Biological Impacts of Climate change

Overall trend of temp

warming

Climate change denial

Rife worldwide but especially in the U.S.

Can be attributed to ‘wishful thinking’

“It is a habit of humans to entrust to careless hope what they long for, and to use sovereign reason to thrust aside what they do not desire.” - Thucydides (460-400 BC)

Deniers then use special arguments: ‘climate warming is natural’

2 problems with wishful thinkings

1. We now have data that can disentangle human effects from natural effects on climate warming

2. Current climate warming is occurring at the scale of decades to hundreds of years; natural climate warming occurs at scales of tens – hundreds of thousands of years

Milankovitch cycles

‘natural’ climate change

Detection

given the many influences of humankind on biodiversity over thousands of years and especially in the last 100 years, how is it possible to detect an influence of climate change on wildlife?

Several reviews show that 20th & 21st century climate change has had a wide range of consequences for diverse taxa in disparate geographic regions

However, tackling the question of climate change impacts is enormously challenging

Evolutionary responses

• evolutionary rescue

  • Problem: today’s climate change (warming) is much faster than has ever occurred in the past…

    • …meaning that the number of generations during the change is important in the response: more generations or short generation time is better because there is less climate change per generation

    • Species with short generation times are typically those with short lifespans (these will do better in response to climate change)

evolutionary rescue

Lineages of species have successfully survived climate change periods for millions of years

Rapid evolutionary responses

In shorter-lived species we might expect adaptations to save the day

• Drosophila subobscura, native to Europe, has longer wings in the north and shorter wings in the south

• Essentially, larger wings provide better lift at lower temperatures, giving them an advantage in colder climates

• When introduced into the western US all had the same wing length

• 20 years later the flies had mimicked their European ancestors and evolved latitudinal gradient in wing length from southern California to Oregon

Can species with longer generation times persist as the climate warms?

• Water dragons occur from hot tropics to cold temperate mountains in Australia

• They possess temperature-dependent sex determination

• How can they produce a healthy mix of offspring sexes across such disparate climates?

  • What traits vary geographically across temperature clines/gradients?

  • Possibilities: timing of nesting, pivotal temps, nest site choice behavior

Can species with longer generation times persist as the climate warms? Studying patterns in wide space to understand process in deep time - findings

• Pivotal temperature (incubation temps dividing the sexes) did not vary across latitudes & elevations

• Timing of nesting (phenology) only partially compensated for diff. climates

• Mothers nested in more open areas at cooler latitudes & elevations

• Mothers can offset climate change by adjusting nest temperatures & offspring sex ratios though nest site choice (Doody et al., 2006)

phenology changes

First blooming of flowers, first leafing out of trees, first nesting in birds & other animals

This timing (phenology) is caused by seasonal temperature changes, food, photoperiod, lunar tides, wet season floods, and phenology of other organisms (arrival of migratory prey species)

a shift in the timing of biological events in plants and animals, like flowering, leafing out, or migration, caused by alterations in temperature, precipitation, and other climatic factors brought on by global warming

phenology changes - ex: birds

Breeding season in Mexican Jays advanced by 10 days (on average) between 1971 and 1998

In Tree Swallows it was 9 days (1959-1991)

In both cases the trend was correlated with spring temperatures

phenology changes - ex: Butterfly milkweed

Butterfly milkweed bloomed 18 days earlier, on average, during the 1980’s-1990’s compared to the 1930’s-1940’s

phenology changes - ex: male frogs

Male frogs began calling 10-13 days earlier during 1990-1999 compared to 1900-1912, coinciding with an increase of 1.0-2.3ºC in the months important to reproduction (Gibbs & Breisch, 2001)

phenology changes - ex: amphibian

Amphibian breeding has advanced by 1-3 weeks per decade in England (Beebee, 1995)

phenology changes - ex: butterflies

Crick et al (1997) found that mean laying dates for 20 European bird species advanced by 8.8 days, on average

