly

• Fragment into refugia

• Coalesce with formerly disjunct populations

• Foster non-equilibrium genetic diversities

• Accommodate population extirpations and colonizations

• Sustainability in this context implies encouraging successful adaptation to conditions that cannot be turned back

Millar and Brubaker

Keep using local material?

• Could the use of local material for restoration be limiting?

• “By insisting on the exclusive use of local material, we may be consigning restoration projects to a genetic dead end that does not allow for the rapid adaptation to change…”

“Ecological Restoration and Global Climate Change”: Harris et al., Restoration Ecology, 2006

Restoration in the context of global change

• Rethink our concepts about what and where native habitat is

• What are “healthy” population sizes, what are causes of changes in population size, and when is change acceptable and appropriate.

• “Society may choose not to accept such consequences and manage instead for other desired conditions. In such cases we will benefit by knowing that our management and conservation efforts may run counter to natural process, and thus restoration efforts may require continuing manipulative input to maintain the desired conditions.”

Millar and Brubaker

Positive feedback loops:

• Restoration could actually help mitigate some of the effects of climate change

• “Agricultural and forestry -- afforestation, reforestation, slowing deforestation, improved forest, cropland and rangeland management, including restoration of degraded agricultural lands and rangelands, promoting agroforestry, and improving the quality of the diet of ruminants”

Robert T. WatsonChair Intergovernmental Panel on Climate Change

November 13, 2000

Multiple-use restoration

• In eastern Britain, some areas have been realigned and the seawall breached to recreate areas of salt marsh and intertidal habitat.

• This strategy is expected to assist in the restoration of natural balance in estuaries and to provide flood alleviation benefits.

Restoration considerations

• Ecosystems are complex, and our understanding of their function is already rudimentary and we often have to learn as we go.

• “The past should serve as a guide, not a straightjacket” (Harris et al., Ecol. Rest.)

• What is the proper balance between building past systems and attempting to build resilient systems?

Natural buffers exist

“Species ranges have, and will—even in the absence of human influence—shift naturally and individualistically over small to large distances as species follow, and attempt to equilibrate with, changes in climate. In the course of adjustment, plant demography, dominance and abundance levels change, as do vegetation associates and wildlife habitat relations.”

Climate Change and Paleoecology:New Contexts for Restoration EcologyConstance I. Millar and Linda B. Brubaker

• Elevated [CO2] (+300 ppm)

• Warming (+3 °C)

• Wet and Dry

• Elevated [CO2] (+300 ppm)

• Warming (+3 °C)

• Wet and Dry

OCCAM Experimental design Old-field Community Climatic and Atmospheric Manipulation

Dry Wet

↓ CO2

↓ Temp

↓ CO2

↑ Temp

↑ CO2

↓ Temp

↑ CO2

↑ Temp

↓ CO2

↓ Temp

↓ CO2

↑ Temp

Expectations for plant community responses to warming

Advanced green-up

← Time →

← N

DV

I →

Delayed senescence

← Time →

Extended growing season

← Time →

Ambient temperature

Warmed

Warming extends the growing season in dry plots

2005

Sep Oct Nov Dec

Can

op

y g

reen

nes

s

0.4

0.5

0.6

0.7

0.8

0.9

Amb. Temp WetWarmed WetAmbient Temp DryWarmed Dry

Amb. Temp

Warmed

Dry plots

COMPLICATED

Within a site, driest sites were most sensitive to annual variation

In the year 2100, Nevada could be 8°F warmer in the

summer.

chewbaccaacca : i think the big kicker is that it isn't getting much 'hotter' even though it is called warmingchewbaccaacca : summer maxs aren't getting much higher but winter mins are increasingchewbaccaacca : thus the growing season is getting longerchewbaccaacca : that is the main selective pressure acting on organismschewbaccaacca : so organisms aren't adapting by becoming more 'heat tolerant' or anything like that - they are changing their phenologychewbaccaacca : there is actually NO evidence in either plants or animals that there is an adaptive response to climate change through thermal tolerancechewbaccaacca : but if you think about the phenology stuff - here is somethingchewbaccaacca : if you want to plant something in an area, but it hasn't been there in a whiel, it is likely that it is going to ahve to adapt to the new seasonal environment therechewbaccaacca : something that Bill and I have been throwing around is the idea of pre-adapting things (crops, etc...) by imposing selection for the proper seasonal timing before plantingchewbaccaacca : one of the main problems of planting crops and such in new places is the lack of concordance of the genetically determined seasonal response and the seasons themselveschewbaccaacca : or introducing species for bio control or whatever

Changes in precipitation, increased drought

• Significantly increased precipitation in eastern parts of North and South America, northern Europe and northern and central Asia.

• The frequency of heavy precipitation events increased over most land areas - consistent with warming and increases of atmospheric water vapor

• Drying in the Sahel, the Mediterranean, southern Africa and parts of southern Asia.

• More intense and longer droughts observed since the 1970s, particularly in the tropics and subtropics.

Palmer Drought Severity Index (PDSI) for 1900 to 2002.

The time series accounts for most of the trend in PDSI.

Drought is increasing most places

In summary, global climate models predict:

• Precipitation in the tropics and at midlatitudes and high latitudes will increase

• Precipitation at subtropical latitudes will decrease.

• Increased between-year variability in precipitation

• More intense precipitation, more frequent extreme events, more frequent extreme drought events