Understanding Climate Change

Climate Breakdown

• Environmental causes and ecological consequences are to be examined.
• The physical basis of climate change must be understood.
• Climate model predictions have variability.
• Six main biological and ecological consequences exist.

Defining Climate Change

• Climate is the prevailing conditions in a region, defining any changes over time.
• A change in climate is identified by shifts in the mean and/or variability of its properties.
• The change must persist for an extended period, typically decades or longer.
• Climate change can result from natural variability or human activity.
• The Intergovernmental Panel on Climate Change (IPCC) publishes reports on climate change.

Evidence of Climate Change

• Empirical observations are taken such as with weather station time-series.
• Historical reconstructions such as with dendrochronology or with corals..
• Ancient proxies like ice cores, and or lake and marine sediments are examined.

Spatial Warming Patterns

• Global warming is universal.
• Terrestrial and aquatic warming are both occurring.
• The Arctic experiences the strongest warming.
• Warming is worst in winter.

Drivers of Climate Change

• The climate can be altered in three ways.
• Changes happen in incoming solar radiation, such as alterations in Earth's orbit or the Sun itself.
• The fraction of solar radiation that is reflected, called 'albedo' can be changed.
• Changing the fraction of solar radiation can be impacted by variations in cloud cover, atmospheric particles, or vegetation.
• Alternations happen to the long wave (infra-red) radiation from Earth back towards space can occur.
• Long wave radiation changes occur through changes in greenhouse gas concentrations.

Impact of Sulphur and Greenhouse Gasses

• Heavy shipping fuels emit sulphur dioxide.
• Sulphur molecules reflect solar radiation back into space, causing a cooling effect.
• Low-sulphur fuel was introduced in 2020.
• The immediate cessation of the cooling effect from sulphur is accelerating warming.

Solar Radiation

• Long-term patterns in solar radiation have been related to past climate changes.
• No recent association with short-term cyclical changes has been found.

Feedback Loop

• A feedback loop exists where higher global temperatures thicken cloud cover, trapping more heat which causes further warming.
• Less ice cover results in more heat being absorbed by the oceans.

Greenhouse Gasses

• As of Feb 2025 Global CO2 concentrations are at 422ppm.
• Methane (CH4) and Nitrous oxide (N2O) are examples of other GHGs.
• Fossil fuels, cement, and land use change (deforestation) are sources of GHGs.

Historical Understanding

• Jean-Baptiste Fourier (1824) first described the greenhouse effect.
• The greenhouse effect is how the atmosphere traps solar energy to increase earth's surface temperature.
• John Tyndall (1859) identified water vapour and CO2 as greenhouse gasses.
• Svante Arrhenius (1896) suggested that burning fossil fuels produces carbon dioxide and that human activity produces greenhouse gasses.
• ExxonMobil climate research (1982) accurately projected current warming but lobbied against actions.

Representative Concentration Pathways (RCPs)

• RCP 2.6 assumes GHG emissions peak between 2010-2020, with emissions declining substantially thereafter.
• RCP 4.5 peaks around 2040, then declines.
• RCP 6 peaks around 2080, then declines.
• RCP 8.5 emissions continue to rise throughout the 21st century.

IPCC 1.5C Report

• It would take Jeff Bezos just 893 days to accrue $300 billion.
• We could solve climate change in 45 years if we taxed him 50%.

Biological Consequences of Climate Change

• Global sea levels are expected to rise by up to 1m.
• Coastal inundation and flooding will increase.
• Habitat loss is expected
• A shift in resources will occur

Polar Habitat Loss

• Direct habitat loss increases extinction risk.
• Reduced access to food occurs
• Polar bears experience dropping in body condition.
• Lower cub survival rates.
• Polar bears have an increase in drowning.
• Polar bears have an increase in cannibalism.
• Loss of access to denning areas.

Ocean Acidification

• Calcium carbonate shells are impacted by decreasing pH.
• Pteropods, or "sea butterflies", are tiny shelled sea creatures about the size of a pea.
• They are eaten by organisms from tiny krill to whales.
• They are a major food source for North Pacific juvenile salmon.

Ocean Warming

• The oceans have been largely ignored until recently.
• Sea surface temperatures and deep ocean waters reserves of heat are warming.
• Over 93% of all global warming is being observed by the oceans.
• The lag effect removes heat from the atmosphere, slowing atmospheric warming, but it will retain it for millennia and interrupt ocean circulatory systems.

Range Shifts

• A species range is captured by its hypothetical multidimensional ecological niche.
• The fundamental niche of a species is determined by its tolerances of a combination of variables.
• A species distribution will define its fundamental geographic range.
• Species Distribution Models (SDMs) use computer algorithms to generate predictions about the bioclimatic space.
• SDM's can be distributed with geographical projections inferred.

Lagomorpha Case Study

• Order Lagomorpha are a major food source, laboratory animal, game animal, and pest.
• They are agriculture significance.
• They form the base of predator/prey relationships
• They are listed as 25% IUCN Red-Listed.
• The species have restricted diversity.
• These span a huge range of environmental conditions so effects of climate change may be evident.
• Global lagomorph origin data comes from GBIF, literature, and members of the IUCN Species Survival Commission.

Species Distribution Model

• Models indicate the Order Lagomorpha will shift ~1° poleward and ~165m in elevation.
• Climate change will affect more than two-thirds of Lagomorphs.
  • Leporids will undertake poleward shifts.
  • Pikas will show extreme shifts to higher altitudes.
  • Kozlov's pika may become extinct by the 2080s.
• Smaller-bodied species are more likely to exhibit range contractions and elevational increases, but showing little poleward movement.

Disease

• Hawaiian Honeycreepers are a case study in disease.
• There were originally 29 species, now 19 due to habitat loss, disease, and predators.
• Avian malaria has pushed their distributions to altitudes where the mosquito is rare.
• A 2ºC increase will reduce habitat by 50%, 96%, and 100% in their three established refuges.