The red admiral butterfly of Great Britain is appearing more than a month earlier than it did 20 years ago (Roy & Sparks, 2000)

Of 55 butterfly species studied by Bradley et al (1999), 19 (35%) showed advancement of spring events. On average spring events occurred 7.6 days earlier in 1990 compared to 61 years earlier. This coincided with an increase in March temperatures of 2.8ºC

range shifts

the phenomenon where plant and animal species are altering their geographic distribution, moving to new areas, typically towards higher latitudes or elevations, in response to changing climate conditions like rising temperatures, altering precipitation patterns, and shifting seasons

range shift - ex: birds

A study of 59 bird species in Great Britain showed more northward than southward expansions of ranges; the mean shift was 19 km over a 20-year period (Thomas & Lennon, 1999)

range shift - ex: foxes

In Canada, the red fox has expanded northward over the last 70 years while the arctic fox has contracted northward towards the Arctic Ocean

range shift - ex: butterflies

Two-thirds of 59 species of butterflies in both North America and Europe have shifted their ranges northward; some by as much as 100 km per decade

In Edith’s checkerspot butterfly, extinctions were 4X higher along the southern range boundary than the northern range boundary

range shift - lowland birds

Lowland birds have begun breeding on mountain slopes in Costa Rica (Pounds et al., 1999)

range shift - alpine flora

have expanded towards the summits in Switzerland (Grabherr et al., 1994)

range shift - sachem skipper butterfly

The Sachem Skipper Butterfly has expanded from California to Washington State (420 miles) in just 35 years (Crozier 2003a,b)

range shift - ex - Swartruggens Vexator

near Capetown, South Africa; by 2050 it will be restricted to the highest mountain peaks (black & dark grey areas on the map)

Range shift effects on reserves

Current protection of many species relies on reserve systems

Current and future warming may threaten the suitability of these reserves because of a shifting climate envelope

Abundance & community changes

Monterrey Bay, California is located in a small region of overlap between northern species (that range to Alaska) & southern species (that range to Mexico)

Survey plots for kelp forest fish species were established in the 1930’s & resurveyed in the 1990’s

Abundances of nearly all southern species had increased significantly, while the abundances of nearly all northern species had decreased significantly

Sea level rise

Sea level rises can cause contractions of species ranges

The Pine forest barrens in the Florida Keys have been steadily pushed out of the lowest-lying areas due to increased groundwater salinity caused by sea level rise (Ross et al., 1994)

ocean acidification

A 2015 coral bleaching event had dramatic effects on this reef in American Samoa

The 2015 event was the third global bleaching event in recorded history, the others taking place in 2010 and 1998; all three events coincided with periods of abnormally high ocean temperatures

increase in CO2

• Increase in CO2 = acts as a fertilizer for plants; can change C:N ratio in plants which can affect herbivores: leaf chewers (e.g., butterflies, moths) tended to eat more, take longer to develop, be smaller, and more likely to die when fed high CO2 host plants (Bezemer & Jones, 1998)

• The Alaskan tundra is currently a net sink for CO2 – when plants die they become frozen and thus CO2 is in storage (permafrost). However, this tundra is now warming at an unprecedented rate, and soon the net rate of decomposition of dead matter will exceed the rate of plant growth, resulting in the tundra becoming a net source of CO2

First attribution of the connection between atmospheric carbon and climate

1896

Svante Arrhenius made the connection between CO₂ and atmospheric temperature and speculated that burning fossil fuels such as coal could increase the concentration of carbon in the atmosphere in the future and lead to an increase in global temperatures. His research was widely disregarded by other scientists at the time.

First World Climate Conference

(1979): Human-induced climate change is identified as a potential threat.

Montreal Protocol

(1980): World leaders meet to sign an agreement designed to gradually phase out the production and use of chemicals that destroy atmospheric ozone.

Formation of IPCC

(1988): The United Nations Environment Program (UNEP) and the World Meteorological Organization (WMO) create the Intergovernmental Panel on Climate Change (IPCC) to coordinate research and analysis of climate change.

