Lecture 8: Climate Change

Question 1

How is the climate changing?

Answer 1

• Always undergone periods of stability and change.
• Climate has generally been warmer than it is today, but ecosystems adapted for current conditions.
• Life likely to go on even with extreme climate change, just may have extinctions.
• Many previous period’s of rapid climate change are associated with mass extinctions.
  1. Ordovician - rapid cooling & sea level change
  2. Devonian - changes in sea level & ocean hypoxia, possibly triggered by global cooling
  3. Permian - a large meteor impact, massive volcanism, & rapid warming
  4. Triassic - climate change, flood basalt eruptions, and an asteroid impact
  5. Cretaceous - asteroid impact (odd one out)
  6. Now

Question 2

How is the climate changing?

Answer 2

• After period of being relatively cool, we experiencing rapid warming, this happened since the 1780s (start of Industrial Revolution - burning fossil fuels).
• Past warming has been much slower: 4 - 7 ˚C over ~5000 years when moving out of ice ages.
• Now ~ 10 times faster
• Now at ~1.2 ˚C above pre-industrial levels.

Question 3

Causes of climate change: anthropogenic

Answer 3

• The Greenhouse Effect (when light from the sun hits a planet e.g. earth, some goes to warming the surface but a lot is reflected back into space, in the atmosphere (around earth) have greenhouse gases that prevents heat from escaping into space, making temperature more stable over night). But anthropogenic-related increases in greenhouse gases are leading to rapid increases in global temperatures.

Question 4

Causes of climate change: anthropogenic

Answer 4

• Extensive climate modelling has shown humans are driving rapid warming.
• When looking at natural drivers (solar radiation, volcanic activity) wouldn’t expect much change in temp. If add human drivers (changes in green house gases) would increase temp.

Question 5

Causes of climate change: anthropogenic

Answer 5

• Main greenhouse gas driving temp rise is CO2.
• In past couple hundred years CO2 risen hugely.
• Now average ~419ppm April-June 2021.
• Almost entirely from burning fossil fuels. (Some from land use e.g. cutting down / burning forests).

Question 6

Causes of climate change: anthropogenic

Answer 6

• Methane is next largest contributor.
• atmospheric concentration increased by ~ 150% since 1750.
• Sources include: livestock production - belch methane (there’s work to see if we can create foods for livestock that reduces this) , waste management (produced as part of the decaying process), release from sediments e.g. (as areas of Artic warm and the ground defrosts its realising methane) in Artic, previously encased permafrost.

Question 7

Environmental consequences

Answer 7

• Warming is not occurring evenly across globe.
• Most warming is on land rather than at sea.
• Certain areas warming particularly fast.

Question 8

Environmental consequences

Answer 8

• Doesn’t just affect temp, patterns of rainfall also changing rapidly.
• Some areas getting wetter (prone to flooding), some dryer (desertification).

Question 9

Environmental consequences

Answer 9

• Sea ice is melting, especially in Artic.
• Nearly halved in just 100 years.
• Polar bears not able to find enough food so starving.
• Hasn’t reduced so much in the Antarctic, but is mostly land.

Question 10

Environmental consequences

Answer 10

• Sea levels are rising. Low lying areas vulnerable, some islands may disappear completely.
• ## oceans becoming more acidic. (CO2 reacts with the water)

Question 11

Environmental consequences

Answer 11

• An increase in extremes of heat, heavy rainfall & agricultural / ecological drought.

Question 12

Future climate change

Answer 12

• Climate depends on what we do now.
• currently at 1.2 ˚C above preindustrial levels.
• Could reach 4 ˚C by end of century unless large changes are made on a global level.
• Isn’t distributed evenly so will have a huge impact in certain areas.
• Same with precipitation.

Question 13

Responses to climate change

Answer 13

• Environmental change alters the adaptive peak of high fitness.
• Species need to change accordingly or risk extinction.
• To get there can change: a) Spatial distribution (move to diff area) b) Local phenotype (behaviour, physiology) c) Phenology (timing of life events).

Question 14

Responses to climate change: Extinction

Answer 14

• If species unable to change rapidly.
• Future extinctions depend on extent of climate change. a) ‘Business as usual’ approach (don’t change) will lead to 4 - 4.5 ˚C changes. b) assumptions made when making predictions.
• Many predictions come from models of species distributions under predicted future climatic conditions.
• As temp increases more species at risk of extinction.
• If does reach over 4 ˚C then is likely 15% of species extinct.
• Mean extinction risk is 7.9% with a 95% confidence interval.

Question 15

Responses to climate change: Extinction

Answer 15

• Some taxonomic groups & locations more vulnerable than others.
• Amphibians & reptiles particularly vulnerable. (Probs because they terrestrial endotherms - regulate body temp based on environment so more vulnerable to temp changes).
• Many have temp-dependent sex determination.
• Areas with many endemic species that have small ranges are vulnerable (e.g. Africa).

Question 16

Responses to climate change: Extinction

Answer 16

What makes certain popualtions more vulnerable to extinction?