First IPCC Report

1990: The IPCC states global climate is clearly changing, and these changes are probably a result of human activity.

Rio Convention

(1992): The United Nations Conference on the Environment and Development (also known as the Earth Summit or Rio Convention) convenes in Rio de Janeiro, Brazil. A total of 154 nations sign the United Nations Framework Convention on Climate Change (UNFCCC), which asks signatories to reduce greenhouse gas emissions and creates a feedback mechanism for future talks. Developed nations (also known as Annex 1 countries) will be asked to make larger reductions than developing nations.

Second IPCC Report

(1995): The second report states that "the balance of evidence" leads the authors to conclude that there was a "discernible human influence on the global climate system." New evidence suggests that climate change processes are more serious than they were described in 1990, and the first attempt at reducing human impacts seems weak. Many policymakers and scientists believe the UNFCCC needs stronger teeth.

COP1: The Berlin Mandate

(1995): At the first Council of the Parties (COPs) meeting, the Berlin Mandate is signed, which formally recognizes the ineffectiveness of UNFCCC calls for voluntary greenhouse gas reductions. A committee drafts protocols to design other strategies for the 1997 COPs meeting.

COP3: The Kyoto Protocol

(1997): Delegates in Kyoto, Japan, agree that Rio Convention targets are insufficient and emissions should be reduced more quickly. Global emission levels should be 5% less than 1990 levels by 2012, Annex 1 nations are asked to make much more substantial reductions to meet the global figure. The U.S. agrees to a 7% reduction and Canada to 6%; the European Union level is an 8% reduction. Some nations go much farther. Germany promises to reduce emissions by 25% and the United Kingdom by 15%. About 160 nations sign the accord, which must then be ratified or acceded to in each country. The treaty does not become activated until the 1990 emissions levels of ratifying countries total at least 55% of 1990 levels. At this point, a stepwise series of greenhouse gas emissions kicks in. Greenhouse gas reduction mechanisms will be detailed at COP6 in 2000.

COP6: The Hague, Netherlands

(2000): The U.S. under George W. Bush (elected in 2000) and Canada under Jean Chrétien want larger amounts of carbon sink credit for forest growth (thereby allowing for higher net carbon emissions) than other signatories will allow. The meeting fails to negotiate an agreement on mechanisms and breaks up. A second meeting held shortly afterwards again dissolves without an agreement. Since the U.S. is the largest emitter of greenhouse gases worldwide, many observers feel that the Kyoto Protocol will have little impact without U.S. support. The Kyoto Protocol is widely pronounced to be dead.

COP7: Bonn, Germany

(2001): Some 180 countries constituting all of the Kyoto Protocol signatories except the U.S. and Australia (but now including Canada) approve the mechanism framework for implementing the accord. Supporters of the Kyoto Protocol focus on pressuring other large emitters (e.g., Russia and Japan) to ratify the treaty.

Third IPCC Report

(2001): More sophisticated modeling leads IPCC authors to write "globally averaged mean surface temperature is projected to increase by 1.4° to 5.8°C over the period 1990 to 2100." The third report also compiles substantial evidence of biotic effects.

Rio + 10: Johannesburg, South Africa

(2002): The U.N. World Summit on Sustainable Development follows up on issues raised by the Rio de Janeiro summit in 1992 (hence the conference’s alternate name: Rio + 10), with special attention to finding means to create climate-friendly development.

Moscow

Russia’s president Vladimir Putin ratifies the Kyoto Protocol, which immediately activates provisions of the treaty

Fourth IPCC Report

(2007): Work has begun already to prepare the next scheduled IPCC report, due in 2007.

5th IPCC report

2015

Paris Agreement signed by President Obama

2015

2017

President Trump withdraws the United States from the Paris Agreement

2020

President Biden rejoins the U.S. to the Paris Agreement

2025

President Trump withdraws the U.S. from the Paris Agreement (again)