• Biggest risks were ‘occupied area’ so if species only present in small area, if climate in that area changes likely to go extinct.
• Population size is important. Smaller population size more likely to go extinct.
• Spacial correlation - correlation in conditions between different populations. So if all populations live in similar climatic conditions and those conditions change then more likely to go extinct than if they live over a range of different conditions.
• Wasn’t very important was the ‘Current trends in population size, fragmentation and occupied area ‘

Question 17

Responses to climate change: Extinction

Answer 17

What has happened so far?

• Few extinctions; 33 of 872 (3.7%) of extinctions from IUCN Red List cite climate change as a potential cause.
• But climate change has increased the extinction risk of extant species by an average of 14% so far.
• Local extinctions more common.
• The first species to go extinct due to anthropogenic climate change = the Bramble Cay melomys - extinct after rising oceans flooded the island.

Question 18

Responses to climate change: Geographic range shifts

Answer 18

• Many species move away from equator as temp rises.
• e.g. Hickling et al (2006) found 84% of 329 British species showed clear evidence of northward range shifts between 1960 and 2000. (Showing adaptation to climate change).
• But not always habitat for them to move into.
• Marine species also shifting, probs faster than terrestrial species.
• Most mobile (e.g. phytoplankton) moved 470 km per decade.
• have huge impact on food web (as most based of them)

Question 19

Responses to climate change: Altered phenologies

Answer 19

• Changes in timing of life events (e.g. reproduction).
• Records from Japanese cherry blossom (Prunus jamasakura). Have earlier blossom dates.
• By themselves, not necessarily threat to biodiversity.
• but may lead to population asynchronies: timing of reproduction of great tits has not changed with climate, but peak data for caterpillars (their food source) has, leads to reduction in fitness of late-laying birds.

Question 20

Responses to climate change: Biome regime shifts

Answer 20

• Woody plants started growing at higher latitudes (e.g. Artic tundra) & altitudes. Doesn’t make much difference to plants able to move but ones not able to move potentially become extinct.
• E.g. a heather heathland in Spanish mountains replaced by oak forest (as gotten warmer).
• e.g. Kelp forests dominated along Western Australia until 2011, when extreme heat caused the kelp to die off. Replaced by a different community that suppresses kelp. (Not easy to restore).
• Same heatwaves caused repeated mass bleaching of the Great Barrier Reef in recent years.

Question 21

Effects go well beyond biodiversity

Answer 21

• Food source.
• Ecosystem services functioning.

Question 22

Managing effects of climate change: International agreements

Answer 22

Most important:
- The Paris Agreement: a legally binding international treaty on climate change.
- Adopted by 196 Parties at COP 21 in 2015.
- Goal is to limit global warming to well below 2˚C, preferably to 1.5˚C.
- Requires substantial cuts in greenhouse gas emissions.
- The pledges & targets made are not sufficient to reduce global warming to 1.5˚C.

Question 23

Managing effects of climate change: Refugia and safe havens

Answer 23

• During past climatic shifts, many species able to survive in refugia; areas that avoided the worst impacts of climate change.

Where will these be?
- describe species’ modern distributions in terms of the climate. (Where lives currently)
- search for same climatic conditions / niche using forecast future climatic conditions

Question 24

Managing effects of climate change: Optimising migration pathways

Answer 24

• Species need to reach refuges.
• Need to ensure migration corridors exits.
• E.g. Yellowstone to Yukon (Y2Y) project. Covers 2 countries, 5 U.S. states, 2 Canadian provinces. Named by IUCN-World Conservation Union as one of worlds leading conservation initiatives.

Question 25

Managing effects of climate change: Assisted colonisation

Answer 25

Should we help move specie to new suitable habitats?
- E.g. critically endangered western swamp turtle (Pseudemydura umbrina) has been moved 250 km outside its current range in Australia to cooler areas after its swamp started drying up (due to climate change).
Or are we increasing invasive species?
- e.g. introducing disease free Tasmanian devils (Scarophilus harrisii) to an island in 2012 to protect them from facial tumour disease. They have done well but have wiped out some of the islands breeding sea bird colonies.

Assisted colonisation may be useful tool in some cases but careful risk assessment is required.

Question 26

Managing effects of climate change: Building evolutionary resilience

Answer 26

• Some species might be able to evolve to cope with changing climate.
• To maximise chances this can occur, we need to ensure sufficient genetic variation by:
  a) increasing population sizes
  b) locating & protecting areas of high genetic diversity
  c) Translocate genes e.g. translocate individuals from the warmer parts of the species range to cooler parts, or translocate corals that show resistance to bleaching (re establish populations and transmit genes that help resistance)
  d)Assisted evolution captive breeding individuals with greater ability to survive climate change e.g. corals
  f) Identify species with low adaptive potential for other conservation measures

Question 27

Managing effects of climate change: Climate mitigation and green infrastructure

Answer 27

• Biodiversity has role in halting climate change.
• e.g. carbon sequestration via reforestation, afforestation (i.e. planting trees on lands not previously forested), protecting from deforestation & ecosystem restoration.
• e.g. biodiversity can protect us from climate related disasters.
• Chinas ‘sponge city’ project aims to use green infrastructure to absorb water, preventing floods.